Mosquito & Vector News

Methods for Nucleic Acid Extraction from Ticks: Challenges and Potential for Advancement

D. Damian. 2025. Vector-Borne and Zoonotic Diseases [ahead of print]
https://doi.org/10.1089/vbz.2024.0125

Abstract Background: DNA extraction from ticks is essential for research on tick-borne diseases, yet the methodologies currently employed exhibit significant variability in terms of yield and purity. This systematic review aims to consolidate existing literature on DNA extraction from ticks, evaluate the various methodologies, challenges, and research gaps. Methodology: A systematic review of existing literature was conducted to assess the efficacy, yield, and purity of DNA extracted from various tick species using the aforementioned methods. Comparative analyses focused on factors such as extraction efficiency, contamination issues, and the impact of tick exoskeleton resilience. Results: Phenol-chloroform extraction achieved high DNA yields (50–100 ng/µL) but posed safety risks and was time-consuming. Silica-based methods provided yields of 40–80 ng/µL, effective for many species but less so for those with high microbial loads. Magnetic bead-based extraction offered rapid results with yields ranging from 20 to 70 ng/µL, although it faced challenges such as bead carryover and equipment requirements. Variability in extraction efficiency was noted across different tick species, necessitating method optimization.

Conclusion: The review identified several critical research gaps in DNA extraction methods for tick-borne disease diagnostics and research. Currently, methods such as mechanical disruption combined with chemical lysis and column-based methods have shown effectiveness in extracting DNA from ticks, but they come with limitations, including high cost, labor intensity, and reduced efficiency under certain conditions. Despite their utility, these methods often face challenges in resource-limited settings or in varying environmental conditions. To address these issues, there is a need for standardized protocols, cost-effective extraction techniques, and longitudinal studies to evaluate performance under diverse conditions. By addressing these gaps, we can improve diagnostic accuracy, enhance our understanding of tick-borne diseases, and advance both research and public health efforts.

Note: These comparisons may prove useful in understanding some of the differences among laboratories.

Request for Participation in Oropouche Virus Vector Surveillance

With the recent emergence of Oropouche virus (OROV) as a potential public health concern in the United States, the American Mosquito Control Association (AMCA) is collaborating with the CDC to collect surveillance data on its primary vector, Culicoides paraensis.

As part of this effort, we are seeking mosquito control districts willing to assist by deploying modified CDC light traps on a weekly basis. This will help us assess the distribution of potential OROV vectors across the country.

We have limited funding available through our grant to support the purchase of traps and other necessary supplies, if needed.

Attached you’ll find:

• A detailed protocol for the collection, storage, and shipment of biting midge samples
• Instructions for modifying standard CDC light traps for Culicoides collection
• A sample data sheet

If your district is able to participate, or if you know of another district or agency that might be interested, please contact Dan Markowski, AMCA Technical Advisor at 662-822-1270 or email at AMCA.TA@mosquito.org.

Culicoides Surveillance Protocol

Trapping Datasheet Template

Mosquito Trap PDF

Withdrawal of the United States from the WHO — How President Trump Is Weakening Public Health

G. Yamey and B. K. Titanji. 2025. New England J. Medicine. Perspective. DOI: 10.1056/NEJMp2501790

On July 6, 2020, during his first presidency, Donald Trump notified the United Nations secretary-general that the United States would withdraw from the World Health Organization (WHO). The withdrawal never happened because the process takes a year, as outlined in a 1948 joint resolution of Congress,1 and President Joe Biden reversed the decision on his first day in office. But Trump has done it again: on the day of his second inauguration, January 20, 2025, he issued an executive order saying the United States will withdraw from the WHO and pause the future transfer of U.S. funding to the organization. The order also recalls U.S. personnel working with the WHO in any capacity. [read more].

Note: Pathogens and vectors don’t respect political boundaries and these actions may have dire consequences for surveillance and control of communicable diseases, especially considering DOGE cuts to the US CDC and USAID.

Woods TA, Johnson SF, Evans AB, Peterson KE. Neutralizing Antibodies against California Serogroup Orthobunyaviruses in Human Serum Samples, Montana, USA

Emerg Infect Dis. 2025;31(4):699-709.
https://doi.org/10.3201/eid3104.241520

Abstract
Viral encephalitis is often underreported and undiagnosed. To understand the potential causes of viral encephalitis in the state of Montana, USA, we examined the relative incidence of human infections for the California serogroup (CSG) of Orthobunyaviruses by screening random convenience serum samples obtained from different hospitals across Montana. We initially screened deidentified samples for neutralizing antibodies against Jamestown Canyon virus (JCV), a CSG virus that has caused encephalitis in Montana. We then analyzed JCV-positive samples for neutralization of other CSG viruses, and detected neutralizing antibodies against La Crosse virus, California encephalitis virus, and Trivittatus virus. We also found a high level of cross-reactivity, particularly between JCV and California encephalitis virus. Our findings indicate that the relative CSG virus infection rates in humans are quite high, between 21% and 40%. Clinicians should consider CSG viruses in differential diagnosis for cases of encephalitis of unknown etiology in Montana.

Note: CSG viruses are endemic to California, frequently isolated from endemic Aedes and Culiseta mosquitoes, and similar to this study sera from high risk groups have shown a high level of previous infection but little overt disease.

MYIASIS – MEXICO: NEW WORLD SCREWWORM (COCHLIOMYIA HOMINIVORAX, HUMAN

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Date: Tue 11 Mar 2025
Source: Diario de Yucatan [in Spanish, machine trans., abridged, edited]
https://www.yucatan.com.mx/mexico/2025/03/11/mas-casos-humanos-del-gusano-barrenador-devorador-de-hombres-en-mexico.html

More human cases of the man-eating screwworm in Mexico

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Mexico’s Ministry of Health (SSA) has reported new human cases of myiasis as the country faces outbreaks of the man-eating screwworm, or larvae of the fly _Cochliomyia hominivorax_, in livestock and even in pets in southeastern Mexico. The new cases of myiasis are 2 women from Chiapas; both were diagnosed in week 8 (16-22 Feb) of 2025, according to the Epidemiological Bulletin of week 9 (23 Feb-1 Mar) published yesterday, Monday, 10 Mar [2025] [https://www.gob.mx/cms/uploads/attachment/file/982667/sem09.pdf]. Both patients were detected just one month after Mexico reported its first human case of the man-eating screwworm, a woman from Campeche diagnosed in week 4 (19-25 Jan [2025]).

Note [from Kim Hung]: While NWS [New World Screwworm] is primarily a pest of animals, more importantly, cattle and deer, they can cause myaisis in humans. Their native range includes California when you look at the maps of where they were long ago. A couple of colleagues noted that if this trend continues, they can potentially reach the US this year, perhaps starting with Texas. Extra note – We have a related species in California that is not as pestiferous (in terms of myiasis, they eat dead tissue) – Cochliomyia macellaria. The adults look very similar with the distinguishing three stripes on the thorax, but there are some minor differences if we look carefully. There are keys available to distinguish between the two species if we need to confirm the ID at some point. Additionally, our colleagues in the USDA would be happy to help confirm ID if such a need arises. In other words, got a fly question? Bring ’em to me. =)

Note [WK Reisen]: The NWS was contained for years just north of the Darien Gap by the USDA and partners using SIT methods. The flies appear to have breached this containment and re-established themselves in Mexico. How will budget cuts to the USDA further facilitate this northern invasion?

Mark-Release-Recapture of Packed and Shipped Aedes aegypti with Wolbachia: Implications for Conducting Remote Incompatible Insect Technique Programs

DENGUE/DHF UPDATE (33): AMERICAS, CDC

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Date: Tue 18 Mar 2025 10:00 a.m. ET
Source: CDC Emergency Preparedness and Response [edited] 
View here

Summary
———
The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) health update to provide additional information to healthcare providers, public health departments, and the public about the ongoing risk of dengue virus (DENV) infections and updates to testing recommendations in the United States. Dengue activity remains high in some parts of the United States and globally, with many countries reporting higher-than-usual number of dengue cases in 2024 and 2025. Healthcare providers, public health departments, and the public are urged to continue to take steps to prevent, detect, diagnose, and respond to dengue as described in the June 2024 HAN Health Advisory (CDCHAN-00511) on dengue in the United States. Updates include the following:

1. Dengue virus transmission remains high in the Americas region, including in the US territories of Puerto Rico and the US Virgin Islands. Spring and summer travel coincide with the peak season for dengue in many countries, increasing the risk of both travel-associated and locally acquired cases in the United States.

2 Use the CDC DENV-1-4 real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay when dengue is the most likely diagnosis.

3. New resources are available for public health professionals including a job aid for reviewing medical records and guidance for investigating and responding to dengue cases in non-endemic areas of the United States.

Note: This Health Alert targets the awareness of the increased risk for dengue infection in travelers returning from the tropics.

Lack of Competence of US Mosquito Species for Circulating Oropouche Virus

Payne AF, et al. 2025. Emerg Inf Dis. Vol. 31, No. 3, March 2025
DOI: https://doi.org/10.3201/eid3103.241886

Abstract. Given recent outbreaks of Oropouche virus in Latin America and >100 confirmed travel-associated cases in the United States, we evaluated the vector competence of US mosquitoes, including Aedes albopictus, Culex quinquefasciatus, Culex pipiens, and Anopheles quadrimaculatus. Results with historic and recent isolates indicates transmission potential by these species is low [only 1/50 Cx. pipiens transmitted virus].

Note: Similar to the literature, a low percentage of females became infected, but practically all were not able to transmit. This and similar reports indicate the risk of secondary transmission by mosquitoes from imported cases is very low.

Assessing pyrethroid resistance mechanisms in individual Culex tarsalis (Diptera: Culicidae)

B.M. Mortola et al. 2025. J. Med. Entomol., tjaf001, https://doi.org/10.1093/jme/tjaf001

Abstract
The evolution of pyrethroid insecticide resistance in Culex tarsalis Coquillett is a growing concern in Northern California. Common mechanisms of resistance include the target-site mutation, kdr, and increased levels of detoxification enzymes, such as mixed-function oxidases, GSTs, and esterases. The goal of this study was to compare the prevalence of kdr mutations (L1014F and L1014S) and detoxification enzymes between pyrethroid susceptible and resistant Cx. tarsalis individuals. Individual mosquitoes, categorized by resistance status from permethrin bottle bioassays, were prepared for both molecular and enzymatic testing by separating the legs of a mosquito from the remaining body. Legs were used to test for the presence of kdr mutations, while the bodies were used to test for the activity of detoxification enzymes. The number of phenylalanine (F) alleles present at the kdr target-site as well as levels of GST were increased in mosquitoes that survived the bottle bioassay compared to those that were knocked down. Individuals with 2 F alleles and an active GST level greater than or equal to 0.052 µg/ml showed a higher survival rate than either mechanism independently demonstrating resistance to pyrethroids in Cx. tarsalis is likely the result of multiple resistance mechanisms acting collectively. Further work is needed to determine the interplay of multiple resistance mechanisms to achieve phenotype resistance in this mosquito species.

Note: Relating bottle assay results to specific resistance mechanisms is an important step in teasing apart the evolution of resistance.

Gene drive: communication, hype, and the publics C.

Sugar feeding by Aedes albopictus in the Torres Strait, Australia

Sebayang, BF, et al. 2025. PLoS Neglected Tropical Diseases https://doi.org/10.1371/journal.pntd.0012856

Abstract Background
The establishment of Aedes albopictus in the Torres Strait Islands in 2005 is a threat to dengue control in the islands and on mainland Australia. Attractive targeted sugar baits (ATSBs) have been proposed as a control strategy for outdoor mosquitoes like Ae. albopictus. The sugar feeding behaviours of Ae. albopictus was studied to ascertain the potential of ATSBs to mitigate the risk of Ae. albopictus invading mainland Australia from the Torres Strait Islands.

Methodology/Principal Findings
Aedes albopictus was sampled by sweep net collections in village and bushland habitats across two islands both in the mornings and afternoons. Samples were analysed to determine adult abundance as well as fructose prevalence and content by cold-anthrone test. Sampling stations were characterised by vegetation surveys and included the prevalence of flowers and fruit, and canopy cover. Among the 6,186 captured Ae. albopictus, the prevalence of fructose was 31.6% ± 1.4 in males and 30.5% ± 1.2 in females, with fructose averaging 62.9 µg (± 1.4) in fructose-positive Ae. albopictus.

Conclusions
Mosquito sex and collection time were associated with the abundance of Ae. albopictus as well as fructose prevalence and content in Ae. albopictus. Male and female Ae. albopictus exhibited sugar abundance and prevalence comparable to studies where ATSBs were effective suggesting that ATSBs could potentially reduce Ae. albopictus populations in the Torres Strait Islands.

Note: This study concluded that Ae. albopictus fed frequently on plant sugar and that ‘attractive targeted sugar baits’ may be useful for population suppression. Similar studies on Cx. tarsalis produced similar results, but developing an attractive bait for control proved problematic.

DENGUE/DHF UPDATE (13): AMERICAS, PAHO/WHO OUTBREAK RISK

Date: Fri 7 Feb 2025
Source: PAHO/WHO Epidemiological Alert [edited] https://www.paho.org/en/documents/epidemiological-alert-risk-dengue-outbreaks-due-increased-circulation-denv-3-americas

The occurrence and magnitude of dengue outbreaks are usually associated with the introduction or increase in circulation of a serotype other than the one that previously predominated in an affected region. Given the risk of an increase in the circulation of DENV3 in the southern hemisphere of the Americas Region during the peak dengue season, the Pan American Health Organization / World Health Organization (PAHO/WHO) urges Member States to prepare for a possible increase in cases and ensure early diagnosis and timely care dengue and other arbovirus cases, in order to prevent severe cases and deaths associated with these diseases.

Summary of the situation in the Americas Region
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In 2024, there was a historic increase in dengue cases in the Americas Region with 13 027 747 cases reported by 50 countries and territories. Of this total, 6 906 396 were laboratory confirmed, 22 684 were characterized as severe dengue (0.17%), and 8186 were fatal cases (case fatality rate 0.063%). The countries that reported the highest proportion of cases were Brazil with 10 232 872 cases, Argentina with 581 559 cases, Mexico with 558 846 cases, Colombia with 320 982 cases, and Paraguay with 295 785 cases (1). Note: This detailed update provides country by country updates on the 2024 and present situation. The risk for further travel related cases persists.

Rickettsial Pathogens in Dogs and Ticks During an Epidemic of Rocky Mountain Spotted Fever in Ensenada, Baja California, México

L. Backus et al. email: J Foley jefoley@ucdavis.edu DOI: https://doi.org/10.4269/ajtmh.24-0497 

Abstract: A Rocky Mountain spotted fever (RMSF) epidemic has spread through the state of Baja California, Mexico over the last decade and a half, beginning in Mexicali, and subsequently to Tijuana and to Ensenada by 2018. In October of 2022, we surveyed dogs and homes in randomly selected Áreas Geoestadisticas Básicas (AGEBs) with and without reported human cases. Brown dog ticks (Rhipicephalus sanguineus sensu lato) were found on 33.9% of dogs and in the yards of 23.6% of homes. Homes from AGEBs with cases had over a 6-fold increased odds of ticks being present in the yard than AGEBs without reported cases. Both dogs that were permitted to roam and the presence of roaming dogs in the neighborhood were strongly associated with tick infestation of dogs and homes. No ticks or blood samples were polymerase chain reaction-positive for Rickettsia (R.) rickettsii, the causative agent of RMSF, although 54.6% of dogs were seropositive for spotted fever group rickettsiae, and 17.4% were seropositive for typhus group rickettsiae. R. massiliae and R. felis were detected in eight (1.3%) and 29 (4.8%) ticks, respectively; and R. felis was also detected in eight (4.6%) dog blood samples. Although the pathogenic potential of these other rickettsial species and their role in RMSF transmission remains unclear, our data on tick burdens in dogs and homes as risk factors for RMSF exposure provide further support to the pivotal need to reduce tick burdens and the numbers of roaming dogs to successfully manage the RMSF epidemic in northern Mexico.

Note: This paper clearly shows the importance of animal control and the importance of inspecting/quarantining imported dogs.

Assessing the Relationship Between Entomological Surveillance Indices and West Nile Virus Transmission, United States: Systematic Review

T.C. Moore, X. Tang, H.E. Brown [<heidibrown@arizona.edu>] Vector-Borne and Zoonotic Diseases https://doi.org/10.1089/vbz.2024.0072

Abstract
Background: Entomological surveillance indices are used to estimate the risk of West Nile virus transmission. To determine when and where to initiate mosquito control activities, integrated vector management programs establish action thresholds based on entomological surveillance indices. Herein, we examine the evidence from studies that investigated the quantitative relationship between entomological surveillance indices and human WNV cases using systematic review methods. Results: Across three databases, 5378 articles were identified. Using the selection criteria, 38 studies were included for study. Most articles explored entomological indices weekly and devised unique geographic scales to aggregate human and/or mosquito data. The most used models were logistic and negative binomial regression. Maximum likelihood estimates (MLEs) and vector index (VI) demonstrated the greatest ratio of number of positive results to number of times tested. Among all selected articles, 35 unique U.S. locations assessed MLE and/or VI. Human WNV infection had a significant association with MLE across 81.25% (13/16) of locations. VI showed successful performance across 80.00% (24/30) sites tested.

Conclusions:
This systematic review identifies methods for quantifying relationships between entomological and human WNV infection data. We found entomological surveillance indices applied to human WNV risk should include a measure of virus presence, such as MLE and VI. Model type and covariates were too variable to identify geographic or species-specific trends, though, when tested, including temperature, land cover, population density, and time improved the model. This study is meant to be informative and designed to assist public health agencies in seasonal WNV preparations but are not meant to be a panacea for all WNV surveillance challenges.

AVIAN INFLUENZA (27): USA, MULTIPLE STATES, POULTRY

Dengue-mediated changes in the vectorial capacity of Aedes aegypti (Diptera: Culicidae): manipulation of transmission or infection by-product?

I. Mateescu & S. Lequime. 2025. J. Med. Entomol. 62(1), 19–28 https://doi.org/10.1093/jme/tjae134

Abstract [shortened]. An arthropod’s vectorial capacity summarizes its disease transmission potential. Studies have shown that mosquito-borne pathogens may alter important vectorial capacity traits of their mosquito vectors, thus directly impacting their transmission and epidemic potential. Here, we compile and discuss the evidence supporting dengue-mediated changes in Aedes aegypti (L.) and evaluate whether the observed effects represent an evolved trait manipulation with epidemiological implications. Dengue infection appears to manipulate essential traits that facilitate vector–host contact, such as locomotor activity, host-seeking, and feeding behavior, but the underlying mechanisms are not understood. Conversely, life-history traits relevant to vector population dynamics, such as survival, oviposition, and fecundity, appear to be negatively impacted by dengue virus. However, methodological disparities among studies render comparisons difficult and limit the ability to reach well-supported conclusions. This highlights the need for more standardized methods for research into changes in virus-mediated traits.

Note: This review paper focusses on dengue virus and aegypti, but may be relevant for other mosquito-borne arboviruses.

Reduction in Aedes aegypti Population After a Year-Long Application of Targeted Sterile Insect Releases in the West Valley Region of Southern California

West Valley Mosquito and Vector Control District recently published their third paper on SIT. The latest paper discusses the efficacy of SIT targeted approach in the control of Aedes aegypti.

Click here to view

Tularemia — United States

Tularemia — United States, 2011-2022. Rich SN, Hinckley AF, Earley A, et al. 2025. MMWR Morb Mortal Wkly Rep. 73(5152):1152-1156. http://dx.doi.org/10.15585/mmwr.mm735152a1

Tularemia is a rare nationally notifiable zoonosis, caused by the tier-1 select agent _Francisella tularensis_, that has been reported from all USA states except Hawaii. Clinical manifestations typically include fever and localized symptoms that vary by route of infection. The case fatality rate of tularemia is typically <2%, but can be higher depending on clinical manifestation and infecting strain. Tularemia is treatable with antimicrobials. During 2011-2022, a total of 47 states reported 2,462 tularemia cases, but 4 central states (Arkansas, Kansas, Missouri, and Oklahoma) accounted for 50% of all reported cases. Note: This report describes the epidemiology of reported cases and brings attention to this bacteria that has been reported infecting more than 250 species of wild and domestic animals. Infection is through insect or tick bites as well as contact with infected wild animals [e.g., cottontail rabbits] or immersion or ingestion of contaminated water. Ticks may be an important reservoir as they can maintain infection transstadially [pathogen remains within the vector from one life stage (“stadium”) to the next] and transovarially [transmission of a pathogen from an organism (as a tick) to its offspring by infection of eggs in its ovary].

Evidence of Limited Laboratory Infection of Culex tarsalis (Diptera: Culicidae) by Usutu Virus

Beyers et al. 2025. Evidence of Limited Laboratory Infection of Culex tarsalis (Diptera: Culicidae) by Usutu Virus. Vector-Borne and Zoonotic Diseases 25(1) https://doi.org/10.1089/vbz.2024.0054

Background: Usutu virus (USUV) is an emerging flavivirus, closely related to West Nile virus (WNV), that has spread into Europe from Africa. Since Culex tarsalis Coquillett is an important vector for WNV transmission in the United States, we tested the ability of USUV to replicate in and be transmitted by these mosquitoes. Materials and Methods: USUV was used to infect 3-4 day-old Cx. tarsalis with 5.6 to 7.5 log10 pfu/ml in goose bloodmeals. Saliva, heads, and bodies were collected on day 13 or 14 and analyzed by RT-qPCR for detection for USUV vRNA. Blotting paper punches were also collected daily to assess viral transmissibility. Results: The low and high dose blood meal resulted in 0% and 19.6% of the mosquitoes having established infections, respectively. All of the high dose females had a dissemination of USUV RNA to the heads and none of the filter papers had detectable USUV RNA, but five of the capillary saliva collections were positive, representing 45.5% of the infected mosquitoes.

Conclusions: Limited infection of Cx. tarsalis was observed when exposed to bloodmeals with greater than 10^7 pfu/mL of USUV, indicating this vector is not likely to have a key role in transmission of the virus. Note: USUV caused frequent epiornitics in blackbirds in Europe, but has not produced noticeable human disease, unlike WNV before its introduction into North America.

Clinical and Epidemiological Information Required for Lyme Disease Surveillance in a Low-Incidence State, California 2011–2017

Clinical and Epidemiological Information Required for Lyme Disease Surveillance in a Low-Incidence State, California 2011–2017. Brummitt et al. 2024. Vector-Borne and Zoonotic Diseases [ahead of print]. https://doi.org/10.1089/vbz.2024.0043

Abstract [shortened]: Background: Between January 1, 2011, and December 31, 2017, over 12,000 case reports of Lyme disease (LD) were submitted to the California Reportable Disease Information Exchange for further investigation. The number of case reports has tripled compared to previous years, emphasizing the need for efficient estimation and classification methods. We evaluated whether estimation procedures can be implemented in a low-incidence state such as California to correctly classify a case of LD.

Objective: This study identified whether a minimum number of variables was sufficient to reliably classify LD cases in California and potentially reduce workload. Methods: To determine the relative value of diagnostic information, we compared five candidate logistic regression models that were used to classify cases based on information that varied in its degree of difficulty for collection. Results: Our results showed that automatically reported data were not sufficient, additional information such as a patient’s clinical presentation and travel history were necessary to improve the sensitivity of the models. Conclusion: This study demonstrated that both clinical and travel information were required to accurately classify a case of LD in California.

Note: These results were critical to interpret data from a passive case surveillance system to identify areas of high risk endemic transmission.

A scoping review to determine if adverse human health effects are associated with use of organophosphates for mosquito control

A scoping review to determine if adverse human health effects are associated with use of organophosphates for mosquito control. Tai, Z. et al. 2024. Journal of Medical Entomology, 2024, 1–11.

https://doi.org/10.1093/jme/tjae130

Abstract [shortened]. Organophosphate insecticides are widely used for adult mosquito control. Although proven effective in reducing mosquito populations and limiting arbovirus transmission, public concern exists regarding potential human health effects associated with organophosphate exposure. The aim of this scoping review was to describe any reported human health conditions associated with organophosphates during their use for adult mosquito control in the United States and Canada. Original peer-reviewed articles published in English language journals from 1 January 2000 to 22 May 2024 identified 6,154 screened articles. Following an independent review, 10 studies were identified that described human health conditions associated with organophosphate exposure during adult mosquito control applications. Of the 10 included studies, only two articles were published within the last 11 years (2013 to 22 May 2024). The included studies could not determine causality between exposure to adulticides and development of illness or adverse impacts. The available and limited evidence indicates that organophosphates can be used safely to control nuisance mosquitoes or mosquitoes that transmit arboviruses. Continued research regarding the human health effects associated with organophosphate applications for adult mosquito control could help evaluate the basis of the public’s concerns and inform public health decision-making.

Special Collection: Chagas Disease and Kissing Bugs

Severe and Fatal Rocky Mountain Spotted Fever After Exposure in Tecate, Mexico — California

New World Screwworm: Latest Update from USDA-APHIS

Malson,M. [downloaded: 30 Nov 24] https://www.bovinevetonline.com/news/education/new-world-screwworm-latest-update-usda-aphis

[Abbreviated]
On Nov. 25, USDA’s Animal and Plant Health Inspection Service (APHIS) held a meeting to discuss the U.S. response to the news of a single case of New World Screwworm (NWS) found in a cow in Chiapas, Mexico. U.S. and Mexican officials are working closely together, but the border has been temporarily closed to live cattle imports.

“Our priority is to ensure there is no risk to our domestic industry, followed by the goal of reopening the border as soon as possible,” says Dr. Michael Watson, administrator of USDA’s APHIS.

In September, work had already begun on protocols in the event NWS was found in Mexico. Those protocols have been reviewed with Mexico for their understanding and will be made public once finalized.

Points of Protocol

Dr. Burke Healey, senior leader for policy and operations for APHIS, shared protocol will likely include pre-export inspections by Mexican veterinarians overseen by SENASICA, the equivalent to APHIS, before allowing cattle imports to resume. The inspections will make sure:

– appropriate logs accompany animals coming into and leaving the facility cattle are treated with ivermectin

– there’s a seven-day quarantine period

Upon passing inspection, cattle will again be inspected by U.S. officials, along with additional inspections for tuberculosis and ticks. The cattle will be dipped, and then presented to cross the border. Healey says federal inspection sites will focus on ports in Chihuahua and Sonora. “Those five ports are on the Mexican side, so those inspections and all of that protocol are taking place in Mexico and not on U.S. soil,” he explains.

Mexico has not completed its investigation, but acknowledges the infested cow might have been imported from Guatemala. While the timeline for reopening trade is tentatively estimated to be at least three weeks, it quite possibly could extend into January as Mexico typically closes ports for two weeks during Christmas and New Year’s, Healey says.

The U.S. imports 1 million to 1.1 million cattle from Mexico annually. All Mexican cattle are required to have a Mexican origin ear tag and documentation of the herd of origin, TB test of that herd of origin and a TB test of the specific animals being presented for export. These requirements will remain in place.

Sterile flies from a Panama facility will be sent to Mexico to help control the spread of NWS further south and into Central America. Capacity from that facility is around 95 million per week. Mexico is also looking at retrofitting fruit fly plants to produce about 60 million sterile files a week.

Note: The continued release of millions of sterile males from a mass production facility in Panama supported by the USDA historically established a barrier for these flies at the Darian Gap. However, recently the flies have bridged this barrier and re-established infestations in Guatemala, perhaps in association with uncontrolled migrant convoys. This has triggered the increase in sterile fly production and releases, but has not eliminated this population. Historically, the screwworm was eradicated in Guatemala and Belize in 1994, El Salvador in 1995, and Honduras in 1996.

Perspectives of Infectious Disease Physicians on Bartonella quintana Cases, United States, 2014–2024

Louis, S. et. al. 2024. Emerg Inf Dis 30(12). DOI: https://doi.org/10.3201/eid3012.240655.

Abstract
In a US survey of infectious disease specialists, 61 respondents reported seeing >1 Bartonella quintana [‘trench fever’] infection during 2014–2024. Diagnostic challenges included limited healthcare provider awareness, inadequate testing, and inconsistent healthcare access among affected populations. Early recognition of B. quintana infections is needed to improve outcomes among affected populations. Note: This letter extends previous findings in California by CDPH reporting the isolation of this pathogen from body lice collected from the homeless and serves as a reminder of the importance of providing basic health care and sanitation for all members of society.

DENGUE/DHF UPDATE (117): PUERTO RICO

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Date: Tue 19 Nov 2024 16:20 ET Source: CNN Spanish [in Spanish, trans. Mod.TY, edited] https://cnnespanol.cnn.com/2024/11/19/alerta-puerto-rico-aumento-dengue-orix

The Puerto Rico Department of Health (DSPR) reported on Sunday [17 Nov 2024] that the number of confirmed positive cases of dengue on the island so far in 2024 is 4798, a significant increase of more than triple compared to 2023, when 1242 were recorded.

In a press release, the DSPR indicated that “to date, 9 deaths have been confirmed and an additional one is under investigation.”

“The Department of Health has implemented all the necessary tools to deal with this situation. It is fundamental that communities commit to eliminating mosquito breeding sites, using repellent and protecting themselves from bites. Without citizen participation, it is impossible to contain this epidemic,” said Dr. Carlos Mellado, Secretary of Health, in the letter.

The Puerto Rico Department of Health explained that mosquito repellents have been given to people at mass events and training has been conducted for field health professionals, in addition to updating the guide for ordering dengue diagnostic tests.

Among the municipalities with the highest incidence are San Juan with 995 cases, followed by Carolina with 293 and Rincón with 240. The most affected age groups are people from 40 to 59 years old (936 cases), adolescents from 15 to 19 years old (737), and children from 10 to 14 years old (683), the statement said.

Last March [2024], the department had issued a public health emergency declaration for dengue because the reported cases were at historic levels. At that time, 549 cases of dengue had been recorded.

Note: An advanced warning for those planning to attend the 2025 AMCA meeting in San Juan. All the hurricanes and rain this winter may extend these case numbers by March. Bring repellent!

Aedes aegypti control in breeding sites through an insecticidal coating with dual effect: Laboratory trials and safety assessment

Cardenas, R. et al. 2024. Med Vet Entomol. 2024;1–14. DOI: 10.1111/mve.12776 Abstract [Shiortened]. Ground water tanks are known to be preferred Aedes aegypti oviposition places providing opportunities for adult and larvae control. A dual-effect insecticidal coating (IC) (alphacypermethrin/ pyriproxyfen) with a slow-release mechanism represents a promising option. Bioassays were designed to determine the mortality and sterilizing effects on gravid mosquitoes exposed to IC. The inhibition of emergence was evaluated in eggs, larvae and pupae exposed in different containers. For the water safety assessment con-centrations of active ingredients were determined by reverse phase high performance liquid chromatography (RP-HPLC) and the health risk was calculated. The IC applied to the interior walls of water-holding containers showed efficacy against Ae. aegypti in terms of high gravid-female mortality (81% at 24 h, p < 0.01), sterilizing effect (inhibition of oviposition by 63%, p < 0.01) and emergence inhibition (100% in eggs, L3 and L4; 97% in pupae). Emergence inhibition was recorded up to 12 months and adult mortality >80%up to 6 months. The use of water stored in treated containers, either for washing or drinking, is not expected to pose a health risk to users. IC applied to domestic water containers has dual and complementary action that reduces Ae. aegypti densities (immature and adult stages).

Note: This approach could be useful in problem underground storm water systems as well as electrical vaults in California.

Larval crowding enhances dengue virus loads in Aedes aegypti, a relationship that might increase transmission in urban environments.

HLC Dutra, et al. PLoS Negl Trop Dis 18(9): e0012482. https://doi.org/10.1371/journal.pntd.0012482

Abstract Background: We sought to understand how ambient temperature and larval densities in the immature aquatic phases determine adult life history traits and dengue virus loads post-infection. We predicted that larval crowding and high temperatures would both lead to smaller mosquitoes that might struggle to invest in an immune response and, hence, would exhibit high viral loads. Methods. We first examined larval densities from urban and rural areas via a meta-analysis. We then used these data to inform a laboratory-based 2×2 design examining the interacting effects of temperature (21 vs. 26˚C) and density (0.2 vs. 0.4 larvae/mL) on adult life history and dengue virus loads. Results. We found that urban areas had an ~8-fold increase in larval densities compared to more rural sites. Crowding led to slower development, smaller mosquitoes, less survival, lower fecundity, and higher viral loads. The higher temperature led to faster development, reduced fecundity, and lower viral loads. The virus-reducing effect of higher temperature rearing was, however, overwhelmed by the impact of larval crowding when both factors were present. Conclusions. These data reveal complex interactions between the environmental effects experienced by immature mosquitoes and adult traits. They especially highlight the importance of crowding with respect to adult viral loads. Together, these data suggest that urban environments might enhance dengue virus loads and, therefore, possibly transmission, a concerning result given the increasing rates of urbanization globally.

Prevalence and Knowledge of Tick-Borne Disease Among Forest Management Workers in Santa Cruz, California

F. Rubino and J. Foley Vector-Borne and Zoonotic Diseases Vol. 24, No. 11

https://doi.org/10.1089/vbz.2024.0012

Abstract Background: This study aimed to compare the exposure histories to ticks and tick-borne pathogens, knowledge, and prevention practices between individuals engaged in fire-related forest management and those participating in recreational activities within Santa Cruz County, CA, in an area of high risk of tick exposure. Methods: Blood samples from 55 forest workers and 58 members of the public were tested for bacterial DNA of and antibodies to Borrelia burgdorferi, Anaplasma phagocytophilum, and Rickettsia species. In addition, a questionnaire was administered to 54 workers and 84 members of the public to identify gaps in knowledge and prevention practices. Results: Although workers had a higher percentage of positive B. burgdorferi antibodies than the public (5.5% compared with 1.7%), the difference was not statistically significant. Conversely, rickettsial antibodies were more prevalent among the public (17.2% versus 3.6% for workers), but specificity to pathogenic bacteria could not be confirmed. No DNA for the three pathogens or antibodies against A. phagocytophilum were detected. Many workers and members of the public reported tick bites (67.4% of participants), with a notable 11% increase among workers in the odds of being bitten for each additional year spent working in forests. Although workers took greater precautions, significant knowledge and practice gaps were identified among both populations, such as an inability to distinguish tick species from common arthropods (mites, spiders, fleas), overestimating the size of ticks, and inappropriate tick-removal techniques. Conclusion: This study underscores the risk of tick-borne diseases faced by fire management workers in Lyme disease–endemic regions. The findings emphasize the necessity for future studies of Lyme disease within this population, and highlight the urgent need for enhanced training programs to minimize these risks.

Evidence of Limited Laboratory Infection of Culex Tarsalis (Diptera: Culicidae) by Usutu Virus

Byers, NM, et al. Evidence of Limited Laboratory Infection of Culex Tarsalis (Diptera: Culicidae) by Usutu Virus. VECTOR-BORNE AND ZOONOTIC DISEASES Volume 00, Number 00, 2024. DOI: 10.1089/vbz.2024.0054

Abstract
Background: Usutu virus (USUV) is an emerging flavivirus, closely related to West Nile virus (WNV), that has spread into Europe from Africa. Since Culex tarsalis Coquillett is an important vector for WNV transmission in the United States, we tested the ability of USUV to replicate in and be transmitted by these mosquitoes. Materials and Methods: USUV was used to infect 3-4 day-old Cx. tarsalis with 5.6 to 7.5 log10 pfu/ml in goose bloodmeals. Saliva, heads, and bodies were collected on day 13 or 14 and analyzed by RT-qPCR for detection for USUV vRNA. Blotting paper punches were also collected daily to assess viral transmissibility. Results: The low and high dose blood meal resulted in 0% and 19.6% of the mosquitoes having established infections, respectively. All of the high dose had a dissemination of USUV RNA to the heads and none of the filter papers had detectable USUV RNA, but five of the capillary saliva collections were positive, representing 45.5% of the infected mosquitoes. Conclusions: Limited infection of Cx. tarsalis was observed when exposed to bloodmeals with greater than 10^7 pfu/mL of USUV, indicating this vector is not likely to have a key role in transmission of the virus.

Note: USUV is in the same Japanese encephalitis complex within the family Flaviviridae as WNV and SLEV. Cx. tarsalis is considered a potential vector of JEV based on vector competence studies [Reeves & Hammon. 1946. J. Exp. Med. 83: 185]. Because USUV causes extensive mortality in blackbirds, it is possible that mosquitoes could be exposed to higher blood meal titers in nature than used in these experiments. Also useful to remember that Cx. tarsalis is less suseptible to WNV than SLEV, and yet WNV is more prevalent because of its higher titers in infected avian hosts.

Read more

DENGUE/DHF UPDATE (91): AMERICAS, PAHO/WHO

A ProMED-mail post http://www.promedmail.org ProMED-mail is a program of the International Society for Infectious Diseases http://www.isid.org Date: Mon 7 Oct 2024 Source: PAHO/WHO Epidemiological Alert [edited] https://www.paho.org/en/documents/epidemiological-alert-increase-dengue-cases-americas-region-7-october-2024

Due to the increase in dengue cases reported by countries of the Central American Isthmus and Mexico during 2024 and considering the beginning of the dengue season in South America, the Pan American Health Organization/World Health Organization (PAHO/WHO) encourages Member States to continue their efforts in surveillance, early diagnosis, and timely care of dengue and other arbovirus cases, in order to prevent severe cases and deaths associated with these diseases, and, especially for countries in South America, to review their dengue response plans.

Summary of the situation in the Americas Region

———————————————–

In the Americas Region, the number of dengue cases recorded during the first half of 2024 exceeded the number of cases historically reported in a year, as compared to all previously recorded years. As of epidemiological week (EW) 36 of 2024, 47 countries and territories in the Americas Region have reported 11 732 921 dengue cases; this number is 2.5 times as high as the number of cases recorded throughout 2023, which was 4 594 823 dengue cases (Figure 1 [for all figures, see source URL]) (1). Between EW 1 and EW 36 of 2024, of the total reported dengue cases, 6 253 754 (53%) were laboratory confirmed. Of this total, 17 610 were characterized as severe dengue (0.15%) and 6650 fatal cases were recorded (case fatality rate of 0.057%) (1). Cases from 6 countries make up 97% of the fatal dengue cases in the Americas Region: Brazil with 5303 (82.4%), Argentina with 408 (6.1%), Peru with 234 (3.5%), Colombia with 131 (1.97%), Paraguay with 121 (1.8%), and Ecuador with 59 (0.88%) fatal dengue cases (1). All 4 serotypes of the dengue virus have been circulating in the Americas Region as of EW 36 of 2024. Brazil, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, and Panama report simultaneous circulation of the 4 serotypes (DENV-1, DENV-2, DENV-3, and DENV-4). Additionally, Argentina, French Guiana, Peru, and Puerto Rico reported simultaneous circulation of DENV-1, DENV-2, and DENV-3 (1). Note: The rest of the posting provides regional data for Mexico, Central and South American countries, all of which have marked increases in cases this year. The medical situation is complicated further by the circulation of all 4 strains of DENV which when contracted serially can lead to serious hemorrhagic disease complications.

NEW WORLD SCREWWORM – PANAMA (02): CATTLE, HUMAN

A ProMED-mail post

http://www.promedmail.org

ProMED-mail is a program of the International Society for Infectious Diseases

http://www.isid.org [1]

Date: Wed 2 Oct 2024

Source: Prensa Latina [in Spanish, machine trans., edited]

https://www.prensa-latina.cu/2024/10/02/alertan-en-panama-sobre-rebrote-epidemico-de-gusano-barrenador/

Panama warns of new outbreak of screwworm epidemic

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Panamanian authorities have warned of a new epidemic the country is currently facing with cases of the cattle screwworm which also affects humans.

In statements to Prensa Latina, Carlos Moreno, from the Panama-United States Commission for the Eradication of the Screwworm (COPEG) specified the rise of the plague in mid-2023 was due to the lack of vigilance by both citizens and authorities during the COVID-19 pandemic.

In addition, he explained, the increase in cases, some 27 330 from 2022 to date, was due to other factors such as climate change, movement control, and greater awareness among the population.

The screwworm is not only affecting livestock; humans and other animal species are also being harmed.

In Panama, the Ministry of Health (MINSA) has recorded some 79 cases, according to epidemiologist Damaris Contreras, who called on people not to treat wounds at home but to go to health centers or hospitals.

The screwworm, which is laid by the fly _Cochliomyia hominivorax_, feeds on the living tissue of animals and can be fatal if not treated properly. This fly seeks to lay its eggs in “fresh wounds” of any type of warm-blooded animal. In a single wound, this fly can lay between 150 and 300 eggs, explained Lester Reyes, from Animal Health Epidemiology at the Ministry of Agricultural Development (MIDA). Once the larvae develop, they leave the wound and drop to the ground, where they bury themselves until they reach the pupal stage and thenbecome adult flies. Therefore, when healing these wounds, the maggots must be removed and eliminated immediately, because if they are left alive they turn into flies.

Panama has the only plant for the production of sterile flies which counteract the reproduction of flies laying the eggs of the screwworm. Specifically, the impact is occurring in other countries has led Panama to suspend the distribution of sterile flies, said Reynaldo Vivero, from MIDA, who also explained sterile flies are not being distributed in the country, since they are being sent to other countries to control the outbreak.

See attached for additional postings, comment and information.

—

Communicated by: ProMED

Note: The screwworm fly historically was endemic in the USA and was eradicated by the first SIT program. The fly eventually was pushed south of Mexico, with Panama being the southern border maintained by surveillance and further fly releases. Panama has the only remaining sterile fly production facility. The fly is still endemic in parts of South America. Northern dispersal, if not immediately contained, would require a large scale eradication effort that would be very costly.

DENGUE/DHF UPDATE (87): USA (CALIFORNIA) MORE TRANSMISSION

A ProMED-mail post http://www.promedmail.org

ProMED-mail is a program of the International Society for Infectious Diseases http://www.isid.org

Date: Thu 3 Oct 2024

Source: KOST [edited] https://kost1035.iheart.com/featured/la-local-news/content/2024-10-03-5th-locally-acquired-dengue-case-confirmed-in-la-county/

Los Angeles County health officials Thursday [3 Oct 2024] continue to investigate a 5th locally acquired case of the mosquito-borne illness dengue, this time in a resident of El Monte. The latest patient does not appear to have any connection with the 4 previous reported infections, the county Department of Public Health said Wednesday [2 Oct 2024].

Health officials again stressed that locally acquired cases of dengue are extremely rare in areas where it has not been previously transmitted by mosquitoes. The county previously reported a cluster of 3 infections in the Baldwin Park area, and last week a 4th case was confirmed in a Panorama City resident. Health officials called the spate of local cases “unprecedented.”

None of the local patients had any history of travel to areas where dengue is endemic. In October and November of last year [2023], single locally acquired cases of dengue were confirmed by health officials in Pasadena and Long Beach.

Health officials noted that the symptoms of dengue often mirror those of other viruses, and they urged health-care providers to be “vigilant for dengue fever in patients with acute febrile illness and test for and report such cases of mosquito-borne diseases.”

— Communicated by: ProMED

FROM PROMED [It is interesting to note that the latest patient does not appear to have any connection with the 4 previous reported infections. There is a previously reported cluster of 3 cases in the Baldwin Park area, a single case in Panama City and now the latest one in El Monte. One wonders if there are several other dengue virus infected individuals in these 3 localities that have asymptomatic or very mild infections that have not resulted in medical attention so are not reported.

The above report does not indicate which vector mosquito was likely involved in dengue virus transmission in the 3 localities. As noted in the previously posted comment, the mosquitoes most likely involved are _Aedes aegypti_ or _Aedes albopictus_, both of which have been detected in California over the past 20 years. The preventive measures to avoid ongoing transmission are avoidance of mosquito bites and reduction of the mosquito populations. Mosquito control districts are undoubtedly attempting to control these vector mosquitoes, but that is a difficult task and requires collaboration with local residents to eliminate the water catchments in which these mosquitoes breed around their homes and other buildings.

Note that both _Aedes aegypti_ and _Aedes albopictus_ have been found in Los Angeles County. Which of these transmitted dengue virus to the residents is unknown. Locally acquired dengue virus infections remain extremely rare in California but occurrence of this cluster of cases indicates that local acquisition of dengue virus can occur. – Mod.TY

Note: The juxtaposition of these cases to the primary or imported cases has not been reported. As indicated above, it would seem that potentially other perhaps milder secondary cases have gone unnoticed, although these could still be a source of virus for mosquito infection making a vector control response difficult to focus geographically.

DENGUE/DHF UPDATE (80): USA (CALIFORNIA) LOCALLY ACQUIRED

A ProMED-mail post
Date: Tue 17 Sep 2024 17:05 EDT
Source: Newswise [edited]

Amid southern California’s recent record-breaking heat wave and fast-moving wildfires, public health officials reported the third locally acquired case of dengue fever in the Los Angeles area. Although the events seem unrelated, they actually are connected — and for troubling reasons. Communicated by: ProMED “”This is the third locally acquired dengue case in the Los Angeles, California area this year (2024). This resident was bitten by a dengue virus-infected mosquito, most likely _Aedes aegypti_ or _Aedes albopictus_, both of which have been detected in California over the past 20 years. The question with all these locally acquired infections is: where, when and from whom did the vector take the infectious blood meal? Did that infected individual acquire their dengue infection locally or in a dengue-endemic country and subsequently traveled to Los Angeles County, California while viremic? The risk of ongoing transmission depends on the presence of vector mosquitoes. There are 24 counties in California in which _Aedes aegypti_ and _Aedes albopictus_ have been found over the past 20 years.”

Read more

Call for Research Proposals – Coachella Valley Mosquito and Vector Control District

The Coachella Valley Mosquito and Vector Control District is requesting research proposals. This funding opportunity is aimed at improving our Integrated Vector Management Program targeting mosquitoes, red imported fire ants, and flies in the Coachella Valley. Past research projects have included spatial mosquito repellents, virus transmission models, vegetation management in wetlands, biological control of fire ants, and activity of house flies. Because of the unique environment including very high temperatures and low precipitation, projects designed to work with the environmental conditions for surveillance of vectors and vector-borne diseases and projects that tailor control methods to the habitat here are of great interest.

Please see our website for guidelines on proposal submission, interests of the District, and a budget worksheet (you can obtain these at https://www.cvmosquito.org/bids-rfqs-rfps under Research Program FY 2024-2025).

93rd Annual MVCAC Conference – Call for Papers

The theme for the 93^rd Annual MVCAC Conference is “Vector Control- A path to a more hospitable world”. The prime topics for consideration are below but please consider submitting even if your paper does not fit into one of these topics. All submissions will be considered. The deadline for submission has been extended to October 18, 2024. Requests made following this date may not be honored and may not appear in the conference program.

• Network System Security Preparedness
• Droplet Deposition/Characterization
• Data Visualization Tools/CalSurv
• Reducing Vector-borne Disease Risk through Messaging Campaigns
• Vertebrate Vector Control
• Vector-borne Disease in California
• WNV, SLE, Zika, Dengue, Malaria
• Hantavirus, Plague, Typhus
• Invasive Aedes Successes & Failures
• Novel Mosquito Control Trials
• Application Equipment
• 3D Printing Symposium
• Mosquitofish Rearing & Transport
• Suspect Pool ID Access and treatment strategies

Questions? Please reach out to Senior Meeting Manager, Rachel Hickerson at rhickerson@amgroup.us.

CLICK HERE TO SUBMIT

National Mosquito Control Awareness Week – June 16-22, 2024

National Mosquito Control Awareness Week, observed June 16-22, 2024, educates residents about mosquitoes and how to help prevent the spread of mosquito-transmitted diseases. Join us in spreading the word within your districts by posting our press release and on social media using our content calendar.

• Press Release: California Mosquito Experts Use Innovative Technologies to Control Disease-Spreading Mosquitoes

• Social Media Calendar 

CDPR has approved WB1 Males for use in California

May is Lyme Disease Awareness Month

Nymphal Ixodes pacificus are most active in the spring and early summer in California. These tiny ticks pose a greater risk of transmitting Lyme disease.\

Messaging and resources to share in May:

• Social media:
  • Lyme disease messaging – CDPH Toolkit or MVCAC PR Google Drive
  • Nymphal tick messaging – MVCAC PR Google Drive

• Brochures (available to order):
  • Lyme Disease in California (English | Spanish)
  • Prevent Tick Bites – Prevent Disease (English | Spanish)

• Weblinks:

• CDPH Lyme Disease webpage
• CDPH Tick-Borne Disease Prevention webpage
• CDPH Ticks & Tick-Borne Diseases webpage

MVCAC- California Air Resources Board Fact Sheet

Beginning in 2024, the California Air Resources Board (CARB) is implementing new equipment and vehicle regulations to limit the purchase of gasoline powered equipment and promote the use of electric instead. The MVCAC Regulatory Affairs and IVM Committees have created a fact sheet to guide the membership through these changes.

VIEW FACT SHEET.

Want insecticide resistance training and testing in your area?

If you would like to collect and test mosquito (Aedes or Culex) samples for insecticide resistance, PacVec provides training and testing services at no charge. Michael Bollinger in Dr. Anton Cornel’s laboratory is leading this activity and is available to discuss testing strategies or to provide on-site training on bottle bioassay testing in your area. We offer three options for testing or training:

1. Partnering with a local agency to host a resistance testing workshop that includes the host agency and neighboring agencies in a single event.

2. Partnering with a local agency to perform mosquito collection and testing with the agency’s staff.

3.Collecting and testing mosquitoes from areas where data are lacking with/without involvement of local agency staff.

Any of the above activities will yield immediate data to guide your control decisions. Involvement of local agency staff is ideal to provide a learning experience. If a single agency would like to host a training that can involve neighboring agencies, that is also very helpful to increase the value of each workshop. If larval bioassays are wanted in addition to CDC bottle bioassays, please let us know that as well.

Contact us as soon as possible at bioassays@pacvec.us to make plans for summer testing and training.

West Nile Virus and Dead Bird Call Center Now Live

The California WNV and Dead Bird Call Center opened for the season on Monday, April 8, 2024. Now through mid-October, members of the public can report a dead bird by calling 1-877-WNV-BIRD (1-877-968-2473). Online reporting continues to be available year-round at: https://westnile.ca.gov/report. 

For questions about Call Center operations, please contact: Marie.Cerda@cdph.ca.gov.

As you plan for the upcoming WNV season, CDPH has resources available to assist your communication and outreach efforts:

• WNV & Mosquito Social Media Plan for Local Agencies
• WNV Sample Social Media (including sample messaging for dead bird reporting)
• WNV brochure (available in English and Spanish)
• To order print copies free-of-charge, please email: VBDS@cdph.ca.gov For additional WNV information, including data for 2024, please visit: https://westnile.ca.gov/. 

Roaming Dogs, Intense Brown Dog Tick Infestation, and Emerging Rocky Mountain Spotted Fever in Tijuana, Mexico.

Foley J., et al. Am. J. Trop. Med. Hyg., 00(00), 2024, pp. 1–16 doi:10.4269/ajtmh.23-0410

Abstract. A two decades–long epidemic of Rocky Mountain spotted fever in northern Mexico reached the U.S. border city of Tijuana in 2021. Cases were near the city periphery in marginalized areas, some lacking infrastructure such as streets or utilities. We worked in the three census areas where human cases were reported and in 12 additional control Areas Geoestadisticas Basicas. Of 191 examined dogs, 61.8% were tick-infested, with 6-fold increased odds if they were allowed to roam. Although no dogs were Rickettsia polymerase chain reaction–positive, we found one R. rickettsii and 11 Rickettsia massiliae–infected ticks. The rickettsial IgG seroprevalence by immunofluorescence antibody assay was 76.4%, associated with unhealthy body condition, adults, dogs with> 10 ticks, more dogs being seen in the area, and dogs being permitted in the street. Insufficient medical and canine management resources have contributed to a case fatality rate of RMSF that has exceeded 50% in areas. High canine seroprevalence suggests risks to people and dogs; unfortunately, herd immunity is impeded by high turnover in the canine population owing to the birth of puppies and high death rates. Binational One Health workers should monitor disease spread, enact canine population management and tick eradication, and provide prevention, diagnostic, and treatment support.

Note: Abandoning dogs in Mexico by legal and illegal immigrants may only add to this public health issue and perhaps provide some risk for border communities.

Female Aedes aegypti mosquitoes use communal cues to manage population density at breeding sites.

Costa-da-Silva AL, et al.

COMMUNICATIONS BIOLOGY | (2024) 7:143 | https://doi.org/10.1038/s42003-024-05830-5 | www.nature.com/commsbio 1 1234567890

Abstract: Where a female mosquito lays her eggs creates the conditions for reproductive success. Here, we identify a communal behavior among ovipositing female mosquitoes. When choosing equal breeding sites, gravid Aedes aegypti aggregate more often than expected. This aggregation occurs when water contact is restricted and does not require the presence of eggs. Instead, the aggregation is regulated by the number of females present at the breeding site. Using assays with both occupied and empty oviposition sites, we show that the Orco olfactory co-receptor and a carbon dioxide receptor, Gr3, detect the presence of mosquitoes. Orco mutants aggregate more often in empty sites, suggesting attractive olfactory cues influence females to associate with one another. Gr3 mutant females do not prefer either site, suggesting that the CO2 receptor is necessary to evaluate mosquito population density at breeding sites. Further, raising CO2 levels is sufficient to cause wild-type mosquitoes to avoid empty oviposition sites. Our results demonstrate that female mosquitoes can regulate their own population density at breeding sites using attractive and repellent communal cues.

Note: These results are based on a series of well done laboratory choice experiments that begin to tease apart the patterns of oviposition site choice and therefore the distribution of this mosquito in nature — information useful for surveillance and control.

Emerging and lesser-known arboviruses impacting animal and human health

A Faraji1, G Molaei, T Andreadis. J Med Entomol, 60(6), 2023, 1139–1141.

https://doi.org/10.1093/jme/tjad140.

In an effort to address problems surrounding emerging vector-borne pathogens, we have dedicated a series of Forum Articles for a special issue of the Journal of Medical Entomology titled “Emerging and Lesser-Known Arboviruses Impacting Animal and Human Health”. It is our hope that this series will further contribute to our understanding of these lesser-known arboviruses for the benefit of vector control personnel, clinicians, and public health stewards within a One Health approach. This issue will encompass arboviruses transmitted by biting midges (Diptera: Ceratopogonidae), mosquitoes (Diptera: Culicidae), and hard ticks (Ixodida: Ixodidae).

Note: Included within this series are papers on Cache Valley, Jamestown Canyon and Snow shoe hare, viruses thought to occur in California [see Reeves’ Monograph published by the MVCAC], but not included within current molecular surveillance diagnostics.

The mosquito knows no borders: Regional challenges for global confrontation in the dengue battle

Barcante JMP, Cherem J (2024)

https://doi.org/10.1371/journal.pntd.0011830

Note: Paper reviews the increasing international public health importance of dengue and calls for improved prevention focusing on vector control. The remarkable increase in cases throughout Central and South America undoubtedly will increase the risk of cases imported into California. The expanding distribution and abundance of Aedes aegypti concurrently will increase the risk of local transmission.

Do it yourself: 3D-printed miniature CDC trap for adult mosquito (Diptera: Culicidae) surveillance

Bibbs CS, Reissen N, Dewsnup MA, Sorensen RB, Faraji A, White GS (2024)

https://doi.org/10.1371/journal.pntd.0011899

Abstract: 3D printing could improve the accessibility of the CDC trap by eliminating some of the supply chain variables. We present here several trials with the Salt Lake City (SLC) trap, a three-dimensional (3D) printed trap design. No statistically significant differences were found when comparing CO2 line height(above vs. below fan), battery types (sealed lead acid vs. USB battery pack), and trap body collection shape (funnel body vs. simple/straight body). The SLC trap was compared directly to a commercial equivalent, the Clarke ABC trap, with comparative assessment on species diversity and abundance and found to be statistically equivalent on all metrics. Our final design is presented here with the publicly published stereolithography (STL) files and a detailed outline of the transport container system.

Note: This trap design was presented at the Annual MVCAC conference and is cited here for reference.

Response to An Outbreak of Locally Transmitted Dengue in Key Largo, FL

The Florida Keys Mosquito Control District. J Am Mosq Control Assoc., 39 (4), 2023, pp. 251–257.

Doi: https://doi.org/10.2987/23-7145

ABSTRACT: Seventy-two cases of locally acquired dengue were contracted by residents and visitors of Key Largo, FL, in 2020. The primary vector, Aedes aegypti, has been a large focus of the Florida Keys Mosquito Control District’s (FKMCD) control measures for over a decade. This paper recounts the 2020 outbreak of DENV in Key Largo, FL, and the FKMCD’s Ae. aegypti operational response. The overall House Index (13.43%) during the outbreak was considered high (>5%) risk for local transmission. Larval habitat characterized from property inspections was similar to previous larval and pupal habitat studies. Adult surveillance of the active dengue transmission area provided 3 positive pools out of 1,518 mosquitoes tested resulting in a minimum infection rate of 1.976. Increased personnel response with long-term larvicide formulations and increased aerial, truck, and handheld ultra-low-volume adulticide control measures quickly reduced the Ae. aegypti surveillance numbers below the action threshold. No active cases of dengue have been reported since October 2020.

Note: This article provides a case study of one district’s response to a local dengue outbreak. Here, two initial cases were reported on 3 Mar 2020 but subsequent suspect cases were not recognized until 17 Jun after considerable transmission. Two cases that occurred in Jan 2020 were not reported until late 2021. This cascade of events clearly shows the importance of case surveillance and reporting and fits well with our conference discussions as districts review existing response plans following California’s first two cases of locally transmitted dengue.

Tick Resources Reminder

Adult Ixodes pacificus ticks are most active in California from fall through early spring. Now is a great time to encourage repellent use and tick checks for tick bite prevention.

For sample messaging and educational materials about ticks and tick bite prevention, please visit go.cdph.ca.gov/ticks and the following resources:

• CDPH Tick-Borne Disease Prevention webpage (now available in Spanish)
• Sample social media messages and graphics
• CDPH Common Ticks in California ID card (English version now updated; to order copies, please email VBDS@cdph.ca.gov)

2024 Sentinel Chicken Order Forms Available Now!

ORDER NOW!

Chickens are being supplied by Gemperle Family Farms in Turlock, CA

Please return order form by March 1, 2024 Via email or fax to 916-444-7462

Northern and Southern Region

Pick-up date: Mid-April. Specific date, and location TBD (Turlock/Hilmar area)

The address for the farm will be provided as soon as we have it.

Questions: please email or call R’Mani White in Membership at rwhite@amgroup.us or (916) 440-0826 ext 125.