From KVPR

August 7, 2023

One mosquito abatement district in Tulare County has reportedly purchased its first-ever drone, amphibious vehicle and airboat.

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Los Angeles County, California, 2022

August 1, 2023

Recently, locally acquired cases of malaria in Florida and Texas have received national media attention. MVCAC has developed the below statement for member agencies to use when responding to questions regarding these detections and the risk of locally acquired cases in California. MVCDs are encouraged to tailor this statement with information specific to their district.

Despite reports of recent malaria cases in Florida and Texas, local transmission of malaria in the U.S. is very rare. Most malaria cases are acquired when people travel outside of the U.S. where malaria transmission occurs. Anopheles mosquitoes that can spread malaria are present in California, but the parasites that cause malaria are not currently found in these mosquitoes in California. The last cases of local transmission of malaria in California were reported in 1990. About 100 cases of malaria are reported each year in California from people who were infected while traveling in other countries. Since malaria is a reportable disease, all diagnosed imported cases are tracked by the state and local public health departments. The patient’s history and potential for exposure to local malaria vectors are evaluated and if need be, actions are made to prevent possible transmission within the local community.

Mosquito and vector control agencies in California monitor many species of mosquitoes including those that carry West Nile Virus, invasive mosquitoes, and those that have the ability to carry malaria. Mosquito and vector control agencies do this to protect public health and quickly respond when mosquito-borne diseases threaten residents.

Residents are encouraged to wear EPA-registered insect repellent and dump and drain all standing water in and around their homes to prevent mosquito bites. To learn more about mosquito prevention please visit mvcac.org. To learn more about malaria please visit the CDC and the California Department of Public Health.

From Hoodline

August 1, 2023

In response to the discovery of West Nile virus-positive mosquitoes in San Jose and Milpitas, the Santa Clara County Vector Control District has initiated truck-mounted insecticide treatments to control and kill adult mosquitoes in the affected areas. 

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June 2023

For vector control districts that wish to use pyriproxyfen in WOTUS, an updated Notice of Intent form and Pesticide Application Plan needs to be submitted to the State Water Board. Examples of completed documents can be found on the Water Board NPDES Vector Control Permit website. Due to web accessibility requirements, the State Water Board is no longer allowed to post 3^rd party documents unless they are ADA-compliant. Therefore, the Water Board requests applicants post documents on their webpage and provide a link which will then be used to post on the State Water Board website for 30-day public comment as required per the permit.

Email Gurgagn Chand, Gurgagn.Chand@waterboards.ca.gov, your website link for the document. After the application link is posted for 30-day public comment, Water Board staff will notify you of any items that need to be addressed within the amended application package as well as any public comments received. If everything checks out, generally an amended Notice of Applicability approving the revisions will be issued by the Deputy Director of Water Quality within 1-2 weeks. 

Email MVCAC Regulatory Affairs Committee Chair (Erika Castillo, erika@mosquitoes.org) if you have any additional questions.

Click here to read

Summary:  CDC is collaborating with two state health departments on an investigation of six locally acquired cases of Plasmodium vivax malaria in Sarasota County, FL and one case in Cameron County, TX. There is no evidence to suggest that the cases in the two states are related. All patients were promptly treated at area hospitals and are recovering.

Most malaria cases diagnosed in the United States are imported, usually by persons who travel to countries where malaria is endemic. However, locally acquired mosquito-transmitted malaria cases can occur, as Anopheles mosquito vectors exist throughout the United States. In 2003, for example, there were 8 cases of locally acquired P. vivax malaria identified in Palm Beach County, FL.

Note: These vivax cases were travel related, but the source of the initial infection was not indicated. Possibilities include tourists visiting malaria endemic countries or immigrants with active parasitemia or relapsed chronic liver infections. The last outbreak of locally transmitted malaria in California occurred among farm workers in San Diego County during 1988 with Anopheles hermsi as the reputed vector

[https://www.cdc.gov/mmwr/preview/mmwrhtml/00001559.htm]. These events serve to remind us that we have vectors of travel related pathogens other than invasive Aedes.  

[Submitted by the Vector and Vector-borne Disease committee]

KK Brisco, CM Jacobsen, S Seok, X Wang, Y Lee, OS Akbari, AJ Cornel

J Med Entomol 60: 364–372, https://doi.org/10.1093/jme/tjad005

Abstract [condensed]: Our In2Care trial was performed in the coastal settlement of Miloli’i in the southwest of Big Island where both Ae. aegypti and Ae. albopictus are found. This trial from Jul – Oct 2019 fell within the traditional wet season. No significant reduction in egg or adult counts were observed following 12 wk of two In2Care trap placements per participating household. In fact, an increase in adults during the trial required the local mosquito abatement program to stop the In2Care trap trial and institute a thorough source reduction and treatment campaign. The source reduction campaign revealed that a large variety and quantity of water sources competed with the oviposition cups that we had placed, which likely lowered the chances of our oviposition cups being visited by pyriproxyfen-contaminated Aedes adults exiting the In2Care traps.

Note: This report indicates that abundant alternative oviposition sites can compromise control that focuses on oviposition behavior. 

[submitted by the Vector and VectorBorne Disease committee].  

From ABC 50 Action News

May 26, 2023

Officials are asking residents to use insect repellent with DEET, wear long sleeves outdoors and drain any standing water.

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Laroche, M. and Weeks, E.N.I.

University of Texas, Galveston, TX and University of Florida, Gainseville.

Med. Vet. Entomol. 2023: 37: 177-178. DOI: 10.1111/mve.12646

Summary [VVBD Committee]: This short but interesting editorial reviews the bacteria transmitted by arthropods and concludes that although the burden of bacterial arthropod-borne bacterial diseases remains lower than the joint burden of parasitic and viral arthropod-borne diseases, there is an undeniable need to study these neglected pathogens. Significant gaps in their ecology, transmission pathogenesis still need to be filled.

Morgan E. Gorris*, James T. Randerson, Shane R. Coffield, Kathleen K. Treseder, Charles S. Zender,

Chonggang Xu, and Carrie A. Manore

Environmental Health Perspectives 2023. Vol. 131, No 4. https://doi.org/10.1289/EHP10986

*Author email:  mgorris@lanl.gov

Summary [by Vector and Vector-borne Disease committee]: Using human case report data from 2005 to 2019 and seasonally averaged climate variables, the authors developed a predictive module to estimate mean annual WNV incidence. They found that regions with dry and cold winters and wet and mild summers have higher WNV incidence rates. Among the climate variables considered, winter precipitation, fall precipitation, and winter temperature were the three most important predictive variables. The authors believe this model may be a tool to predict the future spatial extent of WNV risk related to climate change. They acknowledged that subregional patterns of WNV are likely to be strongly influenced by a series of environmental variables such as land use, vegetation coverage, and hydrology. Dry agriculture landscapes that require significant irrigation also will influence patterns of WNV incidence.

From ABC7
May 3, 2023

For the first time, drone technology is taking off to combat mosquitos in the South Bay after an unprecedented rainy winter.

Mosquito season just started and this week the Santa Clara Vector Control District will begin using drones to reduce the mosquito population.

Nayer Zahiri, the county’s Vector Control District manager, said other districts in the state are using it.

“As you see a lot of standing water, a lot of waters around and we want to make sure we are able to control the stages we can control before they become adults,” Zahiri said.

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From Times of San Diego
April 20, 2023

San Diego County will conduct its first larvicide drop of the year on up to 51 local waterways as part of a campaign to combat diseases spread by mosquitoes such as West Nile virus, it was announced Wednesday.

Aerial larvicide drops are carried out once a month between April and October each year, covering around 1,300 acres of mosquito breeding areas.

The routine helicopter drops will be conducted next Wednesday, and Thursday if necessary, according to a news release from the county.

County officials say the larvicide does not hurt people or pets.

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Posted by Vector and Vector-borne Disease Committee
April 19, 2023

Leslie Foss*, Tina Feiszli, Vicki L. Kramer, William K. Reisen, Kerry Padgett.

*Leslie.Foss@cdph.ca.gov

PLoS ONE April 6, 2023 https://doi.org/10.1371/journal.pone.0284039

Abstract [condensed]

Since 2003, the California West Nile virus (WNV) dead bird surveillance program (DBSP) has monitored publicly reported dead birds for WNV surveillance and response. We examined DBSP data from the early epidemic years (2004–2006) with recent endemic years (2018–2020) to characterize changes in program operations, patterns of dead bird reports, and WNV prevalence among dead birds and their utility as early indicators of WNV activity. In recent years fewer agencies collected dead birds for testing, but updated protocols enhanced the efficiency of the program. The number of dead bird reports was approximately ten times lower during 2018–2020 compared to 2004–2006; reports from the Central Valley and parts of Southern California decreased the most. Dead corvid, sparrow, and quail reports decreased the most compared to other bird species reports. In the early years, WNV positive dead birds were the most frequent first indicators of WNV activity; in contrast, during 2018–2020 mosquitoes were the most frequent first indicators. Evidence for WNV impacts on avian populations and susceptibility are also discussed.

Note: Despite declines in the number of birds reported by the public, dead bird surveillance remains important to better understand changes in WNV ecology and adds critical data to a comprehensive environmental surveillance program.

From ABC 7
April 12, 2023

ORANGE COUNTY (KABC) — Southern California is still a couple months away from mosquito season, but this season could potentially be one of the worst because of all the rain to start the year.

However, the Orange County Mosquito and Vector Control District is being proactive.

Heather Hyland, director of communications for OC Vector, said spots that didn’t have standing water before may have some now.

“There’s areas due to the rain that are filling up that are producing more egg laying sites for mosquitos per usual,” Hyland said.

She said they’re seeing more mosquitoes in traps laid out to monitor their population.

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Mosquito Awareness Week, observed April 16 – 22, 2023, educates California residents about mosquitoes and how to help prevent the spread of mosquito-transmitted diseases

Press Release

• Record Amounts of Rainfall Create Perfect Conditions for Mosquitoes

Social Media Graphics:

Invasive Aedes Toolkit

This invasive Aedes toolkit is designed to assist MVCAC members in their public education and outreach efforts.

Communities with Invasive AedesCommunities without Invasive Aedes

• Factsheet: English, Spanish
• Quickbites: English PDF, English PNG, Spanish PDF, Spanish PNG
• Social Media Graphics: English, Spanish
• Videos: English, Spanish

Communities without Invasive Aedes

• Factsheet: English, Spanish
• Quickbites: English PDF, English PNG, Spanish PDF, Spanish PNG
• Social Media Graphics: English, Spanish
• Videos: English, Spanish

Posted by Vector and Vector-borne Disease Committee
April 5, 2023

Vindhya S. Aryaprema, Madeline R. Steck, Steven T. Peper, Rui-de Xue, Whitney A. Qualls*

*wqualls@amcdfl.org

PLoS Neglected Tropical Diseases 2023.  https://doi.org/10.1371/journal.pntd.0011173

Condensed abstract.   Many different methods are used and new methods are evolving to control nuisance and vector mosquito populations across the world. Implementation of such control methods at the optimal time has been identified as critical to maintaining the populations below unacceptable levels. The establishment of evidenced-based action thresholds is encouraged to achieve maximum results under available resources. This review identified 87 publications: 30 reported originally generated thresholds, 13 inclusions reported a statistical method with a computable action threshold model, and 44 inclusions mentioned only previously generated thresholds. Overall, the inclusions with thresholds that were directly related to disease transmission conditions (“epidemiological thresholds”) outnumbered the inclusions with thresholds that were directly related to mosquito abundance (“entomological thresholds”). The majority of the thresholds originated in Asia targeting dengue and dengue vectors. The review discusses the associated surveillance characteristics such as the possibility of using external data (previously recorded data), spatial and temporal variations in data, and the importance of an adequate lead time to initiate control interventions that would help guide to plan better surveillance programs for the development of action thresholds.

Note:  Paper could provide useful references for decisions on the control of invasive Aedes. 

From ABC7
March 29, 2023

DUARTE, Calif. (KABC) — With so much rain drenching Southern California this season, there is another pesky problem lurking around the corner: mosquitoes.

“It doesn’t take long for mosquitoes to go from the larva you see to full grown ones that’ll look for someone like you to sting,” said Pablo Cabrera with the San Gabriel Valley Mosquito & Vector Control District.

Dense vegetation and stagnant water allow mosquitoes to grow and hide. Just a small amount of water is all mosquito needs to lay their eggs and with the historic rainfall, residents are being asked to do three things: tip, toss and protect.

The San Gabriel Valley Vector Control District urges resident to tip out stagnant water weekly, toss any unused containers left outside that can collect stagnant water, and protect yourself with some sort of mosquito repellent.

Cabrera said the SGVMVCD hasn’t captured any adult mosquitoes at the moment, but once the dry, warmer weather hits, that will change.

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From the San Francisco Gate
March 26, 2023

SACRAMENTO COUNTY, Calif. — It is that time of year: Mosquitoes are back.

From NBC Bay Area
March 24, 2023

As we just hit spring, experts say mosquitoes are already multiplying, taking advantage of all the recent flooding.

In Belmont, families can still see and smell the flood waters that have been inundating them all year.

The conditions and all the standing water found around the bay area are a concern for The San Mateo County Vector Control Department who said, they’ve had more mosquito related requests than usual in the past few months.

In a statement. they wrote they anticipate water will continue to stand in many locations into the warmer month, so their acting now, regularly checking 40,000 sites throughout the county to prevent a large mosquito population and the viruses that come with them.

The county added they’re also working closely with communities prone to flooding by checking their crawlspaces something they recommend all families should do in case of any standing water.

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Posted by Vector and Vector-borne Disease Committee
March 22, 2023

Note:  The program is only available after registration for non-members.  

From KCRA 3
March 22, 2023

It is that time of year in the Sacramento Valley: mosquitoes are back.

The bad news? You’ll likely see more of them this season, and with more mosquitoes comes a higher risk of West Nile virus.

The Sacramento-Yolo Mosquito and Vector Control District says the ongoing wet winter storms across the region since New Year’s Eve weekend are to blame.

“I think the amount of water we’ve seen over the last month or so is definitely a big concern,” Gary Goodman, the district manager, told KCRA 3.

He says standing water is the issue, especially in many places that haven’t seen a lot of water over recent years due to the drought, and believes we will have higher mosquito populations by the summer.

“We are anticipating a much busier year from an abundance standpoint and a [West Nile] virus standpoint,” Goodman said.

The main places of concern are agricultural areas and around rivers, creeks, and streams.

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Posted by Vector and Vector-borne Disease Committee
March 20, 2023

MMWR Morb Mortal Wkly Rep 2023;72:290–291. http://dx.doi.org/10.15585/mmwr.mm7211a5

A Maricopa County, Arizona resident was hospitalized with Dengue-like symptoms on October 19, 2022 after brief travel to Mexicali, Mexico 7 days prior. RT-PCR testing was positive for dengue virus (DENV). Twenty-one mosquito pools within 5 miles of patient’s residence were tested retrospectively. One pool collected on October 5 tested positive for DENV. Whole genome sequencing identified both to be a DENV-3 strain not closely related to known strains in the area of travel. Preexisting response plans were activated and residences within a 150-meter radius were canvassed and residents interviewed. Twelve residents reporting recent Dengue-like symptoms were tested, all of which were negative by RT-PCR. Antibody testing of one of 53 resident without travel history was positive for Dengue antibodies, which were confirmed as DENV-3 by plaque reduction neutralization assay. Retrospective testing of 4,299 mosquito pools were negative. Aedes aegypti collected in BG-Sentinel traps were negative for DENV. The outbreak (2 cases) was declared over on January 4, 2023, following >45 days without additional cases.

Note: This outbreak provides a case study of a local DENV outbreak in a new area and shows the benefits of having a preexisting response plan in the event of local transmission of an Aedes aegypti transmitted virus.  

Posted by Vector and Vector-borne Disease Committee
March 20, 2023

Pascoe, EL et al.   

2023. Journal of Vector Ecology, https://doi.org/10.52707/1081-1710-48.1.19

Condensed abstract:

In 2018, the River Fire burned a forest in the far-western U.S.A. where the ecology of tick-borne pathogens had been studied for decades. Forest structure, avifauna, large and small mammals, lizards, ticks, and tick-borne pathogens were assessed after the wildfire in 2019 and 2020. Burning reduced canopy cover and eliminated the layer of thick leaf litter that hosted free-living ticks, which over time was replaced by forbs and grasses. Tick abundance and the vertebrate host community changed dramatically. Assays for pathogens found no B. miyamotoi in either questing or host-feeding ticks, A. phagocytophilum DNA in 4% (1/23) in 2019, and 17% (29/173) in 2020 for questing and host-feeding ticks combined, and B. burgdorferi DNA in just 1% of all ticks collected in 2020 (2/173).Authors concluded that a moderately severe wildfire can have dramatic impacts on the ecology of tick-borne pathogens, with changes posited to continue for multiple years.

Posted by Vector and Vector-borne Disease Committee
March 8, 2023

DR Abdel-Haleem, EE Badr, AM Samy, SA Baker

2023. Medical and Veterinary Entomology. https://doi.org/10.1111/mve.12645

Condensed Abstract:

Novel cationic gemini surfactants were synthesized to assess their insecticidal activities using laboratory and field strains larvae of Culex pipiens L. in comparison to clove oil and spinosad. The two surfactants G1 and G2 showed good insecticidal activities against the laboratory strain with LC₅₀ 0.013 and 0.054 ppm, respectively, relative to spinosad with LC₅₀ 0.027 ppm, 48 h posttreatment. Although spinosad showed high efficiency against lab strain, it exhibited a high resistance ratio (RR) of 15.1 and 13.1 toward the field strain at 24 and 48 h posttreatment, respectively. The two gemini surfactants have a good safety profile and low RR (RR <5). The results of this study are promising in terms of developing novel, effective, affordable, and safe approaches for mosquito control.

Notes:  Use of similar products is not new, but this work provides perhaps a useful alternative.

From the Sacramento Bee
March 7, 2023

As spring rolls in and temperatures warm, hiking one of Northern California’s many trails is an obvious activity to indulge, but it’s important to be wary of ticks.

The eight-legged arachnids are most active in warmer months, and the parasites thrive in humid and rainy environments, which increase tick populations and risk of Lyme disease.

The Sacramento-Yolo Mosquito and Vector Control District performs routine tests at Sacramento and Yolo county hiking trails. In Sacramento County, it has 15 testing sites. The Vector Control District has been testing along the American River, starting at Ancil Hoffman to Folsom Zoo.

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