Large-scalereleases and establishment of wMel Wolbachia in Aedes aegypti mosquitoes throughout the Cities of Bello, Medellı´n and Itagu¨ı´, Colombia. PLoS Negl

Velez ID, Uribe A, Barajas J, Uribe S, A´ ngel S, Suaza-Vasco JD, et al. (2023)

Trop Dis 17(11): e0011642.

The introduction of the naturally occurring wMel Wolbachia strain into Aedes aegypti mosquitoes has been shown to reduce the ability of the mosquitoes to transmit dengue and other viruses. Following engagement with communities to gain acceptance and support, a series of large-scale releases of Ae. aegypti mosquitoes that contained wMel Wolbachia, were undertaken across the cities of Bello, Medellı´n and Itagu¨ı´ in Colombia. These releases were undertaken under operational conditions with the aim of rapidly scaling the intervention in response to the Zika virus crisis. Mosquito populations were monitored during and after releases to determine the levels of Wolbachia and whether it persisted in the local mosquitoes. Wolbachia was found to be stable and established at consistent levels in local mosquito populations in the majority of areas. On-going monitoring in these areas will determine whether Wolbachia persists and also whether it establishes at a high level in the remaining areas. This intervention forms the basis of an epidemiological study to assess the impact of operational deployment of wMel Wolbachia on the reduction of the incidence of notified dengue cases and virologically-confirmed dengue.

Note: This important study shows the establishment of the wMel Wolbachia and the companion paper shows the reduction of dengue in the treated cities. However, this method does not reduce the biting pressure of Aedes aegypti and insecticide applications would be counter intuitive to this public health response.

Fitness costs in the presence and absence of insecticide use explains abundance of two common Aedes aegypti kdr resistance alleles found in the Americas.

Silva JJ, Fisher CR, Dressel AE, Scott JG (2023) 

PLoS Negl Trop Dis 17(11): e0011741 

Resistance to widely used pyrethroid insecticides can occur by mutations in the voltage gated sodium channel (Vgsc) and alleles with these mutations are collectively known as knockdown resistance (kdr). The frequency of resistance alleles is driven by selection with pyrethroid insecticides, but kdr alleles decrease in frequency in the absence of insecticide. The relative fitness of different kdr alleles to each other is largely unknown. We show through cage experiments that the 1534C allele is favored in the absence of pyrethroid applications, but that the 410L+1016I+1534C allele is favored when deltamethrin selection occurs. These results help to explain the relative frequency of these alleles that have been detected in field collections.

Q&A: New York Times Reporter Reflects on Global Malaria Fight

November 28, 2023

From Pest Control Technology

New York Times Global Health Reporter Stephanie Nolen traveled to five countries in Africa and Latin America to crack the code on what’s being done to control mosquito-borne diseases. Here’s what she found.

Read full article

CALL FOR NOMINATIONS: AMCA Social Media Coordinator

The American Mosquito Control Association (AMCA) is on the lookout for a Social Media Coordinator to join their dynamic team! It might be you or someone you know.

*Must be an AMCA member to apply*

Apply Today

Special Collection: Emerging and Lesser-Known Arboviruses Impacting Animal and Human Health: Emerging and lesser-known arboviruses impacting animal and human health.

A Faraji, G Molaei, T Andreadis. Special Collection: Emerging and Lesser-Known Arboviruses Impacting Animal and Human Health: Emerging and lesser-known arboviruses impacting animal and human health. J Medical Entomol, 60(6), 2023, 1139–1141.

This paper is the introduction to Special Collection of 10 papers on the epidemiology and ecology of emerging and lesser-known viruses of public and veterinary importance within the United States. Included within the series are papers on orbiviruses transmitted by Culicoides, lesser known viruses transmitted by mosquitoes including Cache Valley, Everglades, Jamestown Canyon, and LaCrosse, and recently discovered viruses transmitted by ticks including Bourbon, Heartland, Colorado tick fever, and Powassan.

FDA Approves First Vaccine Against Mosquito-Borne Virus Chikungunya

November 10, 2023

From The Washington Post

The Food and Drug Administration has approved the world’s first vaccine to prevent chikungunya, a mosquito-borne illness that can cause debilitating joint pain for months to years.

Read more here

Aedes Aegypti Oviposition-Sites Choice Under Semi-Field Conditions

David,M.R.,Maciel-de-Freitas,R., Petersen,M.T.,Bray,D.,Hawkes,F.M.,Fernández-Grandon, G.M.etal.(2023)

Aedes aegypti oviposition-sites choice under semi-field conditions. Medical and Veterinary Entomology, 37(4),683–692.

Available from:

Aedes aegypti in Brazil were offered a variety of oviposition containers within a semi-field cage. Gravid females preferred to oviposit close to the ground and in open water containers with organic compounds from plant watering. Domestic large artificial containers containing tap water received significantly fewer eggs, except for car tires, which received as many eggs as potted plants. Visual (potted plant shape) and olfactory clues (odor of the plant or from water containing organic matter) were equally attractive separately as they were together. These data may be useful in surveillance and control operations searching for larval sources.

First locally acquired case of dengue virus discovered in Pasadena

From CBS Los Angeles

October 20, 2023

Public health officials confirmed Friday the first locally acquired case of dengue virus in a Pasadena resident. This case is the first in California that is not associated with travel, according to Manuel Carmona, acting director of Public Health for the City of Pasadena. 

Read More

Rodent-targeted approaches to reduce acarological risk of human exposure to pathogen-infected Ixodes ticks.

Lars Eisen

Ticks Tick Borne Dis. 2023 Mar;14(2):102119,

Condensed abstract: In the United States, rodents serve as important hosts of medically important Ixodes ticks, including Ixodes scapularis and Ixodes pacificus, as well as reservoirs for human pathogens, including Anaplasma phagocytophilum, Borrelia burgdorferi sensu stricto (s.s.), and Babesia microti. Over the last four decades, different methods to disrupt enzootic transmission of these pathogens between tick vectors and rodent reservoirs have been developed and evaluated. These techniques include the application of topical acaricides, antibiotics, or a vaccine against Bo. burgdorferi s.s., delivered orally via rodent food baits. This review outlines the general benefits and drawbacks of rodent-targeted tick and pathogen control methods, and then describes the empirical evidence for different approaches to impact enzootic pathogen transmission and acarological risk of human exposure to pathogen-infected Ixodes ticks. Note: This review paper describes various rodent-targeted tick management techniques, summarizing results of experiments and compiling the benefits and drawbacks.

MVCAC’s Response to Dengue Case in Pasadena

In response to the locally acquired dengue case recently reported in Pasadena, MVCAC drafted a statement to assist with your outreach efforts and if you receive questions from residents and stakeholders.

Podcast Episode: The Mosquitoes Are Winning

From The Daily

For decades, the world seemed to be winning the war against mosquitoes and tamping down the deadly diseases they carried. But in the past few years, progress has not only stalled, it has reversed. Stephanie Nolen, who covers global health for The Times, explains how the mosquito has once again gained the upper hand in the fight.

Listen Now

CA West Nile Virus & Dead Bird Call Center closes for the season on October 13, 2023

This season, the California Department of Public Health received over 5,900 dead bird reports to the CA West Nile Virus & Dead Bird Call Center (1-877-WNV-BIRD) and website. Over 1,700 dead birds were collected for testing, with 773 birds testing positive for West Nile virus (WNV). On October 13, the Call Center will transition to internet-only reporting at WNV testing is limited in the fall and winter as WNV activity decreases, but dead bird reports are appreciated all year round.


Dengue Will ‘Take Off’ in Southern Europe, US, Africa This Decade, WHO Scientist Says

October 9, 2023

From MedScape

Dengue fever will become a major threat in the southern United States, southern Europe and new parts of Africa this decade, the WHO’s chief scientist said, as warmer temperatures create the conditions for the mosquitoes carrying the infection to spread.

Read more

AMCA Research Fund Day of Contributing: October 10, 2023

Date: Tuesday, October 10th, 2023

What Is It? It’s a day for everyone in the AMCA community to come together and support mosquito control research. Your contribution, no matter the amount, can make a significant impact.

How Can You Participate?

  1. Mark Your Calendar: Set a reminder for October 10th.
  2. Donate: We’ll provide a donation link on the day.
  3. Spread the Word: Share our social media posts to encourage your community to contribute too.

Why Do We Need Your Support? Your involvement can help us advance research, nurture young scientists, and protect public health. We are hoping our community can gather together to help us support one additional project each year!

Donate Today!

Convergent Trends and Spatiotemporal Patterns of Aedes-Borne Arboviruses in Mexico and Central America

Bernardo Gutierrez ,Darlan da Silva Candido,Sumali Bajaj,Abril Paulina Rodriguez Maldonado,Fabiola Garces Ayala,María de la Luz Torre Rodriguez,Adnan Araiza Rodriguez,Claudia Wong Arámbula,Ernesto Ramírez González,Irma López Martínez,José Alberto Díaz-Quiñónez,Mauricio Vázquez Pichardo,Sarah C. Hill, [ … ],Marina Escalera-Zamudio [ view all ]

Published: Plos Neglected Tropical Diseases, September 6, 2023

Results indicate that CHIKV, DENV-1 and DENV-2 in Mexico share evolutionary and epidemiological trajectories. The southwest region of the country was determined to be the most likely location for viral introductions from abroad, with a subsequent spread into the Pacific coast towards the north of Mexico. Virus diffusion patterns observed across the country are likely driven by multiple factors, including mobility linked to human migration from Central towards North America. Considering Mexico’s geographic positioning displaying a high human mobility across borders, our results prompt the need to better understand the role of anthropogenic factors in the transmission dynamics of Aedes-borne arboviruses, particularly linked to land-based human migration.

Direct Mosquito Feedings on Dengue-2 Virus-Infected People Reveal Dynamics of Human Infectiousness

Louis Lambrechts, Robert C. Reiner

Plos Neglected Tropical Diseases Sept 2023

This study in Iquitos, Peru, showed that dengue patients with mild disease were most infectious to Aedes aegypti mosquitoes 2 d after the onset of symptoms and that these mosquitoes were able to transmit their infection 7 – 16 d after blood feeding.  This empirical study provided a timeline for when secondary dengue cases could be expected following the onset of symptoms in an imported dengue case, thereby providing a timeline for preventive control operations.    

Article Series: Mosquitoes Are a Growing Public Health Threat, Reversing Years of Progress

September 29, 2023

From New York Times

Climate change and the rapid evolution of the insect have helped drive up malaria deaths and brought dengue and other mosquito-borne viruses to places that never had to worry about them.

Read more here

The late-summer itch: Ankle-biting mosquitoes are in extra full force in L.A. Why?

From LA Times

September 21, 2023

When you think “so L.A.,” Erewhon smoothies, Barbie-pink sunsets and baristas with IMDB credits might come to mind. Now you can add mosquitoes to the list.

Read more here


CA Endures Worst Mosquito Season In Years. When Will It End?

From Patch

September 16, 2023

As the blood-sucking ankle-biters take bite out of the Golden State, human West Nile Virus cases are spiking.

Read Here

The biting rate of Aedes aegypti and its variability: A systematic review(1970–2022).

:ZahidMH, VanWykH, MorrisonAC, ColomaJ, LeeGO, CevallosV, etal.(2023)

Author summary: Half of the world’s population is now at risk of dengue infection, which transmits to humans mostly through the bite of an infected female Aedes aegypti mosquito. Disease transmission models have played an important role in understanding the dynamics of dengue transmission and helping to develop control measures. The mosquito biting rate is one of the central parameters used in these models. Mosquito biting rates used in existing works are taken from a variety of studies, each with its strengths and limitations. To understand how existing study designs are used to estimate biting rate and how these estimates may vary over time, space, and environmental factors, we perform a systematic review of biting rate studies. We identify three study designs (human landing catch, marked-release-recapture, and histological) that play an important role in estimating per mosquito biting rates and capturing variability across a number of environmental factors. In particular, human landing catch studies can capture the variability of biting rates and marked-released-recapture studies along with histological studies can quantify the multiple feeding that occurs between ovipositions. Transmission modeling studies should be more informed by the biology of mosquito behavior. By understanding the biology of blood-feeding and context-specific factors, we can arrive at more informed per mosquito biting rate estimates for site-specific transmission model analysis.

[Submitted by the Vector and Vector-Borne Disease Committee]

West Nile virus is a growing threat this summer in California. What you need to know

August 30, 2023

From Los Angeles Times

West Nile virus infections are on the rise this year in California after a particularly wet winter led to more mosquito reproduction, according to health experts.

Read More

In the US, West Nile virus is leading cause of viral disease spread by insects, CDC study says

August 24, 2023

From CNN

The United States has seen a flurry of West Nile virus deaths reported in the last few days, including most recently in Illinois, Nebraska and Colorado.

Read More 

Community-based Integrated Tick Management Programs: Cost and Feasibility Scenarios

TL Schulze, L Eisen, K Russell, RA Jordan
Journal of Medical Entomology, tjad093,
Abstract: Numerous studies have assessed the efficacy of environmentally based control methods to suppress populations of the blacklegged tick (Ixodes scapularis Say), but few of these estimated the cost of control. We estimated costs for a range of tick control methods (including habitat management, deer exclusion or population reduction, broadcast of acaricides, and use of host-targeted acaricides) implemented singly or in combination and applied to a model community comprising 320 residential properties and parklands. Using the high end for cost ranges, tick control based on a single method was estimated to have mean annual costs per household ranging from $132 for treating only forest ecotone with a broadcast synthetic acaricide to kill host-seeking ticks (or $404 for treating all residential forested habitat) to >$2,000 for deployment of bait boxes (SELECT TCS) across all residential tick habitat to treat rodents topically with acaricide to kill infesting ticks. Combining different sets of multiple methods in an integrated tick management program placed the annual cost between $508 and 3,192 annually per household, underscoring the disconnect between what people in Lyme disease endemic areas say they are willing to pay for tick control (not more than $100–150 annually) and the actual costs for tick control. Additional barriers to implementing community-based tick management programs within residential communities are discussed.
Notes: Surveillance and determination of pathogen risk provide a basis for public health messaging to warn the public in affected areas, but do little to actually mitigate the problem. As risk elevates so does the mandate for a coordinated response. Schulze et al. provide estimates of mitigation costs to residents residing within Lyme disease endemic areas in the Eastern USA. These data are useful for MVCAC agencies considering mitigation in response to increasing threats of tick-borne diseases. 
[Submitted by the Vector and Vector-Borne Disease Committee]

Delftia Tsuruhatensis TC1 Symbiont Suppresses Malaria Transmission by Anopheline Mosquitoes

Huang, W., J. Rodrigues, E. Bilgo, J. R. Tormo, J. D. Challenger, C. De Cozar-Gallardo, I. Pérez-Victoria, F. Reyes, P. Castañeda-Casado, E. J. Gnambani, D. F. Hien, M. Konkobo, B. Urones, I. Coppens, A. Mendoza-Losana, L. Ballell, A. Diabate, T. S. Churcher, and M. Jacobs-Lorena. 2023. delftia tsuruhatensis TC1 symbiont suppresses malaria transmission by Anopheline Mosquitoes. Science. 381: 533–540. DOI:
Abstract: Malaria control demands the development of a wide range of complementary strategies. We describe the properties of a naturally occurring, non–genetically modified symbiotic bacterium, Delftia tsuruhatensis TC1, which was isolated from mosquitoes incapable of sustaining the development of Plasmodium falciparum parasites. D. tsuruhatensis TC1 inhibits early stages of Plasmodium development and subsequent transmission by the Anopheles mosquito through secretion of a small-molecule inhibitor. We have identified this inhibitor to be the hydrophobic molecule harmane. We also found that, on mosquito contact, harmane penetrates the cuticle, inhibiting Plasmodium development. D. tsuruhatensis TC1 stably populates the mosquito gut, does not impose a fitness cost on the mosquito, and inhibits Plasmodium development for the mosquito’s life. Contained field studies in Burkina Faso and modeling showed that D. tsuruhatensis TC1 has the potential to complement mosquito-targeted malaria transmission control.
Notes: This article describes the findings of a study investigating the role of harmane, a compound secreted by Delftia tsuruhatensis TC1 bacteria, in the disruption of Plasmodium development in the midgut and the reduction of sporozoite prevalence in salivary glands of anopheline mosquitoes. The authors also describe the efficacious delivery of D. tsuruhatensis TC1 to larvae and adult mosquitoes in laboratory and field settings, indicating the versatility of potential deployment in the field.  Studies like this show the importance of understanding the mosquito microbiome in variability seen in pathogen transmission in the laboratory and field. 
[submitted by the Vector and Vector-Borne Disease Committee]

Near Tulare Lake, State Disaster Relief Includes Millions for Mosquito Abatement


August 7, 2023

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

Read More

Fleaborne Typhus–Associated Deaths

Los Angeles County, California, 2022

Alarcón J, Sanosyan A, Contreras ZA, et al. MMWR Morb Mortal Wkly Rep 2023;72:838–843. DOI:
Abstract. Fleaborne typhus (also known as murine typhus), a widely distributed vectorborne zoonosis caused by Rickettsia typhi, is a moderately severe, but infrequently fatal illness; among patients who receive doxycycline, the case-fatality rate is <1%. Fleaborne typhus is a mandated reportable condition in California. Reported fleaborne typhus cases in Los Angeles County have been increasing since 2010, with the highest number (171) reported during 2022. During June–October 2022, Los Angeles County Department of Public Health learned of three fleaborne typhus–associated deaths. This report describes the clinical presentation, illness course, and methods used to diagnose fleaborne typhus in these three cases. Increased health care provider and public health awareness of the prevalence and severity of fleaborne typhus and of the importance of early doxycycline therapy is essential for prevention and treaogy oftment efforts.
Comment.  For detailed accounts on the evolution and extent of this problem in Los Angeles and Orange Counties see Cummings et al. (2022: PMVCAC 90: 33-42).  As reviewed, the epidemiology and etiology of typhus has been somewhat confounded by the occurrence of two rickettsia with differing life cycles and transmission patterns. However, the expansion of urban rodent, opossum and feral cat populations clearly have exacerbated the problem. The spread of homeless encampments is a related issue. Clinical research is needed to identify which rickettsia are involved in human disease, to delineate the extent of human infection in California, and to identify risk factors that may be targets for public health/vector control district intervention. Although human cases mostly seem confined to southern California, Rickettsia felis most likely is present wherever cat flea populations are found.  
[Submitted by the Vector and Vectorborne Disease Committee]    

Statement on Locally Acquired Malaria Cases in Florida and Texas

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 To learn more about malaria please visit the CDC and the California Department of Public Health.

West Nile Virus Strikes Again: Mosquito Spraying Ramps Up in San Jose, Milpitas

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. 


Read more

Dangerous virus detected in mosquitoes in New Hampshire

From WMUR9

July 26, 2023

Health officials urge residents to take precautions. The mosquito-borne Jamestown Canyon virus has been detected in seven batches of mosquitoes in New Hampshire this year but has so far not been found in people.

Read more

New Process for Submitting Updated NOIs and PAPs to the State Water Board

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 3rd 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,, 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, if you have any additional questions.

Locally Acquired Cases of Malaria in Florida and Texas

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

[]. 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]

Field Evaluation of In2Care Mosquito Traps to Control Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in Hawai’i Island.

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

J Med Entomol 60: 364–372,

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].  

Mosquito Samples in Tulare County Test Positive for West Nile Virus

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.

Read more

Vector-Borne Bacterial Diseases: a Neglected Field of Infection Diseases Research

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.

Assessing the Influence of Climate on the Spatial Pattern of West Nile Virus Incidence in the United States

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.

*Author email:

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.


How drones in South Bay are combatting an expected heightened mosquito season

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.

Read more

Fight the Bite: County to Drop Mosquito Larvicide in Local Waterways Next Week

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.

Read more

Epidemic versus endemic West Nile virus dead bird surveillance in California: Changes in sensitivity and focus.

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

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


PLoS ONE April 6, 2023

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.

This mosquito season could be worse than before after SoCal’s historic rainfall

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.

Read more

Mosquito Awareness Week

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

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

Communities without Invasive Aedes

A systematic review of published literature on mosquito control action thresholds across the world

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*


PLoS Neglected Tropical Diseases 2023.

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. 

Will SoCal see more mosquitoes after all this rain? Officials urge residents to prepare now

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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‘Big concern’: Unusual mosquito season may be coming to California

From the San Francisco Gate
March 26, 2023

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

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Health Experts Warn of Mosquitoes in Standing Water Following Recent Storms

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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2023 International Branch Virtual Symposium Program Now Available

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

The online program for the 2023 International Branch Virtual Symposium now available! Check out the program and start planning your schedule. Plus, register now for FREE! Registration is free for ESA members and non-members alike. Spread the word and build excitement for insect science. Register nowreview the program, and learn more about the plenary speakers below.

April 24: Climate Change and Its Impact on Biological Control April 25: Endangered Species, Diversity/Taxonomy, Pest Management, and Social Insects April 26: Virus Vector Interaction

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

Why Sacramento Valley experts believe you will see (and feel) more mosquitoes this season

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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Kretschmer M, Collins J, Dale AP, et al. Notes From the Field: First Evidence of Locally Acquired Dengue Virus Infection — Maricopa County, Arizona, November 2022

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

MMWR Morb Mortal Wkly Rep 2023;72:290–291.

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.