From the Modesto Bee
July 13, 2022

Stanislaus County public health officials confirmed a case of St. Louis encephalitis Wednesday.

The viral disease spread by mosquitoes is less common than West Nile virus, an endemic illness that generates attention every year in the Central Valley.

According to a county news release, an adult male suffering from neurologic illness tested positive for the St. Louis encephalitis virus. It’s the county’s first case of the viral disease this year.

Officials did not know where the man contracted the illness. As of last week, neither the St. Louis or West Nile viruses had been detected in the environment in Stanislaus County by mosquito abatement districts. The related viruses haven’t been found in mosquito samples or dead birds, and no infections in horses.

“We are not aware whether the individual traveled out of county or not,” a county spokesperson said by email.

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From CBS Los Angeles
July 11, 2022

Nine new samples have come up positive for West Nile virus across Los Angeles County, vector control district officials announced Monday.

New positive samples were collected from six different communities — Granada Hills, Hacienda Heights, Lake Balboa, Northridge, Panorama City, and Whittier, bringing the total number of positive samples in the district to 12 so far this year.

Two samples positive for West Nile have been collected in four communities — Northridge, Panorama City, San Marino, and Whittier.

The virus, which is endemic to Los Angeles County, was first confirmed this year in June, in three dead crows collected in the North Hills area on May 26.It was soon followed by a positive test from a mosquito sample taken in Bellflower.

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From the Daily Journal
July 11, 2022

From KRON4
July 10, 2022

SANTA CLARA CO., Calif. (BCN) — Mosquitoes with West Nile virus have been found in Sunnyvale and Santa Clara.

The County of Santa Clara Vector Control District has confirmed the presence of West Nile virus-positive mosquitoes in ZIP codes 94085, 94086, 94087 and 95051. To reduce adult mosquito populations, Vector Control will be spraying these areas with truck-mounted equipment on Monday, July 11 at about 10 p.m. and concluding a few hours later. Vector Control has not found additional positive mosquitoes in Santa Clara County except for Milpitas where spraying occurred last week.

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Posted by Vector and Vector-borne Disease Committee
July 2, 2022

Authors: Chanida Fongsaran, Krit Jirakanwisal, Natthida Tongluan, Allison Latour, Sean Healy, Rebecca C. Christofferson, Kevin R. Macaluso

Affiliation:  Vector-Borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, and Department of Microbiology and Immunology, College of Medicine, University of South Alabama, Mobile, Alabama, United States of America

Open access:  PLoS Negl Trop Dis 16(6): e0010576. https://doi.org/10.1371/journal.pntd.0010576

Abstract.   Rickettsia felis is an emerging etiological agent of rickettsioses worldwide. The cosmopolitan cat flea (Ctenocephalides felis) is the primary vector of R. felis, but R. felis has also been reported in other species of hematophagous arthropods including ticks and mosquitoes. Canines can serve as a bacteremic host to infect fleas under laboratory conditions, yet isolation of R. felis from the blood of a vertebrate host in nature has not been realized. Cofeeding transmission is an efficient mechanism for transmitting rickettsiae between infected and uninfected fleas; however, the mechanism of transmission among different orders and classes of arthropods is not known. The potential for R. felis transmission between infected fleas and tick (Dermacentor variabilis) and mosquito (Anopheles quadrimaculatus) hosts was examined via cofeeding bioassays. Donor cat fleas infected with R. felis transmitted the agent to naïve D. variabilis nymphs via cofeeding on a rat host. Subsequent transstadial transmission of R. felis from the engorged nymphs to the adult ticks was observed with reduced prevalence in adult ticks. Using an artificial host system, An. quadrimaculatus exposed to a R. felis-infected blood meal acquired rickettsiae and maintained infection over 12 days post-exposure (dpe). Similar to ticks, mosquitoes were able to acquire R. felis while cofeeding with infected cat fleas on rats, infection persisting in the mosquito for up to 3 dpe. The results indicate R. felis-infected cat fleas can transmit rickettsiae to both ticks and mosquitoes via cofeeding on a vertebrate host, thus providing a potential avenue for the diversity of R. felis-infected arthropods in nature.

Note:  The epidemiology of emerging flea borne typhus transmission remains poorly understood, but is becoming an increasing public health problem in southern California [see PMVCAC].  Although R. felis may be maintained vertically in  cat fleas, horizontal transmission via bacteremic mammals has not been shown.   Transmission via co-feeding has been shown for arboviruses in the laboraory and is considered a mode of transmission of tick borne encephalitis virus by Ixodes ricinus.  In the current study, infection by co-feeding was shown using a non-infected rodent or artificial blood meals.   However, unless hosts develop a bacteremia, transmission would seem to rely on co-feeding by infected and non-infected arthropods in close proximity or by non-bacteremia transmission when feeding on small sized hosts with a small blood volume and therefore minimal pathogen dilution.

From the County of Santa Clara
June 29, 2022

Targeted adult mosquito control treatment scheduled for Thursday, June 30 in a limited area within Milpitas

SANTA CLARA COUNTY, CALIF. – The County of Santa Clara Vector Control District has confirmed the presence of West Nile virus (WNV) positive mosquitoes in an area of Milpitas (ZIP Code 95035). Weather permitting, this area will be treated to reduce adult mosquito populations with the use of truck-mounted equipment on Thursday, June 30, starting around 10 p.m., and will conclude a few hours later.

The Vector Control District has a dedicated surveillance program to detect the presence of diseases like West Nile virus, St. Louis encephalitis, and western equine encephalitis, all of which are transmitted through the bite of infected mosquitoes. The data collected through surveillance is used to predict locations that are more likely to have these disease-transmitting mosquitoes. When a WNV-positive mosquito is detected, the District initiates an adult mosquito control treatment to reduce the mosquito population in the area, which reduces the risk of a WNV human infection.

The District has been conducting truck-mounted treatments regularly since 2003 to successfully reduce WNV-transmitting mosquito populations. The District will be adhering to requirements and recommendations from the County of Santa Clara Public Health Department for COVID-19.

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From Action News Now
June 28, 2022

BUTTE COUNTY, Calif. – The mosquito that carries yellow fever has been confirmed in Butte County.

This is the third year in a row that Butte County Mosquito and Vector Control has found one of the Aedes Aegypti. 

It can carry other viruses too, like Dengue and Zika.

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Posted by Vector and Vector-borne Disease Committee
June 27, 2022

Seynabou Sougoufara, Hanna Yorkston-Dives, Nurul Masyirah Aklee, Adanan Che Rus, Jaal Zairi & Frederic Tripet

Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Stafforshire, United Kingdom;   Vector Control Research Unit, School of Biological Sciences, Universiti Sains Malaysia, George Town, Malaysia

Nature Sci Rep 12, 2206 (2022). https://doi.org/10.1038/s41598-022-05754-2

Abstract.  Vector-borne diseases are worldwide public health issues. Despite research focused on vectorial capacity determinants in pathogen transmitting mosquitoes, their behavioural plasticity remains poorly understood. Memory and associative learning have been linked to behavioural changes in several insect species, but their relevance in behavioural responses to pesticide vector control has been largely overlooked. In this study, female Aedes aegypti and Culex quinquefasciastus were exposed to sub-lethal doses of 5 pesticide compounds using modified World Health Organization (WHO) tube bioassays. Conditioned females, subsequently exposed to the same pesticides in WHO tunnel assays, exhibited behavioural avoidance by forgoing blood-feeding to ensure survival. Standardized resting site choice tests showed that pre-exposed females avoided the pesticides smell and choose to rest in a pesticide-free compartment. These results showed that, following a single exposure, mosquitoes can associate the olfactory stimulus of pesticides with their detrimental effects and subsequently avoid pesticide contact. Findings highlight the importance of mosquito cognition as determinants of pesticide resistance in mosquito populations targeted by chemical control.

Note:  Although this study has greatest relevance for control programs using indoor surface sprays and impregnated bed nets, the concept of learning behavior in mosquitoes is intriguing and may have important implications for the use of home fumigation products. 

From Yahoo News
June 25, 2022

Jun. 25—STOCKTON — The San Joaquin County Mosquito and Vector Control District announced Thursday that its mosquito-borne disease surveillance program recently detected West Nile virus (WNV) in six samples of mosquitoes found in the 95209 and 95219 ZIP codes.

The 95209 ZIP code is located in Stockton east of Interstate 5 and north of Hammer Lane. The 95219 ZIP code is located west of I-5.

“These WNV positive mosquitoes are the first indicator that WNV is active in San Joaquin County this year,” district spokesman Aaron Devencenzi said. “As temperatures rise during the summer months, so will mosquito populations. West Nile virus will amplify within the mosquito population, leading to an elevated risk of WNV in humans.”

The district said it will increase is adult mosquito control activities now that WNV has been detected in the county, and planned to conduct ground spraying in the northwest Stockton Friday or Saturday between Stanfield Drive, Mosher Slough, Thornton Road and Bainbridge Palce.

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From the Los Angeles Times
June 24, 2022

Summer is here and so are the mosquitoes in your backyard, waiting to nibble at your ankles. And elbows. And earlobes.

Not coincidentally, the start of the season is also National Mosquito Control Awareness Week, when the American Mosquito Control Assn. and other experts share tips for keeping these bloodsucking pests away.

Like most blood-feeding insects, mosquitoes are attracted to humans from a distance by the carbon dioxide we exhale, said Daniel Markowski, the AMCA’s technical advisor. Once they get close, they use a variety of other cues, such as shapes, sizes and colors, to home in on their hosts.

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From the Merced Sun-Star
June 21, 2022

The year’s first local confirmation of West Nile Virus was announced by the Merced County Mosquito Abatement District Tuesday, along with an appeal to the public to help suppress mosquito activity.

No human cases have been detected in Merced County at this time, but a mosquito pooled sample collected in the City of Merced recently tested positive for the virus, according to an abatement district news release.

Although no positive human cases have been reported yet this year, the public should citizens should still be concerned, as more confirmations of the virus will likely ensue in the following weeks, the release said.

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Posted by Vector and Vector-borne Disease Committee
June 21, 2022

Kate Varela, Jennifer A. Brown, Beth Lipton, John Dunn, Danielle Stanek and NASPHV Committee Consultants

VECTOR-BORNE AND ZOONOTIC DISEASES 22 (6), 2022;  DOI: 10.1089/vbz.2022.0022

Authors’ Summary.  As ownership of non-traditional pet (NTP) species is increasing, the number and size of outbreaks associated with NTPs in recent years has also increased. Non-traditional pet owners and members of the public who may come into contact with NTPs should be aware of the potential health risks and understand that even apparently healthy animals can transmit pathogens. The recommendations in this Compendium provide public health professionals, animal health professionals, industry, and healthcare providers (including veterinarians, physicians, and allied health professionals) resources to prevent disease transmission and spread. These recommendations aim to benefit all partners by preventing human infections, maintaining animal health and welfare, and providing economic benefits.

Note:  The publication reviews useful information about health problems related to pets, including back yard chicken flocks.  As these pets become more widespread, vector control districts as well as veterinarians undoubtedly will be contacted to resolve public health issues, including arthropod infestations.  

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Posted by Vector and Vector-borne Disease Committee
June 21, 2022

1. Erin Staples,1* Katherine B. Gibney,1,2, Amanda J. Panella,1 Harry E. Prince,3 Alison J. Basile,1  Janeen Laven,1  James J. Sejvar,4  and Marc Fischer1

1Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado; 2Epidemic Intelligence Service Program, CDC, Atlanta, Georgia; 3Quest Diagnostics Infectious Disease, Inc., San Juan Capistrano, California; 4Division ofHigh-Consequence Pathogens and Pathology, CDC, Atlanta, Georgia

Am. J. Trop. Med. Hyg.;  doi:10.4269/ajtmh.21-1234

Abstract. West Nile virus (WNV) IgM antibodies typically indicate a recent infection. However, WNV IgM antibodies can remain detectable for months to years following illness onset. We found that 23% (11/47) of samples tested with a WNV ELISA and 43% (20/47) of samples tested with WNV microsphere immunoassay (MIA) at 16–19 months following WNV illness onset were positive for IgM antibodies. The proportion of samples testing positive for WNV IgM by ELISA decreased over time, but 5% (2/44) of individuals remained positive at 60–63 months after their acute illness and 4% (2/50) were WNV IgM equivocal at 72–81 months. Clinicians and public health officials should consider these findings along with clinical and epidemiologic data when interpreting WNV IgM antibody test results.

Note:  WNV surveillance programs frequently make decisions concerning adulticide applications based on reported human cases.  This study indicates that laboratory confirmation of suspect cases based on IgM ELISA could be the result of previous exposure and not due to recent infection.  Careful evaluation of case data combined with mosquito and mosquito infection data should be included in application decisions. 

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From the Daily Republic
June 17, 2022

FAIRFIELD — The recognition of National Mosquito Control Awareness Week lets area residents know the height of the mosquito season is closing in fast.

“National Mosquito Control Awareness Week, celebrated June 19-25 throughout the country, is a good time for community members to ensure they are doing their part to protect themselves from mosquito-transmitted diseases,” Assemblyman Bill Quirk, D-Hayward, said in a statement released by the Mosquito Vector Control Association of California. “Residents can take simple steps to help eliminate mosquitoes from their community and protect themselves from mosquito bites.”

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From the Manteca Bulletin
June 16, 2022

Free distribution of mosquitofish will be available to residents of Ripon, Manteca, Lathrop and the surrounding San Joaquin County areas.

This was announced Wednesday by the San Joaquin County Mosquito & Vector Control District.

The mosquito fish is a natural and effective way of fighting the breeding of mosquitos. Some species can pose major public health concerns by transmitting anything from the West Nile Virus to malaria and encephalitis.

According to SJC Mosquito & Vector Control District, each fish can eat 80 to 100 mosquito larvae and pupae per day.

A maximum of 15 fishes – ideally placed in ornamental ponds, neglected swimming pools, and animal water troughs – will be provided to residents of cities and rural areas of the county. Required will be a name, address and the location of where the fish will be placed.

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From OCMVCD
June 15, 2022

Garden Grove, CA.  June brings warm weather, more mosquitoes, and National Mosquito Awareness Week. To increase awareness of mosquitoes and the diseases they can transmit, Orange County Mosquito and Vector Control District (OCMVCD) is expanding partnerships with local agencies and promoting new educational resources for residents.

During National Mosquito Control Awareness Week, June 19-25, OCMVCD is launching the Tip, Toss, Take Action campaign and promoting Grandmother Mosquito, a new children’s book teaching families about mosquito breeding. To increase awareness and educational outreach, OCMVCD will be interacting with the public in the following ways:

• Partnering with OC Public Libraries’ Storytime series to promote a new children’s book called Grandmother Mosquito.
• Engaging with residents at the Discovery Cube of Orange County with activities, crafts, and opportunities to speak with experts on June 18^th.
• Releasing an “Ask the Expert” video series that allows community members to submit questions to OCMVCD experts.
• Hosting giveaways and trivia questions. 

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From New Santa Ana
June 15, 2022

Garden Grove, CA. June brings warm weather, more mosquitoes, and National Mosquito Awareness Week. To increase awareness of mosquitoes and the diseases they can transmit, Orange County Mosquito and Vector Control District (OCMVCD) is expanding partnerships with local agencies and promoting new educational resources for residents.

During National Mosquito Control Awareness Week, June 19-25, OCMVCD is launching the Tip, Toss, Take Action campaign and promoting Grandmother Mosquito, a new children’s book teaching families about mosquito breeding. 

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From the Antelope Valley Press
June 15, 2022

From NBC Los Angeles
June 13, 2022

What is the West Nile Virus?

The “West Nile Virus” was first identified in the sub-region of Uganda called The West Nile.

The virus runs during mosquito season, which takes place from summer through fall. It is present within all states of the continental U.S.

The virus survives within several types of birds and is transmitted when a mosquito feeds off of an infected bird. The disease can infect humans, horses, and birds.

It is the most common vector-borne virus in California with more than 7,000 human cases and over 300 deaths in California since 2003.

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From KTLA
June 13, 2022

A mosquito tested positive for West Nile virus in Los Angeles County, marking the first such sample this year, health officials announced Monday.

The positive mosquito sample was collected from a mosquito trap in Bellflower, confirming the presence of the virus in mosquito populations within the community, according to the Greater Los Angeles County Vector Control District.

While this confirmation serves as the first positive mosquito sample this year, West Nile virus was detected in three dead crows found in the North Hills neighborhood on May 26, the agency said.

Surveilling dead birds serves as an early warning detection tool that helps authorities identify when the virus is actively being transmitted between birds in the area.

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From NBC Palm Springs
June 8, 2022

THERMAL (CNS) – Mosquitoes collected in Thermal tested positive for West Nile virus, the first detection of the virus in the city this year, the Coachella Valley Mosquito and Vector Control District announced today.

The mosquitoes were collected near 68th Avenue and Fillmore Street in Thermal, according to the district.

In response, mosquito-control technicians increased their presence in the Coachella Valley, carrying out control treatments in hopes of reducing any spread of the virus. District officials, however, urged residents to take precautions.

“Before going out, apply insect repellent containing the EPA-registered ingredients,” district public information officer Tammy Gordon said in a statement. “There is no cure or vaccine for West Nile virus, it’s not worth getting sick.”

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From Gold Country Media
June 7, 2022

The Placer Mosquito and Vector Control District encourages area residents to prepare now for West Nile virus season by protecting themselves from potential mosquito bites.

With no cure available, West Nile virus is a serious and potentially fatal illness transmitted through the bite of a female mosquito.

Although West Nile Virus has not yet been detected in Placer County this season, the district’s public information officer Meagan Luevano said, the virus has been detected in Yolo and Sacramento counties.

A dead bird that tested positive for West Nile virus was found two weeks ago in Davis and a positive pool of mosquitoes was found last week in Carmichael, according to Luevano..

“The detections are super close to us,” Luevano said. “These detections are not that much earlier than our detections last season. Our first West Nile virus positive mosquito sample was June 23 last year.”

Placer County had one human case of the virus last year.

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From SCV News
June 7, 2022

The Greater Los Angeles County Vector Control District has confirmed the first detection in 2022 of West Nile virus activity in Los Angeles County. The virus was detected in three dead American crows collected in the neighborhood of North Hills Zip Code 91343 on May 26.

This confirmation serves as the District’s first detection of West Nile virus activity in 2022. Mosquito samples have not tested positive for the virus within the surrounding community, nor in Los Angeles County. The dead bird surveillance program serves as an early warning detection tool that helps identify when the virus is actively being transmitted within the bird population. The three dead birds were collected, shipped and tested at the university of California, Davis Arbovirus Research and Training Laboratory which provides testing for multiple vector control agencies across the state.

“American crows can fly up to 40 miles each day from overnight roosting sites, so while there has not yet been virus activity detected in mosquito populations in Los Angeles County, this confirmation serves as an alert that mosquitoes may soon become infected and residents should take precautions,” said Director of Scientific-Technical Services Steve Vetrone.

Since West Nile virus is endemic to Los Angeles County, it is typically detected by local public health agencies during summer. Because there is no human vaccine for West Nile, residents must be proactive against mosquito bites by wearing insect repellent. The Centers for Disease Control and Prevention recommend products with the active ingredients DEET, Picaridin, IR3535, or oil of lemon eucalyptus as being safe and effective against mosquitoes that can transmit disease when used according to the labels.

One in five persons infected with the virus will exhibit symptoms. Symptoms can include fever, headache, body aches, nausea, or skin rash. These symptoms can last for several days to months. One in 150 people infected with the virus will require hospitalization. Severe symptoms include high fever, muscle weakness, neck stiffness, coma, paralysis and possibly death. If residents feel they are experiencing symptoms, it is strongly recommended to consult their primary care physician.

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From CBS Los Angeles
June 6, 2022

West Nile virus has been confirmed in Los Angeles County for the first time this year, authorities said Monday.

The virus was detected in three dead crows collected in the North Hills area on May 26, according to the Los Angeles County Vector Control District. Mosquito samples had not tested positive for the virus in Los Angeles County yet.

“American crows can fly up to 40 miles each day from overnight roosting sites, so while there has not yet been virus activity detected in mosquito populations in Los Angeles County, this confirmation serves as an alert that mosquitos may soon become infected, and residents should take precautions,” Steve Vetrone, director of Scientific-Technical Services, said in a statement.

There is no human vaccine for West Nile virus, which is usually transmitted via mosquito bite. Symptoms of West Nile include fever, headache, body aches, nausea, or skin rash that can last for several days to months. One of 150 people will require hospitalization, and severe symptoms include coma, paralysis, and death, authorities said.

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From ABC 13
June 6, 2022

MONTGOMERY COUNTY, Texas (KTRK) — Officials confirmed a case of West Nile virus has been found in The Woodlands’ first mosquito samples of the 2022 season.

The mosquitos were caught through the course of the week in zip codes 77380 and 77382.

According to city officials, treatment of the affected areas will begin Tuesday, including spraying all streets and county rights of way. The second round of treatment is scheduled for Thursday.

“Our office is working diligently to minimize the risk of contracting a mosquito-borne illness,” Precinct 3 Commissioner James Noack said.

Residents can check the treatment activity map to learn when spraying will occur in their neighborhoods.

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Posted by Vector and Vector-borne Disease Committee
June 6, 2022

Mary E. Danforth1, Robert E. Snyder1, Emma T. N. Lonstrup2, Christopher M. Barker2, Vicki L. Kramer1ID

1 Vector-Borne Disease Section, California Department of Public Health, Sacramento, CA,

2 Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA

PLoS Negl Trop Dis 16(5): e0010375. https://doi.org/10.1371/journal.pntd.0010375

Abstract [partial].  …  We built models to determine the association between risk level and the number of reported symptomatic human West Nile disease cases with onset in the following three weeks to identify the essential components of the risk level and to compare California’s risk estimates to vector index. Risk level calculations based on Culex tarsalis and/or Cx. pipiens complex levels were significantly associated with increased human risk, particularly when accounting for vector control area

and population, and were better predictors than using the vector index. Including all potential

environmental components  created an effective tool to estimate the risk of WNV transmission

to humans in California.

Note.   There has been a trend among MVCAC agencies to reduce the number of surveillance components used to monitor WNV transmission risk.  Currently fewer agencies report and test dead birds, and deploy chicken flocks each year.  These components have been replaced by increased mosquito trapping and testing, and the calculation of the Vector Index.  The current analyses show that the inclusion of avian host as well as mosquito infection data enhances estimates of human disease risk. 

From aginfo.net
June 1, 2022

While much of the western U.S. endures widespread drought, people may think mosquito season won’t be as intense. However, just because there’s no rain doesn’t mean there are no mosquitoes.

“Some of the most significant West Nile outbreaks have happened without significant rainfall,” says Dr. Justin Talley, Head of Entomology and Plant Pathology at Oklahoma State University. “Just because you don’t see water doesn’t mean there are no breeding areas around.”

He shared four tips for protecting horses from West Nile Virus. The first is to vaccinate your horses. Number two is hanging high-powered livestock fans. Third, get rid of as much standing water as possible and clean the horses’ water sources once a week.

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From KGET
June 1, 2022

BAKERSFIELD, Calif. (KGET) – Kern County’s ongoing battle against disease-carrying mosquitoes has a new weapon. A truck-mounted sprayer that’s capable of producing a super-fine, super-effective mist is coming to a neighborhood near you.

It’s called a Wide Area Larvicide Spraying system, and it will specifically target ankle-biters, or as they’re more formally known, Aedes aegypti. Those are the persistent bugs that showed up in Arvin in 2013, made their way to Bakersfield in 2018 and haven’t left since then.

They’re not just annoying – they can carry West Nile Virus. Starting June 6, the Kern Mosquito and Vector Control District’s new spraying system – WILS for short – will embark on a six-week pilot project. But you’re not invited to watch, even if you’re tempted by the rather noisy motor.

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From Fox 40
May 31, 2022

DAVIS, Calif (KTXL) — A dead American Crow collected in Davis was found to be carrying West Nile Virus by the Sacramento-Yolo Mosquito and Vector Control on Tuesday, according to vector control.

This is the first sign of West Nile Virus activity in the Sacramento area this year, according to vector control.

“Finding the first positive bird is always significant because it provides an early warning sign for the disease,” District Manager Gary Goodman said. “It confirms that the virus is present, provides a good indication of where we may find positive mosquito samples and where human cases may develop later in the season”

According to vector control, this is not the first sign of the virus in California as other counties have already seen activity of the virus.

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From the Sacramento Bee
May 31, 2022

Summer has not yet begun, but the Sacramento-Yolo Mosquito and Vector Control District confirmed Tuesday that they already have found one bird that has tested positive for West Nile virus.

“Finding the first positive bird is always significant because it provides an early warning sign for the disease,” said District Manager Gary Goodman. “It confirms that the virus is present, provides a good indication of where we may find positive mosquito samples and where human cases may develop later in the season,”

Found in Davis, the bird is an American crow and is the second West Nile-positive bird discovered statewide this year. Vector districts in Contra Costa, Fresno, Kern, Orange and Riverside counties already have confirmed West Nile activity in mosquito samples, according to the westnile.ca.gov website. Contra Costa officials reported the first dead bird with the virus statewide on May 17 — it was found in an area of Brentwood close to Discovery Bay.

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From Bakersfield.com
May 31, 2022

From the Sonoma County Gazette
May 27, 2022

The Marin/Sonoma Mosquito and Vector Control District is reminding residents to pack mosquito repellent when preparing for outdoor activities this Memorial Day weekend. “The holiday weekend is a time when many residents spend time outdoors,” stated Nizza Sequeira, Public Information Officer for the Marin/Sonoma Mosquito and Vector Control District. “Protection against mosquito bites and mosquito-borne diseases is imperative, especially at dusk and dawn. Personal protection measures include wearing long sleeves and long pants, and applying an effective insect repellent to exposed skin,” said Sequeira

While West Nile virus is endemic to the area, District officials say it has not yet been detected in Marin and Sonoma counties this year. West Nile virus activity has been detected in other areas of California, though, so residents should be extra vigilant about protecting themselves from mosquito bites when traveling to other areas.

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Posted by Vector and Vector-borne Disease Committee
May 26, 2022

ANDALEEB SAJID [HTTPS://ORCID.ORG/0000-0001-6248-4985], AQUELINE MATIAS, GUNJAN ARORA, CHEYNE KUROKAWA, KATHLEEN DEPONT, EXIAOTIAN TANG, et al. 

SCIENCE TRANSLATIONAL MEDICINE [17 Nov 21], Vol 13 [620], <DOI: 10.1126/scitranslmed.abj9827>

Summary [Journal].  Repeated exposures to the black-legged tick, Ixodes scapularis, can lead to acquired resistance against ticks or “tick immunity.” To generate tick resistance, the authors developed an mRNA vaccine that encoded for 19 I. scapularis salivary proteins (19ISP). Guinea pigs vaccinated with 19ISP developed erythema at the site of tick attachment, a feature of acquired tick resistance. This led to poor tick feeding and, in the case of ticks infected with the Lyme disease agent, Borrelia burgdorferi, reduced transmission of the pathogen. Thus, 19ISP is a promising candidate for antitick vaccines that may also prevent transmission of tick-borne spirochetes.

Comment:  The relatively long attachment of ticks on the host during feeding have made them a frequent target for accine development.  In the 1990s, anti-tick vaccines were developed and marketed in Australia against cattle ticks [See A.E. Tabor. 2021. https://doi.org/10.3390%2Fvaccines9091030], but problems with dosing led to disuse.  No anti-tick vaccines have been approved for humans.    

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Posted by Vector and Vector-borne Disease Committee
May 26, 2022

Tiffany D. Tran,1 Brittany M. Nelms,2 Michelle L. Koschik,2 Jamesina J. Scott,2 Tara Thiemann1

1University of the Pacific, Biological Sciences, Stockton, CA 95211, U.S.A.

2Lake County Vector Control District, 410 Esplanade St., Lakeport, CA 95453, U.S.A.

Abstract [paraphrased].  Mosquitoes collected in Lake County, CA, in 2014 were tested for filarial parasite DNA using standard PCR. Filarial parasites were detected in 23 out of 1,008 total pools. Dirofilaria immitis, dog heartworm, was detected in Aedes increpitus (MIR=4.62), Aedes sierrensis (MIR=6.72), Anopheles freeborni (MIR=1.08), and Culex tarsalis (MIR=0.10). Setaria yehi, deer body worm, was detected in Ae. sierrensis (MIR=13.42), Anopheles franciscanus (MIR=0.55), An. freeborni (MIR=2.69), and Culex stigmatosoma (MIR=0.41). The avian parasite Splendidofilaria could not be identified to species but was detected in Cx. tarsalis (MIR=0.20). DNA was also detected for three unidentified filarial parasites in Culex.

Comment:  This research confirms that Aedes sierrensis is an important vector of dog heartworm, but indicates that previous studies using dissection techniques most likely over estimated infection rates that were confounded because of frequent infection with deer body worm.  Further research is needed to elucidate the vector competence of these naturally infected species. 

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Posted by Vector and Vector-borne Disease Committee
May 19, 2022

Trypanosoma cruzi and Other Vector-Borne Infections in Shelter Dogs in Two Counties of Oklahoma, United States.

Kelly E. Allen and Megan W. Lineberry

Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, Oklahoma, USA.

VECTOR-BORNE AND ZOONOTIC DISEASES, Volume 22 (5), 2022.  DOI: 10.1089/vbz.2021.0078

Abstract [condensed]

Trypanosoma cruzi is an emerging zoonotic vector-borne parasite infecting dogs and other mammals in the United States. In this study we evaluated shelter dogs in one northeastern and one southeastern county in Oklahoma for prevalence of exposure and infection with T. cruzi using the Chagas STAT PAKassay and PCR, respectively.  Overall, 26 of 197 (13.2%) shelter dogs had detectable antibodies against T. cruzi and 3 of 189 (1.6%) dogs were PCR positive.   In addition, the dogs were tested for evidence of infection with other vector-borne organisms using the SNAP 4Dx Plus Test and PCR and  42  (21.3%) had evidence of exposure to or were infected with at least one other vector-borne agent including Anaplasma phagocytophilum,Anaplasma platys, Babesia sp. (Coco), Dirofilaria immitis, Ehrlichia canis, Ehrlichia chaffeensis,Ehrlichia ewingii, and Hepatozoon americanum. This study serves to boost state-wide veterinary and public health awareness vector-borne pathogens infecting shelter dogs in Oklahoma.

Note:  This study shows the importance of a One Health approach in detecting the presence of zoonotic pathogens by testing companion animals.  As pointed out in the recent MVCAC annual meeting, T. cruzi and vectors are found in California as well as some of the other tick-borne pathogens detected in this study. 

Posted by Vector and Vector-borne Disease Committee
May 19, 2022

Emerging Mosquito-Borne Viruses Linked to Aedes aegypti and Aedes albopictus: Global Status and Preventive Strategies

Jonas Naslund,1 Clas Ahlm,2,3 Koushikul Islam,2 Magnus Evander,2,3,I, Goran Bucht,2 and Olivia Wesula Lwande2,3

1Swedish Defence Research Agency, CBRN, Defence and Security, Umea°, Sweden.

2Department of Clinical Microbiology, Umea° University, Umea, Sweden.

3Arctic Research Centre at Umea° University, Umea, Sweden.

iORCID ID (https://orcid.org/0000-0001-6034-4807).

VECTOR-BORNE AND ZOONOTIC DISEASES,  Volume 21(10) 2021

DOI: 10.1089/vbz.2020.2762

Abstract [condensed]

Emerging mosquito-borne viruses continue to cause serious health problems and economic burden among billions of people living in and near the tropical belt of the world. The highly invasive mosquito species Aedes aegypti and Aedes albopictus have successively invaded and expanded their presence as key vectors of Chikungunya, dengue, yellow fever, and Zika viruses leading to frequent local outbreaks and infrequent pandemics.  These two mosquito species have gradually adapted to new temperate ecozones inhabited by immunologically naive human populations. Many risk factors, for example, global transportation systems, may result in sporadic local outbreaks. There is an urgent need for improved surveillance of vector populations, human cases, and reliable prediction models. In summary, we recommend new and innovative strategies for the prevention of these types of infections.

Note:  This paper reviews recent Aedes related arbovirus outbreaks and describes their public health and economic impact.  This review clearly supports the need for surveillance and control programs to recognize and mitigate these imported arboviruses – problems addressed daily by the membership of the MVCAC. 

From KRON4
May 17, 2022

BRENTWOOD, Calif. (BCN) – The first case of the year was found recently in a dead American crow in Brentwood, according to the Contra Costa Mosquito & Vector Control District. 

Since 2005, 75 people in Contra Costa have been diagnosed with West Nile virus. Two people died from the disease in 2006. The district said in a press release, “Certain birds carry WNV. Once a mosquito bites an infected bird, the mosquito can become infected. Mosquitoes can spread the virus when they bite another bird or person.” 

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From ABC 7
May 13, 2022

WEST COVINA, Calif. (KABC) — It’s a big problem that comes with warmer weather — more insects. Many, especially mosquitoes, can carry some very serious diseases.

The San Gabriel Valley is working hard to control pests there.

Levy Sun with the San Gabriel Valley Mosquito and Vector Control District says SoCal residents don’t stand a biting chance against mosquitoes this summer, and reports record numbers of the annoying insects.

“If you’re hearing buzzing, it’s definitely not in your head,” Sun said. “There really are more insects and mosquitos out there right now.”

The department warns the Culex, native to SoCal, is the mosquito responsible for spreading West Nile virus, and is known to bite closer to sunset. And a newer, invasive mosquito called Aedes, or ankle biters, bite aggressively during the day.

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From the Antelope Valley Press
May 12, 2022