From KRCR 7
August 31, 2022

SHASTA COUNTY, Calif. — As excessive, triple-digit temperatures engulf our area, the number of mosquitoes infected with West Nile Virus (WNV) continues to grow.

On Wednesday this week, the Shasta Mosquito and Vector Control District (Shasta MVCD) said they saw WNV-positive mosquito sample levels above what they have seen in the last six years.

Shasta MVCD officials said the continued record drought and warm temperatures will encourage a longer season for mosquitoes and the diseases they carry. Out of the hundreds of samples taken from adult mosquitoes in the area, as of Aug. 26, 30 were found to be positive with WNV.

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Posted by Vector and Vector-borne Disease Committee
August 30, 2022

Thomas C Moore, Heidi E Brown

Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson, AZ, USA

Journal of Medical Entomology, Volume 59, Issue 4, July 2022, Pages 1164–1170, https://doi.org/10.1093/jme/tjac070

Abstract  [shortened]:  To generate a more robust estimate of Ae. aegypti flight distance, we conducted a meta-data analysis with the aims 1) to provide a flight distance measurement and 2) investigate how mosquito flight range can be affected by study design and climatic factors. Published studies were retrieved from public databases and reviewed for mean distance traveled (MDT) or maximum distance traveled measurements of Ae. aegypti. Linear regression was used to assess potential relationships between Ae. aegypti flight distance and factors pertaining to climate, degrees of urbanization, and study design. MDT estimates were pooled from 27 experiments to calculate a weighted MDT of 105.69 m. This study addresses the average flight distance of Ae. aegypti with the intention of informing vector control programs in Ae. aegypti prevalent regions of the world.

Comment:  This review incorporates published data to provide a global estimate of flight range, a parameter critical in understanding potential virus transmission patterns and establishing protocols for containment around imported cases.  Although this information was focused on females, male dispersal data establishes possible infiltration rates into areas treated with the releases of genetically altered males for control. 

From the Los Angeles Patch
August 27, 2022

From ABC 30
August 26, 2022

FRESNO, Calif. (KFSN) — You might want to take a closer look at any standing water near your home, from planters to unmaintained swimming pools.

“If you see anything that’s wiggling like this, it’s mosquito larvae, dump it out,” says Katherine Ramirez, the scientific education coordinator with Fresno County Mosquito Control.

She adds: “It doesn’t matter the area. We’re finding the virus in all areas. It could be that your neighbor has an unmaintained swimming pool.”

While these aren’t fully grown mosquitoes, Ramirez says mosquitoes are temperature-dependent, so the hotter the temperature the faster the development.

“That’s why its important to check water sources on a daily basis when we have hot temperatures or at least once a week,” she says.

Read more

From ABC7
August 25, 2022

LOS ANGELES (CNS) — Los Angeles County health officials Thursday confirmed the county’s first human cases of West Nile virus this year, saying six cases have been identified since late July.

No specifics about the patients were released, but according to the county Department of Public Health, they live in the Antelope Valley, San Fernando Valley and San Gabriel Valley. Most of the patients were hospitalized in late July and early August, and all are recovering, according to the county.

“Mosquitoes thrive in hot weather and residents should follow simple steps to reduce their risk of exposure to mosquito-borne diseases, such as West Nile virus,” county Health Officer Dr. Muntu Davis said in a statement.

Read more

From MSN
August 25, 2022

FRESNO COUNTY, Calif. (KSEE/KGPE) – The California Department of Health (CDPH) reported that nine Fresno County residents have tested positive for West Nile Virus (WNV) infections.

Health officials say three of the cases are asymptomatic and were blood donors.

The cases are the first reported in this season and according to CDPH, the Fresno County mosquito control districts have also collected 216 samples of mosquitoes that tested positive for WNV.

Read more

From KRON 4
August 18, 2022

MARTINEZ (KRON) – Contra Costa County has identified its first group of invasive mosquito species.

The Contra Costa County Mosquito and Vector Control District is now doing surveillance and treatment in the area where the mosquitos were found in Martinez to make sure they are eliminated before becoming widespread.

Officials say these mosquitoes are very aggressive day biters that can transmit viruses like Zika and the virus that causes Yellow Fever. The species, Aedes aegypti, is originally from West Africa, and was first detected in California in 2014.

Mosquitoes can hide in vegetation and debris which makes it hard to find and eliminate them, so the control district is setting up traps and going door-to-door.

Read more

From the Los Altos Town Crier
August 17, 2022

From SCV News
August 16, 2022

The Greater Los Angeles County Vector Control District has confirmed 13 additional mosquito samples that tested positive for West Nile virus.

This brings the total number of positive samples within the District’s service area to 76 this year.

This is the first detection of the virus this year in the following communities: Canoga Park, Downey, Eagle Rock, Elysian Valley, Los Angeles city and Winnetka.

West Nile virus is endemic to Los Angeles County, and warm temperatures can increase virus activity and mosquito populations. Visit VectorSurv Maps or WestNile.ca.gov for a comprehensive look at this year’s West Nile virus activity throughout Los Angeles County and Southern California.

Join Mosquito Watch to access online tools and resources such as the DIY Mosquito Source Checklist or request door hangers to be distributed in their community at MosquitoWatch.org.

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From ABC 7
August 13, 2022

ORANGE, Calif. (KABC) — Orange County has its first reported case of West Nile virus after a man tested positive this week.

Details surrounding the man’s condition weren’t immediately released. It’s also unclear of what portion of Orange County the resident resides in.

People over age 50 and those with certain medical conditions are at an increased risk of getting the virus, health officials warn.

“West Nile Virus is endemic in Orange County, recurring every year during the summer months and continuing into the fall,” said Deputy County Health Officer Dr. Matthew Zahn. “The best way to avoid West Nile Virus infection is to take precautionary measures to avoid mosquito bites.”

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From The Press Democrat
August 13, 2022

Former Bay Area news anchor Leslie Griffith died Aug. 10, according to a report by KTVU Channel 2 News. Family members say Griffith had been suffering from Lyme Disease since she was bitten by a tick while living in Oregon in 2015.

In California, the western black-legged ticks — the species that carries the bacterium that causes Lyme disease — have been found in 56 of the state’s 58 counties, including Sonoma County, according to the California Department of Public Health.

Yet officials at the Marin-Sonoma Mosquito and Vector Control District say residents can employ several precautions to avoid ticks outdoors and around their homes.

“In Sonoma County, ticks are actually active year-round,” said Nizza Sequeira, public information officer for Marin-Sonoma Mosquito and Vector Control District.

Read more

From CBS Los Angeles
August 12, 2022

A man who tested positive for West Nile virus infection is the first human case reported in Orange County this year, public health officials said Friday.

The patient was described only as an adult male, and the Orange County Health Care Agency gave no further information about the case or where the man may have contracted the virus. However, no one in Orange County has ever died of West Nile virus, and last year there were just three reported cases of human infection.

West Nile virus has already been detected throughout Los Angeles County. Three dead crows in North Hills tested positive for the virus, but LA County has not yet reported any human infections.

West Nile virus is spread most often by mosquitos, which can infect humans, birds, horses, and other mammals. Most people who become infected do not become sick, but about 20% will develop flu-like symptoms, including fever, headache, body aches, nausea, fatigue, and sometimes a skin rash. More serious symptoms include neck stiffness, confusion, muscle weakness, and paralysis, but those cases are rare.

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From the Martinez, CA Patch
August 12, 2022

Posted by Vector and Vector-borne Disease Committee
August 10, 2022

Mary E. Danforth1, Robert E. Snyder1, Tina Feiszli1, Teal Bullick2, Sharon Messenger2, Carl Hanson2, Kerry Padgett1, Lark L. Coffey3, ChristopherM. Barker3, William K. Reisen3, Vicki L. Kramer1

1 California Department of Public Health, Vector-Borne Disease Section, Richmond and Sacramento, California, 2 California Department of Public Health, Viral and Rickettsial Disease Laboratory, Richmond, California, 3 Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America

PLoS Negl Trop Dis 16(8): e0010664. https://doi.org/10.1371/journal.pntd.0010664

Author summary.   St. Louis encephalitis virus is a mosquito-borne virus that can cause human disease and is found in California, where it was detected every year from 1938 to 2003. However, after

West Nile virus arrived in 2003, St. Louis encephalitis virus was not detected again until 2015, when it re-emerged in Riverside County. From 2015 through 2020, St. Louis encephalitis virus has been detected in mosquito pools and sentinel chicken sera samples in 16 counties and a total of 24 human disease cases have been reported. However, during that same time-period, West Nile virus has been detected in 10 times as many mosquito pools and 60 times as many chicken sera samples across 58 counties and over 2,400 human disease cases have been reported. Although mosquitoes are tested routinely for both viruses, surveillance is not uniform throughout the state, and there has been a steady decline in the use of sentinel chickens. Since St. Louis encephalitis virus patient screening is dependent upon environmental detection, California may be underestimating the incidence of human disease due to this virus.

Note:  Although WNV and SLEV cycle enzootically in basically the same vectors and avian hosts, historically SLEV in California never amplified to the levels documented for WNV.  This may be because SLEV does not elicit elevated viremias in a wide diversity of avian hosts which limit transmission efficiency and therefore amplification.   In addition, recently widespread WNV activity may have ‘immunized’ avian populations against SLEV as well as WNV, because previous infection with WNV produces sterilizing immunity against subsequent infection with SLEV.     

From the County of Santa Clara
August 9, 2022

SANTA CLARA COUNTY, CALIF. – The County of Santa Clara Vector Control District has confirmed the presence of West Nile virus-positive mosquitoes in a small area of Cupertino (ZIP Code 95014). Weather permitting, this area will be treated to reduce adult mosquito populations with the use of truck-mounted equipment on Thursday, August 11, starting around 10 p.m., and concluding a few hours later.

The District’s mosquito management program largely focuses on preventing mosquitoes from reaching adulthood by proactively targeting immature stages of mosquitoes (eggs, larvae, and pupae). When a mosquito with West Nile Virus (WNV) is detected, however, the District takes the added step of conducting a mosquito control treatment to reduce the adult mosquito population in the area, which reduces the risk of a WNV-human infection.

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From SCV News
August 9, 2022

The Greater Los Angeles County Vector Control District has confirmed 28 additional mosquito samples that tested positive for West Nile virus.

This brings the total number of positive samples within the District’s service area to 63 this year.

The new positive samples were collected from 11 different communities: Artesia, Cerritos, Hawaiian Gardens, La Habra Heights, Long Beach, Porter Ranch, Rowland Heights, San Fernando, Santa Fe Springs, South Whittier and Tarzana.

Read more

From ABC 7 News
August 6, 2022

MARTINEZ, Calif. (KGO) — On Friday, the Contra Costa Mosquito and Vector Control District announced that an invasive mosquito species has been discovered in the city of Martinez.

Measuring about one-quarter of an inch, with a black body and white stripes, they’re called Aedes aegypti.

According to a press release from the county, Aedes mosquitos are described as being very aggressive day biters that can transmit diseases such as Zika, Yellow and Dengue fevers.

Read more

From KCRA3
August 4, 2022

YOLO COUNTY, Calif. —

Health officials in Yolo County said Wednesday that the first human case of the mosquito-borne West Nile virus so far this year has been detected in the county.

The person became ill last month and is recovering, officials said. Most people infected with the virus do not show symptoms, but the virus can lead to severe illness for some. Health officials say that people should take precautions to reduce the risk of being bitten by mosquitos who may carry the virus.

“By making regular checks of their yards and draining standing water, people can help cut down on mosquito breeding areas,” Yolo County Health Officer Dr. Aimee Sisson said. “Wearing protective clothing and using insect repellent will also reduce the risk of mosquito bites.”

Here’s what else to know about West Nile virus this year.

Read more

From ABC 7
August 4, 2022

The Butte County Public Health agency (BCPH) confirmed this year’s first human case of West Nile Virus (WNV) infection in Butte County, making this the seventh reported incident of WNV infections in California. The individual who was exposed to the virus “is over 65 years of age and is experiencing a severe WNV illness.”

BCPH reminds residents of Butte County that “WNV is active June through October, with August typically being the peak month”. Mosquitos are seen as the primary carrier of the virus.

Those with the infection “fall into three categories”:

• Asymptomatic (8 in 10 people)
• Mild to moderate fever illness with fatigue and body aches (1 in 5 people)
• Severe illness with neurologic symptoms such as encephalitis or meningitis (less than 1 in 150 people). For those who develop a severe WNV illness, symptoms may last several weeks and some symptoms may be permanent.

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From KRON 4
August 3, 2022

(BCN) — Four days after Contra Costa County reported mosquitoes carrying West Nile virus, officials in Santa Clara County reported Tuesday that they too have found mosquitoes that have tested positive.

The county’s Vector Control District announced plans to begin spraying insecticide from trucks Thursday night in neighborhoods where virus-positive mosquitoes were found in Sunnyvale, Santa Clara and San Jose, confined to ZIP codes 95054, 94089 and 95002. In a news release, county officials said it is normal to see an increase in infected mosquitoes in the summer as they thrive in the heat, and that such spraying has been conducted regularly since 2003.

Read more

From ABC 10
August 3, 2022

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

Kerry A. Padgett,1 Anne Kjemtrup,1 Mark Novak,1 Jason O. Velez,2 and Nicholas Panella2

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

2Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA.

Vector-Borne and Zoonotic Diseases.    2022.  DOI: 10.1089/vbz.2022.0018

Abstract [condensed].   In the past few decades, reported human cases of Colorado tick fever in the western United States have decreased dramatically.  … This study conducted surveillance for Colorado tick fever virus (CTFV) in Dermacentor ticks in recreational sites in Colorado, Wyoming, and California to determine whether the virus is still present.  Adult Rocky Mountain wood ticks (Dermacentor andersoni), Pacific Coast ticks (Dermacentor occidentalis), and winter ticks (Dermacentor albipictus) were tested by PCR and a subset of PCR-positive D. andersoni ticks (n = 7) were cultured in Vero cells. CTFV-positive Rocky Mountain wood ticks were found in all states: Colorado (58% prevalence), Wyoming (21%), and California (4%). Although no winter ticks tested positive, Pacific Coast ticks tested positive in one county (Siskiyou County, 15% prevalence) and were positive only in a location that also maintained Rocky Mountain wood ticks and golden mantled ground squirrels, a known CTFV host. In summary, although the number of human CTFV cases has declined dramatically, this decrease in reported disease does not appear to be due to the disappearance or even the decline in prevalence of this virus in ticks in historically endemic regions of the country.

Note:  This and related recent studies continue to emphasize the public health importance of multiple tick species.  Although the incidence of human infection has remained low and restricted geographically in California, landscape and climate change have been shown to enhance transmission.

From ABC 30
August 2, 2022

TULARE COUNTY, Calif. (KFSN) — Tulare County Public Health has confirmed a human case of St. Louis Encephalitis Virus.

Officials say it’s similar to West Nile, and both are transmitted by the same type of mosquitoes.

Five other cases are under investigation as potential encephalitis or West Nile Virus infections.

Health officials say people infected with encephalitis may show flu-like symptoms, such as a fever or headache, or no symptoms at all.

Severe cases can affect the central nervous system.

Officials want to remind you to drain standing water that could attract breeding mosquitoes.

Use insect repellent and wear long sleeves and pants to avoid getting bitten.

Read more

From NBC Bay Area
August 1, 2022

Contra Costa County health officials are warning people to be careful after its first positive case of West Nile in a group of mosquitoes. 

Workers with the county’s Mosquito and Vector Control District checked catch basins near the Marsh Fire site looking for any type of mosquito activity Monday.

“We don’t want adult female mosquitoes capable of laying eggs and leading to more mosquitoes flying from here and over to the marsh,” said Nola Woods with the Contra Costa Mosquito and Vector Control District 

She’s referring to the site of the Marsh Fire where more the 200 million gallons of water was pumped onto the site to finally put it out after it burned for a few weeks. 

But the big body of water could potentially serve as the ideal breeding environment for mosquitoes. A cause for concern with the county confirming its first pool of mosquitoes in Oakley carrying West Nile. 

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From 23ABC
August 1, 2022

BAKERSFIELD, Calif. (KERO) — Every year in Kern County people and animals are infected by the West Nile Virus. According to Kern County Public Health in 2019 there were 32 human cases. In 2020 there were eight, in 2021 there were three and so far this year, two confirmed cases.

Officials say there are steps you can take to try and avoid coming in contact with mosquitoes.

“I think if you talk to anyone they’re going to tell you they’ve come into contact with mosquitos and so this is the time where transmission is typically the highest,” explained Michelle Corson, public information officer with the Kern County Public Health.

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From the Concord, CA Patch
July 29, 2022

From the Lake County News
July 28, 2022

LAKEPORT, Calif. — Mosquitoes are here, despite the drought, and the high temperatures are ideal for both mosquitoes and West Nile virus to thrive.

Although no Lake County mosquitoes have tested positive yet for West Nile virus, or WNV, in 2022, the warm nights mean that the virus will be detected here soon in mosquitoes, dead birds or sentinel chickens.

In California, the number of mosquitoes testing positive for West Nile virus activity increased sharply in the last two weeks.

So far, six California residents have been diagnosed with mosquito-borne illnesses this year.

“Both mosquito and West Nile virus activity increase when the overnight temperatures are 60°F or warmer,” said Jamesina Scott, Ph.D., district manager and research director of the Lake County Vector Control District. “In a dry year like this, many people don’t think about mosquitoes or the diseases they carry, like West Nile or St. Louis encephalitis viruses. The best way to protect yourself is avoid mosquito bites.”

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From 23ABC
July 25, 2022

KERN COUNTY, Calif. (KERO) — Kern Public Health has confirmed the first West Nile infection of the year. West Nile Virus is a disease primarily spread by mosquitoes during the summer there have been 400 local cases since it first arrived in Kern in 2004.

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From ABC10
July 25, 2022

Posted by Vector and Vector-borne Disease Committee
July 25, 2022

Cynthia Hopf, Elizabeth Bunting, Anne Clark, and Sara Childs-Sanford        

From the Janet L. Swanson Wildlife Hospital and the Department of Clinical Sciences, College of Veterinary Medicine (Hopf, Childs-Sanford), and the Department of Population Medicine and Diagnostic Sciences (Bunting), Cornell University, Ithaca, NY 14853, USA; and the Department of Biological Sciences, Binghamton University, Binghamton, NY 13902, USA (Clark).

Journal of Avian Medicine and Surgery 36(1), 85-91, (2 May 2022). https://doi.org/10.1647/20-00112

Abstract [condensed].   …  American crows with WNV infections are received and treated at the Janet L. Swanson Wildlife Hospital (Cornell University, Ithaca, NY, USA) on a regular basis during the summer and fall and have historically had a 100% mortality rate. The 5 American crows in this case series were tested, when possible, by polymerase chain reaction (PCR) and plaque reduction neutralization on admission and monitored with both PCR and plaque reduction neutralization throughout their rehabilitation process. Four of the 5 birds had a negative PCR test before release, and 1 bird had a “suspect” positive PCR test result before release. One of the crows was confirmed to have survived for at least 2.5 years after release. Viral shedding was documented up to 93 days after initial hospitalization, which is longer than any previous report of WNV shedding in an American crow.

Note:  The study documents the survival of some crows after infection with WNV.  Expansion of this trend may reduce the sensitivity of the dead bird surveillance program and perhaps attenuate WNV amplification through increasing flock immunity.  

Posted by Vector and Vector-borne Disease Committee
July 25, 2022

Camila Lorenz,* and Francisco Chiaravalloti-Neto

Department of Epidemiology, School of Public Health, University of S~ao Paulo, S~ao Paulo, Brazil

The Lancet Regional Health – Americas 2022;12: 100276;

Published online:   https://doi.org/10.1016/j.lana.2022.100276

Note:  Historically the North American encephalitis viruses have more or less ‘disappeared’ into the Neotropics, with sporadic detection during enhanced surveillance and small outbreaks documented in Argentina.  The current Comment piece proposes the following hypotheses.  1) Under-reporting.  Diagnosis of WNV fever cases may be lost among the frequent occurrence of other arboviruses such as DENV, ZIKV and Mayaro.   2) Co-circulation.  Other viruses such as Rocio and SLEV may provide cross protection and limit amplification.  However, this would seem poorly supported given the recent resurgence of SLEV in the SW USA where WNV remains endemic.  3) Evolution of attenuated strains.  Several isolates from the Neotropics have been attenuated and may not produce neuroinvasive disease and therefore are not detected.

From FOX 40
July 22, 2022

GRANITE BAY, Calif. (KTXL) — On Tuesday, the Placer County Mosquito and Vector Control District announced that on July 14 Aedes aegypti, yellow fever mosquitos, were found in Granite Bay.

The invasive species was found in a residential area of the community south of Granite Bay High School, according to Placer Mosquito.

“We are following our invasive mosquito response plan to determine the extent of the infestation,” Placer Mosquito General Manager Joel Buettner said in a news release. “We ask residents to help us by allowing our technicians to inspect front and back yards of nearby properties.”

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From the Fresno Bee
July 22, 2022

An increase in West Nile virus-positive mosquitoes prompted officials Friday to issue an alert for Fresno County residents.

Katherine Ramirez of the Consolidated Mosquito Abatement District called the discovery of more virus-carrying insects concerning, and urged people to prevent development of mosquito infestations around their homes.

The district has collected West Nile virus-positive mosquitoes from areas within the cities of Fresno, Clovis, Sanger and Reedley, Ramirez said.

Read more

From the Valley Press
July 22, 2022

Posted by Vector and Vector-borne Disease Committee
July 20, 2022

Lucas S. Blanton1, Bethany R. Quade1, Alejandro Ramírez-Hernández2, Nicole L. Mendell3, Alejandro Villasante-Tezanos4, Donald H. Bouyer3, John L. VandeBerg5, and David H. Walker3

1 Department of Internal Medicine—Division of Infectious Diseases, University of Texas Medical Branch, Galveston, Texas; | 2 Veterinary Parasitology Research Group, National University of Colombia, Bogotá, Colombia; | 3 Department of Pathology, University of Texas Medical Branch, Galveston, Texas; | 4 Department of Preventive Medicine and Population Health, University of Texas Medical Branch, Galveston, Texas; | 5 Department of Human Genetics, South Texas Diabetes and Obesity Institute, and Center for Vector-Borne Diseases, The University of Texas Rio Grande Valley, Brownsville, Texas

Am. J. Trop. Med. HYg.  107:  102-109;  DOI: https://doi.org/10.4269/ajtmh.21-1076

Abstract:   Murine typhus is an acute undifferentiated febrile illness caused by Rickettsia typhi. In the United States, its reemergence appears to be driven by a shift from the classic rat–rat flea cycle of transmission to one involving opossums (Didelphis virginiana) and cat fleas. Little is known of the ability of opossums to act as a reservoir and amplifying host for R. typhi. Here, we use Monodelphis domestica (the laboratory opossum) as a surrogate for D. virginiana. Opossums were inoculated via the intraperitoneal (IP) or intradermal (ID) route with 1 × 10⁶ viable R. typhi. Blood and tissues were collected on days 6, 13, 20, and 27 or if moribund. Although one ID-infected opossum died, the remainder did not appear ill, whereas half of the IP-inoculated animals succumbed to infection. Rickettsemia was demonstrated in all animals through week 2 of infection and sporadically in weeks 3 and 4. Rickettsia typhi DNA was detected in all tissues, with most animals demonstrating the presence of bacteria into weeks 3 and 4. Akin to infection in rats, the demonstration of disseminated infection, typical inflammation, and prolonged rickettsemia with relatively few clinical effects (especially in the more natural route of ID inoculation) supports the potential of opossums to act as a competent mammalian reservoir and component of the zoonotic maintenance cycle of R. typhi. Understanding the dynamics of infection within opossums may have implications for the prevention and control of murine typhus.

Note:  With the rise in the number of human typhus cases in southern California, this work establishes opossums [an important host of cat fleas] as a critical reservoir for the rickettsia. 

From The Horse
July 19, 2022

The California Department of Food and Agriculture confirmed a 4-year-old unvaccinated Quarter Horse gelding in Kern County, California, positive for West Nile virus (WNV) on July 11. On July 2, he presented with acute pelvic limb ataxia (incoordination) that progressed to recumbency (down and unable to get up), and fever. The horse has been euthanized due to the severity of his signs. The boarding facility where he resided is not currently under quarantine.

This case marks California’s second confirmed horse with WNV in 2022. 

Read more

From KRON4
July 18, 2022

Mosquitoes carrying West Nile virus have been found in Santa Clara and Sunnyvale, the County of Santa Clara Vector Control District confirmed on Monday. On Tuesday night, the area will be treated to reduce adult mosquito populations, if weather permits.

The Vector Control District has a surveillance program to detect West Nile virus and other diseases that are transmitted through mosquito bites. It has been conducting these treatments regularly since 2003 to reduce mosquito populations that might be carrying the virus.

In an interview with KRON4 on Friday, experts with the Contra Costa County Vector Control District said drought conditions were ideal for mosquito-borne illnesses to spread. There are mosquito-eating fish available at CCMVCD for Contra Costa County residents in need of them.

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From the Lake Balboa Neighborhood Council
July 18, 2022

The Greater LA County Vector Control reminds everyone that we no longer have a “mosquito season.” Mosquitos remain active throughout the year and can cause sickness and even death. Luckily, there are ways to combat these insects and take back the outdoors, our neighborhoods, and our community. Take a closer look at the important information attached and take action to protect yourself and your family.

Health & Public Safety Committee, LBNC

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From FOX 26 News
July 15, 2022

KINGS COUNTY, Calif. — The first positive human case of West Nile (WNV) has now been reported in Kings County, the first in the entire state of California this year.

According to the Kings County Department of Public Health, they reported the positive case on Tuesday to the California Department of Public Health.

FOX26 first reported on July 5, about the positive samples the Kings Mosquito Abatement District (KMAD) had collected throughout Hanford, Armona and Corcoran. Out of 46 samples, nine came back positive.

Health officials say people who have been infected often experience flu-like symptoms but elderly people can see more severe and dangerous signs that may require medical attention.

Those severe symptoms can be neurological, fever, headache, stiff neck, rash, joint pain, disorientation, and interference with consciousness.

Read more

Posted by Vector and Vector-borne Disease Committee
July 13, 2022

Christopher M Roundy, Sarah A Hamer, Italo B Zecca, Edward B Davila, Lisa D Auckland, Wendy Tang, Haley Gavranovic, Sonja L Swiger, Jeffery K Tomberlin, Rebecca S B Fischer, Alex Pauvolid-Correa, Gabriel Hamer. 

Texas A&M University and AgriLife Research, College Station, TX 77843, USA

Journal of Medical Entomology, 30 May 2022, tjac055, https://doi.org/10.1093/jme/tjac055

Author’s Abstract.   Flies and other arthropods mechanically transmit multiple pathogens and a recent experimental study demonstrated house flies, Musca domestica L. (Diptera: Muscidae), can mechanically transmit SARS-CoV-2 [Balaraman et al.  JME 58: 1948]. The purpose of this study was to explore the possibility of mechanical transmission of SARS-CoV-2 by domestic insects and their potential as a xenosurveillance tool for detection of the virus. Flies were trapped in homes where at least one confirmed human COVID-19 case(s) resided using sticky and liquid-baited fly traps placed inside and outside the home in the Texas counties of Brazos, Bell, and Montgomery, from June to September 2020. Flies from sticky traps were identified, pooled by taxa, homogenized, and tested for the presence of SARS-CoV-2 RNA using quantitative reverse transcription PCR (RT-qPCR). Liquid traps were drained, and the collected fluid similarly tested after RNA concentration. We processed the contents of 133 insect traps from 40 homes, which contained over 1,345 individual insects of 11 different Diptera families and Blattodea. These individuals were grouped into 243 pools, and all tested negative for SARS-CoV-2 RNA. Fourteen traps in seven homes were deployed on the day that cat or dog samples tested positive for SARS-CoV-2 RNA by nasal, oral, body, or rectal samples. This study presents evidence that biting and nonbiting flies and cockroaches (Blattodea) are not likely to contribute to mechanical transmission of SARS-CoV-2 or be useful in xenosurveillance for SARS-CoV-2.

Note:  This negative data is good news.   Multiple studies have shown that SARS-CoV-2 does not replicate within insects after ingestion, so even experimental mechanical transmission only occurs with a relatively short time period.   This combined with a low humoral viremia indicated little risk of biological transmission by biting flies/mosquitoes.   The current study showed that even though surfaces may be contaminated with virus within households with infectious persons, the risk of insect acquisition and transmission was undetectable.   

From the Mercury News
July 13, 2022

West Nile virus season has kicked off in Solano County with the discovery of a deceased and infected bird, county officials announced Tuesday.

“The Solano County Department of Health and Social Services, Public Health division, and the Solano County Mosquito Abatement District (SCMAD) have confirmed that a bird has tested positive for West Nile virus (WNV),” officials stated in a press release. “The specimen sample was collected in late June in Vacaville. As of July 11, 2022, the California Department of Public Health reports that there are no human cases of WNV.”

Christine Wu, the county’s deputy health officer, advised preparation when spending time oudoors.

“Residents should take the necessary precautions to reduce the risk of getting an infection by using insect repellent when spending time outdoors and removing standing water sources in the home,” she said in the statement.

Read more