Mosquito & Vector News

Press Release: First Detection of St. Louis Encephalitis Virus in Merced County

MERCED, CA– The Merced County Mosquito Abatement District received confirmation that one sentinel chicken from Merced County tested positive for St. Louis Encephalitis Virus (SLEV). SLEV is related to West Nile Virus (WNV) and is transmitted via the bite of Culex mosquitoes, the same mosquitoes that transmit WNV.

Like WNV, most people who become infected with SLEV will never feel sick. People who do feel sick may have mild flulike symptoms; a small number of people will exhibit symptoms that include: headache, confusion, disorientation, and dizziness. Seizures, paralysis, coma, and sometimes death may occur. People who are older and those with weakened immune systems are more likely to develop the severe symptoms. There is no specific treatment for SLEV.

“The sentinel chicken sample that tested positive for SLEV is the first detection of the virus in Merced County in over 40 years”, according to General Manager Rhiannon Jones of Merced County Mosquito Abatement District. “People need to continue to take precautions by protecting themselves and their families from mosquito bites.”

Read more

First human case of West Nile virus this year found in Northern California

From The Sacramento Bee

The first human case this year of West Nile virus in Northern California was reported by Butte County health officials Tuesday.

The virus was identified by a blood donation center while it was performing regular screening on blood samples Friday. The donated blood was discarded, and the person in whose blood the virus was found has been notified, said Lisa Almaguer, a Butte County Public Health Department spokeswoman.

Almaguer said she could not disclose the location of the blood donation center or the city where the human case was found. Statewide, 22 cases of West Nile virus have been reported this year, mostly in Kern, Kings, Los Angeles and San Bernardino counties.

The Butte County Mosquito and Vector Control District said it is not notified of the locations of human cases until people show symptoms, District Manager Matt Ball said.

Read more

Mosquitoes carrying West Nile virus on the rise in Elk Grove

From The Sacramento Bee

Mosquitoes carrying West Nile virus have increased in the Elk Grove area, and authorities are boosting efforts to control their spread, the Sacramento-Yolo Mosquito and Vector Control District said Monday.

Most mosquitoes testing positive for the virus were trapped south of Elk Grove, between Interstate 5 and Highway 99 and between Laguna Boulevard and Twin Cities Road, district manager Gary Goodman said in a statement.

Parks in the zone are being fogged, and any areas of standing water that might be breeding grounds for mosquitoes are being treated, said district spokeswoman Luz Robles.

Read more

CDC Supports UC Researchers in Fighting Vector-Borne Diseases

By Trina Wood on August 10, 2017, in Human & Animal Health

This week, the U.S. Centers for Disease Control and Prevention announced a bold step to enhance public-health preparedness for diseases transmitted by mosquitoes and ticks in the nation’s southwest. With an $8 million grant from the CDC, University of California, Davis and Riverside researchers will launch the Pacific Southwest Regional Center of Excellence in Vector-Borne Diseases later this month.

“The southwestern U.S. is facing many new challenges in recent years from invasive mosquitoes and emerging pathogens, such as Zika virus, and we urgently need better options for their control,” said UC Davis epidemiologist and center Co-Director Chris Barker. “Funding for this center will enable important research to optimize the tools we have and to look for new ways forward, while training the next generation of public-health scientists.”

Drawing on just one area of science is not going to be sufficient for addressing the challenges presented by vector-borne diseases, which is the strength of the collaboration between the two UC campuses. Both are top-tier research and teaching institutions with leading experts in vector-borne diseases, including entomologists, epidemiologists, virologists and computer scientists who train a diverse group of scholars interested in public health.

According to entomologist and center Co-Director William Walton of UC Riverside, “this Center of Excellence will bring together researchers using the latest cutting edge approaches in the laboratory and field, with practitioners protecting public health to develop a community of practice and provide new technologies to prevent the occurrence of vector-borne diseases.”

The center’s funding begins later this month and continues through the end of 2021. The center has three specific goals:

  • Conduct applied research to develop and test effective prevention and control tools to anticipate and respond to vector-borne disease outbreaks;
  • Train vector biologists, entomologists, and physicians in the knowledge and skills required to address vector-borne disease concerns; and
  • Strengthen and expand existing collaboration among academic communities and public health organizations at federal, state and local levels.

UC Davis and UC Riverside already have strong collaborations with the California Department of Public Health and Mosquito and Vector Control Association of California, who will be critical partners in the center.

“The CDC’s support will enable us to build on these partnerships to ensure that our region of the U.S. will be ready to respond to future threats from vector-borne diseases,” Barker said.

Mosquito district goes from scandal to praise

From the San Mateo Daily Journal

Countywide agency recently commended for fiscal management, transparency

From an employee embezzlement scandal to receiving commendations for accountability practices, a little-known special district charged with public health has made significant strides over the last five years.

There hasn’t been much media buzz around the San Mateo County Mosquito and Vector Control District in recent times, and that’s a good thing. In the years since two former employees were caught embezzling nearly half a million dollars, officials now overseeing the district have tightened the reins on the agency responsible for protecting against vector-borne diseases. 

The mosquito district was recently praised in a San Mateo County Civil Grand Jury report that investigated local special districts’ transparency practices. Its accomplishments include being awarded the District Transparency Certificate of Excellence and the District Distinction Designation from the California Special District Leadership Foundation this year. 

“The public’s trust in us is a first priority, we’re always looking for ways to be transparent and accountable, because ultimately we work for the citizens of this county,” said mosquito district spokeswoman Megan Sebay.

Read more

A deadly virus returns to Stanislaus County. Why it’s back and how you can avoid it.

From The Modesto Bee

A mosquito sample in Stanislaus County tested positive for the St. Louis encephalitis virus, which is capable of causing a potentially deadly illness.

The mosquitoes infected with St. Louis encephalitis were southwest of Modesto in the Grayson area.

The St. Louis variety is similar to the West Nile virus and is carried by the same kind of mosquitoes. Like a West Nile infection, a person bitten by an infected mosquito may come down with encephalitis, or inflammation of the brain, with headache, dizziness, confusion, seizures or paralysis.

Most people infected won’t feel sick but some will have mild flu-like symptoms, health officials said. Older people and those with weakened immune systems are more susceptible to getting the serious illness. No county residents are known to have come down with the St. Louis illness thus far.

Read more

UC Zika research aims to ‘collapse’ mosquito populations

From The Sacramento Bee

Zika, dengue fever and other mosquito-born illnesses have surged to public attention in recent years, with Zika afflicting thousands of people across the Americas. The Zika outbreak that began in 2015 resulted in 1,835 babies born in Brazil with abnormal brain development or problems with their central nervous systems, according to the World Health Organization. Worldwide, another 3.2 million cases of dengue fever, which causes high fever and vomiting, were reported in 2016, according to the WHO.

University of California researchers are tackling the problem by working to develop genetic defenses against mosquito-borne diseases. The team, led by UC Riverside researcher Omar Akbari, recently received a four-year grant from the federal Defense Advanced Research Projects Agency totaling $14.9 million.

Read more

Pregnant Women Urged to Avoid Going to Areas with Zika Risk


SACRAMENTO – The California Department of Public Health (CDPH) advises pregnant women, and men and women of childbearing age, not to go to areas with Zika. If they must go to places with known transmission of the Zika virus, CDPH recommends they protect themselves against sexual transmission of Zika and take steps to prevent mosquito bites. Pregnant couples in which one or both partners were in an area with Zika should use condoms every time they have sex, or not have sex during the pregnancy in order to reduce the risk of transmitting Zika to the fetus.
“Whether you work in a location with Zika, visit family who live in places with Zika or travel for leisure to places with Zika, you need to protect yourself,” said CDPH Director and State Health Officer Dr. Karen Smith. “Anyone living in or traveling to areas with ongoing Zika activity may be at risk for infection. It is very important to protect yourself, and if you are pregnant, protect your developing baby from the serious birth defects that can result from Zika infection.”

Mosquito samples in Inyo test positive West Nile Virus

From Sierra Wave Media

Inyo County press release

The Owens Valley Mosquito Abatement Program (OVMAP) confirmed Tuesday that some mosquito samples trapped last week tested positive for West Nile Virus.

This is the first occurrence of West Nile Virus in Inyo County since 2011. Prior to that, West Nile Virus had been detected periodically in the Owens Valley after first being discovered in our area in 2004. During that period, no human infections were reported, but 3 horses died after being infected with West Nile Virus.

The three positive samples in Inyo County come during the same week that 214 samples were positive for the disease statewide.

“For every 100 people who are bitten by a West Nile Virus-carrying mosquito, only 20 are risk of contracting West Nile Virus, and of those, fewer than 1% are likely to experience life-threatening reactions” according to Inyo County Health Officer, Dr. James Richardson. Nevertheless, the public is urged to take precautions discussed below.

Read more

Aggressive, stinging colonies of wasps out early this year in Sacramento County

From The Sacramento Bee

Yellowjacket infestations are hitting Sacramento County early this year, prompting specialists to eradicate the sometime aggressive insects whose sting can sometime kill.

The Sacramento-Yolo Mosquito & Vector Control District has received numerous calls from residents battling yellowjacket nests on their property. The yellowjacket population problem usually shows itself in late summer or fall.

“It’s definitely early to see yellowjackets now,” said Gary Goodman, district manager.

The district has recently received calls from Rancho Cordova and Folsom, but the biggest problem has come from Herald, a rural community in southeastern Sacramento County.

“We recently treated nearly 90 yellowjacket nests on a five-acre property near the eucalyptus groves,” said Goodman. “When you consider that each nest can have hundreds to thousands of yellowjackets, this can quickly become a threat to residents.”

County residents may call the district if they need help in removing nests. If a colony is disturbed, the wasps can become persistent and pugnacious, increasing the risk of stings.

Read more

Mosquito pool tests positive for West Nile virus in Butte County


PALERMO, Calif. – According to the Butte County Mosquito and Vector Control District, a mosquito pool in an area of north Honcut south Palermo has tested positive with the West Nile Virus. 

Officials said with increasing mosquito populations and the detection of WNV within Butte County, the Butte County Mosquito and Vector Control District urges residents to take all precautions necessary to drain any and all un-needed standing water, report any suspected mosquito-breeding sites to the District, and protect themselves from the bites of mosquitoes. 

This is the first positive indicator of WNV in the county for 2017. WNV is active throughout the State of California. WNV has been identified in Butte County every year since its arrival in 2004. Since 2004, 229 residents have been infected with the virus, eight of which lost their lives. 

Read more

Mosquito batch infected with West Nile virus found in Costa Mesa

By LOUIS CASIANO JR. | Orange County Register

A batch of 22 mosquitoes infected with the West Nile Virus was discovered late last month in Costa Mesa’s Fairview Park, the city said in a statement.

The mosquitoes were found June 27 by Orange County Mosquito & Vector Control District crews in a drainage ditch at the park’s south end during an inspection of mosquito traps, said Robert Cummings, laboratory director for the control district.

“We are definitely seeing more activity,” Cummings said, adding that about seven infected mosquito batches have been found throughout the county this year.

The area around the traps was treated and is being closely monitored, said Costa Mesa spokesman Tony Dodero.

Read more


NASA Citizen Science App Tackles Mosquito-Borne Disease


In many parts of the world, mosquitoes are more than just a summertime nuisance. They spread diseases that kill nearly 2.7 million people a year. Now citizen scientists can use a NASA app to help those working to understand and reduce mosquito-borne diseases.

NASA has introduced the Mosquito Habitat Mapper as part of its GLOBE Observer app available for iPhone and Android. The app includes training, making it easy for anyone to use.

The Mosquito Habitat Mapper guides users through the process of identifying and eliminating mosquito breeding sites. It also gives citizen scientists the option to identify the mosquito species to determine whether it could transmit Zika, dengue fever, yellow fever, chikungunya, and other diseases.

Read more

California Zika By The Numbers


This graphic details the Zika virus infections among California residents from 2015 through June 30, 2017. All cases on record have been among people who were infected while traveling to areas with ongoing Zika transmission, through sexual contact with an infected traveler or through maternal-fetal transmission. No direct transmission from mosquitoes to people has been documented in California. Birth defects have been detected in seven infants infected with Zika before, during or shortly after birth.

Read more

Zika 101 (Vector Control) Rap

A rap video with simple steps for personal protection against Aedes aegypti and Aedes albopictus, the two known mosquito vectors of Zika virus. Prevent Zika by avoiding mosquito bites and taking actions to limit mosquitoes on your property. The mosquitoes that spread Zika develop exclusively in small containers commonly found holding water around the yard. 

Giant Inflatable Mosquito Makes an Appearance to Increase Public Awareness about Invasive Mosquitoes

National Mosquito Control Awareness Week is a Reminder to Orange County Residents to Protect Themselves

Garden Grove, CA. There is a new giant inflatable mosquito in town. The Orange County Mosquito and Vector Control District (OCMVCD) is introducing a giant black-and-white inflatable mosquito, depicting the two recently established invasive species of mosquitoes, for National Mosquito Control Awareness Week (June 25 – July 1), to raise awareness and educate residents about the threats mosquitoes pose in Orange County, and throughout the nation. The 13-foot mosquito will be displayed for the first time in public on Friday, June 30th at 4 PM on Historic Main Street (12891 Main St.) in the city of Garden Grove.   

“This giant inflatable mosquito is a fun way to educate Orange County residents about a not-so-fun fact: we now have these aggressive day-biting invasive mosquitoes that can make people sick and will change our quality of life in Orange County,” said Mary-Joy Coburn, Public Affairs Coordinator. “When a member of the public enters the booth, they learn facts about mosquitoes, how to eliminate breeding sources, and how to protect themselves from mosquito bites and mosquito-borne illnesses.”

Click here to read the full press release.

Record Rainfalls and Warm Temperatures Could Mean an Explosion of Mosquitoes

National Mosquito Control Awareness Week is a Reminder to Californians to Protect Themselves 

SACRAMENTO, June 22, 2017 – While California’s wettest winter in 122 years ended the state’s historic drought, the surge in rainfall could contribute to another threat: an active mosquito season with the potential for increased mosquito-borne virus transmission to people.

Heavy rains over the past six months have produced new sources of standing water throughout the state. As the weather heats up, these sources become ideal breeding grounds for mosquitoes which could result in tens of thousands of potential virus transmitters, posing a health risk to Californians.

Mosquitoes in California actively transmit West Nile virus and Saint Louis encephalitis each year, and invasive mosquitoes detected in the state have the potential to transmit even more viruses such chikungunya, dengue, yellow fever, and Zika.

Click here to read the full press release.

Updated CDC map shows 21% increase in US counties reporting mosquito that transmits Zika

Last year, with the Western Hemisphere in the grip of a surprising Zika virus epidemic, CDC researchers used a survey to compile a list of U.S. counties where the mosquito at the heart of the epidemic, Aedes aegypti, had been documented over the past 21 years. They also documented counties that reported finding another mosquito, A. albopictus, known to transmit chikungunya and dengue viruses. The researchers said their data could be used to guide surveillance and mosquito control efforts across the country.

Read more

California’s wet winter could lead to an early mosquito season and increased virus transmission

Mosquito Awareness Week educates California residents on preventing mosquito-borne viruses

SACRAMENTO, APRIL 13, 2017 – As California’s extremely wet winter comes to a close, mosquito experts throughout the state are ramping up for what will most likely be an early and active mosquito season. While the heavy rains were good for the state’s historic drought, they also produce new sources of standing water, the ideal breeding grounds for mosquitoes.

Mosquitoes and warm weather go hand in hand. Spring temperatures will further determine how early and aggressive the mosquito season will be.

With potentially the perfect storm of conditions for mosquito activity, Californians need to be aware of the serious risks mosquitoes present to their health including West Nile, Saint Louis encephalitis, and potentially dengue, chikungunya, and Zika viruses.

Click here to read the full press release.

In valley, Indio at center for fight against Zika

Barrett Newkirk, The Desert Sun – Wednesday, March 15, 2017

Saturdays at dawn, a single-seat helicopter swoops over an Indio neighborhood, low enough that people hear the engine whir before they see the chopper flying just above the trees.

Trailing behind it are four streams of brown mist.

At first, the spraying worried Veronica Cruz, who said the noise would get her out of bed.

“Later we found out it was because of the mosquitoes,” Cruz said.

The Coachella Valley Mosquito and Vector Control District has used the helicopter since February to target the area the public agency says has become the epicenter of its battle with an invasive species of mosquito capable of spreading the Zika virus and other dangerous diseases. The aerial spraying is expected to continue well into April.

Read more

California residents urged to dump out standing water as mosquito season heats up

Kristin Hanes, SFGATE – Tuesday, March 7, 2017

The heavy rains may be wiping out California’s drought, but they’re breeding a different sort of problem. One that’s tiny, irritating, and makes a high pitch buzzing sound in your ear.

“Persistent rains require persistent mosquito control,” said Jamesina Scott, district manager and research director for Lake County Vector Control, and President of Mosquito and Vector Control Association of California. “We have had a lot of heavy rain and a lot of standing water. Our early season mosquitoes are taking full advantage of it. Mosquito control workers across the state have been inspecting all the standing water that’s out there now to find the best control solution.”

There are 56 different types of mosquitoes that live in California. Every one has its own season, is own habitat, its own hosts, and ability to transmit disease.

Read more

In the Fight Against Zika, Insecticides Hit a ‘Dead End’

Wall Street Journal – Jan. 5, 2017

Health workers have a thinning arsenal of insecticides capable of killing mosquitoes that carry Zika and similar viruses as the Southern Hemisphere’s summer begins and as outbreaks persist in other areas.

One reason: Eliminating disease-carrying mosquitoes is a niche business with costly barriers to entry.

“We may be hitting a dead end,”…

Learn more

CDPH media release: Zika and Travel

Today CDPH issued a media release “Holiday Travelers Reminded to Take Precautions to Prevent Zika”, there is also an accompanying travel advisory.

Mosquito Control and Vector-Borne Disease in California: The Interjurisdictional Relationship of Water Management

Recent article that discusses the need for interaction and cooperation between mosquito and vector control agencies and water management agencies.

Click here to view

With Zika Taking Center Stage, We Can’t Forget About West Nile Virus

National Mosquito Control and Awareness Week is a Reminder to Californians

SACRAMENTO, June 24, 2016 – By now we are all very aware of the Zika virus that has continued to make headlines in the United States over the past several months. With much of the attention on Zika, it is important not to forget about the continued threat of West Nile virus (WNV).

WNV is responsible for hundreds of reported cases each year. It can cause severe disease that infects peoples’ nervous system, potentially resulting in death. In 2015, in California alone, 53 people were killed by the virus and 783 cases were confirmed.

As June 26 – July 2 has been declared National Mosquito Control Awareness Week by the American Mosquito Control Association, now is an ideal time to remind individuals that Zika virus is not the only mosquito-borne threat. This week is intended to educate the general public about the significance of mosquitoes in their daily lives and the important service provided by mosquito control workers throughout the United States and worldwide.

Click here to read the full press release.

Enlisting Mosquitoes to Fight Zika

A NY Times video-report on Consolidated Mosquito Abatement’s collaborative Aedes aegypti/Wolbachia male release project.

Click here to view on the NY Times website

Media Advisory: “Fight the Bite” at California’s State Capitol

The Mosquito and Vector Control Association of California to hold “Fight the Bite” public education event urging prevention and protection methods against mosquitos and vectors as summer months approach

Click here for more information

Press Release: West Nile Virus Remains a Serious Threat in California as Summer Months Approach

West Nile Virus and Mosquito and Vector Control Awareness Week educates California residents on preventing mosquito-borne viruses. 

SACRAMENTO, APRIL 18, 2016 – Mosquitoes and warm weather go hand in hand.  With summer rapidly approaching, Californians need to be aware of the serious risk West Nile virus (WNV) presents to their health.

To raise awareness and educate Californians about the threat mosquitoes and vectors pose to our communities, the California Legislature declared April 17 – 23, 2016 as West Nile Virus and Mosquito and Vector Control Awareness Week.

“While a lot of attention has been given to Zika virus, West Nile virus killed more Californians in 2015 than any other year before,” said Senator Bob Wieckowski, chair of the Environmental Quality Committee and author of Senate Concurrent Resolution 121. “Properly funded local mosquito abatement programs are vital to protecting public health and saving lives.”

Read more

Press Release: SB 1246 Puts Californians at Increased Public Health Risk

SACRAMENTO, March 10, 2016 – A new bill introduced in the California state senate poses a significant threat to the health of residents and visitors. SB 1246 (Nguyen) would require local mosquito control agencies to provide notice to governmental agencies, school districts, chambers of commerce, and elected officials at least seven days before administering pesticides by aircraft or unmanned aerial vehicles over a residential area. The proposed requirement would impair mosquito control agencies’ ability to manage mosquito populations and protect public health.

Read more

We Can’t Expect the Government to Save Us From Disease-Carrying Mosquitoes, by Kenn Fujioka

The Arrival of the Zika Virus in the U.S. Reminds Us That the First Line of Defense Is Our Own Backyards

“We need you to come take a look at something.” Ecologist Angela Brisco and technician Marc Mitchell, employees of the San Gabriel Valley Mosquito and Vector Control District, peered over the short wall of my cubicle. Whenever our staff neglected to use my “front door,” I knew something was wrong.

They showed me a single female mosquito under the microscope. It didn’t look good: I focused up and down, trying desperately to make the black and white stripes on her legs and the white “ax mark” on her thorax disappear.

“Where did you find her?” I asked.

“El Monte,” Marc said sadly. “A woman complained about being bitten during the day by mosquitoes, and I caught this one at her home.”

Read more


A Century of Mosquito Control in California: 1915 – 2015, by Joseph Wakoli Wekesa

A recent article by MVCAC Member Joseph Wakoli Wekesa that appeared in the Winter issue of the AMCA Wingbeats.

“It was no accident that the first “service request” for relief from mosquito bites in 1904 by the Chair of the San Rafael Improvement Association was delivered to Professor Charles W Woodworth of University of California at Berkeley (UC Berkeley).  The previous year Woodworth surveyed mosquitoes in the San Rafael salt marsh with his entomology class, which attracted the attention of local residents…”

Read more

Mosquito-Borne Viruses And Transmission

To help answer the public’s questions and concerns about the Zika virus, UC Davis Health System is hosting a community forum on Saturday, featuring a panel of leading experts on the transmission, treatment and prevention of the disease.

One of the panelists, epidemiologist Chris Barker, BS, MS, PhD, who specializes in the surveillance and control of mosquito-borne viruses, joins Insight to explain more about mosquito transmission.

Read more and listen to MVCAC Member Chris Barker’s interview with Capital Public Radio here.

MVCAC Press Release: Mosquito Control is Key to Preventing the Spread of Zika Virus

Local mosquito control agencies will continue to employ protection and prevention methods to ensure lowest level of public health threat.

SACRAMENTO, FEBRUARY 8, 2016 – As Zika virus spreads through the Americas, it is important to understand the reality of California’s exposure to the virus and the measures state and local vector control districts take to shield more than 38 million residents from this and other mosquito transmitted diseases.

Zika virus has federal, state, and local health agencies at an increased level of alertness as they inform U.S. residents about how the virus spreads and the risk of disease, areas where Zika virus is being transmitted, symptoms to look out for, and how to protect oneself from being bitten by mosquitoes.

Read more

LA Times – Aggressive nonnative mosquitoes spreading across state carry disease risk

It has the makings of a science-fiction film: the threat of deadly disease, a metropolis oblivious to the impending danger and, of course, extraordinarily hostile insects.

That’s the scenario California health officials say they’re facing as they track the arrival of nonnative mosquitoes that can carry infectious diseases.

The insects are quickly spreading across Southern California — aided by the statewide drought — and have the potential to transmit dengue, chikungunya and yellow fever, all of which kill thousands of people around the world each year.

Read more



Press Release: California’s Hot, Dry Summer Calls for Robust Mosquito Abatement

National Mosquito Control and Awareness Week Puts Californians on High Alert

SACRAMENTO, June 19, 2015 – By now, it comes as no surprise to most Californians that the driest year in the state’s history has had a number of implications for its residents and communities. However, it may come as a surprise that as a result of these conditions, mosquitoes are prolific and their ability to spread disease is at an all-time high.

Read more

Battling mosquito-borne diseases in dry California

Click here to view the full article

By: Robert Ferris, CNBC News

The state’s Department of Public Health recently announced that 2014 was a record year for potentially dangerous mosquito-borne West Nile virus cases, and some mosquito-control experts are concerned about the effect that warm weather and drought will have on mosquitos in 2015.

Given that the parasitic insects like to lay their eggs in water, it may be tempting to assume that California’s severe, 4-year-old drought would make the mosquito problem better, not worse. But there are many aspects to the drought that are seen exacerbating the problem.

California’s largest city, Los Angeles, has a vast network of storm drains that carry rainwater out to the ocean via the Los Angeles River. Over time, earthquakes have damaged some of these waterways, creating small interruptions where stagnant water collects.

The mosquito that lives there, Culex quinquefasciatus, remains active all year round, laying eggs in the pools. Wetter years produce regular storms that wash out the waterways. The last few years, which have been very dry, have not provided that safeguard.

Then there’s the fact that people throughout California have taken steps to conserve or catch water. Other homeowners have stopped filling or maintaining their pools. Both cases can result in small pools of stagnant water, which in turn become an excellent home for mosquitoes.

Susanne Kluh of the Los Angeles County Vector Control District, which combats mosquitoes in order to prevent disease, said her group is trying to work with cities to strike a balance between water conservation efforts and mosquito control.

Predicting epidemics is impossible to do precisely—factors include the health of mosquito and bird populations, climate and water availability, and others—but people who work in the state’s disease control groups are already seeing insects in the air.

Kluh said she and her colleagues are already observing population numbers slightly higher than their five-year average, even though the group had been chemically treating nests all winter.

“Right now, we are closer to what our numbers would be like during the summer,” Kluh said.

Vector control agencies like Kluh’s test samples of mosquito populations for viruses. They’ve already seen one sample test positive for West Nile this year. That’s unusual for this early in the year, and it’s not a guarantee of an outbreak in the same area, Kluh told CNBC.

Aside from the dry conditions, hotter summers and milder winters are also making the problem worse lately.

“We have a lot more infected mosquitoes in the area during some of these years that have very mild winters,” said Joel Buettner, president of the Mosquito & Vector Control Association of California, an association of public agencies given the task of reducing mosquito populations and testing for viruses in animal and insect populations.

Data from other states show a similar correlation between warm winters and West Nile epidemics, including a recent study of epidemics in Dallas.

California had a mild winter, so vector control technicians had to start tackling active mosquito populations early in the season, Buettner said.

Hotter summers also make a difference. The warmer weather speeds up the lifecycles of the insects. They feed more, they metabolize the blood they feed on faster, and the viruses they carry replicate faster in their bodies. All of those factors can spread the disease more quickly.

A hot summer also can extend the mosquito season from two or three months to five months, which heightens chances of a human case. Two outbreaks in Saskatchewan, Canada, both occurred toward the tail end of a long and hot season.

Other factors may limit dangers, of course.

West Nile virus is a disease that mostly affects birds, not humans. Mosquitos become carriers of the virus when they bite an infected bird. The insect can then transmit the disease to any human it bites after that. But mosquitos can pass the disease only from bird to bird or bird to human. Biting an infected human won’t by itself make a mosquito into a carrier; only contact with an infected bird will.

That’s why a sufficient number of susceptible birds is necessary to produce fast-spreading West Nile virus epidemics, according to Dr. Bill Reisen, a professor of veterinary medicine at UC Davis. But many of the affected birds have died off, and immunity has built up among those that remain.

“What we have found is that when you have epidemics that go to fruition, such as they did in Los Angeles or Orange County, usually the following year is a pretty light year, regardless of the heat and the drought or any everything else.”

The areas most likely to suffer an outbreak in the coming years are those that went mostly untouched in recent years, and since Los Angeles was hit hard in 2014, it may have an easier go of it this year.

“Areas like Bakersfield and some other Central Valley cities didn’t have a huge year, so they might be at risk,” Reisen said.

But West Nile is only one of the mosquito-borne diseases worrying some health and disease prevention groups. More recent invasive mosquito species, such as Aedes aegypti and Aedes albopictus, transmit Dengue fever, yellow fever and chikungunya. Those mosquito species are already in California cities, though they have not yet contributed to epidemics. But most people who watch disease-carrying insects are keeping eyes on outbreaks elsewhere, especially in areas where Californians travel.

While West Nile virus requires birds to spread, chikungunya and Dengue fever can be transferred by mosquitoes that are only biting the human population. Fighting those mosquitoes will require a different set of strategies, Kluh said. And, unlike West Nile-carrying Culex mosquitoes, Aedes mosquitoes can lay eggs individually, in spaces as small as a bottlecap.

“Everyone in the mosquito-control business in California is pretty worried about this as an inevitability,” Reisen said.

In most people, West Nile virus produces only mild symptoms, if any, according to the Centers for Disease Control and Prevention. There is roughly a one in five chance of developing a fever or other flulike symptoms (with fatigue and weakness that could last for months), and, usually, a less-than-1 percent chance of contracting a serious brain infection, such as meningitis or encephalitis. There are no vaccines, and no treatment other than managing symptoms at home or in a hospital, if needed.

There were 801 cases of West Nile virus in California last year, according to the California Department of Public Health. A highly unusual 561 of them were severe cases of brain infection, and 31 patients died. Health officials are unable to explain the spike in brain infections, but it’s possible that a large number of cases with milder symptoms went unreported or unrecognized by doctors.

The biggest number of cases occurred in Orange County, and the highest per-capita number was in Glenn County, where a large number of flooded rice fields provide an ideal breeding ground for the insect.

Warm Weather and Drought May Lead to Abundance of Mosquitoes

West Nile Virus and Mosquito and Vector Control Awareness Week educates California residents on preventing viruses transmitted by mosquitoes

SACRAMENTO, APRIL 17, 2015 – With California’s unusually warm weather and the driest year in the state’s history, Californians may see an unprecedented number of mosquito transmitted diseases in 2015.

To raise awareness and educate Californians about the public health threats mosquitoes and vectors can have on our local communities, the California Legislature declared April 19 – 25, 2015 as West Nile Virus and Mosquito and Vector Control Awareness Week in California.

With 2015 marking the 100-year anniversary of California’s Mosquito Abatement Districts Act (AB 1590 enacted in 1915), local mosquito and vector control agencies need to be more diligent than ever. California experienced record-breaking West Nile virus (WNV) activity in 2014 and several exotic mosquito species capable of transmitting deadly diseases have been discovered in the last couple of years and are now permanently established in some California communities.

The California Department of Public Health (CDPH) reported 801 human cases of WNV, 561 of which were the serious neurological form of the disease, and 31 deaths, the highest number of fatalities in California since the disease was first detected in 2003. A contributing factor for the staggering number of WNV cases could be a result of the ongoing drought, which reduced the number of sources of water for birds and mosquitoes.

Invasive species capable of transmitting a number of life-threatening diseases including chikungunya, dengue, and yellow fever, are posing an increasing threat to Californians. While these diseases have not been transmitted locally in California at this point, efforts to control these mosquitoes are adding increasing challenges to vector control agencies statewide.

Predicting the level of WNV in any given year is not possible as WNV activity depends on a number of factors including climate, number and species of birds and mosquitoes in an area, as well as the level of immunity in birds to WNV. However, if California continues to experience warm temperatures, we can count on an early start to mosquito and WNV season, extending the number of months local communities and residents are at risk of contracting potential deadly diseases transmitted by mosquitoes.

“It is critical that public agencies do their job to protect nearly 38 million Californians that are at risk and exposed to mosquitoes on a nearly daily basis. Education is key to protection and prevention,” said Joel Buettner, President of the Mosquito and Vector Control Association of California (MVCAC). “It is our job to increase awareness about the severe public health threats mosquitoes pose to our state and residents. Equally as important is communicating prevention methods that can be employed to protect yourself and your local communities,” added Buettner.

To minimize exposure to mosquito bites and WNV, practice the “3 Ds:”

  1. DEET – Apply insect repellent containing DEET, picaradin, oil of lemon eucalyptus, or IR3535 according to label instructions. Repellents keep mosquitoes from biting. DEET can be used safely on infants and children 2 months of age and older.
  2. DAWN AND DUSK – Mosquitoes capable of transmitting WNV are most active in the early morning and evening, so it important to wear protective clothing and repellent if you are outside during these times. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.
  3. DRAIN – Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including in flower pots, old car tires and buckets. If you know of a swimming pool that is not being properly maintained, please contact your local mosquito and vector control agency.

To increase awareness and enforce prevention and control programs statewide, the MVCAC provides support to more than 65 districts throughout California. As a result, approximately half the land area and 85 percent of California’s population are within the boundaries of a mosquito control program.

MVCAC represents special districts, other subdivisions of local government, and the state of California which are responsible for mosquito and vector control, surveillance of WNV and other vector-borne diseases, as well as public education programs to help Californians protect themselves from disease. MVCAC advocates safe, effective, and environmentally friendly methods of mosquito and vector control.

The MVCAC will be participating in a public education effort, “Fight the Bite 2015,” at the State Capitol on Thursday, April 23rd from 9:30 am – 1:00 pm.

Data Collection on mosquito control expenditures on state lands

February 9, 2014
To: MVCAC Member Agencies
Fr: Joel Buettner
Re: Data Collection on mosquito control expenditures on state lands

At our recent MVCAC Board meeting in Monterrey, we discussed next steps for implementation of AB 896 (Eggman). As you will recall, AB 896 requires the Department of Fish and Wildlife to consult with local vector control districts on best management practices (BMPs) for state wildlife management areas. We will soon be meeting with the Department to discuss next steps but need your help to compile critical data beforehand.

Please click here to read the memo

Please click here to view the State Lands Report Template

Public Health Experts Warn Lack of Planning in Development Projects Increases Risk of Mosquito-borne Disease Threats

Download the .pdf

White Paper: How Better Planning and Use of the California Environmental Quality Act Can Prevent Mosquitoes and Vector-Borne Disease

While many local governments have done a good job improvising from existing CEQA guidelines and other planning tools to begin to address this issue, a significant gap exists between state regulations and the resources that most local planning agencies need to address vector issues in the planning process. To address this concern, MVCAC has developed the enclosed white paper, “How Better Planning and Use of the California Environmental Quality Act Can Prevent Mosquitoes and Vector-Borne Disease,” that discusses the benefits for developers, natural resources and public health when adding vector control considerations to local government project planning and design.

MVCAC’s White Paper presents a number of case studies that identify problems and recommended solutions specific to the local planning and CEQA review process and is intended to be a tool for local governments and other lead agencies to manage, analyze, and address the impacts of mosquito and vector breeding inherent in certain types of projects.

To view the entire White paper, “How Better Planning and Use of the California Environmental Quality Act Can Prevent Mosquitoes and Vector-Borne Disease” please click here.

Capital Public Radio – Bloodsucking Insects – July 28, 2013

Listen here

LA Times Article – New Study on Mosquito Monitoring and Prevention of West Nile Outbreaks

Mosquito monitoring can prevent West Nile outbreaks, study says

By Melissa Pandika
July 17, 2013

About 100 cases of West Nile virus infection — and a dozen deaths — could have been prevented last year if public health officials in Dallas had kept track of the proportion of infected mosquitoes caught in traps, a new study says.

A detailed analysis of the 2012 outbreak in Dallas gave researchers the perfect opportunity to test a long-held theory that monitoring mosquitoes, rather than human cases, could predict epidemics and allow for early intervention. Keeping tabs on mosquitoes allows public health officials to estimate the rate of infection in the local mosquito population, as well as the mosquito population size; multiplying the two numbers produces a figure called the “vector index.” Experts at the Centers for Disease Control and Prevention thought the vector index would make it easier to see where the virus was spreading and take early action to slow or halt that spread.

West Nile virus, which is most commonly transmitted by mosquitoes, can cause fever, encephalitis and meningitis, according to the CDC. Although most people who are infected won’t display symptoms, about 1 in 5 will develop a fever with other symptoms. Less than 1% of patients will develop a serious, sometimes fatal, neurologic illness. Currently, no medications or vaccines for the virus exist.

The virus first emerged in New York City in 1999. It then spread across the U.S, with the first outbreak in Dallas occurring in 2006. After a five-year lull, the virus came roaring back in 2012, infecting 7.3 out of every 100,000 residents and killing 19 people.

Dr. Robert Haley, an epidemiologist with UT Southwestern in Dallas, and his colleagues calculated the vector index for each week during the 2012 epidemic. Frequent monitoring is crucial, because symptoms normally take a week to appear and subsequent lab tests can take another two to three weeks to produce results. By then, the epidemic would have almost finished running its course.

“It can take three or four weeks before you know about people who are infected,” said William Reisen, an epidemiologist at UC Davis who was not part of the study. “By that time, there are that many more infected, and you’re far, far behind.”

Based on those figures, they used statistical models to determine that Dallas public health officials could have prevented 100 cases and 12 deaths had they intervened a week after the vector index hit its threshold. Instead, they took action only after several patients had been hospitalized.

Weather conditions in 2006 and 2012 created “a perfect storm” for a West Nile epidemic, Haley said. Within the 11-year period studied, both years had the fewest hard freeze days — when the temperature low measured less than 28 degrees Fahrenheit — and the warmest spring temperatures. Both years also saw drought punctuated by rainstorms “so there was always a little standing water around,” Haley explained.

Experts say that global warming trends forecast more epidemics. “Diseases that typically only occurred in the tropics are starting to creep northward,” Haley said. “West Nile is one of them.”

Merging surveillance with Census tract data, the researchers also found that, in both the 2006 and 2012 epidemics, cases tended to cluster around affluent, housing-dense areas with a higher percentage of unoccupied homes — not in low socioeconomic neighborhoods, as often occurs with other urban epidemics.

Haley explained that the abundance of housing in these hotspots might have provided a more hospitable environment for the common house mosquito, which carries the West Nile virus, than poorer Dallas neighborhoods, which attract less development.

“The Dallas study is a very cogent reminder that the virus is certainly still here and it’s still capable of causing a very significant public health problem,” said Dr. Stephen Ostroff, an epidemiologist at the Pennsylvania Department of Health who wrote the editorial that accompanies Haley’s study. “You don’t want to take your eye off the ball.”

Ostroff added that preventing and controlling the virus requires “an integrated vector management approach” that involves identifying potential breeding sites in the winter and spring, well before mosquito season hits. Regularly cleaning clogged gutters and maintaining swimming pools would eliminate many breeding sites, he said. Mosquito monitoring and targeted pesticide use are also key. “It’s the proverbial ‘an ounce of prevention is worth a pound of cure,’ ” he said.

Haley cautioned that his group’s findings may not apply to regions outside of Dallas, adding that the CDC recommends that each region conduct a similar study to begin developing their own prevention program. “This paper gives them ideas,” Haley said. “They can follow along and do some of the same types of things.”

In the editorial accompanying the study, Ostroff warned against complacency among policymakers and the public, which he partly blamed for the delayed response to the Dallas epidemic in 2012. Federal funding for the CDC Epidemiology and Laboratory Capacity program, which distributes funds to states and some large cities for mosquito surveillance and disease prevention efforts, peaked at $35 million with the emergence of West Nile in 2000, but dropped to less than $10 million by 2012, he wrote.

But policymakers should also “invigorate” treatment options, Ostroff said, adding that almost 15 years after the first West Nile outbreak, no human virus vaccine, specific treatment, or method to disrupt the transmission cycle has been developed.
Twitter: @mmpandika

Copyright © 2013, Los Angeles Times

Districts Fight Two New Invasive And Disease Carrying Mosquito Species While West Nile Virus Activity Increases Throughout The State

Download the .pdf

ACR 21 – 2013 West Nile Virus and Mosquito and Vector Control Awareness Week

Download the .pdf

UC Davis Assistant/Associate Professor of Vector Virology Candidate Seminars

Candidates for appointment to Assistant/Associate Professor of Vector Virology in the Center for Vectorborne Diseases and the Department of Pathology, Microbiology and Immunology will soon begin visits. MVCAC members and the vector biology community are invited to attend candidate seminars as follows:

  • April 29, 2013: Nikolaos Vasilakis
  • May 1, 2013: Lark Coffey
  • May 13, 2013: Douglas Brackney
  • May 15, 2013: Brian Bird

Candidates for the position of Vector Virologist will give seminars from 12:00 to 1:00 p.m. on the above dates. All seminars will be held at 1035 Valley Hall on the UC Davis campus. For questions regarding the seminars contact Dedra Hamilton at 530-752-2015.

Download Candidate Curriculum Vitae
Brian Bird
Douglas Brackney
Lark Coffey
Nikolaos Vasilakis

MVCAC has moved!

1 Capitol Mall, Suite 320
Sacramento, Ca 95814
Fax 916-444-7462

Phone and email are still the same