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It’s still January, but with all the rain, mosquitoes are on the way. And Ryan Clausnitzer, district manager of the Alameda County Mosquito Abatement District, is making the rounds at public meetings and in schools warning of the dangers of mosquito-borne diseases in the coming months.
At a recent Pleasanton City Council meeting, Clausnitzer talked about the risks of the West Nile virus and Zika virus caused by mosquito bites and how his agency is working to stop mosquito breeding here.
His 16 full-time staff and six hired on a seasonal basis are already out with a full fleet of vehicles collecting samples from stagnant water locations for larvae of what he calls “one of the most voracious predators of humans on earth” — the Aedes Aegypti and Aedes Albopictus mosquitoes. They can spread everything from dengue, yellow fever, encephalitis, malaria, dog heartworms and the two most feared viruses, West Nile and Zika.
Clausnitzer said surveillance provides the district with valuable information on what mosquito species are present, when they occur, where they occur, how many there are, and if they are carrying diseases that affect humans. Equally important is the use of surveillance in evaluating the effectiveness of control actions in reducing mosquitoes and mosquito-borne diseases.
District technicians inspect known mosquito breeding sites on a regular basis. Clausnitzer showed photos of larval surveillance being conducted in Pleasanton by the use of a “dipper,” a one-pint cup attached to the end of a stick.
Water is dipped or sampled for the presence of mosquitoes. Samples are examined in the field or laboratory for the abundance, species and life-stage of the mosquitoes found and then this information is compared to historical records and used as a basis for treatment decisions.
Adult mosquito surveillance is done for two primary reasons. First, it allows the technician to locate new, undiscovered sources of larval breeding, or calls attention to the fact that a known larval breeding source needs to receive closer inspection and treatment.
Second, the collection of live adult mosquitoes is useful for virus testing. Adult populations are sampled using traps for mosquito-borne diseases. The public helps by reporting dead birds that may be tested for West Nile virus infection.
These samples, which can be found in as little as a bottle cap of water in both indoor and outdoor locations, are taken to the district’s laboratories in Hayward where technicians inspect the larvae and chart a response.
The dreaded Zika virus was discovered in Florida and, at this point, is the only known area where the virus has been spread domestically. Still, there are many communities in California where the mosquitoes capable of transmitting Zika have been found. Clausnitzer said while the disease has not been spread locally here, hundreds of California residents acquired the virus in 2016 while traveling abroad so he urged people to always protect themselves from mosquito bites wherever they may be.
His advice for Pleasanton residents:
* Inspect your yard regularly and remove any clutter or containers that may hold water.
* If you store water, make sure all containers are tightly covered to keep mosquitoes out.
* Scrub outdoor containers that have held water with hot, soapy water to kill any potential mosquito eggs.
* Wear mosquito repellent when spending time outdoors, and especially if you will be traveling to an area with the Zika virus.
Clausnitzer said that statewide in 2016 a total of 1,283 dead birds, 3,249 mosquito samples, 296 sentinel chickens and 276 humans tested positive for the West Nile virus. Nine human fatalities were reported.
The totals for California’s West Nile virus activity are updated weekly and can be found at www.westnile.ca.gov.
