Prevention only cure for West Nile virus

The current outbreak of West Nile virus in the United States is the largest ever known since it was fist discovered in Uganda in 1937, said Porshnikoff.

"This is the biggest outbreak ever recorded," Porshnikoff said. "The virus strain is more than 98 percent similar to the one [found] in Israel. There has been some genetic mutation [to the virus in the United States]."

There is no need to get alarmed, assures Porshnikoff. Most people infected by the virus do not fall ill.

"We are not trying to create hysteria. If we don't have a large epidemic, then it means we are doing our job."

A very small percentage of the population is infected with the virus and only about 10 percent of those show any symptoms. Deaths from the infections have occurred among those above the age 50 or with weak immune systems.

However, those without any symptoms but carrying the virus can transmit it through blood transfusions and organ donation, Porshnikoff said. The Centers for Disease Control and Prevention in Atlanta said that at least six people became infected through blood transfusions last year despite donation screening. A small risk of infection still exists despite the screenings, according to CDC.

Prevention the only option

The San Mateo County Mosquito Abatement District is leaving no stone unturned in its effort to minimize the impact of West Nile virus in the county. The silver lining, however, is that only mosquitoes can infect humans. The typical West Nile virus cycle is: an infected mosquito bites a bird and infects it; an uninfected mosquito bites the infected bird and acquires the infection and the cycle goes on. Breaking this cycle is the key to preventing the spread of the virus.

"California's program is mainly preventative. That way you can stop the cycle of [the virus-carrying mosquito larvae] growing into adult," Porshnikoff said.

To prevent mosquito colonies from exploding, the district sprays Golden Bear Oil or GB 1111, a petroleum product, extensively as a larvicide. The oil works as a barrier between air and water and suffocates air-breathing insects such as mosquito pupae. These are safe for humans.

"[Golden Bear Oil] breaks down in a few days," said Angela Rory, assistant vector ecologist at the district. "We also use BTI, a bacteria specifically targeted at mosquitoes. All that we use are mosquito-specific and do not harm humans in any way."

The district also has a hovercraft and all-terrain vehicle to reach marsh areas and into the Bay during low tide for collecting samples and spraying chemicals. It also has a small boat in addition to about eight trucks that are fitted with special equipment to carry the chemicals and sprayers.

Expanding prevention

Recently, the Mosquito Abatement District expanded its borders. Before, the district served Millbrae, South County and eastern parts of East Skyline Boulevard. With the expansion, the entire county comes under the district's wings.

"It is nice we are helping the county and [its] people. In a way, it is also more work for us. In the short-term it is difficult, but it will help in the long-term," said Porshnikoff.

There are 20 species of mosquitoes in San Mateo County. Just three species make up the "primary concern," but Porshnikoff said half of those 20 species can potentially carry West Nile virus. Another three species are identified as carriers of malaria.

"Typically, malaria comes when military people return home from abroad," Porshnikoff said.

Warm weather and humid conditions are ideal for the spread of viruses carried by mosquitoes. Porshnikoff said all Bay Area mosquito control agencies are working together and sharing information because "mosquitoes can keep moving from place to place."

The public can play an important role in helping the district's preventive measures. It can immediately report incidents of dead birds; stagnant water with signs of mosquito activity; any suspicious mosquito bites and sightings of ticks.

Hikers and campers are relatively safe since West Nile virus is carried only by the common house mosquito. Mosquito repellent containing DEET (n,N-diethyl-meta-toluamide) can be used to keep insects away.

Pets are safe

West Nile virus infects pets too. An alligator died of West Nile virus, Porshnikoff said. The good news, however, is that cats and dogs do not produce enough West Nile virus in their bodies to fall sick or to retransmit it to another mosquito.

Horses, however, can. Actually, the virus is more deadly in horses than in humans. But horses have a vaccine and Porshnikoff said San Mateo County horse owners are well aware of it.

Though many companies are working toward it, a human vaccine for West Nile virus is not yet in sight. For now, the only cure we are left with is prevention.

West Nile virus facts

a.. There is no cure or vaccine available for humans

b.. Vaccine is available for horses

c.. Not a danger to cats and dogs

d.. Only contracted through the bite of an infected mosquito

e.. Blood transfusion and organ transplant can transmit the virus

f.. Death is possible in adults older than 50 and those with weak immune

system

Symptoms:

a.. Fever, headache and body aches

b.. Skin rashes

c.. Swollen lymph glands

d.. Symptoms can last two or more days

e.. After infection, it is assumed the individual acquires lifelong

immunity

How to prevent?

a.. Eliminate standing water around your home

b.. Keep surroundings clean

c.. Make sure screens on doors and windows are in good shape

d.. Ultrasonic devices are NOT effective mosquito repellants

e.. If you are bitten, try to keep a sample of the mosquito and

immediately call your local Mosquito Abatement District: Phone: 344-8592

f.. Report dead bird sightings to dead bird hotline: (877) 968-2473.