- The ARC - California Edition -

El Nino Raises Encephalitis Fears

After a winter of record rainfall, California is potentially the target for one of the worst mosquito seasons in 15 years. Mosquitoes in California are known to carry two types of encephalitis virus, the western equine encephalitis, which strikes horses as well as humans, and the more frequently seen, the St. Louis encephalitis.

Both diseases produce the same symptoms and cause mild, flu-like symptoms in most people. Often it is not even reported as the illness is mistaken for the flu. But, encephalitis virus can cause a deadly brain inflammation, and in severe cases, this may result in paralysis, coma or even death.

Mosquitoes contract the disease by biting migrating birds and spreads it through bites to animals and humans. The mosquito is very good at sensing the carbon dioxide which is exhaled by most living things. They use their needle-like beaks to attack anything that contains blood. The nutrients from one bite can sustain one mosquito long enough to breed several hundred offspring.

A mosquito’s life is mostly spent in pools of water and their eggs are usually laid in standing water of an inch or more. The eggs float on top and incubate for several days before hatching into larvae. The most effective method for preventing the spread of the virus has been found to be the elimination of the stagnant water which the mosquitoes usually use as their breeding sites.

During 1983, we also had about 30 inches of rainfall in Los Angeles county. That year we had a 50% increase of mosquitoes in the spring and 250% increase of mosquitoes during the summer.

Mosquitoes are mostly active in the mornings and evenings. If you or others in your charge like to be outside during the morning or evening hours, it is recommended that you wear long-sleeve shirts and long pants. Repellents are effective.