California reported its first West Nile death earlier this month, an 88-year-old woman living in Kern County. As of Aug. 21, there are 33 other confirmed cases in humans, with more than half classified as neuroinvasive.
The rapid acceleration of West Nile cases in birds has been startling. By this time last year just 175 dead birds had tested positive for West Nile in California. This year the number is 717.
While no human cases have been reported in the Bay Area, the disease has been killing birds and animals.
The state reports that in Santa Clara County ten birds and one squirrel have died.
The breakdown for San Mateo County is more thorough:
- Red-shouldered hawk picked up June 11 in Woodside (WNV+)
- Eastern gray squirrel picked up July 3 in Menlo Park (WNV-chronic)
- Lesser goldfinch picked up July 22 in Redwood City (WNV-chronic)
- House sparrow picked up July 31 in Atherton (WNV-chronic)
- Canada Goose picked up July 31 in San Mateo (WNV-chronic)
- American crow picked up August 2 in Atherton (WNV-chronic)
- Eastern gray squirrel picked up August 2 in Menlo Park (WNV-chronic)
Thus far in 2012, there have been a total of 693 cases of West Nile Virus in people, including 26 deaths, according to the U.S. Centers for Disease Control. That's the highest number ever reported at this point in the year since the virus was first detected in the U.S. in 1999.
Dr. Lyle Petersen, director of the CDC's Division of Vector-Borne Infectious Diseases, said that if cases continue to grow at this pace, the outbreak could be the largest ever in the United States.
West Nile Symptoms
Most people bitten by an infected mosquito show no symptoms of illness. However, some become sick three to 15 days after exposure. People 50 and older are more susceptible to severe symptoms.
Mild symptoms, according to the Pennsylvania West Nile Virus Control Program, include:
- Body Aches
- Occasional Skin Rash
- Occasional Swollen Lymph Glands
More severe symptoms include:
- High Fever
- Neck Stiffness
- Muscle Weakness
West Nile Prevention
Mosquitoes breed in small collections of stagnant water, are common around people’s homes and often bite people indoors. While few mosquitoes may be noticed outdoors, those that are present and biting are likely to be the type that potentially carry the virus.
The months of August and September are when most human cases of West Nile occur in California. The end of summer is when mosquitoes are older and more likely to carry the virus. The types of mosquitoes that transmit the virus bite during evening and nighttime hours.
Palo Alto residents are encouraged to take the following steps to avoid West Nile Virus:
- Maintain window and door screening to help keep mosquitoes out of buildings.
- Empty water from mosquito breeding sites such as buckets, unused kiddie pools, old tires or similar sites where mosquitoes lay eggs.
- Apply insect repellents that contain the active ingredient DEET, or other EPA approved repellent to exposed skin or clothing, especially during peak mosquito activity periods such as dusk and dawn.
- Wear light colored, long-sleeved shirts and long pants when outdoors.
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