Residents in Santa Clara County can be thankful this week, as cases skyrocket one of the worst outbreaks of West Nile virus in the country, climate and prevention has local communities virtually unscathed.
With 66 deaths and 1,590 illnesses as of Tuesday, according to the U.S. Centers for Disease Control and Prevention, it appears that six states —Texas, South Dakota, Mississippi, Oklahoma, Louisiana, and Michigan—are experiencing 70 percent of the cases. Compared to last year, the virus is up 40 percent nationally.
One key in Santa Clara County has been prevention and quick fogging to break the cycle of active infection of mosquitoes, the Santa Clara County Vector Control District says.
"It's having a good surveillance system in place," said Russ Parman, a spokesman for the county's vector control district. "Nationally it's an unusal year, and it underscores why we need to have these programs in place."
Even if there are low numbers of mosquitoes, the virus is very easily picked up from sick birds by the mosquitoes, he said, so once they find a dead bird, they test for the disease. "There is just so much virus on the sick bird that just about every mosquito that lands on a sick bird is going to have the virus."
Then, he said, it becomes a numbers game in terms of human risk. "The more mosquitoes the higher the case rate."
West Nile Virus is hot in the Central Valley, Southern California the county is experiencing a "mild year," Jóse Colomé of the vector control said Aug 22. Local residents can take some of the credit.
A section of after vector control found mosquitoes that tested positive. Even then, the incidence—one in 75 mosquitoes—was relatively low compared to one in 20, which has been the case in other parts of the state, said Russ Parman, another spokesman at county vector control.
Parman told Patch that since that fogging, no more mosquitoes have tested postitive. More testing is being done this week. In comparison with elsewhere in the country and the state, the county is in much better shape.
So far, the Los Altos-Mountain View case is the only fogging campaign the district has had to do this year. Last year, there were four fogging campaigns, Colomé said.
According to the Centers for Disease Control, as of Aug. 21, there have been 1,118 cases of West Nile Virus disease in people, including 41 deaths in 47 states. Fifty-six percent of these cases, or 629, have been classified as neuro-invasive, which means they can cause meningitis or encephalitis. The CDC reports that 75 percent of these cases are in the states of Texas, Mississippi, Louisiana, South Dakota, and Oklahoma.
In 2011, there were a total of 712 cases nationwide.
In the state of California, to date there have been 34 cases of human infection reported so far, the majority in the Central Valley, according to the California Department of Public Health. On Aug. 3, the state announced the death of an 88-year-old woman from Kern County who died from the virus. By that date, there had only been ten human cases of West Nile Virus detected in the state compared to seven human cases and no deaths in 2011.
Climate and other factors are part of the reason that the county has not had a worse infection rate, Colomé said. And, the district's program of prevention and treatment is another part. The district paid for aerial surveillance to spot neglected swimming pools—detected by color of the water—in March, he said.
"One swimming pool can breed thousands, millions (of mosquitoes)," Colomé said.
Neighbors are encouraged to report neglected pools anonymously so that the district can offer no-cost treatment. About 700 pools were treated this way. They use mosquito-eating fish very effectively, he said.
The district, in fact, gets a lot of cooperation and involvement from the public, which is a big part of the district's success, Colomé said. In Silicon Valley, people actively report neglected pools, as well as dead birds and small animals, he said.
When reports of dead birds or animals are made on California's dead bird/squirrel reporting page, the state gives the district the location, and the animal is picked up.
The district then sets up mosquito traps around the location of the bird or squirrel. While the bird may have flown from another location, it is important to find out if the West Nile disease is present in the place it was found and is in an active transmission cycle. If mosquitoes test positive for West Nile Virus, the district makes plans to quickly kill mosquitoes within a one-mile radius to prevent transmission to humans, Colomé said.
Colomé said that county residents should keep on reporting dead birds and squirrels (toll-free: 877-968-2473), so they can stay on top of the possibility of active transmission cycles. And yes, he said, with the number of foreclosures that have taken place in the county, please continue to anonymously report swimming pools and other standing water in your neighborhood, he said.
Here are recommmendations of precautions that can be taken against mosquito bites:
AT HOME
- DRAIN or DUMP standing water weekly since this is where mosquitoes lay eggs. Check items such as flower pots and planter bases, toys, cans, leaky water faucets and sprinklers, rain gutters, buckets, pools, ponds, and old tires.
- Make sure your DOORS and windows have tight-fitting screens.
OUTDOORS:
- Limit activities during DUSK & DAWN to prevent mosquito bites. Those are the times when the mosquitoes that transmit WNV are most active.
If you need to go outside at dusk or dawn, or if you're in an area where mosquitoes are active:
- Apply insect repellent, following the label instructions.
- DRESS in long sleeve shirts and long pants, preferably of light colors.
