Santa Monica residents learned this week that a second bird found dead in the coastal city has tested positive for West Nile virus.
The bird had been examined at the end of July, but the notification from the Los Angeles County West Vector Control District was not posted on the city's website until Wednesday. The District does not divulge specific locations, but revealed the bird was found in the 90402 zip code on Santa Monica's northside. Another bird testing positive for West Nile has been found in May in the 90404 zip code to the south near the 10 Freeway.
The virus is spread to humans and animals alike by infected mosquitoes.
In the past month, additional infected birds and/or squirrels have been found in other Westside neighborhoods, including Venice, according to the activity report posted on the Disrict's website.
"I better go home and put on my Deet," said Santa Monica bicyclist Sonya Anselmo, referring to the mosquito repellent.
Indication of West Nile have now been found by the West Vector Control District in 50 of the county's 361 zip code areas.
This is significantly less widespread than a year ago, when the virus was found in 136 zip codes.
What's more, no west virus illnesses have been reported on the Westside this year, and only five in all of Los Angeles County, without a single fatality. This is far below last year's 63 illnesses that included four fatalities.
Southern California's low numbers this season stand in stark contrast to much of the rest of the nation, where the incidence of West Nile virus has surged, with more than 1,100 illnesses, the largest outbreak since the virus appeared in the United States in 1999.
More than half of the cases are concentrated in Texas, where aerial spraying has begun in an effort to reduce the mosquito population. Spraying is not planned in California. In the state as a whole, there are reports of more than 30 cases and at least one fatality.
Why Southern California is faring so much better in comparison is not known for certain, according to Jonathan Fielding, MD, MPH, LA County Health Officer. It's possible that from prior exposure, many Southern Californians have developed antibodies, Fielding said.
Whatever the reason, Fielding noted that the incidence is undoubtedly larger than reported, because 80% of West Nile infections are so mild they go unnoticed. It's believed less than 1% are severe enough to require hospitalization.
"I think we should think about this as a countywide issue," said Dr. Fielding. "And even though it's a lighter year, people should take the usual precautions."
Residents who are outside, particularly in the dawn and dusk hours when mosquitoes are most active, can defend themselves against mosquitoes by covering bare skin and using a mosquito repellent with DEET.
In the middle of zip code 90402 runs San Vicente Blvd, known as a haven for cyclists, runners, and walkers, many exercising in the dawn and dusk hours before and after work.
NBC4 medical correspondent Bruce Hensel, MD sees no reason for the exercisers to abandon their workouts or even time-shift, so long as they are mindful of mosquito precautions.
"You don't have to get off the bike, you don't have to avoid running, you don't have to avoid any area," Dr. Hensel said. "Just wear insect repellent, long shirts, long pants."
Two other suggestions from the experts are directed at residents: Don't allow pools of water to stagnate and become mosquito breeding grounds, and repair any holes or gaps in window screens.