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So Far This Year, No Human West Nile Cases Reported In San Diego

An Aedes triseriatus mosquito.
Robert S. Craig / CDC
An Aedes triseriatus mosquito.

No human cases of West Nile virus have been reported so far this year in the San Diego region or anywhere in California, but more batches of infected mosquitoes have been found locally than in all last year, local environmental health officials reported Thursday.

County officials have discovered 53 batches of mosquitoes with the West Nile virus this year, compared to 49 in 2015.

The increased number of mosquito batches might be skewed slightly higher because vector control workers in May conducted several repeat tests of mosquitoes trapped around the Los Penasquitos Lagoon due to an outbreak of the insects there, according to the county Department of Environmental Health.


Vector control reported this week that, in addition to the mosquito batches, 132 dead birds and a horse — the first in the county reported this year — had also tested positive for the virus. While there is no human vaccine for West Nile virus, there is one for horses.

County officials urged horse owners to ask their veterinarians about getting their animals vaccinated.

Last year in San Diego County, 44 people tested positive for West Nile virus and six died. Statewide, 753 people tested positive and 53 died.

Even though no one has contracted the disease this year, the recent findings should remind people to remain alert, county officials said.

The best protection is to empty out areas of standing water where mosquitoes breed, stay indoors at dusk and dawn when the insects are most active, and wear long sleeves and pants or use repellent when outdoors.


About 80 percent of people with the West Nile virus don't get symptoms, while the remainder will have headaches, fever, nausea, fatigue, a skin rash or swollen glands.

An estimated one in 150 cases is life-threatening, with the risk going up for patients over age 50, according to the county Health and Human Services Agency.