West Nile virus infects San Francisco man

For just the second time in the last seven years, a San Francisco resident has contracted the West Nile virus.

Health department officials said in a statement that the unidentified man was recovering at home after being diagnosed with the mosquito-borne disease.

The man had not traveled outside of the Bay Area recently, though officials could not pinpoint exactly where in the Bay Area he may have contracted the disease. West Nile virus is transmitted to humans by bites from infected mosquitos.

Only one other human case of West Nile has been reported in San Francisco since reporting began for the disease in 2005. In 2010, a San Francisco resident contracted the West Nile virus via an organ transplant.

The Health Department has issued a health update to San Francisco medical providers asking that clinicians be on the lookout for other human cases, and to report them to The City.

Last week, the health department sounded a warning over West Nile virus after an infected dead bird was found near City College. It was only the third West Nile virus-infected bird found in San Francisco since 2007.

Four in five people infected with West Nile virus experience no illness or symptoms. The elderly or people with immune system deficiencies are susceptible to more serious problems, including encephalitis, meningitis or death.

The Centers for Disease Control website shows 126 total West Nile virus human infections in California in 2012 through last Tuesday, including six deaths.

Of the 3,142 cases reported nationally — the highest number since 2003 — 134 people have died.