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West Nile / Zika

West Nile / Zika

Words like "West Nile" and "Zika" are thrown around in the media and it could be because mosquitoes, the carriers of these diseases, are one of the deadliest animals in the world. San Francisco residents and visitors should be better informed about the risks these diseases and carriers pose to humans and how San Francisco is combating these pests.

West Nile virus is an infection that can cause minor illness, encephalitis, or meningitis. The biggest threat in the city is from the common house mosquito. These mosquitoes feed on birds infected with West Nile and can then pass the virus onto humans. To date there have been no human cases of this disease in San Francisco, but one case of an infected dead bird has been reported.

Zika virus is an illness that can have mild symptoms and last up to a few weeks. However, more serious complications can arise with pregnant women causing birth defects in newborns. The yellow fever mosquito is less of a threat in this area because it is not a native California species. To date, the closest this mosquito has been to the city is the county of San Mateo. Also, there has also been no local mosquito-borne transmission of Zika virus in the entire state.

The risk from mosquitoes is increasing globally including in the United States, and here at home in San Francisco. Although, the risk is much lower in this city than the counties neighboring our state’s southern border. The United States, with the help of Vector Control districts across the country, is doing its part to reduce the risk the common house mosquito and the yellow fever mosquito pose to U.S. residents.

Here are more resources on these diseases and the mosquitoes that transmit them.