In a follow-up on two infectious disease issues in San Diego County, mice with hantavirus and tularemia positive ticks, San Diego County Vector Control has issued some updated information and warnings for the public.


Vector Control officials said five Western harvest mice caught in routine trapping in open fields in 4S Ranch and in the rural Black Mountain area have tested positive for hantavirus, bringing this year’s total number of rodents to test positive to 17. That is the highest number of rodents to test positive in San Diego County since 2012, when 35 mice and one meadow vole tested positive over the course of the year.

Vector Control officials said the high number was not a cause for alarm. Hantavirus is common in San Diego County, but it is mainly carried by wild mice that do not live around humans so people are rarely exposed to the virus. In addition, the 17 rodents that tested positive represent 4.8 percent of the 351 wild rodents that Vector Control has trapped  and tested this year, a figure within normally-expected ranges.

Still, officials said people should remember to protect themselves from potentially being exposed to hantavirus. The virus can cause deadly infections in people and there is no vaccine or cure for it.

In addition, County Vector Control officials said Friday that several more batches of ticks trapped along Lopez Canyon Trail in Sorrento Valley have tested positive for tularemia, a potentially dangerous bacterial disease also known as “rabbit fever.”

County officials are reminding people again to protect themselves and their pets from ticks — which can transmit tularemia and other diseases when they bite people — whenever they are hiking, bicycling or walking in grassy backcountry areas, on trails or in the wild.

Vector Control officials said last week that several batches of ticks trapped in routine monitoring in the area of Lopez Canyon Trail had tested positive for the disease. Because they are small, ticks are “batched” together into larger groups to conduct testing.

County officials said they posted signs warning people to protect themselves from ticks last week and have posted additional signs in the wake of the new find.