In Mexicali, an uncontrolled epidemic of Rocky Mountain spotted fever has affected more than 1,000 people since 2008.
Researchers examined dogs, ticks, and surveyed households in 200 neighborhoods. Half of the neighborhoods in the study had diagnosed human cases of the disease. The team discovered that even though citywide only one in 1,000 ticks were infected, there were neighborhoods at very high risk where almost one in 10 ticks were infected.
“If you live in one of these high-risk neighborhoods and you get five brown dog tick bites, that means you have a pretty good chance of being exposed to Rocky Mountain spotted fever,” says lead author Janet Foley, with the department of medicine and epidemiology at the University of California, Davis, School of Veterinary Medicine.