Brown dog ticks sparked a fever epidemic in Mexico. The US may be next, researchers say

A new species of tick is causing Rocky Mountain spotted fever to ravage Mexico and may soon invade the United States, according to a study published Wednesday in the journal of Emerging Infectious Diseases.

The brown dog tick — not to be confused with American dog tick — is a cosmopolitan parasite that thrives in warm climates and is more likely to bite humans than other types of ticks, although it favors dogs for hosts. It's also the cause of an epidemic of Rocky Mountain spotted fever that killed 80 people in one Mexican state alone.

Rocky Mountain spotted fever is spread by ticks carrying Rickettsia bacteria. It can be fatal and is characterized by fever, headache and muscle aches with a rash that has crusted skin at the bite site. 

The fever has existed in epidemic proportions in human and dogs in the Mexican city of Mexicali since 2008, according to researchers from the Autonomous University of Baja California and University of California, Davis.

Thirteen people living in the impoverished neighborhood of Las Santorales In Mexicali in 2008 to 2009 died from the fever. Over 80 percent of local dogs in the neighborhood were infected with brown dog ticks, the Autonomous University of Baja California veterinary team reported.

Researchers say the fever is responsible for more human deaths than any other tickborne disease in North America, killing 10 percent of those infected, depending on the outbreak. 

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In 2016, over 4,000 people in the U.S. had the fever, according to the Centers of Disease Control and Prevention. Arizona and the Mexican state Sonora have experienced recent outbreaks, researchers said. 

"The RMSF epidemic in Mexicali has not been contained and may be spreading to other parts of Baja California and into the United States," researchers said. 

However, a temporary solution was found by aggressively intervening in the local  Arizona and Sonora epidemics. The researchers are working to answer why the epidemic started and where these infected ticks are primarily located. 

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