The U.S. Center for Disease Control and Prevention has issued a health alert warning travelers to Baja California, Mexico, about Rocky Mountain spotted fever, a potentially life-threatening bacterial infection spread through tick bite.

The CDC said five cases, including three deaths, have been reported in Southern California due to Rocky Mountain spotted fever since July. All affected people had a travel or residence history to Tecate, a city in Baja California, within two weeks of falling sick, officials said.

"Four patients were under the age of 18 years. Three patients were U.S. residents, and two were residents of Mexico," the CDC said in a news release Friday. "RMSF (Rocky Mountain spotted fever) is endemic in multiple border states in northern Mexico, including but not exclusive to Baja California, Sonora, Chihuahua, Coahuila, and Nuevo León."

Rocky Mountain spotted fever is a serious illness spread by the bacteria Rickettsia rickettsii through tick bites. It is a rapidly progressive disease that can turn fatal within days if not treated early with antibiotic doxycycline.

"Healthcare providers should consider RMSF in their differential diagnosis of patients who have reported recent travel to Tecate, Mexico, or other areas of northern Mexico and subsequently develop signs or symptoms of an unexplained severe febrile illness. Consider initiating doxycycline based on presumptive clinical and epidemiologic findings, and do not delay treatment pending the result of a confirmatory laboratory test. Early treatment with doxycycline saves lives," the release read.

Although Lyme disease and Rocky Mountain spotted fever are both tick-borne illnesses, the underlying bacteria that cause the infections and the symptoms are different.

Signs of Rocky Mountain spotted fever

The symptoms begin within two days to two weeks after the tick bite. The signs include headache, nausea, high fever, rash, stomach pain, lack of appetite and sensitivity to light. As the infection gets severe, the patient may develop confusion, numbness, shortness of breath, seizures and agitation.


Rocky Mountain spotted fever cannot spread from one person to another. The most common carrier is the American dog tick and the Rocky Mountain wood tick.

Around 6,000 cases of Rocky Mountain spotted fever are reported each year in the U.S. The cases occur throughout the country but are most commonly seen in North Carolina, Tennessee, Missouri, Arkansas and Oklahoma.


There are no vaccines to prevent the infection. Hence, the best way to prevent the infection is to protect yourself and your pets from tick bites. CDC recommends reducing exposure to grassy, brushy or wooded areas that are prone to ticks, using insect repellants, and showering within two hours of coming indoors to reduce the risk of tick-borne illnesses.