CDC Warns of New Rocky Mountain Spotted Fever Outbreak

( – The CDC is warning Americans about a new outbreak of Rocky Mountain spotted fever (RMSF) in California. The sudden uptick in cases between July and December is raising concerns about the spread of potentially serious tick-borne illnesses.

According to an official alert issued on December 8, all five of the patients the CDC identified were diagnosed with RMSF sometime between July and December. All had either traveled to or from Tecate, Mexico, within the two-week period before they became ill.

All five of the patients identified in this alert sought care at Southern California hospitals, where they were admitted and treated for RMSF. While the CDC did not disclose their identities for privacy reasons, they did reveal that three of the individuals are US citizens. The remaining two are residents of Mexico. Notably, at least four of these patients are under 18 years old.

Three of the patients cited in the alert died as a result of their illness. It wasn’t immediately clear whether the other two recovered or were still in the recovery process.

The bacteria that causes RMSF, known in the science world as Rickettsia rickettsii, is most commonly transmitted by a specific species of brown dog tick. The CDC notes that this particular insect is “endemic” across most of northern Mexico and present in most warmer climates. It targets domestic dogs, giving them easy access to humans.

Early symptoms of RMSF are often non-specific or even unnoticeable. Patients may experience a low-grade fever, headaches, gastrointestinal upset, a rash, or abdominal pain — all easily confused for seasonal colds and flu. But RMSF, if left untreated, can rapidly progress and become life-threatening. In fact, nearly all of the patients who die after contracting it fall victim within just eight days.

While that may sound frightening, there’s no need to panic about RMSF just yet. Early intervention with the antibiotic doxycycline is often enough to halt the illness in its tracks. The CDC is recommending that anyone with symptoms contact a doctor for testing and do regular tick checks after being outside, especially if they were recently in Tecate, Mexico.

NYU Langone Medical Center’s Dr. Marc Siegel told Fox News Digital that he has serious concerns about how porous borders could facilitate tick migration. He noted that most cases occur in Mexico rather than on US soil. “These ticks carrying disease could cross with migrants,” he explained.

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