SAN DIEGO — Cases of Rocky Mountain spotted fever increased nearly threefold between 2001 and 2005, John Openshaw reported at the annual meeting of the Infectious Diseases Society of America.
The rising number of suburban homes that encroach on rural areas is one possible reason for the spike in reported cases. “Increased physician awareness and increased surveillance efforts are [also] involved,” Mr. Openshaw said during a press briefing. “The true explanation is likely a combination of many factors.”
Rocky Mountain spotted fever is caused by the Rickettsia rickettsii bacteria, which are typically spread through tick bites. Early signs include acute onset of fever and other flulike symptoms followed by rash.
“The biggest problem is that people don't often remember being bitten by a tick, and by the time the classic rash appears, the disease has already progressed significantly, and it may be too late,” Dr. David Swerdlow, previous team leader for the rickettsial zoonoses branch of the Centers for Disease Control and Prevention, said in a statement.
Researchers analyzed data from the National Electronic Telecommunications System for Surveillance and found that during 2001–2005, there were 6,598 cases of Rocky Mountain spotted fever reported in 45 states, said Mr. Openshaw, a medical student at the University of Pennsylvania, Philadelphia, who worked on the study during a CDC Applied Epidemiology Fellowship in 2006. The disease resulted in death in 22 people (0.3%).
The number of cases in the United States increased from 695 cases in 2001 to 1,936 cases in 2005. The incidence was higher in suburban areas than rural ones, and the largest increase was in the southern Atlantic states.
Despite the increase in cases, the rates of hospitalization fell from 29% in 2001 to 18% in 2005, while the rates of complications from the disease fell from 8% to 4%. Immunocompromised patients were most likely to be hospitalized with the disease (41%), followed by adults over the age of 70 (40%) and children under the age of 5 (35%).
The disease was reported in every state except Alaska, California, Hawaii, Maine, and Washington. “Physicians should be aware of the increase in Rocky Mountain spotted fever,” he said.
'Physicians should be aware of the increase in Rocky Mountain spotted fever.' MR. OPENSHAW