Back to Health Topics
New Study Underscores the Importance of Protecting Mid-South Children from Tick-Infested Areas
Seven of the top 10 states where Rocky Mountain Spotted Fever (RMSF) is found are in the southeastern U.S., but the infection may often go undetected because the public and many doctors perceive the risk in these areas to be small. A recent analysis of children in several cities showed that the actual prevalence of human infection with Rickettsia rickettsii (the cause of RMSF) is significantly higher in some areas than the reported incidence of Rocky Mountain Spotted Fever, suggesting that health care professionals may fail to test for RMSF when it fails to present itself with the most common symptoms of fever, rash, and headache.
"Despite its name, Rocky Mountain Spotted Fever can occur anywhere, and summer is the peak season for the tick-borne infection as families spend more time outdoors," says Dr. Steven C. Buckingham, pediatric infectious disease specialist with UT Medical Group, Inc. (UTMG), one of the study authors and assistant professor at The University of Tennessee Health Science Center.
"Unfortunately, it is sometimes difficult to diagnose the disease promptly because symptoms can mimic other infections, leading to delayed treatment that can increase the chances of fatality."
Although less than 1,000 confirmed cases of RMSF are reported to the U.S. Centers for Disease Control and Prevention each year, previous studies have suggested that the infection may actually be more widespread than these figures indicate. Investigators from the University of Tennessee participated in the most recent analysis, which was a collaboration among universities throughout the central and southeastern United States. The results were published in the May 2003 issue of Archives of Pediatric and Adolescent Medicine.
In addition to UT, other study sites included the University of Louisville School of Medicine, University of Arkansas for Medical Sciences, University of Missouri-Kansas City, University of Oklahoma Health Sciences Center, Wake Forest University School of Medicine, and Vanderbilt University School of Medicine.
Because most reported cases of RMSF are reported in children, researchers examined about 300 specimens from children at each of seven pediatric referral centers in the following central and southeastern cities: Memphis, TN; Little Rock, AR; Nashville, TN; Winston Salem, NC; Louisville, KY; Kansas City, MO; and Oklahoma City, OK. Specimens were tested for antibodies to R. rickettsii using an indirect fluorescence antibody assay. The data was then analyzed at cutoff titers of 1:64, 1:128, and 1:256 to represent increasing levels of diagnostic stringency and specificity for the infection.
Results showed that overall, 12% of children had R rickettsii antibody titers of at least 1: 64, 7.3% at least 1:128; and 4.3% at least 1:256. Little Rock showed the highest rate at 21.9% of children showing R rickettsii antibody titers at 1:64, followed by Nashville at 19.5%, Oklahoma City at 16.9%, Kansas City at 8.6%, Memphis at 8.0%, Winston-Salem at 5.0%, and Louisville at 3.5%.
"The study suggests that exposure to R rickettsii is much more widespread than indicated by Rocky Mountain Spotted Fever case reports," says Dr. John Devincenzo, UTMG Pediatric Infectious Disease specialist, Children's Foundation Research Center investigator, and UT Associate Professor. "These data underscore the importance of protecting children from tick-infested areas and remind both parents and health care professionals to be alert to the possibility of RMSF infection, especially in this area of the country. "
