Rocky Mountain Spotted Fever Hits Some American Indians Hard

Veronica Hackethal, MD

June 24, 2015

The Rocky Mountain spotted fever (RMSF) epidemic that emerged in 2003 has hit American Indian communities in Arizona hardest. Estimated economic losses from the epidemic on two reservations have totalled $13.2 million, according to a study by the Centers for Disease Control (CDC) and Indian Health Service (IHS) published online June 1 in the American Journal of Tropical Medicine and Hygiene.

"[RMSF] is completely preventable. State, federal and tribal health authorities have been working together since the start of the epidemic to build effective community-based tick control programs, and these efforts have produced remarkable reductions in human cases," first author Naomi Drexler, MPH, an epidemiologist at the Rickettsial Zoonoses Branch, Division of Vector-borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, CDC, Atlanta, Georgia, said in a news release. "These programs are costly, but medical expenses and lives lost cost four times more than RMSF prevention efforts. Increasing access to these prevention efforts is critical to save lives and protect communities."

RMSF mostly affects previously healthy children and young adults, a population with the highest earning potential.

The disease is transmitted through tick bites. Because no vaccine exists, prevention focuses on controlling ticks, which are sometimes carried by dogs and other pets. Tick control programs are effective, but the costs have sometimes hindered control efforts, according to the CDC news release.

If left untreated, RMSF can lead to death or neurological and internal organ damage that can cause permanent disability. More than 20% of untreated cases prove fatal, with an average time from symptom onset to death of 8 days.

Although endemic in the United States for more than a century, RMSF emerged on American Indian reservations in Arizona in 2003. Between 2002 and 2014, Arizona reservations reported 300 cases and 20 deaths, the news release revealed.

Arizona has a higher case fatality rate for RMSF compared with the rest of the nation (7% vs <1%, respectively), the authors write. Between 2000 and 2007, American Indians experienced four times the burden of RMSF compared with whites.

The authors reviewed medical records for patients who received treatment for RMSF at IHS facilities and referral hospitals in two Arizona American Indian communities between June 1, 2002, and September 30, 2011. Then they looked at the financial burden, adjusted to 2011 dollars, of RMSF.

They identified 205 cases of RMSF, of which 29 required ICU care; 15 (7%) people died.

Between 2002 and 2011, the costs of acute care for RMSF on these two American Indian reservations totalled more than $1.3 million. Estimates of acute productivity losses were about $181,000, and lifetime productivity losses from premature death reached more than $11.6 million.

Estimates of average lifetime productivity lost because of death from RMSF ($775,467 per death) were far greater than similar estimates for pneumococcal disease ($140,862). The young age of fatal RMSF cases (median, 14 years) could explain this difference. Eighty percent of deaths caused by pneumococcal disease occur in adults aged 65 years and older, the authors point out.

The researchers estimated costs using all-inclusive rates reimbursed by Medicaid, which usually represent minimum costs. These estimates did not include costs for expensive medical treatments such as extracorporeal membrane oxygenation or the long-term costs of rehabilitation and ambulatory care.

"These calculations likely represent a gross underestimation of the costs sustained, but are valuable in that they underline the social and economic impact on affected communities and emphasize the need for a more comprehensive study to document the economic impact of this disease," the authors conclude.

The authors have disclosed no relevant financial relationships.

Am J Trop Med Hyg. Published online June 1, 2015. Full text

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