Assessing the magnitude of fatal Rocky Mountain spotted fever in the United States: comparison of two national data sources.

Abstract

Abstract. To assess the magnitude of fatal Rocky Mountain spotted fever (RMSF) and to evaluate the completeness of national surveillance for this occurrence from 1983 through 1998, two independent sources of RMSF mortality data were analyzed using a capture-recapture method. Two hundred twenty-four deaths reported through RMSF case report forms (CRFs) were compared with 304 RMSF-associated deaths recorded in the United States multiple cause-of-death (MCD) database. Demographic, geographic, seasonal, and temporal characteristics of decedents were remarkably similar between sources. Median annual deaths ascertained from CRF and MCD data sources were 11 (range ‫ס‬ 5−35) and 18 (range ‫ס‬ 5−39), respectively. Decedents were matched between sources by year, state, age, sex, race, and month-of-death; 111 deaths were matched to both sources, and percent concordance between CRFs and MCD data during the 16-year study period was 27% (range ‫ס‬ 7−45%). An estimated 612 RMSF-associated deaths occurred during the study period (median ‫ס‬ 37 per year, range ‫ס‬ 16−64), suggesting that approximately 400 fatal cases of RMSF went unreported to national surveillance during the period 1983−1998, for an estimated completeness of CRF reporting of 36%.

Phylogeography of Rickettsia rickettsii Genotypes Associated with Fatal Rocky Mountain Spotted Fever

“…Among the casepatients from the United States, no significant differences were noted between the percentages of male (54%) and nonwhite (18%) individuals evaluated in our study and the corresponding percentages (59% and 18%, respectively) among RMSF deaths documented by CRF surveillance data during 1983-2007. 22, 23 However, our analysis included significantly more United States case-patients 10 years of age (40% versus 15%, P value 0.0001), and significantly fewer casepatients 40 years of age (29% versus 63%, P value 0.0001) when compared with the ages of United States RMSF decedents reported to CDC during the same approximate period.…”

“…In fact, among United States case-patients, significantly more young children and fewer persons 40 were represented when compared with national surveillance statistics for fatal RMSF in the United States during 1983-2007. 23,24 Chronic alcohol abuse is another risk factor that may increase the severity of RMSF, 34 in a manner similar to its demonstrated association with cases of fatal Mediterranean spotted fever, caused by the closely related bacterium, Rickettsia conorii. 46,47 Although information regarding alcohol use was not available for most case-patients in our series, it is important to note that the single Hlp-associated death occurred in a patient with alcohol dependency.…”

“…Fisher's exact two-tailed test was used for comparisons of gender, race, and age between the case-patients in this series and the same categorical data summarized by CRFs during 1983-2007. 23, 24 The Wilcoxon rank-sum test was used to compare survival times of case-patients in this series with survival times presented for 84 RMSF decedents from the Bitterroot Valley during 1885-1903. from each case-patient were processed. A 16-μm section was cut from each tissue block, deparaffinized in xylene, washed twice in absolute ethanol, and air-dried.…”

“…These data corroborate previous capture-recapture analyses of national mortality statistics for fatal RMSF, which estimated that~65% of the RMSF deaths that occurred during 1983-2007 were not reported for national surveillance. 23,24 More than a century following its discovery, RMSF continues to kill otherwise healthy persons throughout the Western Hemisphere every year. With the recognition that infection with any of the known clades of R. rickettsii may result in a fatal outcome, additional investigations are needed to better characterize specific host factors that place infected patients at greatest risk for the most severe forms of this disease.…”

Co-Infection of Rickettsia rickettsii and Streptococcus pyogenes: Is Fatal Rocky Mountain Spotted Fever Underdiagnosed?

“…Other reports have demonstrated that fatal RMSF cases are underreported, 7,8 and this type of co-infection may demonstrate another reason why a fatal case would go undiagnosed. Serologic results are not likely to be positive for a patient who dies on the fifth day of symptoms, and a specialized diagnostic test such as PCR may not be pursued in cases that have positive cultures for another pathogen.…”