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High Seroprevalence for Typhus Group Rickettsiae, Southwestern Tanzania - Vol. 19 No. 2 - February 2013 - Emerging Infectious Disease journal - CDC

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High Seroprevalence for Typhus Group Rickettsiae, Southwestern Tanzania - Vol. 19 No. 2 - February 2013 - Emerging Infectious Disease journal - CDC

Georges de La Tour (1593‒1652) La Femme à la puce (The Flea Catcher) (1638) Oil on canvas (90 cm × 120 cm) Musée Lorrain, Nancy. Photo P. Mignot

High Seroprevalence for Typhus Group Rickettsiae, Southwestern Tanzania

Tatjana Dill¹, Gerhard Dobler¹, Elmar Saathoff, Petra Clowes, Inge Kroidl, Elias Ntinginya, Harun Machibya, Leonard Maboko, Thomas Löscher, Michael Hoelscher, and Norbert Heinrich

Author affiliations: Author affiliations: Medical Centre of the University of Munich, Munich, Germany (T. Dill, E. Saathoff, P. Clowes, I. Kroidl, T. Löscher, M. Hoelscher, N. Heinrich); DZIF German Centre for Infection Research–Ludwig Maximilian University of Munich, Munich (G. Dobler, E. Saathoff, M. Hoelscher, N. Heinrich); Bundeswehr Institute of Microbiology, Munich (G. Dobler); NIMR-Mbeya Medical Research Centre, Mbeya, Tanzania (P. Clowes, I. Kroidl, E. Ntinginya, L. Maboko, M. Hoelscher); Regional Medical Office, Mbeya (H. Machibya)

Abstract

Rickettsioses caused by typhus group rickettsiae have been reported in various African regions. We conducted a cross-sectional survey of 1,227 participants from 9 different sites in the Mbeya region, Tanzania; overall seroprevalence of typhus group rickettsiae was 9.3%. Risk factors identified in multivariable analysis included low vegetation density and highway proximity.

Murine, or endemic, typhus is primarily caused by Rickettsia typhi (typhus group rickettsiae [TGR]) and is usually manifest as a benign disease. A systemic vasculitis causes a clinical triad of fever, headache, and maculopapular rash (1). Because these signs and symptoms are nonspecific, the disease is often misdiagnosed or overlooked and can frequently be misclassified as malaria (2,3). In rare cases, murine typhus can lead to severe systemic complications such as acute renal failure, interstitial pneumonia, and complications of the central nervous system. The case-fatality-rate is <5 a="" href="http://wwwnc.cdc.gov/eid/article/19/2/12-0601_article.htm?s_cid=eid-gDev-email#r2" title="2">2

), in contrast to the situation for epidemic, or louse-borne, typhus caused by R. prowazekii, which can produce severe disease and fatality rates up to 30% if untreated. Serologic tests cannot distinguish these 2 infections, however. We assume that the antibodies detected in Tanzania in this study were caused by R. typhi, because, to our knowledge, no severe or epidemic illness compatible with louse-borne typhus has been described in the study region. Murine typhus is found throughout the world, widely distributed in subtropical and tropical regions, and is most apparent in port cities with large rat populations (2,4), which provide a reservoir for the pathogen and its main vector, the rat flea (Xenopsylla cheopsis). Additional transmission cycles have been described in Texas and California, USA, which involved mainly suburban cats and opossums as reservoir hosts and the cat flea (Ctenocephalides felis) as vector (5). Other yet unknown cycles may exist.
In Tanzania, information on typhus is sparse. A seroprevalence study among pregnant women from the port city of Dar es Salaam found a seropositivity prevalence of 28% (4). In the landlocked northern Tanzanian town of Moshi, murine typhus was detected in 0.5% of febrile patients (6).
A predictive risk model for endemic typhus based on environmental conditions has not been established, but because plague is also transmitted by X. cheopsis fleas, some of the findings regarding plague transmission might also apply to murine typhus. However, no data are available on the vector flea C. felis, the predominant flea harvested from rodents in a study in Uganda (7).