T. whipplei Bacteremia and Fever in West Africa
T. whipplei Bacteremia and Fever in West Africa
Abstract & Commentary
By Dean L. Winslow, MD, FACP, FIDSA, Chief, Division of AIDS Medicine, Santa Clara Valley, Medical Center; Clinical Professor, Stanford University School of Medicine, is Associate Editor for Infectious Disease Alert.
Synopsis: Blood samples from febrile patients from two Senegalese villages were prospectively collected over a nine-month period. T. whipplei DNA was identified by PCR in blood of 13 (6.4%) of 204 samples. Cough and sleep disorders were observed more commonly in PCR+ patients than either febrile PCR- patients or in French control patients.
Source: Fenollar F, et al. Tropheryma whipplei bacteremia during fever in rural West Africa. Clin Infect Dis. 2010;51:515-521.
As part of a longitudinal study of host/parasite relationships, which was initiated in two Senegalese villages in 1990 (and initially focused on malaria and tick-borne borreliosis), the potential of T. whipplei to cause infection in patients with fever of unknown etiology and negative test results for malaria was initiated in late 2008 and continued until the summer of 2009. Both passive (patients from the two villages visiting the local clinic because of fever) and active (daily home visits) surveillance were carried out during the period of study. Fever was defined as an axillary temperature > 37.5 deg C.
Blood analyses included Giemsa-stained thick and thin smears. In patients with negative blood smears, additional blood was obtained for quantitative real-time PCR analysis for T. whipplei DNA using assays targeting two different regions of the organism's genome.
T. whipplei was present in the blood of 6.4% of the 204 febrile patients. All of the positive samples were obtained from samples drawn in November, December, and April (suggesting higher prevalence during the colder months of the year). Seven PCR+ patients were female and six were male. Ages ranged from 10.7 months–16.3 years (median age three years). Common clinical manifestations included cough (10 patients), thirst (8), headache (7), rhinorrhea (6), and sleep disorders (5). When compared with 191 episodes of fever not associated with T. whipplei bacteremia only, cough and sleep disorders remained as being statistically more frequent in the PCR+ patients. Among the 13 PCR+ patients, stool samples were analyzed from 10, and four of these also had positive stool samples. Twenty-five patients with negative T. whipplei blood specimens had a positive stool specimen. Seven of the 13 bacteremic patients had saliva analyzed by PCR for T. whipplei, and all were negative.
Commentary
T. whipplei was thought to be a rare organism causing an even rarer disease characterized by PAS-staining bacteria in infected small bowel macrophages. Later, this bacterium was recognized as being capable of a variety of localized infections, including endocarditis, spondylodiskitis, meningoencephalitis, uveitis, and pneumonia. More recently, the bacterium has been identified in 15% of children in France with gastroenteritis. Its prevalence fecal samples from asymptomatic adults in France has ranged from 1%-11%, but stool carriage rate was shown in one recent study to be as high as 44% in children 2-10 years of age in rural Senegal. The environmental source of T. whipplei remains unclear, and water from eight Senegalese village wells tested negative by PCR.
Overall, I thought this paper (like most work from Didier Raoult's group) contained fascinating, although clearly preliminary, results. Some potential criticisms of this study include its small size, confinement to just two villages, and the lack of an asymptomatic control group in the villages studied. As with all studies which rely on PCR as the sole microbiological method, there is almost always the concern about PCR amplicon cross-contamination of samples. Despite these limitations, the data suggest that T. whipplei may be a cause of unexplained cold season fever with cough in rural West Africa. Much remains to be studied regarding T. whipplei, including studies that define the ecology of T. whipplei in the environment, as well as the mode of transmission of this organism. Larger studies are clearly needed to confirm and expand on these findings. As always, I am looking forward to reading Didier's next paper!
As part of a longitudinal study of host/parasite relationships, which was initiated in two Senegalese villages in 1990 (and initially focused on malaria and tick-borne borreliosis), the potential of T. whipplei to cause infection in patients with fever of unknown etiology and negative test results for malaria was initiated in late 2008 and continued until the summer of 2009.Subscribe Now for Access
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