Tropheryma whipplei: A Common Bacterium in Rural Senegal

Abstract

Background Tropheryma whipplei is known as the cause of Whipple's disease, but it is also an emerging pathogen, detected in stool, that causes various chronic localized infections without histological digestive involvement and is associated with acute infections, including gastroenteritis and bacteremia.Methods/Principal FindingsWe conducted a study in 2008 and 2009 using 497 non-diarrheic and diarrheic stool samples, 370 saliva samples, 454 sera samples and 105 samples obtained from water samples in two rural Sine-Saloum villages (Dielmo and Ndiop) in Senegal. The presence of T. whipplei was investigated by using specific quantitative PCR. Genotyping was performed on positive samples. A serological analysis by western blotting was performed to determine the seroprevalence and to detect seroconversion. Overall, T. whipplei was identified in 31.2% of the stool samples (139/446) and 3.5% of the saliva samples (13/370) obtained from healthy subjects. The carriage in the stool specimens was significantly (p<10−3) higher in children who were between 0 and 4 years old (60/80, 75%) compared to samples obtained from individuals who were between 5 to 10 years old (36/119, 30.2%) or between 11 and 99 years old (43/247, 17.4%). The carriage in the stool was also significantly more common (p = 0.015) in subjects with diarrhea (25/51, 49%). We identified 22 genotypes, 16 of which were new. Only one genotype (#53) was common to both villages. Among the specific genotypes, one (#52) was epidemic in Dielmo (15/28, 53.4%, p<10−3) and another (#49) in Ndiop (27.6%, p = 0.002). The overall seroprevalence was estimated at 72.8% (291/400). Seroconversion was detected in 66.7% (18/27) of children for whom PCR became positive in stools between 2008 and 2009.Conclusions/Significance T. whipplei is a common bacterium in the Sine-Saloum area of rural Senegal that is contracted early in childhood. Epidemic genotypes suggest a human transmission of the bacterium.

Looking for Tropheryma whipplei Source and Reservoir in Rural Senegal

“…We performed studies in Dielmo and Ndiop, which are two villages that are endemic for malaria in Senegal. Included in the Dielmo project was a study initiated in 1990 for the longterm investigation of host-parasite associations 10,17 ; this cohort study was approved by the national ethics committee of Senegal, and written informed consent was obtained from all individuals.…”

“…On the basis of our previous studies, 3,10,18 we searched households in which T. whipplei had never been previously detected and households in which T. whipplei was highly prevalent. People were mainly T. whipplei carriers but there are also patients with T. whipplei bacteremia.…”

“…8 The prevalence of T. whipplei carriage in stool and saliva specimens from healthy individuals depends predominantly on the geographic area, the occupation of the subjects, and their proximity to T. whipplei carriers. [9][10][11][12] In two Senegalese villages, the incidence of T. whipplei DNA in stool samples is~17.4% among the healthy adult population, reaching 75% among healthy children younger than 5 years of age. 10 Currently, two important, yet unsolved issues are the habitat of T. whipplei and its route of infectious transmission.…”

“…[9][10][11][12] In two Senegalese villages, the incidence of T. whipplei DNA in stool samples is~17.4% among the healthy adult population, reaching 75% among healthy children younger than 5 years of age. 10 Currently, two important, yet unsolved issues are the habitat of T. whipplei and its route of infectious transmission. In Europe, the first risk factor that has been shown is occupational: the rate of infection among underground sewer workers suggests the danger of exposure to human feces.…”

“…However, there are families with very high prevalence of the diseases and others with very low or even negative prevalence. 10 Our approach was to identify the factors associated with a high incidence of T. whipplei carriage in different households and to identify the possible environmental factors that play a role in the transmission of T. whipplei.…”