A Sero-epidemiological Approach to Explore Transmission of Mycobacterium ulcerans

Abstract

The debilitating skin disease Buruli ulcer (BU) is caused by infection with Mycobacterium ulcerans. While various hypotheses on potential reservoirs and vectors of M. ulcerans exist, the mode of transmission has remained unclear. Epidemiological studies have indicated that children below the age of four are less exposed to the pathogen and at lower risk of developing BU than older children. In the present study we compared the age at which children begin to develop antibody responses against M. ulcerans with the age pattern of responses to other pathogens transmitted by various mechanisms. A total of 1,352 sera from individuals living in the BU endemic Offin river valley of Ghana were included in the study. While first serological responses to the mosquito transmitted malaria parasite Plasmodium falciparum and to soil transmitted Strongyloides helminths emerged around the age of one and two years, sero-conversion for M. ulcerans and for the water transmitted trematode Schistosoma mansoni occurred at around four and five years, respectively. Our data suggest that exposure to M. ulcerans intensifies strongly at the age when children start to have more intense contact with the environment, outside the small movement range of young children. Further results from our serological investigations in the Offin river valley also indicate ongoing transmission of Treponema pallidum, the causative agent of yaws.

Isolation of Nontuberculous Mycobacteria from the Environment of Ghanian Communities Where Buruli Ulcer Is Endemic

“…All of the studied communities along the Offin River basin were designated endemic; the communities included Ntobroso and Achiase in the Atwima district, upstream and midstream of the river, respectively, and Mfantsiman in the Upper Denkyira district, downstream of the river. Extensive seroepidemiological studies (34)(35)(36) conducted in these communities indicated high levels of serological evidence of exposure of community members to M. ulcerans 18-kDa small heat shock protein (hsp) (33), irrespective of the disease burden.…”

Buruli Ulcer, a Prototype for Ecosystem-Related Infection, Caused by Mycobacterium ulcerans

“…The highest detection rates were found sometimes in 75-to 79-year-old patients in West Africa, probably due to the reactivation of disease from a latent infection of M. ulcerans (380). It was proven in Africa that children less than 5 years old rarely develop antibody responses to the 18-kDa small heat shock protein (shsp) of M. ulcerans and thus seem to be considerably less exposed to the pathogen than older children (381,382). As Buruli ulcer is not known to be an immunizing infection, this may reflect a greater exposition to sources and vectors (381,382).…”

Laboratory Diagnosis of Buruli Ulcer: Challenges and Future Perspectives

“…However, this antigen is not suitable as target for a BU-specific serological test, as anti-shsp antibodies are also frequently found in sera of healthy individuals living in BU endemic areas [75]. This circumstance however has opened up the opportunity for seroepidemiological studies assessing the exposure of populations to M. ulcerans [76][77][78].…”