Order Hemiptera: The true host involved in Mycobacterium ulcerans transmission, or is it an innocent by-stander?

Burul ulcer disease is an infection of the subcutaneous layer. The causative organism, Mycobacterium ulcerans is a slow-growing environmental pathogen often associated with wetland and slow moving streams. One insect order believed to be associated with M.ulcerans is the order hemiptera, in which the aquatic bugs (Naucoris sp and Belostoma sp) belong. Some Mycobacteria species are endosymbiont of Acanthamoeba and laboratory experiments has confirmed this in M. ulcerans in an endemic area in Benin persisting in an amoeba for 14 days. Aquatic insect are believed to feed on amoeba, planktons, snail and fish from which they get infected. Protozoan and planktons may be the true resorvior or host of M. ulcerans but little research has been done in this area. Though many studies have found M. ulcerans in these insects, the exact mechanism of transmission to humans is still elusive. This study aims to review the available data on aquatic bugs, protozoans and other invertebrates (snail and fish) to ascertain if aquatic insects are themselves victims of the M. ulcerans through feeding.