Human-based parasites and enterobacteria carried by cockroaches (ORDER: BLATTODEA) in households of Wakiso District, Uganda

Abstract

Cockroaches are insects, with both structural and behavioural adaptations including chewing mouth parts, brown to black colouration, nocturnal habit, high reproductive potential and occupation of insanitary habitats. These promote their capacity to mechanically transmit pathogens that cause diseases which threaten the lives of humans particularly in over-populated, with enormous and varied wastes, combined with rampant unplanned settlements and high prevailing poverty levels, all of which are typical of Wakiso district. Despite their public health importance, there is scanty information on the cockroach species and pathogens transmitted. This study therefore set out to assess the potential role of cockroach species in transmitting human-based pathogens among peri-urban and rural households in Wakiso district with a view to raise awareness on the public health risks posed by the insects. Cockroaches collected from households and latrines using baited sticky traps were taxonomically identified in laboratory basing on morphological features. Bacteria and parasites were isolated from external surface and gut of cockroach species. Parasites were examined under microscopes after sedimentation while bacteria were cultured on Endo agar. Results were analyzed using Zero-inflated Poisson and binomial models to obtained chi-square values. Three cockroach species including Periplaneta americana, Blattela germanica and Blatta orientalis were identified. The most predominant amongst them was P. americana. Five parasite species; Balantidium coli, Enterobius vermicularis, Strongyloides stercoralis, Ascaris lumbricoides and Taenia species were recorded. B. coli (67%) and E. vermicularis (22.7%) were the most prevalent. Seven different bacterial species dominated by Escherichia coli and Klebsiella pnuemoniae were recorded. These parasites and bacteria were more prevalent on P. americana than other cockroach species. Bacterial contamination on this species of cockroach was higher on external surface than in the gut, however, no significant difference was observed in the level of contamination by parasites. The suitable warmth and humidity coupled with presence of food items in latrines and human dwellings might have favoured rapid multiplication and infestation with P. americana than Blattela germanica and Blatta orientalis. Also rearing of livestock next to human dwellings might have caused observed parasites and bacteria since these pathogens can be zoonotically transmitted. Therefore, a better understanding of the role of cockroaches in mechanical transmission of pathogens to humans in the Wakiso communities was necessary for design of control strategies and as a basis for advising vermin control departments at the local governments.