Some Aspects of Epidemiology of Filth Flies: Musca domestica, Musca domestica vicina, Drosophilia melanogaster and Associated Bacteria Pathogens in Ekpoma, Nigeria

Abstract

Between January 2005 and December 2005, including the wet and dry seasons, 1,358 filth flies (Musca domestica, 737 [54.3%]; M. domestica vicina 556 [41%]; and Drosophilia melanogaster 65 [5%]) were caught by quadrant samplings using nets twice each month (early and later) in each of the various sites with varying sanitary conditions in Ekpoma, Nigeria. These sites were markets, hospitals, houses/human habitations, pit latrines, stalls of local food vendors, abattoirs/slaughterhouses, and dairy farms. These filth flies were studied for their potential to carry bacterial species. The identified filth flies were found to carry bacterial pathogens, with each harboring 2-10 bacteria. Seven bacterial species and their load namely, Escherichia coli (189 x 10(10) organisms per milliliter), Proteus species (210 x 10(10) organisms per milliliter), Streptococcus species (192 x 10(10) organisms per milliliter), Klebsiella species (213 x 10(10) organisms per milliliter), Salmonella species (386 x 10(10) organisms per milliliter), Staphylococcus species (163 x 10(10) organisms per milliliter), and Serratia macenscens (5.0 x 10(10) organisms per milliliter) were isolated. The highest mean bacterial load for all bacteria isolated from pooled flies was 200 x 10(10) organisms per milliliter. The mean bacterial loads of 150, 90, and 10 x 10(10) organisms per milliliter were recorded for M. domestica, M. domestica vicina, and D. melanogaster, respectively. Approximately 15(4)-23(6) bacterial colonies per fly were recorded. The total number of bacteria isolated from flies caught in the dairy farms were higher than those isolated from flies caught in any other studied sites. Lower prevalence of associated bacterial pathogens was established from flies caught in areas where hygienic conditions prevailed. Salmonella species was the most prevalent bacterial pathogen isolated amongst the flies that perched on dairy products sampled. Bacterial load was most prevalent during the wet season. Resistances of some bacterial pathogens to common available antibiotic drugs shown by zone of inhibition (<or=10 mm) include: E. coli (penicillin G and erythromycin), Streptococcus species(tetracycline, erythromycin, and cloxacillin), Serratia species (streptomycin, erythromycin, and ampicillin), Proteus species(cloxacillin and clindamycin), and Klebsiella species (cloxacillin). Indeterminate results were observed with Serratia species using gentamycin and clindamycin.