1.1 Background Information
The housefly Muscado mestica is a fly of the order Diptera, it is the most common of all domestic flies, accounting for about 91% of family Muscidae and indeed one of the most widely spread insects found all over the world (Jeffrey et al., 2000). It is considered a pest that can carry pathogens responsible for diseases (Scott et al., 2014). Houseflies Muscadomestica L. are ubiquitous (found everywhere) and transmit more than 100 human and animal diseases, including bacterial infections such as salmonellosis, anthrasophthalmia, shigellosis, typhoid fever, tuberculosis, cholera and infantile diarrhea (Jeffrey et al., 2000). It is considered one of the most important pests which cause health problems in the environment as it accompanies human during their daily activity everywhere, on work site or in rest places causing many disturbances to them (Howard, 2011).
Houseflies are of human and veterinary concern, because it acts as a mechanical vector for a range of pathogens (Peter and Chiodui, 1997). An almost invisible dot of feces in the environment may contain the eggs or larvae that can develop further and transmit to nearby humans (Graczyk et al., 2001).
It has been reported by regulatory agencies concerned with sanitation that and public health that housefly are associated with unsanitary condition and involved in dissemination of human enteropathogens that serve as causative agents of gastro-intestinal diseases to humans, based on strong attraction of filth and human food (Otronto and Tarsitano, 2003). The filthy breeding habit, feeding mechanism and indiscriminate travel between filth and food make houseflies as an efficient vector and transmitters of human enteric protozoan and helminth parasites such as cysts of Entamoeba histolytica, Entamoeba coli, Giardia intestinalis and oocyts of Toxoplasma gondii, Isospora spp and Egg or larvae of Ascaris lumbricoides, Trichuris trichuria (Graczyk et al., 2001).
The transmission of these human protozoan and helminth parasites by houseflies is predominantly mechanical, which occurs through mechanical dislodgement from external body, fecal deposition and regurgitation (Graczyk et al., 2005). Since houseflies feed on contaminated substances such as human and animal excreta, sputum, excretion from wound, the flies can carry pathogens from their spongy mouth parts, body and leg hairs, which is directly transmitted to the next visited site e.g. human food (Manzon and Sanchoz, 1997).
Flies also transmit pathogens responsible for eye diseases such as trachoma and epidemic conjunctivitis and infect wounds or skin with diseases such as cutaneous diphtheria, mycoses, yaws and leprosy (Westley et al., 2014).