Parasitism data of Glossina palpalis and G. tachinoides (Diptera: Glossinidae) by trypanosome species in parts of Abia State, Nigeria

Glossina species are important medical and agricultural vectors transmitting the African animal trypanosomes and also the agent of sleeping sickness in human. Parasitism data of Glossina species by trypanosomes were carried out over a period of one year, from April 2003 to March 2004 using bioconical traps to catch tsetse at some selected Local Government Areas of Abia State, Nigeria. Four hundred and twenty seven (427) flies were dissected and examined microscopically for the presence of trypanosome infection. The survey found Glossina palpalis as the predominant tsetse species in the area. Out of the 427 flies dissected, 17 (3.9%) were infected with trypanosome. The highest infection was recorded among G. palpalis (3.7%) and this was significantly higher (P<0.001) when compared with those of G. tachinoides (0.2%). Female flies had higher infection than males (2.3% as against 1.6%, respectively). Majority of the infected flies were caught during rainy season (2.8%) and few were caught in dry season (1.1%). Twelve (2.8%) of all the parasites were located in the proboscis indicating Trypanosoma vivax infection, while 5 (1.1%) were from mid-gut of the flies indicating T. congolense infection. No parasite was observed in all the Glossina species caught at Ikwuano and Umuahia South areas, while trypanosome parasitism was highest in Glossina species caught at Isuikwuato, 2.5% of the flies in this area were parasitized. The low parasitic infection rate observed here indicates a marginal effect on the vector population of trypanosomes in Abia State, Nigeria.