ABSTRACT
A study of the species composition and distribution of tsetse flies was conducted between January to December, 2007 at Kamuku National Park, Birnin Gwari Local Government Area, Kaduna State, using Biconical (Charlier and Laviessiere, 1973) and Nitse traps (Omoogun, 1994). Four traps each were placed for two days along five streams (i.e.Dagara, Kabungu Bungu, Kango Kabungu, Kuzomani and Kurishi) and the trap catches were harvested every day. Five hundred and two tsetse flies caught during the study period, differ significantly between streams. Dagara, Kabungu Bungu, Kango Kabungu, Kuzomani and Kurishi streams had 166 (33.1%), 33 (6.6%), 45 (9%), 41 (8.2%) and 217 (43.2%) flies respectively. Glossina tachinoides and Glossina palpalis were trapped in the area with one species Glossina morsitans submorsitans encountered during the preliminary studies only. Overall, Glossina tachinoides 309 (61.6%) dominated over Glossina palpalis 193 (38.4%), and in Kurishi, (98.2%), Kango Kabungu (97.8%) and Kabungu Bungu (93.9%) streams, while Glossina palpalis catches were more in Dagara (97%) and Kuzomani (61%) streams. Male tsetse flies were significantly higher than females (ratio 2:1), more teneral flies were caught than non-teneral. Tsetse catches were not significantly higher in the dry season than wet season and correlated positively with temperature and negatively with relative humidity. Overall apparent density of 0.1 fly per trap per day obtained in the study and for each species suggest a low density area; 0.2 fly per trap per day were obtained for both season. February had the highest fly density 3.0 while July had the least 0.2. The estimated age of male population was 11 days while females under ovarian category O with an approximate age of 0-10 days dominated. The Mean Hunger Stage (MHS) of 3.6 and 3.5 for Glossina palpalis and Glossina tachinoides, respectively, indicated hungry populations. Insemination rate (93.8%) was high whereas parity rate (25.8%) was low. Overall infection rate of 6.6% was high and infection due to T. vivax (5.2%) dominated followed by T. congolense (0.9%) while T. brucei (0.5%) was lowest. Infection rates were higher in Glossina tachinoides (9.4%) than Glossina palpalis (3.1%). The study has shown that Glossina morsitans submorsitans probably declined as a result of seasonal, vegetation and food factors; also that the high fly density observed in February is a significant month to carry out control. The presence of trypanosome infection in the park may constitute a public health risk to nomadic cattle and ecotourism in the park.
CHAPTER ONE
1.0 INTRODUCTION
Tsetse flies are large biting flies from Africa which live by feeding on the blood of vertebrate animals. They are similar to other large flies such as housefly Musca domestica, but can be distinguished by two visually distinctive characters such as the forward projecting proboscis and the discal cell on the wing, shaped like a cleaver and referred to as the ‘hatchet cell’ which lies between the fourth and fifth wing veination (Buxton, 1955).
Tsetse flies belong to the genus Glossina, a name described by Wiedemann (1830) and monotypic family Glossinidae. They have existed in the modern morphological form for at least 34 million years since Fossil tsetse have been recovered from the Florissant Fossil Beds in Colorado (Cockerrel, 1917).
1.1 Tsetse Flies as Vectors of Trypanosomiasis
Tsetse flies are biological vectors of African Trypanosomiasis and are responsible for the transmission of Trypanosomes, the pathogenic agents of Human African Trypanosomiasis or sleeping sickness and Animal African Trypanosomiasis or Nagana in cattle (Boulanger et al., 2002). They are obligatory blood feeders which transmit Trypanosomes either mechanically or cyclically during the processes of feeding. Tsetse- transmitted trypanosomiasis affect various vertebrate species including human, antelopes, horses, sheep, goats, pigs and cattle. The trypanosomes transmitted may also survive in wild animals such as crocodile and monitor lizards. A number of wild animals serve
as reservoir host of the parasite. The diseases have different distributions across the African continent and are therefore transmitted by different species of tsetse.
The Human African Trypanosomiasis also called sleeping sickness is caused by the trypanosomes of the Trypanosoma brucei species and is transmitted by the palpalis group species. The strain which infect humans are divided into two subspecies; the Trypanosoma brucei rhodesiense which causes the Rhodesian form of sleeping sickness in East Africa, and the Trypanosoma brucei gambiense which causes the Gambian form of sleeping sickness in West Africa. These two subspecies although morphologically undistinguishable, differ on the basis of their virulence and can be fatal if left untreated (Hoare, 1970; Kennedy, 2006).
African animal trypanosomiasis, nagana, is a disease complex caused by the tsetse fly-transmitted Trypanosoma congolense, T. vivax, or T. brucei brucei or simultaneous infection with one or more of these trypanosomes. They constitute a major constraint limiting the optimal utilization of land for agricultural (crop and livestock) production (Mahama, 2003).
1.2 Economic importance of Tsetse Flies
Tsetse fly and the diseases it transmits are one of the most severe medical and veterinary problems in Africa, infecting more than 500,000 people, killing 50,000 people and three million livestock annually (FAO, 2002; Okhoya, 2003); therefore, preventing the development of sustainable and productive agricultural systems (Vreysen, 2001). Tsetse fly and trypanosomiasis is widely
recognized as one of Africa’s greatest constraints to socio-economic development, causing death, debility, diminished productivity in man and domestic animals, massive economic loss and reduction of revenue from tourism (Anon., 2004). The burden imposed by tsetse and trypanosomiasis problem continues to frustrate efforts and hamper progress in development activities, and remain one of the greatest causes of hunger, poverty and immense suffering to communities in Africa. Trypanosomiasis is the greatest cause of mortality, morbidity and low productivity in domestic animals, and severely diminished agricultural productivity (Anon., 2002).
The occurrence of tsetse flies in national parks and game reserves where natural fauna and flora are protected provide ideal habitat for the flies and the pathogenic trypanosomes, and as such, domestic livestock grazing around the periphery of parks are permanently exposed to the risk of trypanosomiasis and, if trypanosomes pathogenic to man occur in the local tsetse, staff and tourist frequenting the parks stand the risk of contracting sleeping sickness (Jordan, 1986).
In view of the problem stated above, a new initiative known as the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) was developed and a decision was passed by the African Heads of State and Government, urging member states (since tsetse-transmitted disease is trans-boundary) to collectively embark on the campaign in order to rid Africa of the threat and burden of tsetse-transmitted disease. The PATTEC initiative seeks to employ an area-wide approach and appropriate fly suppression methods, to
eradicate tsetse from areas of tsetse infestation, progressively and to ultimately create tsetse-free zones (Kabayo, 2002). This initiative was borne out of the successful elimination of tsetse from the Island of Zanzibar through the sterile insect technology (SIT) approach.
1.3 Tsetse Ecology
Tsetse flies are confined only to the subtropical and tropical regions of
Africa from latitude 15oN to 28oS (Davies, 1977). The northern limit extends across the continent from Senegal in the West to Southern Somalia in the East. The southern limits are less well defined, but correspond closely to the northern edges of the Kalahari and Namibian deserts extending to South Africa (Jordan, 1986). The genus Glossina stretches across 10 million square kilometer, covering 37 countries of Africa, thus corresponding approximately to one-third of Africa total land area (Anon., 2002). They occupy a wide variety of vegetation types ranging from the semi-arid margins of the Sahel, through tropical rainforests, to the sub-tropical savannas (Ford and Katondo, 1977) depending on the climatic conditions of temperature, rainfall and vegetation
type. In Nigeria, they cover all the five agro-ecological zones from latitude 4o –
13oN to longitude 2o – 15oE (Onyiah, 1997).
In the genus Glossina are about thirty four species and subspecies which have been divided into three distinct species group based on a combination of distributional, behavioral, molecular and morphological characteristics. These are the Morsitans group (subgenus: Glossina sensu stricto) which are mostly the
savanna flies and often referred to as the game flies. They are of significant economic importance because, they transmit animal trypanosomiasis; the Palpalis group (subgenus: Nemorhina) are mostly riverine flies, some are known to inhabit forest regions, they are also important transmitters of human trypanosomiasis; and the Fusca group (subgenus: Austennia) are mostly the forest flies which are of little economic importance (Davies, 1977).
Significantly, eleven out of the twenty two known species of Glossina endemic to Africa occur in Nigeria and have been reported to transmit the disease to susceptible host (Jordan, 1961). However, four of these species are major transmitters of the disease in Nigeria namely: Glossina palpalis and Glossina tachinoides (vectors of human trypanosomiasis). Glossina morsitans submorsitans and Glossina longipalpis (vectors of animal trypanosomiasis) (F.M.A, 1981; Onyiah, 1995).
1.4 JUSTIFICATION
Tsetse (Glossina spp) are the primary vector of animal and human trypanosomiasis in tropical Africa; and are a continuing threat to public health, livestock production, agricultural development and is also a major source of economic loss.
Tourism is arguably the world’s largest and fastest growing industry, accounting for about five percent of the world’s Gross National product and six percent of the employment (Glasson et al., 1995). Most governments encourage tourism for its ability to spread economic development and reduce inequalities
in income distribution by providing jobs (Pearce, 1988; Coccossis and Parpairis, 1995; Waheb and Pigram, 1997). Tourism is viewed by government as a catalyst for national and regional development bringing employment, exchange earnings, balance of payment advantages and important infrastructural developments benefiting local and visitors’ alike (Glasson et al., 1995). Nigeria is also not left out in her quest to develop the Nation’s tourism industry. In order to achieve this, National parks and their Governing Board established by Decree 46 of 1999 as amended in 2006 created seven National Parks. National park plays significant roles in science, research and educational development apart from acting as vehicles for the development of eco-tourism.
The threat to tsetse fly infestation exists in most national parks/wildlife park and is a major health risk to tourists coming to tropical Africa (Sabbah et al., 1997; Conway-Klaassen et al., 2002; Jelinek et al., 2002). Blumberg, (2005) reported two cases of East African trypanosomiasis acquired in Kasungu National Park in Malawi. Similar report was made by Moore et al., (2002) of an American tourist who after a trip to Africa was diagnosed as suffering from an infection of Trypanosoma brucei rhodesiense, an East African form of Trypanosomiasis. The continued and occasional importation of African trypanosomiasis to the United States by tourists and immigrants from high-risk areas was reported by Chretien et al. (2005). The work by Ndams, (1987) showed the occurrence of tsetse flies in Pandam Wildlife Park, in Plateau State, Nigeria.
The two types of African trypanosomiasis that exist namely Animal trypanosomiasis and Human trypanosomiasis are determined by the species of tsetse fly. The human trypanosomiasis poses a health hazard to human and will thus have adverse effect on tourism if not checked. This necessitates the study to ascertain the population structure of tsetse flies in Kamuku National Park The information that will be obtained from this study should serve as an input to the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) Programme.
1.4.1 Aim
To determine the species composition and the population structure of tsetse flies in Kamuku National Park.
1.4.2 Objectives
To determine the tsetse fly species present,
To investigate the seasonal density variations of tsetse fly in the park,
To determine the sex, age structure, physiological and reproductive status and infection rates.
1.4.3 Hypotheses
There is no difference in composition of tsetse species among the streams
There is no difference in the structure of the population in relation to sex, age, hunger stages, reproductive status and infection rates.
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