THE PREVALENCE OF ANIMAL TRYPANOSOMOSIS IN KONSHISHA LOCAL GOVERNMENT AREA OF BENUE STATE, NIGERIA

S.O. Omotainse¹, H. Edeghere², G.A. Omoogum¹, E.O. Elhassan², G. Thompson², C.A. Igweh¹, J.A.C. Ukah², M.A. Ikenga2 and I. Halid2

1. Nigerian Institute for Trypanosomiasis Research, P.M.B 03, Vom, Plateau State, Nigeria.

2. Nigerian Institute for Trypanosomiasis Research, P.M.B 2077, Kaduna, Kaduna State, Nigeria.

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Introduction

Trypanosomiasis continues to be a menace in the livestock industry in Nigeria despite the age long attempts to control the disease. The disease has received attention more in organized farms than in domestic and peridomestic animals. However, apart from the organized fulanis, government and some large individual farms, the majority of Nigerian livestock are kept within or around homestead. It is therefore very important to intensify surveillance and treatment of trypanosomiasis in these animals as well as in those that are reared primarily outside the human settlement.

The Benue State of Nigeria falls within the derived savanna region (80E-100E and 60N-80N), where there is perennial feed for livestock. The state is known to be an endemic zone for both animal and human trypanosomiases (1,2). Goboko Local Government Area (LGA) of Benue State, which is to the north of Konshisha LGA, was hyper-enzootic for animal trypanosomiasis with a ruminant infection rate of 33.2% (2).

Konshisha LGA is in the southern Guinea Savanna vegetation of Benue State. This area is suitable for rearing animals all year round. Despite the resultant negative effects of trypanosomiasis on the animal population (3) and the possible zoonotic nature of the disease (4), domestic and peridomestic stock are the main livestock holding of Konshisha LGA. It is therefore important that active surveillance be carried out on such domestic and peridomestic animals. A survey was therefore undertaken in the Konshisha LGA of Benue State to ascertain the state of trypanosomiasis in these animals.

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Materials and Methods

Between the 12-19 January, 1993, domestic and peridomestic animals in 12 villages in the Konshisha Local Government Area of Benue State of Nigeria, were sampled by moving from house to house. The small ruminants graze around the periphery of the towns and villages. The cattle bled were those kept within enclosures in the backyards with access to fish ponds for watering. A total of 7 sheep, 115 goats, 22 cattle and 19 pigs were sampled. The animals consisted of West African Dwarf (WAD) breed of sheep, goat and pig and a mixture of N'dama and Muturu breeds of cattle.

Blood samples were collected from the jugular vein in EDTA for parasitology and haematology. Screening of the blood for trypanosomes was carried out using the standard detection techniques (wet, thin and thick films) for quick assessment and by haematocrit centrifugation technique (HCT) for accurate diagnosis (5). Also, the packed cell volume (PCV) of all animals was recorded using the microhaematocrit method.

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Results

The HCT and PCV analyses are presented in Table 1. Of the 163 samples taken, 68 (41.7%) were positive for various trypanosome infections. Most were T. vivax (83.8%) which occurred in the ruminants only. All the infected sheep had T. vivax, which also affected 94.9% of the goats. A mixed infection of T. brucei and T. vivax accounted for the remaining 4.7%. T. vivax was responsible for 94.9% of the bovine infections, while mixed infections of T. congolense and T. brucei accounted for the remaining 5.1%. All the pigs were T. brucei positive. In the small ruminants and pigs the PCVs of the trypanosome-infected animals were remarkably low.

Table 1. The trypanosome infection rates in the different animal species and their mean packed cell volume.

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Discussion

The importance of small animals, especially ruminants, in the economy of the West African sub-region cannot be over emphasized. They provide up to 30% of the meat supply. The effect of trypanosome on these animals range from anaemiaa, immunosuppression, retarded growth, low milk production and weight loss as well as infertility,  abortion, stillbirth and depressed reproductive performance (6-10). These damaging effects and the manpower and material resources committed to the disease were said to result in more than $23.8 million annually in Nigeria (11). Also, the fact that many animals had T. brucei infection might be of zoonotic importance, since domestic animals are known reservoirs of T. b. gambiense in West Africa (4).

The dominance of T. vivax in ruminant infections in this study is a further confirmation of the earlier findings (2,12,13) in different parts of northern Nigeria. However, the infection rates in this study are higher than those in earlier reports. This might be attributed to the location of Konshisha LGA which is situated south of the areas previously studied (4,12,13) in the southern Guinea Savanna and in the southern fringe of the Sahel ecological zone, respectively. The infection rates evidently showed that Konshisha LGA of Benue State of Nigeria is hyper-enzootic. Although these WAD sheep, goats and pigs appeared to be physically fit, the infected animals had significant lower PCV values (P<0.05) compared with the non-infected ones. Although some of the cattle of the Muturu and N’dama breeds were anaemic, there was no significant difference between the mean PCV values of the infected and the non-infected animals. The ability of these breeds to maintain normal levels of blood cells during trypanosome challenge is a feature of the trypanotolerance which is a heritable trait (14). The ability of all these animals to survive parasitaemia with such a depressed blood level showed their high level of trypanotolerance and this had been attributed to their advantage genetic background (15) compared to the long legged breeds that would easily come down with trypanosomiasis. The other implication is that with adequate chemotherapeutic, chemoprophylactic and insect control measures, Konshisha LGA could be more valuable to livestock production making use of the local breeds of animals. This is required since the sub-clinical status of the disease in these animals will not only make them to become reservoir hosts to infections but also reduces their reproductive and productive capacity. The fact that the infection rate could be higher using other diagnostic methods raises the alarm that a concerted and consistent war should be waged against the disease and the vector. Therefore, there is a need to embark on trypanosomosis control program for this area and others with similar vegetation of the country.

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References

1. Nigerian Institute for Trypanosomiasis Research, NITR 1980-1983: Annual Scientific Report of the Nigerian Institute for Trypanosomiasis Research. Kaduna, pp. 79-80. 1985.

2. Kalu, A.U., Uzoukwu, M., Ikeme, M.M. and Magaji, Y.: Trypanosomiasis in Nigeria. High prevalence among ruminants in Gboko Local Government Area. Bull. Anim. Hlth. Prod. Afr. 39: 3-8, 1991.

3. Luckin, A.G.: Trypanosomiasis in small ruminants: A major constraint to livestock production. Brit. Vet. J. 148: 471-473, 1992.

4. Joshua, R.A., Magaji, Y. and Kayit, Y.S.: Isolation of Human serum resistant Trypanozoon from cattle in Nigeria. Tropenmedizin und Parasitology, 13: 201-202, 1983.

5. Woo, P.T.K.: The haematocrit centrifuge for the detection of trypanosomes in blood. Canad. J. Zool. 47: 921-923, 1989.

6. Anosa, V.O.: Haematological and biochemical changes in human and animal trypanosomiasis. Part 1. Revue Elev. Med. Vet. Pays trop. 41(1): 65-78, 1988.

7. Edeghere, H., Elhassan, E., Abenga, J., Osue, H.O. Lawani, F.A.G and Falope, O.: Effects of infection with Trypanosoma brucei  on different trimesters of pregnancy in ewes. Vet. Parasitol. 43: 203-209, 1992.

8. Elhassan, E., Ikede, B.O. and Adeyemo, O.: Trypanosomiasis and production: 1. Effect of Trypanosoma vivax infection on the oestrus cycle and fertility in the ewe. Trop. Anim. Hlth. Prod. 26: 213-218, 1994.

9. Losos, G.J. and Ikede, B.O.: Review of pathology of disease in domestic and laboratory animals caused by T. vivax, T. brucei, T. rhodesiense and T. gambiense. Vet. Pathol. Suppl. Vol. 9: 1-17, 1972.

10. Ogwu, D.: Effects of Trypanosoma vivax infection on female reproduction in cattle. Ph.D. Thesis. Ahmadu Bello University, Zaria, Nigeria. 1983.