ISRAEL JOURNAL OF
VETERINARY MEDICINE
THE PREVALENCE OF ANIMAL
TRYPANOSOMOSIS IN KONSHISHA LOCAL
GOVERNMENT AREA OF BENUE STATE,
NIGERIA
1
2
1
2
2
S.O. Omotainse , H. Edeghere , G.A. Omoogum , E.O. Elhassan , G. Thompson ,
C.A. Igweh , J.A.C. Ukah , M.A. Ikenga2 and I. Halid2
1
2
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.
Abstract
A survey for trypanosomiasis of cattle, sheep, goats and pigs in Konshisha Local Government
Council of Benue State was carried out between 12 — 19 January 1993. One hundred sixty
three animals were sampled, of which, 68 (41.7%) were positive by haematocrit centrifuge
technique (HCT) for various trypanosomes. All domestic animals in the area were affected.
The infection rate for sheep was 57.1%, while that for goats, cattle and pigs was 33.9%,
81.8% and 36.8% respectively. Overall, sheep, goats, cattle and pigs accounted for 5.9%,
57.4%, 26.5% and 10.3% respectively of the total positive blood samples. Of importance is
the finding that many animals were positive for T. brucei, which might be of zoonotic
importance. The area is ideally suited for livestock production, but has a very high prevalence
rate of trypanosomiasis.
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 (8 0E-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.
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.
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.
The trypanosome infection rates in the different animal species and their
mean packed cell volume.
Table 1.
Species
Positive
# of
samples
Negative
Number
PCV (±SD)
Number
PCV (±SD)
Parasite
species
T. vivax
Ovine
7
4
22.00 (2.5)
3
41.00 (2.7)
Caprine
115
39
25.18 (6.6)
76
30.97 (7.5)
Bovine
22
18
24.56 (5.0)
4
24.75 (4.0)
T. vivax (17),
mixed T. vivax
and T.
congolense (1)
Porcine
19
7
25.14 (5.2)
12
32.67 (5.3)
T. brucei
T. vivax (37),
mixed T. vivax and
T. brucei (2)
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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