This study tested 480 camel sera from northern Nigeria for antibodies to brucellosis. The overall incidence of positive titres was 7.5%, indicating exposure to Brucella abortus. Camel meat and milk are increasingly important sources of protein for humans in the region, presenting a potential public health risk. A national brucellosis control program is needed to address this zoonotic disease in livestock and protect human health.

1. Brucellosis in camels
A. C. Kudi*, D. J. U. Kalla*, M. C. Kudi† & G. I. Kapio*
*Animal Production Programme & †Biology Programme, School of
Science and Science Education, Abubakar Tafawa-Balewa University,
Bauchi, Nigeria
(Received 17 January 1997, accepted 2 May 1997)
Sera from 480 camels of both sexes in the Sahel savannah of Nigeria were
tested for antibodies to brucellosis, using the microtitre serum agglutination
test with Brucella abortus antigen. The overall incidence of positive titres
(titres greater than 1·1) was 7·5%. Brucella antibodies were almost as frequent
in males (7%) as females (8·3%). Camel meat and milk is increasingly
important as a source of protein for the human population in the region. This
study highlights the potential importance of brucellosis for public health and
measures are suggested for a national brucellosis control.
©1997 Academic Press Limited
Keywords: serology; brucellosis; camel; public health; Sahel; Nigeria
Introduction
An increase in the production of camel meat and milk to remedy in part the grossly
inadequate supply of animal protein supplied currently from cattle and sheep, and to
a lesser extent goats and pigs, for the human population, especially in Nigeria, was
advocated by Ghaji & Adogwa (1986). Camel meat is becoming increasingly
important and is replacing beef and mutton in the diet of many families in northern
Nigeria because it is cheap and tastes good (Ghaji & Adogwa, 1986). More than 50%
of human dietary protein, especially in northern guinea savannah is from camel meat,
as desertification is making cattle production in this area difficult (Ajayi, 1995). Camel
hide is used in the famous leather industry in the northern part of the country. The
by-products after slaughter are used in the preparation of poultry feed (Okoh, 1979).
Thus, camel production seems to be an important area that needs to be pursued with
all vigour. The encroachment of desert into northern Nigeria has renewed strong
interest in utilizing camels as a source of milk, meat and farm power since they have
a greater ability than other domesticated livestock to adapt to such an environment
(Ghaji & Adogwa, 1986). About two-thirds of the land in the northern region of
Nigeria is now being used for camel farming. The camel population of Nigeria now
stands at 25,000 (Ajayi, 1995) as compared to 18,000 in 1978 (Food & Agriculture
Organisation, 1978). However, low productivity still hinders the exploitation of these
desert-adapted animals. In addition to late maturity and long calving intervals,
Journal of Arid Environments (1997) 37: 413–417
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2. brucellosis due to Brucella abortus may cause considerable economic loss at the farm
level (Bale, 1991).
Brucellosis, particularly due to B. abortus, is considered one of the most important
zoonotic diseases of camels and other domestic animals of some countries of northern
Africa such as Libya (Gameel et al., 1993). In Nigeria, the disease has been reported
from nearly all camel producing areas (Bale, 1991), as well as being found in cattle
with a prevalence rate of 8·1% (Nuru, 1975; Bale & Kumi-diaka, 1981; Ocholi, 1990),
in sheep and goats with prevalence rates of 14·1% and 4·6%, respectively (Bale et al.,
1982; Chukwu, 1987) and in humans (Falade, 1974). Despite the earlier control
programme undertaken in the country using B. abortus strain 19 vaccine and test-and-
slaughter methods, the disease still remains and its incidence is increasing (Bale,
1991). This could be associated with the nomadic nature of the Fulanis who are the
main livestock-rearers, and also to the porosity of our borders. However, information
on camel brucellosis in Nigeria is scanty (Okoh, 1979).
The possibility that brucellosis may spread from camels, especially through milk
(Gameel et al., 1993), and the lack of current and detailed epidemiological study of the
disease in camels in Nigeria strongly calls for a reassessment of the prevalence of the
disease. This will allow an effective control programme to be designed and serve as a
baseline for further research.
Materials and methods
Four hundred and eighty sera samples were obtained from adult camels (Camelus
dromedarius) of both sexes at Kano abattoir, northern Nigeria, between January and
June 1995. The animals had been managed traditionally, i.e. managed under a
nomadic system where herds are mixed with sheep and goats. This involves
movements during different seasons for grazing or watering (Johnson, 1969; Cole,
1975). The camels were conveyed from different localities in the northern part of
Nigeria with a few from neighbouring Chad and Niger republics. Blood samples were
collected by exsanguination into a collection vessel after slaughter at the slaughter slab.
The blood was allowed to clot and serum separated from each sample. Each sample
was stored at –20°C until ready to use. The sera was examined for Brucella abortus
antibody using the microtitre serum agglutination test ( MSAT) described by Alton et
al. (1988). Samples with titre greater than 1·1 were considered positive. Chi-square
analysis was used to analyse data generated (Remington & Schork, 1970).
Results
Table 1 indicates the occurrence of antibodies to B. abortus in the sera samples. Thirty-
six of the 480 samples (7·5%) were positive (titres greater than 1·1). Most of the
positive sera had titres of 1·2 and 1·3 (5%) while 2·5% had titres of 1·4 or more.
Positive titres occurred in 7·0% of males and 8·3% of females but this difference was
not statistically significant.
Discussion
In Nigeria, brucellosis due to Brucella abortus in camels has not been extensively
studied as compared to bovine brucellosis caused by the same species. The prevalence
of 7·5% reported in our study is very high compared with the previous report of 1% for
camels in the same environment and under similar management (Okoh, 1979). This
high incidence is however not surprising since there is no record of any proper control
A. C. KUDI ET AL.414

3. programme in other livestock in this region and there is a high prevalence of B. abortus
in other domestic species in the same region: 8·1% in cattle, 14·1% in sheep and 4·6%
in goats. The earlier control programme carried out was not successful because of the
nomadic nature of the Fulanis who own most of Nigerian livestock and also because
of the porosity of the borders and the influx of livestock from neighbouring countries
(Bale & Kumi-diaka, 1981; Chukwu, 1987; Ocholi, 1990).
Our results are similar to those of Abu-Damir et al. ( 1984) where 7·5% of camels
surveyed in the Gaderef region of Eastern Sudan reacted to the B. abortus agglutination
test. Gaderef is somewhat similar to the Sahel region of Nigeria in terms of livestock
densities and stock management; the camels are herded together with sheep and goats
and to a lesser extent with cattle and they share the same watering points and pastures,
and so it is not surprising to find a similar incidence of disease. The camels might have
contracted the infection through close contact between infected and susceptible
animals and cross transmission between species, through the alimentary tract from
contaminated feed or water, through the respiratory system via contaminated dust or
droplets, or through the genital system from infected semen (Bale, 1991).
Apart from the economic losses through abortions, reduced fertility and cross
transmission to other animal species, the zoonotic potential of the disease in camels
should not be overlooked. The danger lies in the fact that the western way of eating
undercooked meat and improperly roasted meat, ‘suya’ and ‘kilishi’, is gaining ground
in Nigeria (Bale, 1991), although no study has isolated the organism in such meat. In
the sahel region of Nigeria raw camels’ milk is increasingly becoming a delicacy, as in
Arab nations. Isolation of B. melitensis in camels’ milk (Gameel et al., 1993) and
seropositivity to B. abortus shown in this study therefore indicate that brucellosis is a
hazard to public health in this region. The relative importance of camels in the national
and regional economies of Nigeria in terms of the percentage of the domestic herbivore
biomass is only 0·17% (Food & Agriculture Organisation, 1978). This is because in
Nigeria, camels are distributed in the peripheral northern border, and the country as
a whole does not contain large populations of ethnic groups to which the camel is
important socially or culturally.
Brucellosis is likely to continue to be a serious economic and zoonotic disease in
Nigeria and neighbouring countries. Nomadism is common, and nomads often cross
the borders from neighbouring countries into Nigeria in search of pasture and trade.
At the moment these countries have not instituted any extensive control programmes.
The traditional camel rearers must be educated as to the dangers of the infection and
of the need to properly dispose of any aborted foetus and observe proper hygiene;
equally the persons involved with abattoir operations must be adequately trained.
In some parts of Nigeria, brucellosis was eliminated from camel herds by periodic
blood tests, by isolation of seropositive animals and their eventual slaughter including
Table 1. Prevalence of Brucella abortus in sera from camels (Camelus
dromedarius). Samples with titres greater than 1·1 were considered positive
Negative titres Positive titres
Camels
Sex sampled (N) <1·1 1·1 1·2+1·3 1·4 & over
Male 287 242 25 14 6
(93·0%) (7·0%)
Female 193 146 31 10 6
(91·7%) (8.3%)
Total 480 388 56 24 12
(92·5%) (7·5%)
BRUCELLOSIS IN CAMELS 415

4. those with positive reaction to complement, and by a widespread vaccination
campaign using Brucella strain 19 vaccine in camels (Esuruoso, 1979; Magaji, 1984).
However, the status broke down because a nationwide test and slaughter policy is not
feasible in Nigeria at the moment as there is no organized plan for compensation of
farmers whose animals have tested positive (Esuruoso, 1979).
Since cross-transmission of B. abortus is common in most domestic animals, a
holistic approach should be adopted when devising a control programme. Livestock
herded together with camels, i.e. sheep, goats and cattle, should be tested and positive
reactors should be separated while non-reactors should be vaccinated with the strain
19 vaccine. Positive cases should be slaughtered with adequate compensation of the
farmers by the government. Intergovernmental co-operation between countries is
required to effectively prevent cross-border transmission of the disease. Control could
be achieved through mass test and slaughter with adequate compensation, mass
vaccination and mass education of farmers. Public health could be guarded by making
sure that strict abattoir hygiene is maintained and only safe milk and meat are supplied
to the populace.
Conclusion
From this study, 7·5% of a sample of 480 slaughtered camels in northern Nigeria were
found to be infected with Brucella abortus. Cross-transmission of this agent across other
domestic species is believed to be the most likely source of the infection since camels
are traditionally herded together with other species. Control could only be achieved
when all susceptible domestic species are considered together and intergovernmental
co-operation is initiated to prevent cross-border transmission. Proper abattoir hygiene
and clean handling of milk before consumption are necessary to prevent infection in
humans. However, this study indicates that a widespread and detailed epidemiological
study is needed to ascertain the true extent of B. abortus infection in Nigerian livestock
before initiation of a control programme.
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