A. Maho, K. Youssouf, L. Mbeurnodji, M. Saboune and L.Y. Mopate

A parasitologic investigation was carried out on the faeces of 342 local chickens in the North-Gu¨ra region, Chad, during the rainy season (July - August) 1998. Thirteen species of parasites were identified and the global prevalence of parasitosis was found to be 59 percent, out of which 27 percent for coccidiosis, 18 percent for cestodosis, 13 percent for nematodosis and 1 percent for trematodosis. It was observed that 8 percent of chickens were highly infested with parasites, and 75 percent of the 28 parasitic associations involved Eimeria spp. While the percentage of chickens showing normally coloured faeces was higher (40 percent) than those with abnormally coloured ones (20 percent), the percentage of chickens excreting normally consistent faeces was lower (25 percent) than those with abnormal ones (35 percent).

This investigation showed that, in the North-Gu¨ra region, there is a great spectrum of parasitism of the digestive tract of chickens as well as common parasitic associations. Thus, any effective antiparasitic treatment must take the spectrum of the parasitism as well as parasitic associations into account.

Key words: Chad, digestive tract, local chicken, parasitic association, parasitosis

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The North-Gu¨ra area, situated in the central-east of the country, consists of three sub-prefectures (Mongo, Bitkine, Mangalm¨). It is located at 550 km east of the capital-city NėDjam¨na, Chad. Poultry production is very important in this region, which supplies the capital-city with chickens. Poultry keeping, which is practised traditionally, has to cope with many constraints, especially health-related (Maho et al., 1998; Mopate et al., 1998).

In order to contribute to the knowledge of avian diseases in the area and to undertake improvements in traditional poultry farming, a parasitologic investigation based on samplings and analyses of faeces was carried out.

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The survey was carried out on 19 villages in the area of North-Gu¨ra, out of which nine were from the sub-prefecture of Mongo, six from that of Bitkine and four from that of Mangalm¨. During the rainy season (July - August) 1998, faeces samplings were conducted on 342 local chickens, out of which 122 birds were from Mongo, 108 from Bitkine and 112 from Mangalm¨. Birds were surveyed irrespective of sex and age. The faeces collection was performed in the morning when chickens left their housing or in the evening when they re-entered. The samples, collected in plastic bags, were placed into a refrigerator and conveyed to the laboratory for the coproscopic analysis.

Individual quantitative coproscopies were systematically carried out using a blade of Mac-Master. The flotation fluid used was an over-saturated sodium chloride (NaCl) solution. During macroscopic and microscopic observations, parasites and parasitic associations as well as the colour and the consistency of faeces were registered.

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Prevalence of parasitosis:
Fifty-nine percent of chickens showed parasites in their faeces, and a total of 13 species of parasites were identified. They were especially coccidies (27 percent of the cases), cestodes (18 percent), nematodes (13 percent) and trematodes (1 percent). The dominant species of cestodes identified was Raillietina cesticellus, while the principal species of nematodes encountered was Ascaridia galli. The identification of various species of coccidies was not carried out (Table 1).

Table 1: Prevalence of identified parasites

The existence of a broad spectrum of parasitism of the chicken digestive tract in the study area might be explained by the lack of vermifugation that characterizes traditional livestock farming in Africa.

Parasitic associations encountered:
Twenty-eight cases of parasitic associations were observed, with Eimeria spp representing the species mostly associated (75 percent) with the others (Table 2). The importance of the coccidies in poultry farming is recognized by other authors (Grtillat, 1981; Alamargot et al., 1985; Ibrahim, 1996).

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Table 2: Parasitic associations

Presence of pathogenic agents and aspects of the faeces: With regard to the colour of faeces, 70 (20 percent) of the birds showed abnormally coloured faeces (whitish, reddish, greenish, blackish, ashy) versus 137 (40 percent) having normally coloured faeces. The abnormal colours (reddish, greenish and blackish) were observed in certain birds parasitized by Eimeria spp., Raillietina cesticillus and Cotugnia digonopora.

For the consistency of faeces, 119 (35 percent) of the samples showed an abnormal consistency (liquid, too soft) versus 87 (25 percent) which were normal (firm). Although parasites are not the only agents responsible for modifications observed in the faeces, the contribution of their presence cannot be underestimated.

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The colour and consistency changes in faeces as well as high levels of infestations were noticed in birds parasitized by Eimeria spp, Raillietina cesticillus, Ascaridia galli, Cotugnia digonopora and Davainea proglottina. The pathogenic capacity of most of these parasites was reported by Brugere and Silim (1992), Ibrahim (1996) and Maho et al. (1997).

Importance of the level and rate of infestation: Birds with low infestation (116) were more numerous than those highly (26) and moderately (6) infested. In the 26 highly infested birds, coccidies were found in 17 birds, Raillietina spp. in 4, Ascaridia spp. in 2, Davainea spp. in 1 and Cotugnia spp. in 2.

The highly infested chickens represented only 8 percent of the analyzed sample (Table 3). However, the low number of birds with high infestation level can increase in the event of prolonged stress (Maho, 1997).

Table 3: Level and rate of infestation

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The results of this investigation show the importance of parasitism of the chicken digestive tract in North-Gu¨ra, Chad. To be effective, a bi-annual vermifugation must take the observed spectrum of parasites as well as parasitic associations into account. In addition, any improvement programme for the traditional poultry production system must pay attention to all health aspects, including the parasitism of the digestive tract.

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