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A new species of gongylonematid parasites of the rodent Mastomys erythroleucus is described. Gongylonema madeleinensis n. sp. differs from the other species of the genus by the size of its eggs and spicules-gubernaculum complex, the form and distribution of its cuticular scutella, and the absence of a pore on its cephalic plate. After examination of the esophageal content of 270 continental and 29 insular rodents, G. madeleinensis n. sp. seems to be endemic to the island "des Madeleines" near Dakar, Senegal.

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The purpose of this work was to investigate the use of the ELISA test for the diagnosis of fasciolosis (Fasciola gigantica) in sheep, in Senegal, using Fasciola gigantica metabolic excretion-secretion products as antigens. Coprological analysis results were negative until the fourteenth week following infection; using the ELISA test, the first anti-Fasciola gigantica antibodies can be detected as early as the fourth week following infection.

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An abattoir survey on gastrointestinal parasites of the dromedary (Camelus dromedarius) was carried out in March/April 1987 in northern Mali. Parasitological examination of the digestive tract contents of 11 dromedaries revealed that Haemonchus longistipes was the predominant parasite with a prevalence as high as 85.7%. The genera Impalaia, Trichostrongylus, Cooperia, and Oesophagostomum were also recovered, but with a lower level of infection and frequency. The larval stage of the canine cestode Echinococcus granulosus was recorded in a single instance.

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A recent outbreak of intestinal schistosomiasis (1989) has been reported in Richard-Toll (Delta of Senegal River) with a global prevalence of 43%. A malacological survey has been carried in order to study, the density of Biomphalaria pfeifferi the intermediate hosts, their distribution and rate of infection, and to identify the transmission sites. Ten districts have been selected. The snails have been collected in the different water points of these localities which are the river, the Taouey marigot, the Taouey channel and the irrigation channels and drains of the CSS (Senegal Sugar Company). A total of 1,210 Biomphalaria have been collected in 45 sites with a variable density of 2 to 150 snails. The overall rate of infestation of snails is 44% but varies according to the districts (9 to 64%). The transmission is acting in all the districts mainly in the Taouey channel (28% of infested snails) the Taouey marigot (38% of infested snails) and particularly in the channels of CSS (47% of infested snails). The situation is alarming and requires urgent action be undertaken to decrease the prevalence and reduce the transmission.

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Sheep originating from an heartwater-free area were immunized by the infection and treatment method, using long-acting oxytetracycline. The animals were then exposed, together with control sheep to natural infection in an enzootic area. Tick counts were made to monitor the infestation and establish a correlation between infestation by certain tick species, in particular Amblyomma variegatum, and the occurrence of cowdriosis. In some cases of death associated with ehrlichiosis and anaplasmosis in the group immunized against cowdriosis, groups of Cowdria ruminantium were found in smears of the cerebral cortex, which leaves question marks as to the real nature of immunity to cowdriosis. Furthermore, these losses show the necessity of an integrated approach to the control of diseases of livestock in a given area. The presence of Rhipicephalus e. evertsi, formerly absent from this area, was significant in this respect.

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Observations made in Dakar abattoirs from March to December 1987 revealed that 46.39 per cent sheep and 57.89 per cent goats carried Oestrus ovis larvae. A clear relationship between cause and effect exists between nasal discharge and the presence of mature larvae. Because of their spine covering, they are irritating enough to provoke nasal mucosa inflammation with possible microbic complications. It is thus necessary to take into account the frequency and the pathogenicity of Oestrus ovis infection in the aetiologic study of respiratory affections of the small ruminants in Senegal.

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Study by SEM of the anterior dorsal teguments of male Schistosoma haematobium from infected rodents. Only paired males, at least hundred days post infection, display a typical morphology. Differentiation from other closely related species obtained experimentally from rodents is possible: bovis: no spines on the tubercles; haematobium: tubercles 10 to 15 microns wide with closely packed spines; curassoni: tubercles over 15 microns wide, with large, closely packed spines; intercalatum: tubercles under 10 microns wide, with scattered spines. It is suggested that the three haematobium genotypes A, B and D are slightly different: A: pointed spines, numerous small additional spines between the tubercles; B: pointed spines, no small additional spines between the tubercles; D: blunt spines. Moreover, the lengths of the prepatent periods in the molluscs of the three S. haematobium genotypes are possibly different: A 72-86 days, B 38-46 days, D 55-58 days. The differentiation of A, B and D is supported by limited data and conclusions on this particular aspect are presented only as a working hypothesis.

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Cercarial chaetotaxy of Gastrodiscus aegyptiacus (Paramphistomoidea), parasite of the Horse, is described. Cercariae were shed by experimentally infected Bulinus forskalii. This description is the first one of a Gastrodiscidae. The cercarial chaetotaxy of the Gastrodiscidae is quite different from those of Paramphistomoidea and Diplodiscidae.

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Study of Senegal cercariae emitted by naturally infected snails or by snails experimentally infected using eggs from human urine or from sheep liver, and study of the corresponding eggs. The relative position of the dorsal sensillae of cercariae is described by an "AD index" and the ratio length/width of eggs by an "L/l index." At the present time, we have not finished the epidemiological studies, certain experiments are imperfect and the isoenzyme analysis of the corresponding adults is incomplete. Nevertheless information given by the indices AD and L/l agree and lead us to admit the existence of a Schistosome different to mattheei, haematobium and bovis and which, following Brumpt and Gretillat we refer to as Schistosoma curassoni. If one relies on the indices, the study indicates that: a) S. mattheei has not been found in Senegal, b) S. bovis is quite rare, c) S. haematobium apparently exists in pure infections in Casamance and in mixed infections with S. curassoni in man in the north and in the east, d) S. curassoni is apparently the dominant species in domestic ruminants and in man in the north and in the east, e) Bulinus umbilicatus is the principal vector of S. curassoni and S. haematobium.

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The life cycle of a Paramphistome from North Senegal is completed starting from cercariae shed by naturally infected Isidora guernei: a sheep and then uninfected Isidora guernei were successively infected experimentally. Adults obtained were identifiable as P. phillerouxi or as P. microbothrium. Species determination cannot be made on the basis of argentophilic structures in the miracidium. Morphology of sporocysts and rediae differs from that observed in P. phillerouxi but is undistinguishable from that described in P. microbothrium. Cercarial chaetotaxy differs from that of P. phillerouxi. Mollusc host: Isidora guernei belongs to the same genus as Isidora truncata and I. alluaudi, reported hosts to P. microbothrium. Therefore the material is provisionally identified as P. microbothrium. To confirm this, a strain of P. microbothrium from naturally infected Bos taurus in Egypt was studied. Miracidia were used to experimentally infect Isidora truncata; cercariae obtained were identical to those previously described for this species from I. truncata and I. alluaudi. Cercarial chaetotaxy was not significantly different from that of material from North Senegal. They represent therefore two strains of Paramphistomum microbothrium.

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Superficial argentophilic structures of the miracidium and cercaria of Paramphistomum phillerouxi Dinnik, 1961, are descrifed in detail. Concerning the miracidium they are similar to those of the miracidia of some species belonging to the genus. On the other hand the chaetotaxy of the cercaria is different from that of the cercaria of P. togolense (Alberet et coll., 1978) and therefore this appears to constitute a good criterium for the taxonomy of this group.

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