Excystation of five digenean metacercariae in vitro and in the peritoneal cavity of the mouse.

Excystation of metacercariae of Parorchis acanthus, Posthodiplostomum nanum, Posthodiplostomum sp., Posthodiplostomoides leonensis and Clinostomum tilapiae in mammalian saline at 39 degrees C was similar to their excystation in mouse peritoneal cavity. Extrinsic enzymes were not needed for C. tilapiae excystation but were an absolute necessity for P. acanthus excystation. Extrinsic pepsin enhanced P. nanum excystation but was not obligatory. Acid pepsin was an absolute requirement for Posthodiplostomum sp. and Posthodiplostomoides leonensis excystation. It was noted that acid saline could not be substituted for acid pepsin and that there was diversity in the condition involved in digenean excystation.

Disease and mortality in small ruminants in the North West Province of Cameroon.

Mortality rates and the prevalence of disease were assessed in 115 flocks of traditionally managed sheep and goats in two Divisions of the North West Province of Cameroon by means of a questionnaire to the owners. The mortality rate was significantly higher in sheep than in goats and also higher in young stock than in adults. Tethering the animals during the day resulted in significantly lower mortality in both adult and young sheep and also in kids. Disease problems of small ruminants, identified on the basis of signs reported by their owners, included intestinal parasitism, especially helminthiasis, tick infestation and associated diseases, pneumonia, goat plague (peste des petits ruminants) and Oestrus ovis infestation. Treatment of sick animals was only practised on a very small scale, often by possibly ineffective traditional methods. The owners identified tick infestation and diarrhoea as common causes of death. Recommendations are made on control measures suitable for application in this area.

Management and productivity of small ruminants in the north west province of Cameroon.

A survey showed that in the North West Province of Cameroon 92% of the farmers rear goats as against only 21% who rear sheep. The main constraint on sheep husbandry appeared to be a traditional belief that keeping sheep adversely affects a woman's fertility. Flock sizes are small (three to 48, median seven) but there was some tendency towards larger numbers in mixed flocks. There were considerably more females than males. Six systems for managing small ruminants were identified. The most widely practised was housing at night and tethering in daytime during the cropping season with either tethering or free-range grazing during the daytime in the non-cropping season. The most common housing system was an enclosed shed with walls of sticks, tree fern or bamboo. Floors of planks laid on the earth or slightly raised were used by about 48% of the farmers while 22% constructed raised slatted floors. Most farmers gave their animals salt on a more or less regular basis but otherwise intentional feed supplementation was rare. About 43% of the farmers thought it unnecessary to provide water. Breeding was generally uncontrolled and the progeny of the most active breeding ram or buck was often the main source of replacement males. The overall offtake rates were 20% for sheep and 24% for goats. Several flocks had no offtake while four (three flocks of goats and one of sheep) reported offtake rates of 65 to 80%.

Haemonchosis in sheep and goats in Sierra Leone.

The incidence of haemonchosis in sheep and goats in Sierra Leone showed a seasonal variation with a high peak in the dry season (October to January) and a low one from March to May. Mean relative densities were significantly higher in young hosts and showed two peaks, a high one from August to December and a low one from April to June while the mean relative densities of old hosts were low and exhibited an irregular seasonal pattern with no defined peaks. The peak seasons in young hosts coincided approximately with the dry and rainy seasons. Male hosts showed an overall higher but not a significant mean relative density than females but for most of the months mean relative densities of infection of female hosts were not significantly higher than those of males. The roles of climatic conditions and arrested development (hypobiosis) and self-cure and host age immunity on Haemonchus contortus worm burdens are discussed.

Productivity of sheep and goats under three management systems at Bamenda, Cameroon.

The productivity of sheep and goats was examined under three management systems. A regime by which each animal received five doses of fenbendazole in a year gave similar results in terms of survival and liveweight gain to monthly dosing. Sheep kept by traditional methods without anthelmintic treatment survived and grew less well than goats. In contrast goats grew better and produced more young under traditional management although they were in general lighter than sheep.

The effect of sex on seasonal variation in single and double infection of cattle in Sierra Leone by Dicrocoelium hospes and Fasciola gigantica.

The incidence of dicrocoeliasis (61.8%) is higher than that of fascioliasis (25.5%) and their peaks do not occur at the same time of the year. The peak for the former occurs in the dry season while that of the latter occurs in the rainy season. The incidence of dicrocoeliasis and fascioliasis in female cattle was found to be higher than that of male cattle. Double infection was higher in female (14.7%) than in male hosts (9.6%).

Studies on the excystment of trematode metacercariae in vitro.

Excystment of metacercariae of Parorchis acanthus, Posthodiplostomoides leonensis, Posthodiplostomum sp. and Clinostomum tilapiae was found to be an active process initiated by the metacercariae when the correct physico-chemical conditions exist in the environment; but in the excystment of Posthodiplostomum nanum the metacercaria seems not to take part in the process. Temperature, osmotic pressure, pH and eH are factors which influence all the five species studied. Fresh ox bile was found not to be an absolute necessity for the excystment of the five species studied but its presence in the medium increased the rate of excystment of three species.