Studies on the lung nematodes of sheep and goats in the Levant.

Abstract

Five species of lung nematodes of sheep and goats were found in the Levant countries, namely: Dictyocaulus filaria, Cystocaulus ocreatus, Muellerius capillaris, Protostrongylus rufescens and Neostrongylus linearis. Cystocaulus ocreatus is the commonest, while Neostrongylus linearis is very rare. Descriptions of the morphology of the adults and of all the developmental stages of all these species, except the last, are presented. The presence of a small but well-developed bursa of a protostrongylid type in Muellerius capillaris has been established. The life histories of Cystocaulus ocreatus, Muellerius capillaris and Protostrongylus rufescens have been studied and the susceptibility of various snail hosts has been determined. Experimental infections with larvae of Cystocaulus ocreatus and Muellerius capillaris have been induced in eleven species of terrestrial snails and slugs (belonging to seven genera). Only three of these eleven species proved susceptible to infection with larvae of Protostrongylus rufescens. Experimental infections of definitive hosts with these three species have been obtained. Lowering the temperature retards larval development in the snail. The larval development of P. rufescens is especially retarded and its larvae do not develop at all at temperatures lower than 4–8° C. Natural infection of Helicella barbesiana with the larvae of Cystocaulus ocreatus, Muellerius capillaris and Protostrongylus rufescens has been found in the vicinity of Jerusalem.