Epidemiological studies on infective larvae of gastrointestinal nematodes on pasture grazed by alpacas (Lama pacos) in Valdivia, Southern Chile

In order to study the epidemiology of Trichostrongylid parasites in alpacas (Lama paces), a study was undertaken in Valdivia, Chile, X-th Region (39 d egrees 48' S, 73 degrees 14' W) based on faecal and grass examinations, dur ing a period of fifteen months, starting in January 1995. Animal were group ed according to the age as follows: Group A, 4 animals up to one year old; group B, 11 animals between 1 to 2 years old and 32 animals more than 2 yea rs old. The most frequent genus or species of infective larvae identified were: Nem atodirus spathiger, Ostertagia, Trichostrongylus, Nematodirus filicollis an d Cooperia. During the 1995 summer, a low number of infective larvae were observed as a consequence of the: low contamination of the grass during the previous yea r, and to the dry period in the summer months. In autumn, larvae increased reaching a peak in April with 447 larvae per Kg dry matter. The greatest co ntribution was given by N. spathiger. The other species were less frequentl y identified, Strongylid type eggs, Nematodirus Trichuris sp. and Capillaria sp. were obs erved, few eggs were seen during the observation period. Related with Stron gylid type eggs, more eggs were seen in group A. Related with Nematodirus e ggs, few eggs were seen in group B and C. More eggs were seen in group A. T richuris sp. and Capillaria sp. eggs were less frequently observed. It can be concluded that: weather conditions influence the number of infect ive larvae on the grass. Strongylid egg number are low as a consequence of the deposition of faeces in particular sites.