Ecologie, situations temporelle et spatiale en Algérie de Mashallagia marshalli, parasite des petits ruminants

Abstract

Marshallagia marshalli, abomasum nematode of small ruminants is little known. It is associated to steppe climate. Prevalence and seasonal intensities of strongyles abomasum and their relations with climate were studied in 12 slaughterhouses over 4 bioclimatic areas of eastern Algeria. The average abundance was found to low; 170 and intensities were 37% for Marshallagia marshalli, 37% for Teladorsagia circumcincta, 16% for Trichostrongylus sp., 5% for Haemonchus contortus, 3% for Ostertagia ostertagi and 2% for Marshallagia occidentallis. Parasite dynamics differed between areas particularly between the sub-humid and semi-arid thus suggesting a distinct prophylactic management. The general linear model has demonstrated a seasonal effect in the sub-humid area for T. circumcincta (in April and May), for M. marshalli (July - August) and (November-December) and finally for Trichostrongylus sp. (January- February). There is no clear seasonality in the semi-arid except for M. marshalli in December- January. All parasites were correlated to temperature and rainfall except M. marshalli which had a negative and non-linear but rather quadratic, suggesting an adaptation to local varied climate. Biological and ecological studies after experimental infection with M. marshalli regained a low fertility and prolificacy and a pre patent period longer than other trichostrongyles. The maximum development observed under optimal conditions, the possibility of hatching at temperatures as low as 4 ° C, the slow hatching and sensitivity of L3 desiccation suggests this is the stage egg that is resistant. The study of morphological and morphometric characters of the larva led to the first description of the L3 observed in fecal culture. It is distinguished by a particularly small size and the shortest sheath tail among the species sheep’s strongyles. By the significant presence of M. marshalli and reported drug resistance, this parasite is doing well in Algeria; its impact is evident on sheep farming.