Camel trypanosomosis in Morocco 1: results of a first epidemiological survey.

An epidemiological survey of camel trypanosomosis was conducted for the first time in Morocco in 1997 and 1998. Five provinces located in the south and southeast of the High Atlas mountain chain were included in this study. A total number of 1460 serum samples were collected and tested by a card agglutination test for trypanosomosis (CATT) and enzyme-linked immunosorbant assay (Ab-ELISA) to detect anti-Trypanosoma evansi antibodies. The overall seroprevalence was 14.1% by CATT and 18.2% by Ab-ELISA. Two very active foci were identified in Zagora and Merzouga with high Ab-ELISA prevalences of 43.3 and 35.4%, respectively, for each area. The concordance between the CATT and Ab-ELISA was 94.1%. The age-related distribution of seroprevalence showed a tendency for the infection rate to increase with age up to a maximum in the 7-10 year-old group. Clinical examination revealed that enlargement of lymph nodes was the most frequent sign in seropositive animals (79.7%). The comparison of haematocrit values of seropositive and seronegative animals showed a significant difference that indicated severe anaemia in infected animals. Isolation of the parasite by inoculation of mice allowed us to collect 15 T. evansi isolates from Zagora and three from Merzouga. The study showed that the Saharan provinces of Morocco were slightly affected by camel trypanosomosis but two hyperendemic foci, Zagora and Merzouga, were found to be sources of contamination for the surrounding regions.