[Epidemiology of Cowdria infection in Senegal. II. Results of sero-epidemiological follow-up studies].

The authors report the results of sero-epidemiological monitoring of Zebu, Diakoré and Ndama cattle in the Sahel, Niayes and North Guinea zones, respectively. Calves aged 0-3 or 3-6 months were subjected to blood sampling every three months for a period of 20 months. In the Niayes and North Guinea zones, the immunofluorescence test showed that about 70% of 0-1 month old calves reacted positively to the Cowdria ruminantium antigen, whereas the prevalence was 92% between 3 and 6 months. After the age of 6 months, the results were 100% positive. In the Sahelian area, the prevalence of the infection was null. Results obtained with a sample of about 100 adult cattle from the Sahel, Niayes, North Sudan and North Guinea zones, showed a good correlation between positivity rates and the size of Amblyomma variegatum populations.