In developing countries, livestock resources are often threatened by zoonotic diseases that reduce animal productivity and human labour force. One of these diseases of public health importance is brucellosis. Bovine brucellosis is mainly caused by Brucella abortus. Generally Brucella infects humans through direct or indirect contact with infected animals or contaminated materials, but also by ingestion of animal products such as unpasteurised milk and cheese.

The main objectives of this thesis were to improve the understanding of the epidemiology of bovine and human brucellosis in Western Region (The Gambia) and Kolda Department (Senegal), and to assess the risk of human infection from the consumption of raw milk sold by street vendors.

First an overview is given on bovine and human brucellosis, the current situation in the world, in Africa and at the study sites in The Gambia and Senegal, and on food safety risk assessment. Then, the traditional milk chain in Western Region (WR) and Kolda is described and the risk behaviours of the milk chain actors for milkborne diseases transmission are analysed. This is followed by a study of bovine brucellosis prevalence and risk factors in WR and Kolda and a serological investigation of human brucellosis in villages where serologically positive and/or infected (Brucella isolation from animals) herds were noticed. The purpose was to find out the epidemiological relation between human cases and serologically positive and/or infected herds. Brucella spp. were detected by PCR-based methods in milk and isolated from hygroma fluids. The characterisation of the isolated strains was undertaken by using the classic biotyping and molecular typing methods such as 16 Multilocus Variable-number Tandem-Repeats Analysis (MLVA-16) for genotyping. Finally, a risk assessment of human infection from consumption of different types of milk products sold in WR was carried out.