Vreni Jean-Richard: Crowding at Lake Chad: an integrated approach to demographic and health surveillance of mobile pastoralists and their animals

PhD-Thesis/Dissertation: Crowding at Lake Chad: an integrated approach to demographic and health surveillance of mobile pastoralists and their animals. 2015, University of Basel, Faculty of Science, 2013.

PhD-Project, Swiss TPH, University of Basel

Mobile populations of several ethnic groups share the decreasing resources around shrinking Lake Chad. Demography and density of their communities and their livestock were assessed using mobile phone and GPS technology. Additionally, the occurrence of the liver fluke (Fasciola spp.) in slaughtered livestock was assessed with a transdisciplinary approach.


Pastoralists in the Sahel are adapted to the special conditions of the semi-arid ecology, using mobility as an effective way to manage the uncertainty related to resource availability. However, mobility often hinders access to social and veterinary services and consequently there is a lack of basic data and information on demographic indicators of the human and livestock populations.


1. To assess the demography of mobile pastoralists camps and sedentary villages for people and livestock and to assess their local livelihood priorities 2. To test and evaluate a new approach to mobile demographic and health surveillance for mobile pastoralists and their livestock by means of mobile phone technology. 3. To assess the seasonality of Fasciola gigantica infections of livestock in slaughterhouses and to relate the prevalence to exposure risks of animals

Methods and results telephone study

In south-eastern Lake Chad area (Figure 1), a cohort of 20 mobile pastoralists’ camps was equipped with mobile phones. A pilot mobile demographic surveillance system was established covering 600 people and their livestock during more than one year, with regular telephone interviews with nomadic camps’ heads and their wives (Figure 2). Female pregnancies were followed to establish miscarriage and infant mortality, which is difficult to do in retrospective studies. We also recorded travel routes (Figure 3). During the rainy season, mainly Gorane pastoralists left our study zone to go to he Kanem region. They returned in the dry season to the Lake area.

Transdisciplinary study of geospatial prevalence of Fasciola spp. in livestock

We have assessed local livelihood priorities during the demographic and health study. After water and pasture availability, mobile communities perceived veterinary health as a greater priority than i.e. human health or access to schools. Camp leaders stated that animals feeding in Lake Chad water were often infected with liver-parasites (Fasciola spp.) and the decrease of milk caused by the disease was perceived as devastating, since it affects not only nutrition but also household-economy due to decreasing income of milk sales at markets.
To follow up on this information, all livestock slaughtered in 3 slaughterhouses in the zone was examined for presence of Fasciola spp. during one year (Dec 2010 – Dec 2011). Grazing patterns and origin of the animals were also recorded. Ongoing is the characterisation of the collected parasites (species by genetic methods).

Results and discussion

The slaughterhouse prevalence of Fasciola spp. was 68% in cattle, 12% in goats and 23% in sheep. A clear relation between grazing near the lake and Fasciola spp. infection was demonstrated. Highest prevalences were found in animals of the Peulh ethnic group, who stays close to the lake water or on islands far inside the lake during the dry season. In contrast, Gorane pastoralists usually do not arrive close to the lake. None of the Gorane cows had grazed in the lake. Of the 208 Gorane animals only one goat was infected with Fasciola spp. As expected, Arab seminomads animals showed a prevalence between that of the two other groups, since they only move towards the lake when pastures around their villages are finished. These results strongly suggest the Lake Chad as the source of infection.