Exploring the epidemiology and transmission dynamics of Rift Valley Fever in the Horn of Africa

According to the Food Agriculture organization (2001) more than 40% (about 70 million) of people within the Horn of Africa suffer from chronic food insecurity. Livestock diseases like Rift Valley fever (RVF) threaten the livelihoods of the many communities in the Horn of Africa who are dependent on agriculture and pastoralism. RVF causes disease in both humans and animals and has serious implications on human health, on trading livestock products, and on human movement.

Several paths of transmission of RVF to humans have been postulated during epidemics, with varying contributions to the epidemiologic profile. These transmission patterns have included consumption of raw and unprocessed milk which has been epidemiologically linked to RVF disease in humans in several epidemics. Nevertheless, a causational connection between consumption of milk from infected animals and human infection has not been convincingly confirmed.

Laboratory analysis of milk from experimentally infected animals has neither provided consistent proof of milk being a risk factor for RVF human transmission. Milk plays a useful role in enhancing food security for communities dependent on agriculture and pastoralism in the Horn of Africa. However, during RVF outbreaks, handling and drinking raw (unpasteurised) milk is routinely classified as a substantial risk factor for human RVF infection, hence legislations and advisories are put in place to control its circulation. This occurs despite the lack of consistent data that provides the contribution of milk as a risk factor in human transmissions.

Working in a trans-disciplinary team this study seeks to;

  1. Compare and contrast the possible routes of exposure of the 2018 RVF human cases in Wajir alongside controls, with a special focus on milk as a risk factor by evaluating the different interactions with livestock that could be a source of RVF transmission
  2. Evaluate milk handling and consumption habits before, during and after RVF outbreak
  3. Evaluate herd disease status and exposures to RVF with respect to the 2018 outbreak

In so doing, the study seeks to evaluate the association of milk handling and consumption to disease incidence in humans in intra-epidemic and post-epidemic contexts.

Ruth Omani
Team Lead