Rift Valley fever virus dynamics in a transhumant cattle system in The Gambia

Area of Science:

• Veterinary Epidemiology
• Disease Modeling
• One Health

Background:

• Rift Valley fever (RVF) is a significant zoonotic disease with poorly understood epidemiology in The Gambia.
• Environmental factors, vector activity, and livestock movement drive RVF transmission globally.

Purpose of the Study:

• To develop a compartmental model to investigate RVF dynamics in The Gambia's cattle population.
• To understand the impact of seasonal variations and livestock mobility on RVF virus (RVFV) circulation.

Main Methods:

• A compartmental model was created, incorporating dynamic transmission parameters for transhumant cattle and distinct eco-climatic regions (Sahelian and Gambia river).
• The model was parameterized using serological and household survey data.
• Age-seroprevalence data and weak decay rates were used to validate model predictions against empirical trends.

Main Results:

• The model confirmed endemic RVFV circulation in The Gambia, accurately capturing temporal infection patterns.
• Sustained RVFV transmission was observed in the Gambia river eco-region during the dry season.
• Returning transhumant cattle posed a high risk for seasonal RVFV introduction into the Sahelian eco-region at the wet season's onset.

Conclusions:

• Livestock mobility plays a crucial role in RVFV epidemiology within The Gambia.
• Targeted control strategies, such as cattle vaccination or insecticide treatments for transhumant herds, are recommended.