Understanding Peste des Petits Ruminants (PPR) Transmission Dynamics: A Network Analysis Approach in Pastoral and Agropastoral communities

Mwanandota, Julius Joseph; Nyasebwa, Obed Malangu; Mdetele, Daniel; Ekwem, Divine; Paul, George Omondi; Machuka, Eunice; Chengula, Augustino; Kimera, Sharadhuli; Okoth, Edward; Parida, Satya; Misinzo, Gerald

doi:10.22092/ari.2025.367514.3402

Understanding Peste des Petits Ruminants (PPR) Transmission Dynamics: A Network Analysis Approach in Pastoral and Agropastoral communities

Articles in Press

Document Type : Original Articles

Authors

¹ Box 9254, Dar es salaam

² Ministry of Livestock and Fisheries

³ Ministry of Livestock and Fisheries, P.O Box 2870, Dodoma, Tanzania

⁴ Boyd Orr Centre for Population and Ecosystem Health, School of Biodiversity, One Health & Veterinary Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK.

⁵ University of Nairobi

⁶ International Livestock Research Institute, P.O. Box 30709, Nairobi 00100, Kenya

⁷ College of Veterinary Medicine and Biomedical Sciences, SUA, P.O. Box 3019, Chuo Kikuu, Morogoro, Tanzania

⁸ Food and Agriculture Organization of the United Nations, Viale delle Terme di Caracalla 00153 Rome, Italy

10.22092/ari.2025.367514.3402

Abstract

Peste des petits ruminants (PPR) is a viral disease of economic significance, with uncontrolled sheep and goat movement being a major risk factor. Uncontrolled livestock movements threaten their health and productivity and have been cited as a potential driver of its spatial expansion in the country. Formal evaluation of PPR spread linked to livestock migration is lacking. Here, we investigate the extent to which PPR spread can be attributed to livestock movement while accounting for risk factors such as production system, livestock population, and geographical location. Data on livestock movement from Tanzania were collected to create network patterns that show the risk of PPR circulation across geographical areas and agroecological systems. Our findings demonstrate a notable variation in network structure. Compared to movement related to seasonality variation, trade-related movement was higher by 600 km. Either way, in the dry season, animals travel long distances compared to the wet season. The probability of contracting PPR infection was found to be half that of households with outgoing livestock (outdegree), indicating a lower risk of infection compared to households with more incoming livestock (indegree). The network pattern shows scale-free properties and negative and close to zero assortative mixing in pastoral and agropastoral societies, respectively. We show that pastoral communities in northern Tanzania are prone to PPR infections, suggesting control methods targeting high-potential households in pastoral communities and districts with high livestock populations. The study suggests targeting the pastoral production system in these areas to impede PPR spread. Future research should focus on dynamic modelling and targeted control interventions.

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