Spatio-temporal analysis of peste des petits ruminants in Uganda
Abstract
Peste des Petits Ruminants (PPR) is a transboundary, highly contagious, and fatal disease of small
ruminants. PPR causes global annual economic losses of between USD 1.5-2.0 billion across more
than 70 affected countries. Despite the commercial availability of effective PPR vaccines, lack of
financial and technical commitment to PPR control coupled with a dearth of refined PPR risk
profiling data in different endemic countries has perpetuated PPR virus transmission. In Uganda,
over the past five years, PPR has extended from north-eastern Uganda (Karamoja) with sporadic
incursions in other districts.
To identify disease cluster hotspot trends that would facilitate the design and implementation of PPR
risk-based control methods (including vaccination), we employed the space-time cube approach to
identify trends in the clustering of outbreaks in neighbouring space-time cells. We also used
negative binomial and logistic regression models.
We identified high small ruminant density, extended road length, low annual precipitation and high
soil water index as the most important drivers of PPR in Uganda. The study identified (with 90 - 99%
confidence) five PPR disease hotspot trend categories across subregions of Uganda. Diminishing
hotspots were identified in the Karamoja region whereas consecutive, sporadic, new, and emerging
hotspots were identified in central and southwestern districts of Uganda.
Inter-district and cross-border small ruminant movement facilitated by longer road stretches and
animal comingling precipitate PPR outbreaks as well as PPR virus spread from its initial Karamoja
focus to the central and south-western Uganda. There is therefore urgent need to prioritize
considerable vaccination coverage to obtain the required herd immunity among small ruminants in
the new hotspot areas to block transmission to further emerging hotspots. Findings of this study
provide a basis for more robust timing and prioritization of control measures including vaccination.
Citation
Nkamwesiga, J., Korennoy, F., Lumu, P., Nsamba, P., Mwiine, F.N., Roesel, K., Wieland, B., Perez, A., Kiara, H. and Muhanguzi, D. 2022. Spatio-temporal analysis of peste des petits ruminants in Uganda. Oral presentation at the 16th International Symposium of Veterinary Epidemiology and Economics, Halifax, Canada, 12 August 2022. Nairobi, Kenya: ILRI.
