Spatial and temporal distribution of lumpy skin disease outbreaks in Uganda (2002–2016)

Abstract

BackgroundLumpy skin disease (LSD) is a devastating transboundary viral disease of cattle which causes significant loss in production. Although this disease has been reported in Uganda and throughout East Africa, there is almost no information about its epidemiology, spatial or spatio-temporal distribution. We carried out a retrospective study on the epidemiology of LSD in Uganda between the years 2002 and 2016, using data on reported outbreaks collected monthly by the central government veterinary administration. Descriptive statistics were computed on frequency of outbreaks, number of cases, vaccinations and deaths. We evaluated differences in the number of reported outbreaks across different regions (agro-ecological zones), districts, months and years. Spatial, temporal and space-time scan statistics were used to identify possible epidemiological clusters of LSD outbreaks.ResultsA total of 1161 outbreaks and 319,355 cases of LSD were reported from 55 out of 56 districts of Uganda. There was a significant difference in incidence between years (P = 0.007) and across different regions. However, there was no significant difference in the number of outbreaks per month (P = 0.443). The Central region reported the highest number of outbreaks (n = 418, 36%) followed by Eastern (n = 372, 32%), Southwestern (n = 140, 12%), Northern (n = 131, 11%), Northeastern (n = 37, 3%), Western (n = 41, 4%) and Northwestern (n = 22, 2%) regions. Several endemic hotspots for the circulation of LSD were identified in the Central and Eastern regions using spatial cluster analyses. Outbreaks in endemic hotspots were less seasonal and had strikingly lower mortality and case-fatality rates than the other regions, suggesting an underlying difference in the epidemiology and impact of LSD in these different zones.ConclusionLumpy Skin disease is endemic in Uganda, with outbreaks occurring annually in all regions of the country. We identified potential spatial hotspots for LSD outbreaks, underlining the need for risk-based surveillance to establish the actual disease prevalence and risk factors for disease maintenance. Space-time analysis revealed that sporadic LSD outbreaks tend to occur both within and outside of endemic areas. The findings from this study will be used as a baseline for further epidemiological studies for the development of sustainable programmes towards the control of LSD in Uganda.Electronic supplementary materialThe online version of this article (10.1186/s12917-018-1503-3) contains supplementary material, which is available to authorized users.

Mapping changes in the spatiotemporal distribution of lumpy skin disease virus

“…Additionally, the pronounced seasonality of activity of biting arthropods, with peaks from June to August, is likely an important contributor to the high LSDV incidence observed in summer and fall, particularly in Russia (Sprygin et al, ). Consequently, LSDV transmission is often linked to warm and humid weather conditions that are associated with high population densities of biting arthropods (Ochwo et al, ), and studies in Russia reported most cases during the summer months, when temperatures were on average 22.2°C (Sprygin et al, ). Direct contact between infected and susceptible animals very rarely results in disease transmission (Carn & Kitching, ), although it is possible that the infection spreads by contaminated feed and water (Al‐Salihi & Hassan, ; Haig, ).…”

Mapping changes in the spatiotemporal distribution of lumpy skin disease virus

“…The principal route of transmission for LSDV is apparently driven by arthropod vectors, with mosquitoes, ticks and biting flies believed to play a major role (Chihota et al, 2001; Tuppurainen et al, 2011; Tuppurainen & Oura, 2012). Often LSDV transmission is linked to warm and humid weather conditions that are associated with high population densities of biting arthropods (Ochwo et al, 2018). Direct contact between infected and susceptible animals very rarely results in disease transmission (Carn & Kitching, 1995), though it is possible that the infection spreads by contaminated feed and water (Haig, 1957; Al-Salihi & Hassan, 2015).…”

Molecular detection and phylogenetic analysis of lumpy skin disease virus from outbreaks in Uganda 2017–2018

“…The protein has the main structural features of the superfamily of G-protein-coupled chemokine receptors, such as seven hydrophobic areas and cysteine residues in the first and second extracellular loops. Even though previous studies have explored the epidemiology of LSDV in Uganda [30,31], there is no data on the molecular characterization of circulating LSDV viruses. These data are important for understanding molecular epidemiology and vaccine design for disease control.…”