Transmission patterns of African horse sickness and equine encephalosis viruses in South African donkeys.
Abstract: African horse sickness (AHS) and equine encephalosis (EE) viruses are endemic to southern Africa. AHS virus causes severe epidemics when introduced to naive equine populations, resulting in severe restrictions on the movement of equines between AHS-positive and negative countries. Recent zoning of South Africa has created an AHS-free zone to facilitate equine movement, but the transmission dynamics of these viruses are not fully understood. Here, we present further analyses of serosurveys of donkeys in South Africa conducted in 1983-5 and in 1993-5. Age-prevalence data are used to derive estimates of the force of infection, A. For both viruses, A was highest in the northeastern part of the country and declined towards the southwest. In most of the country, EE virus had a higher transmission rate than AHS. The force of infection increased for EE virus between 1985 and 1993, but decreased for AHS virus. Both viruses showed high levels of variation in transmission between districts within the same province, particularly in areas of intermediate transmission. These data emphasize the focal nature of these viruses, and indicate areas where further data will assist in understanding the geographical variation in transmission.
Publication Date: 2002-05-11 PubMed ID: 12002545PubMed Central: PMC2869820DOI: 10.1017/s0950268801006471Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research paper examines the transmission patterns of both African horse sickness and equine encephalosis diseases in donkeys in South Africa. Using age-prevalence data from serosurveys conducted between 1983 and 1995, researchers found that transmission rates of these viruses vary geographically and have shifted over time.
Background
- The viruses African horse sickness (AHS) and equine encephalosis (EE) are common in southern Africa and can cause severe epidemics among horse populations. The diseases have led to strict restrictions around moving horses between countries identified as AHS-positive and AHS-negative.
- South Africa has recently designated an AHS-free zone to simplify horse transit, but a comprehensive understanding of the transmission dynamics of AHS and EE viruses is lacking.
Study Design and Key Findings
- The research utilizes data from serosurveys of donkeys conducted in South Africa in the mid-1980s and mid-1990s. The aim is to better understand the force of infection (represented as “A”) of both diseases across various regions and over time.
- Results indicated the highest force of infection in the northeast regions and the lowest towards the southwest. The transmission of the EE virus was commonly higher than AHS across most regions.
- On a temporal scale, the force of infection of the EE virus increased between 1985 and 1993 but declined for AHS. This indicates changes in transmission dynamics over the decade-scale period.
Variations in Transmission
- Notably, the study found substantial variations in virus transmission between districts within the same province, particularly in areas of intermediate disease transmission.
- Such patterns underline the focal nature of these diseases, being concentrated or occurring in specific locations.
- Identifying these variations could help pinpoint geographical zones that need further research to understand transmission variability.
Implications and Considerations
- The insights offered by this study highlight the need for more localized data in some regions. Understanding how the transmission of these viruses varies geographically and over time can be critical in devising effective disease prevention and control strategies.
- Furthermore, the study underscores the importance of not treating provinces or even countries as homogenous entities regarding their epidemiological profiles. Virus transmission can show significant variation even in comparatively small geographical scales.
Cite This Article
APA
Lord CC, Venter GJ, Mellor PS, Paweska JT, Woolhouse ME.
(2002).
Transmission patterns of African horse sickness and equine encephalosis viruses in South African donkeys.
Epidemiol Infect, 128(2), 265-275.
https://doi.org/10.1017/s0950268801006471 Publication
Researcher Affiliations
- Florida Medical Entomology Laboratory, University of Florida-IFAS, Vero Beach 32962, USA.
MeSH Terms
- African Horse Sickness / transmission
- Age Factors
- Animals
- Encephalomyelitis, Equine / transmission
- Equidae / virology
- Female
- Geography
- Male
- Movement
- Orbivirus / pathogenicity
- Seroepidemiologic Studies
- South Africa / epidemiology
Citations
This article has been cited 2 times.- Tirosh-Levy S, Steinman A. Equine Encephalosis Virus. Animals (Basel) 2022 Jan 29;12(3).
- Thompson GM, Jess S, Murchie AK. A review of African horse sickness and its implications for Ireland. Ir Vet J 2012 Jul 5;65(1):9.
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