Epidemiology and Risk Factors of Sheep and Goat Pox

Sheep and goat pox (SGP) remains one of the most important transboundary viral diseases affecting small ruminants, with significant implications for animal health, productivity, and disease control. For practicing veterinarians, understanding how the disease spreads, the factors that influence outbreaks, and the conditions that increase susceptibility is essential for timely intervention and effective herd health management. Since the disease is highly contagious and endemic in several regions, recognizing epidemiological patterns can support better surveillance and preventive strategies. 

Understanding the Epidemiological Pattern 

Sheep and goat pox is widely distributed across North Africa, East Africa, the Middle East, and several Asian countries, including India, Pakistan, Nepal, Bangladesh, China, Vietnam, and Turkey. In India, the disease has been reported in nearly all states, with repeated outbreaks establishing the country as an endemic region for small ruminant pox diseases¹. Areas such as Karnataka, Rajasthan, West Bengal, Andhra Pradesh, and Odisha have been categorized among the high-risk regions for sheep and goat pox². More recently, infection has also been documented in wild gorals alongside domestic goats, highlighting the possibility of transmission between domestic and wild animal populations¹. 

How the Disease Spreads 

Close contact remains the primary driver of disease transmission. The viruses responsible for sheep and goat pox are mainly spread through the respiratory route, although infection can also occur through damaged skin or other mucous membranes³. Virus particles are shed in saliva, nasal and ocular secretions, milk, urine, feces, skin lesions, and scabs, allowing infected animals to contaminate their surroundings. 

Capripoxviruses can survive in the environment for prolonged periods, increasing the opportunity for indirect transmission. Mechanical transmission by the stable fly (Stomoxys calcitrans) has been demonstrated experimentally, although the overall role of insect vectors during natural outbreaks remains uncertain¹. Importantly, outbreaks occur throughout the year, indicating that direct and indirect contact between animals plays a greater role than vector activity alone^1,4. 

Environmental and Host Factors That Influence Outbreaks 

Environmental conditions can significantly affect disease occurrence. Incidence often increases between November and May, when adverse climatic conditions may compromise the immune status of susceptible animals. Higher disease occurrence has been associated with regions characterized by low rainfall, elevated temperatures, thorny vegetation such as Acacia species, and red or black soil types¹. 

Host-related factors are equally important. Young animals are particularly vulnerable and often experience more severe disease with higher mortality than adults⁵. Stress and concurrent infections, especially Peste des Petits Ruminants (PPR) and Orf, may further increase susceptibility to infection. Breed also appears to influence disease occurrence, with European breeds reported to be more susceptible than African and Asian breeds⁶. 

Practical Clinical Insights 

Field veterinarians can strengthen disease prevention by identifying situations where the likelihood of SGP introduction or spread is increased. Particular attention should be given to: 

• Young or stressed animals. 

• Flocks experiencing concurrent infections such as PPR or Orf. 

• Farms located in endemic or high-risk regions. 

• Animals introduced from areas with recent outbreaks. 

• Premises where contaminated scabs or secretions may persist in the environment. 

Understanding these epidemiological drivers also supports targeted surveillance, timely reporting, and implementation of appropriate biosecurity measures before widespread transmission occurs. 

Recognizing the interaction between the virus, the host, and the environment allows veterinarians to move beyond treating individual cases and adopt a proactive approach to disease prevention at the flock level. Such an approach is fundamental to reducing the impact of sheep and goat pox in endemic regions while supporting sustainable small ruminant health management. 

References 

1. Jadhav S, Veeregowda BM, Tadakod S, Naragund M, GB MR. Sheep and Goat Pox Disease: Epidemiology, Diagnosis, Prevention and Control. InAdvances in Animal Sciences (Volume 1) 2025 Jul 26 (pp. 35-47). Cornous Publications LLP. https://www.researchgate.net/profile/Sunil_Tadakod/publication/394089319 

2. Bardhan D, Kumar S, Kumar S, Singh RP, Hosamani M. Cost-benefit analysis of vaccination against goat pox. Indian J Anim Sci. 2020 Apr 1;90(4):515-20. https://pdfs.semanticscholar.org/66c0/e24d8b96d9f223a0b43c55f51d8c0263e837.pdf 

3. Hurisa TT, Jing Z, Jia H, Chen G, He XB. A review on Sheeppox and Goatpox: insight of epidemiology, diagnosis, treatment and control measures in Ethiopia. J. Infect. Dis. Epidemiol. 2018;4(3):2474-3658. https://www.researchgate.net/profile/Takele-Tesgera/publication/327975572 

4. Tuppurainen ES, Venter EH, Shisler JL, Gari G, Mekonnen GA, Juleff N, Lyons NA, De Clercq K, Upton C, Bowden TR, Babiuk S. Capripoxvirus diseases: current status and opportunities for control. Transboundary and emerging diseases. 2017 Jun;64(3):729-45. https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/tbed.12444 

5. Manjunathareddy GB, Sumana K, Apsana R, Yogisharadhya R, Prajapati A, Patil SS, Balamuragan V. Investigation of malignant form of sheep pox outbreak in fattening lambs in Mandya, Karnataka. Indian J. Vet. Pathol. 2017 Dec 6;41(3):184-8. https://www.researchgate.net/profile/Apsana-Rizvan/publication/320950370 

6. Mirzaie K, Barani SM, Bokaie S. A review of sheep pox and goat pox: perspective of their control and eradication in Iran. Journal of Advanced Veterinary and Animal Research. 2015 Dec 31;2(4):373-81. https://banglajol.info/index.php/JAVAR/article/download/26044/17443