Emergency Vaccination as a Control Strategy against Sheeppox Outbreak in a Highly Susceptible Population

Area of Science:

• Veterinary Virology
• Epidemiology
• Immunology

Background:

• Sheep pox is a highly contagious viral disease affecting sheep populations.
• Outbreaks can lead to significant economic losses due to high morbidity and mortality rates.
• Emergency vaccination is a critical control measure during outbreaks.

Purpose of the Study:

• To investigate a sheeppox outbreak in a naive Egyptian sheep population.
• To compare the efficacy of two commercial sheeppox vaccines (Romanian strain and RM-65) under field conditions for emergency vaccination.
• To evaluate the impact of vaccination on serum protein profiles.

Main Methods:

• Field investigation of a sheeppox outbreak, including clinical and postmortem examinations.
• Confirmation of sheeppox virus by histopathology and transmission electron microscopy.
• Comparative efficacy trial of Romanian strain and RM-65 vaccines in vaccinated and control sheep groups.
• Serum protein fractionation analysis before and after vaccination.

Main Results:

• The outbreak had a cumulative incidence of 66.2% and an overall case fatality of 51.1%.
• RM-65 vaccine demonstrated significantly higher protection against sheeppox infection and mortality (p < 0.05) compared to the Romanian strain vaccine.
• RM-65 vaccinated animals showed no cases or mortality, while Romanian strain vaccinated animals experienced mild signs in 78% and 35.7% case fatality.
• Serum protein analysis indicated superior immune response with RM-65, increasing α1-globulin and β-globulin levels.

Conclusions:

• The RM-65 vaccine exhibits better performance than the Romanian strain vaccine for emergency sheeppox vaccination in field conditions.
• Emergency vaccination against sheeppox is a valid control strategy.
• Comparative field evaluation of vaccines is crucial; further large-scale studies are needed to confirm these findings and investigate potential reasons for the Romanian strain's lower efficacy.