Methodological aspects of serosurveillance in resource-poor settings

Area of Science:

• Veterinary Epidemiology
• Animal Health Economics
• Disease Surveillance

Background:

• Infectious diseases pose a significant threat to animal production in low-income countries, impacting agricultural economies.
• Serosurveys are crucial for disease detection, monitoring, and establishing disease-free status, but often face methodological constraints.
• Interpreting serosurvey results necessitates understanding limitations in sampling and diagnostic accuracy, particularly in resource-limited settings.

Purpose of the Study:

• To evaluate the limitations of serosurveys for foot-and-mouth disease (FMD), Rift Valley fever (RVF), and contagious bovine pleuropneumonia (CBPP) in cattle.
• To assess potential flaws in sampling strategies and diagnostic methods used in a cross-sectional serosurvey in Western Uganda.
• To understand how these methodological limitations influence the interpretation of serological results.

Main Methods:

• Conducted a cross-sectional serosurvey in three districts of Western Uganda, targeting cattle herds.
• Prioritized sampling of young cattle (2-5 years) to reflect recent infection history.
• Utilized commercial ELISAs for serological analysis of FMD, RVF, and CBPP, and interviewed farmers on herd management and health.

Main Results:

• The study encountered challenges in fulfilling sampling targets and laboratory testing quotas.
• Apparent prevalence was approximately 30% for CBPP, 6% for RVF, and 7% for FMD.
• True prevalence calculations, adjusted for test sensitivity and specificity, indicated slight variations from apparent prevalence for all three diseases.

Conclusions:

• Diagnostic test performance is critical for accurate interpretation of serosurvey results.
• Representative sampling and laboratory execution present significant challenges in low-income countries.
• The study highlights the need for robust methodologies to overcome limitations in veterinary disease surveillance.