An epidemiological investigation of associated risk factors with equine influenza (H3N8) epidemic 2015-16 in Pakistan

Infection with equine influenza viruses in unvaccinated population could cause large-scale morbidity leading to huge economic losses compromising equine welfare in developing countries. Here we conducted a matched case-control study to identify the potential risk factors responsible for the EI epidemic in Pakistan in the year 2015-16. Total of 197 laboratory-confirmed matched pairs of cases and controls were included in the study. A predesigned questionnaire-based epidemiological data was collected for this purpose from all the matched pairs respondents. Conditional logistic regression analysis was conducted analyzing the data. Multivariable regression analysis identified local equine density and frequency of manure removal as potential risk factors for the incidence of EI. Due to lack of vaccination, the spread of EI was favored supported by many infected equine population free movements. The first case of this epidemic was imported from Afghanistan which was considered as a source case for the epidemic. Management and biosecurity practices compliance was very low due to lack of awareness amongst the respondents. These findings agree with the previous findings in various developing countries. Strategic control of infected equines free movement and vaccination of the equine population are suggested in future to control such epidemics.