Re-emergence of Equine Encephalitis in Argentina

Abstract

Introduction: western Equine Encephalitis (WEE) is a mosquito-borne viral disease that primarily affects horses and occasionally humans. After its reappearance in Argentina was confirmed in November 2023, a national Epidemiological Alert was activated.
Objective: to characterize the behavior of equine encephalitis in Argentina.
Method: a review of the available literature on the subject in question was carried out, files from the Ministry of Health of the Nation, epidemiological bulletin, data from Senasa (National Service of Health and Agri-Food Quality) and scientific articles published in PUBMED.
Results: during the period between November 2023 and early January 2024, a total of 1,294 confirmed cases of this disease were recorded in equines, in addition to 165 suspected cases in humans. The incidence in equines increased on average 33 cases per week during this period. Epidemiological reports showed a progressive increase in cases in both animals and humans. Following the introduction of the mandatory vaccine at the end of January 2024, a significant decrease in equine cases was observed, including weeks where no cases were reported. In humans, confirmed cases and deaths have shown a reduction compared to pre-vaccination levels in equines.
Conclusion: mandatory vaccination in equines was crucial to mitigate the spread of equine encephalitis in Argentina. Although there was a stabilization in confirmed cases and a reduction in human deaths after vaccination, the continued need for surveillance and complementary measures to maintain effective control over the epidemic is highlighted.