Post‐exposure vaccination and plasma transfusion as an experimental treatment in the first reported equine cases of West Nile neuroinvasive disease in Poland

Abstract

Summary Background West Nile virus (WNV) has recently expanded its geographical range across Europe, resulting in a growing number of outbreaks among humans and horses. In August 2024, WNV was detected in dead crows in Warsaw, central Poland, following a substantial die‐off of local bird populations. Soon thereafter, the first cases of WNV in the country were confirmed in horses and nontravel‐related cases were suspected in humans. Currently, no specific treatment exists for West Nile neuroinvasive disease (WNND), highlighting the need for further research to establish effective therapeutic protocols. Objectives Describing clinical manifestation and treatment outcomes of three confirmed WNND cases in horses in Poland, treated with experimental therapies comprising immunised plasma transfusions and post‐exposure vaccination, and standard supportive treatment. Study Design Noncomparative study, case series. Methods Three horses presenting with moderate‐to‐severe neurological signs were admitted to the Equine Hospital Sluzewiec in Warsaw. Treatment outcomes were assessed through clinical examination and were accompanied by measurements of anti‐WNV IgM and serum amyloid A levels. Results All three horses exhibited subacute to acute neurological signs, including marked ataxia and hindlimb weakness. Two out of the three horses admitted to the hospital made a full recovery and euthanasia was elected for one of the horses due to poor prognosis. Main limitations Small number of cases, no control group without treatment and lack of confirmation via neutralisation test. Conclusions WNND is a new disease in the horse population in central and northern Europe. Medical professionals in the region should consider WNND as a differential diagnosis of horses presenting with neurological disorders, develop skills to diagnose and manage the disease and recommend anti‐WNV vaccinations as a preventive measure.