Japanese encephalitis in a racing thoroughbred gelding in Hong Kong

Abstract

A horse in Hong Kong that had been vaccinated against Japanese encephalitis suffered a pyrexic episode that culminated in a hyperexcitable state and self-inflicted trauma. Japanese encephalitis was diagnosed on the basis of clinical, pathological and serological observations, and confirmed by the detection of genomic sequences of the virus in spinal cord tissue. Phylogenetic analyses of E gene and NS5-3'UTR sequences revealed divergent clustering of these segments with previously described genotypes, suggesting the possibility that the horse might have been infected with a recombinant between genotype I and genotype II viruses. Horses are considered to be dead-end hosts for the disease, but the occurrence of an infected horse in a population may have implications for the health status of the national herd. The effect that this case had on the horse industry in Hong Kong is discussed with specific reference to the movement of horses and the vaccination programme for Japanese encephalitis.

Serosurveillance for Japanese encephalitis virus infection among equines in India

“…Several outbreaks among humans and domestic animals are reported every year in different regions of the world. Sporadic cases of JE in horses have been observed in Japan [12,25], Hong Kong [14], and Korea [15] despite the use of JEV vaccinations in these countries. JEV outbreaks have been reported in humans from 24 states/Union Territories of India.…”

“…Rates of mortality due to JE range between 5% and 30%. Sporadic cases of JE in horses have been reported in various countries, including Japan [13,25], Hong Kong [14], and Taiwan [15]. In addition, JE seropositivity among equines has been reported in Nepal [19] and Indonesia [24].…”

Viral Diseases of the Nervous System

“…35 JE virus (JEV) in Australasia and WNV in Northern Africa, the Middle East, and Northern and Central America both cover large geographical areas and therefore cause significant disease in both humans and horses each year. [36][37][38][39] West Nile Virus WNV is currently the best-known member of the flavivirus group because of its unprecedented appearance and spread in North America, which started in 1999. Prior to this date, WNV infection in humans and horses was restricted to African countries along the Nile river and to the Middle East (Israel, Jordan, and Syria) with occasional outbreaks of encephalitis in horses in the Mediterranean basin.…”

Isolation and genetic characterization of Japanese encephalitis virus from equines in India

“…Sporadic clinical cases of JE in horses have been reported in various countries including Japan [19,41], Hong Kong [20], Taiwan [21], and India [31]. In addition, JE seropositivity among equines has been reported in Nepal, Korea, Indonesia, and India [2,9,13,23,26,28,31,33,39].…”