Last fall, an outbreak of the rare viral infection known as Getah swept through a racing stable in Japan.

A mosquito-borne arbovirus, Getah is widespread among vertebrate populations in Eurasia and Australasia (Australia, New Zealand, the island of New Guinea and neighboring islands in the Pacific Ocean) but has rarely been associated with illness in horses.

Affected horses usually show mild signs consistent with other viral diseases, such as a fever, leg swelling, skin rashes and enlarged glands around the head. Different strains of the virus produce slightly different clinical signs. With supportive care, most horses make a full recovery in two weeks or less.

The most recent outbreak was detected when several horses at the Miho Training Center developed high fevers. Out of the 49 affected horses, 25 were found to be Getah positive with a reverse transcription polymerase chain reaction (RT-PCR) test. A previous outbreak occurred at the same training center in 1978. Researchers say they do not know what triggered the latest outbreak.

Reference: “Getah virus infection among racehorses, Japan, 2014,” Emerging Infectious Diseases, May 2015

This article first appeared in EQUUS issue #455, August 2015.