1996 - Venezuelan Equine Encephalitis in Mexico
06 August 1996
Disease Outbreak Reported
Thirty-two cases of Venezuelan equine encephalitis have been diagnosed among 2 500 horses in three foci in the State of Oaxaca. These were in rural areas often flooded during rainy periods. The first case was detected on 16 June and the last occurred on 23 July 1996 according to a report from the Ministry of Agriculture dated 31 July. Ten horses have died. No human cases have been detected.
Venezuelan equine encephalitis virus has been isolated from two horses. The virus isolates have been further identified as sub-type 1, variant E which is enzootic in the south-east coast of Mexico and in Central America. The transmission cycle involves small mammals and mosquitos.
The spread out of these three foci has been prevented by restricting movements of horses from the three foci to other parts of the State of Oaxaca and from this state to other parts of Mexico. So far 16 700 horses in the three foci and in 29 neighbouring localities in the State of Oaxaca have been vaccinated. Early outbreak control also included spraying against the mosquito vector in urban areas near affected communities. Active epidemiological surveillance has been instituted throughout the country.
(Source: Information Sanitaires, Vol 9, No. 28 & 29, Office international des Epizooties)