Epidemic Venezuelan equine encephalitis in La Guajira, Colombia, 1995.

The research article discusses an outbreak of Venezuelan Equine Encephalitis in Colombia in 1995, which affected both humans and equines, particularly impacting the native Wayuu Indians. The outbreak was most likely caused by a virus introduced from Venezuela and rapid rainfall, resulting in a high vector density.

Venezuelan Equine Encephalitis Outbreak in Colombia

In 1995, La Guajira State in Colombia suffered its first Venezuelan equine encephalitis (VEE) outbreak in over two decades. The impact was significant, with:

• Approximately 75,000 human cases reported, 3,000 of which suffered from neurological complications and around 300 resulted in fatalities.
• An estimated 8% of the state’s equine population of about 50,000 may have perished due to the virus.

Cause of the Outbreak

The research explores the causes of the VEE outbreak:

• The source of the epizootic IC virus, which triggered the outbreak, was likely introduction from Venezuela.
• The virus was quickly amplified among unvaccinated equines in the region.
• The outbreak coincided with a year of record-breaking rainfall, leading to high densities of the mosquito species Aedes taeniorhynchus, which is a known transmitter of the VEE virus.

Impact on Indigenous Population and Lack of Human to Human Transmission

The study found that the Native Wayuu Indians, who made up nearly a quarter of the state’s population, were particularly vulnerable to the VEE virus infection. Despite this, epidemiological studies found no evidence to suggest that the disease could be transmitted from one human to another.

Abortifacient Role of VEE and Prevention Measures

During the outbreak, researchers noticed an unusually high number of abortions, supporting the long-held suspicion about the VEE infection playing a role in inducing abortions. To curb the spread of the virus, interventions implemented included pesticide applications and a mass equine vaccination program. These measures effectively minimized the southward spread of the outbreak.