Epidemiologic investigations of the 1969 epidemic of Venezuelan encephalitis in Ecuador

Area of Science:

• Epidemiology
• Virology
• Public Health

Background:

• An epizootic of Venezuelan equine encephalitis (VEE), subtype I variant B, occurred in Ecuador in 1969.
• This event prompted investigations into its spread and impact.

Purpose of the Study:

• To describe the 1969 VEE epizootic in Ecuador.
• To report virus isolations from human cases.
• To assess the epidemic's geographic extent through a serologic survey.

Main Methods:

• General description of the epizootic.
• Virus isolation from human samples.
• Serologic survey of the coastal population.
• Mosquito surveillance and control attempts (aerial spraying).

Main Results:

• Virus isolations confirmed human involvement in the VEE outbreak.
• The serologic survey helped map the epidemic's reach along the coast.
• Higher antibody rates in older individuals were observed, with unclear implications regarding risk or accumulated immunity.

Conclusions:

• The 1969 VEE epizootic in Ecuador involved human infections.
• The serologic data suggests potential endemic activity of the VEE IB virus variant, though further proof is needed.
• Mosquito control measures were implemented during the event.