WESTERN
EQUINE ENCEPHALITIS – SCI & TECH
News:
Outbreak of Western
Equine Encephalitis Virus in Argentina
What's
in the news?
●
On December 20, 2023, the International
Health Regulations National Focal Point (IHR NFP) in Argentina alerted the Pan
American Health Organization/World Health Organization (PAHO/WHO) of a human
case of Western Equine Encephalitis Virus (WEEV) infection.
Key
takeaways:
●
The outbreak has grown to 21 confirmed new
cases of the infection in Argentina
and comes after more than two decades since the last case was reported in the
country. The last cases of human infections in Argentina were reported in 1982,
1983, and an isolated event in 1996.
●
The present outbreak also comes in the
context of an ongoing outbreak in horses
in Argentina and Uruguay.
●
Multiple outbreaks and human cases of
Western Equine Encephalitis have been reported in the past from the U.S. and Canada and over 3,000 cases of
infection have been reported over these years.
Western
Equine Encephalitis Virus:
●
It is a mosquito-borne infection caused by the Western Equine Encephalitis
Virus (WEEV), which belongs to the Togaviridae family of viruses.
●
The virus has an approximately 11.5
kilobases long single-stranded RNA genome.
●
It is a recombinant of the eastern equine encephalitis virus (EEEV) and a
Sindbis-like virus.
Transmission:
●
Passerine
birds are thought to be the reservoir and equine species as
intermediate hosts.
●
The primary mode of transmission of the infection to humans is through mosquitoes
which act as vectors for the virus.
Symptoms:
●
While most of the infections are asymptomatic, the infection may lead to
severe consequences in rare cases.
●
An estimated 4-5% of cases may manifest as
infection/inflammation of the brain, resulting in neurological symptoms and sequelae of disease.
Treatment:
●
With no
specific antiviral treatment, symptomatic care is crucial, especially for
neurologic symptoms.