Western Equine Encephalitis Virus Outbreak Sparks Concern in Argentina

Western Equine Encephalitis Virus Outbreak Sparks Concern in Argentina

On December 20, 2023, Argentina’s International Health Regulations National Focal Point (IHR NFP) notified the Pan American Health Organization/World Health Organization (PAHO/WHO) about a case of Western Equine Encephalitis Virus (WEEV) infection. This marks the first occurrence in over two decades, with 21 confirmed cases reported.

Background on Western Equine Encephalitis Virus

  • Nature of the Virus: WEEV is a mosquito-borne infection with an 11.5-kilobase single-stranded RNA genome, belonging to the Togaviridae family.
  • Transmission and Reservoirs: The virus is transmitted primarily through mosquitoes, with passerine birds serving as reservoirs and equine species as intermediate hosts.

Current Outbreak Details

  • Human Cases: The outbreak has seen 21 confirmed human cases in Argentina, with the initial case reporting sudden fever and neurological symptoms on November 19, 2023.
  • Animal Cases: Since December 2023, there have been 374 laboratory-confirmed cases in animals in Argentina and Uruguay. In Argentina, the province of Buenos Aires has the highest number of cases.
  • Severity and Symptoms: While most cases are asymptomatic, 4-5% may result in neurological symptoms. Of the confirmed cases, eight required intensive care, 13 needed general hospitalization, and one resulted in fatality.

Risk Factors and Exposure History

  • Occupational Risk: Three cases involved veterinarians, two were construction workers, and two had engaged in outdoor recreational activities.

PAHO/WHO Response and Recommendations

  • Alert Issued: PAHO/WHO has issued an alert regarding the risk of WEE spread in the Americas.
  • Preventive Measures: Enhanced surveillance, environmental modifications, vector control, and equine vaccination are crucial for controlling the virus.
  • One Health Approach: A comprehensive One Health approach is recommended for effective virus control.

Multiple Choice Questions (MCQs):

  1. What is the primary mode of transmission of Western Equine Encephalitis Virus?
    a. Airborne
    b. Waterborne
    c. Mosquito-borne
    d. Direct contact
    Answer: c. Mosquito-borne
  2. How many confirmed human cases were reported in Argentina as of December 20, 2023?
    a. 10
    b. 15
    c. 21
    d. 30
    Answer: c. 21
  3. What is the primary reservoir for the Western Equine Encephalitis Virus?
    a. Rodents
    b. Passerine birds
    c. Equine species
    d. Amphibians
    Answer: b. Passerine birds
  4. What is the recommended approach for controlling the virus, according to PAHO/WHO?
    a. Strict quarantine measures
    b. Vaccination for humans
    c. One Health approach
    d. Mass testing for mosquitoes
    Answer: c. One Health approach