Yellow Fever

What is Yellow Fever

  • Yellow fever is an acute viral hemorrhagic.
  • The name “yellow” refers to jaundice, a yellowing of the skin and eyes that can affect some patients.
  • Risk is considered “Elevated” as the spillover window for yellow fever, i.e., the period during which the virus moves from animal reservoirs (mostly monkeys) to humans, has been identified as four to eight weeks.

Current Regional Context

  • In 2025, the Pan American Health Organization (PAHO) issued an epidemiological alert due to rising cases in the Americas.
  • Regional Cases 2025/2026: Venezuela 36 cases; Peru 49 cases,19 deaths; Bolivia 8 cases, 2 deaths.
  • Trinidad and Tobago remains vigilant due to its tropical climate and presence of Aedes aegypti mosquitoes, which are capable of transmitting the virus.

How is it Spread

  • Spread by infected mosquitoes.
  • Transmission cycles:
    • Sylvatic (jungle): Monkeys → mosquitoes Haemagogus, Sabethes) → humans.
    • Urban: Aedes aegypti mosquitoes transmit person-to-person in densely populated areas with low vaccination coverage.

Signs & Symptoms

  • Incubation period: 3–6 days.
  • Initial symptoms: fever, muscle pain (especially backache), headache, loss of appetite, nausea/vomiting.
  • Symptoms usually resolve in 3–4 days.
  • Toxic phase (in ~15% of cases):
    • High fever returns
    • Jaundice, dark urine, abdominal pain, vomiting
    • Bleeding from mouth, nose, eyes, or stomach
    • Fatality rate: up to 50% within 7–10 days of toxic phase onset.

Diagnosis

  • Difficult to distinguish from malaria, dengue, leptospirosis, Zika, or poisoning.
  • Laboratory confirmation:
    • RT-PCR (within first 10 days of illness)
    • Serology (antibody detection)
    • Post-mortem tissue testing (liver, other organs).

Treatment

  • No specific antiviral drug exists.
  • Supportive hospital care improves survival:
    • Hydration
    • Management of liver/kidney failure
    • Fever control
    • Antibiotics for secondary bacterial infections.
FAQS

Frequently Asked Questions

About Yellow Fever

What is Yellow Fever?

Yellow Fever is a virus spread by the bite of infected mosquitoes. In Trinidad and Tobago, it is found particularly in the Red Howler Monkey population in forested areas.

Is there an outbreak?

As of March 2026, there is no outbreak in Trinidad and Tobago or the region. The virus was detected in a deceased Red Howler monkey.

While no human cases have been identified, this confirmation requires the Ministry of Health to act proactively through surveillance to prevent human spread.

How is Yellow Fever Spread?

The Yellow Fever virus is transmitted to people primarily through the bite of infected Aedes or Haemagogus mosquitoes.

Mosquitoes acquire the virus by feeding on infected primates (human or non-human) and can then transmit the virus to other primates.

What are the symptoms?

Early symptoms include fever, headache, muscle pain, and nausea.

Severe cases can lead to:

  • Jaundice (yellowing of the eyes and skin)
  • Dark urine
  • Bleeding from the nose or mouth

If you experience these symptoms, seek medical attention immediately.

How can I avoid Yellow Fever?

Yellow fever can be prevented by vaccination. In Trinidad and Tobago, many persons would have been vaccinated as children.

  • Locate your immunization card for proof of vaccination
  • Ensure children are vaccinated
How many shots do I need?

One dose of the Yellow Fever vaccine provides lifelong protection. As of 2016, booster doses are no longer required.

The following persons should ensure their vaccination is up to date:

  • Veterinary personnel
  • Health workers in forested areas
  • Farmers
  • Hunters
  • Forest workers
  • Adventure seekers (e.g. hikers, campers)
  • Unvaccinated migrants and seasonal workers
  • Defense Force personnel
Who should get vaccinated now?

If you have never been immunised for Yellow Fever, visit your nearest health centre to get vaccinated.

High-risk groups should ensure they are vaccinated, including:

  • Farmers
  • Hunters
  • Forest workers
  • Persons living near forested areas
How can I avoid getting mosquito bites?
  • Eliminate mosquito breeding sites around your home
  • Wear long-sleeved clothing
  • Use mosquito repellent
  • Sleep under mosquito nets