Yellow fever: what you need to know

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By Tibor Vovesz
Yellow fever: what you need to know

The authorities of Angola notified WHO of an outbreak of yellow fever in January 2016. The first cases have been identified in the district of Viana. By February the infection had spread to the whole province of Luanda. Later, other affected provinces included Cabinda, Cuanza Sul, Huambo, Huila and Uige: a third of the provinces of Angola.

What is yellow fever?

  • acute viral haemorrhagic disease
  • infected mosquitoes transmit the virus: the same mosquito (Aedes Aegypti) that is also associated with Dengue-, Chikungunya- and Zika-fever, and particular forms of Encephalitis
  • an infected person can spread the virus to others via mosquito bites
  • half of the infected die if untreated
  • approximately 130,000 cases reported anually
  • 90% of cases reported from Africa
  • the name ‘yellow’ refers to the jaundice that affects some patients

Why is yellow fever a challenge?

The infection is difficult to diagnose, especially during the early stages. It can be confused with severe malaria, leptospirosis, some type of hepatitis, other hemorrhagic fevers or poisoning. Blood tests can detect yellow fever antibodies produced in response to the infection.

What are the symptoms?

Symptoms include fever, headache, muscle pain, nausea, vomiting, and fatigue. A small percentage of infected people experience a second more severe phase of illness which includes high fever, jaundice and internal bleeding. At least half of severely affected patients who don’t receive treatment die within 10 to 14 days.

Which countries are at risk?

How does the disease evolve?

  • incubation time 3-6 days
  • two phases of the disease: acute phase may be followed by a toxic phase
  • most of the patients recover from the acute phase in 3-4 days: the symptoms disappear
  • 15% of patients enter the toxic phase usually within a day of an initial remission
  • in the toxic phase the fever returns and several body systems get affected, jaundice, internal pain, vomitting may end with bleeding from the mouth, nose, eyes or stomach, kidney function collapses
  • however, half of the patients in toxic phase recover without significant organ damage

Is there a treatment?

  • there is no specific treatment
  • patients can only get supportive care: decreasing the symptoms such as dehydration, respiratory failure, and fever
  • associated bacterial infections can be treated with antibiotics
  • there is a vaccination against yellow fever
Sources: World Health Organisation

European Centre for Disease Prevention and Control