Yellow fever

Yellow fever impact

Yellow fever is an acute viral haemorrhagic disease transmitted by infected mosquitoes. According to the WHO, 34 countries in Africa and 13 countries in Central and South America are either endemic for, or have regions that are endemic for, yellow fever. There are an estimated 84,000 to 170,000 cases of yellow fever annually. Up to 60,000 people die from the disease every year.

Many people do not experience symptoms after being infected with yellow fever; for those who do, symptoms typically disappear within three to four days. However, after recovering from initial symptoms, a small percentage of patients enter a second, more toxic phase. Half of patients who enter the toxic phase die within seven to ten days.

Systematic vaccination, which can prevent and reduce yellow fever epidemics, has fallen sharply in some African countries, leading to recent outbreaks in Angola and the Democratic Republic of Congo.

For more information: WHO yellow fever fact sheet

Yellow fever facts

  • Transmission: The Aedes aegypti mosquito is the principal vector of yellow fever. Large epidemics occur when infected people introduce the virus into heavily populated areas with high mosquito density and where most people have little or no immunity due to lack of vaccination.
  • Signs and symptoms: Fever, headache, jaundice, muscle pain, nausea, vomiting and fatigue are common symptoms of yellow fever. In severe cases, high fever and internal bleeding may occur.
  • Diagnosis: Yellow fever is difficult to diagnose. Blood tests can sometimes detect the virus in the early stages of the disease. In later stages, testing to identify antibodies is needed.
  • Treatment: There is no specific anti-viral drug for yellow fever, but treatment of dehydration, fever, and liver and kidney failure improves outcomes.
  • Prevention and control: In high-risk areas where vaccination coverage is low, prompt recognition and control of outbreaks using mass immunization is critical for preventing epidemics. Risk of transmission in urban areas can be reduced by eliminating mosquito breeding sites.

MSF activities

From the late 19th century to the early 20th century, yellow fever wreaked havoc in many parts of the world. Research led to the development of a highly effective vaccine, and systematic vaccination campaigns considerably reduced yellow fever epidemics. However, low vaccination coverage has recently allowed new outbreaks of the disease to emerge.

In December 2015, a yellow fever outbreak began in Angola and spread into neighbouring Democratic Republic of Congo (DRC), with the potential to threaten other countries. Deploying the highly effective yellow fever vaccine is key to preventing further spread. The supply of the vaccine is limited and must be used efficiently. Efforts are being made to replenish the global stockpile but there are concerns that global supplies could be deleted if outbreak ignites in other large urban settings.

MSF is working in cooperation with the Angola and DRC Ministries of Health (MoH) and the WHO to help contain the spread of the virus through vaccination, case management, vector control (destruction of mosquitoes and breeding sites) and trainings.

In Angola, MSF has been supporting yellow fever case management in collaboration with the MoH since mid-February 2016. MSF teams are also directly treating yellow fever patients in the capital, Luanda (Kapalanga hospital), as well as in Huambo, Huila and Benguela provinces.

In DRC, MSF conducted a vaccination campaign for the 350,000 residents of Matadi, next to the border with Angola. In Kongo Central and Kinshasa, MSF teams have begun training health staff to care for yellow fever patients and are preparing selected hospitals for case management. Vector control activities are underway to combat the mosquitoes that carry yellow fever. Homes are being sprayed or fumigated to kill adult mosquitoes and destroy breeding sites where the mosquito lays its eggs.

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