Yellow fever is a viral disease, transmitted from the bite of an infected female mosquito (Aedes aegypti.) Symptoms of the disease include fever, chills, loss of appetite, nausea, muscle pains particularly in the back, and headaches. An on-going risk is with kidney disease.
The causative agent is an RNA virus of the genus Flavivirus. The virus is difficult to differentiate from other viruses in the early stages, and this sometimes delays treatment. Confirmation of infection can only be obtained through molecular testing of a blood sample. Vaccination is recommended for travelers to certain countries; and the World Health Organization runs vaccination programs against yellow fever began in West Africa, with a focus upon Benin, Liberia, and Sierra Leone.
An effective vaccine against yellow fever has been in place for several years. With most people, at the standard dose, protection begins by the tenth day after vaccine administration and it lasts for around 10 years. However, due to concerns about supply problems, the United Nations is recommending the administration of a smaller dose of the vaccine. This is termed fractional dosing” and it would provide immunity for only 12 months. The aim is to conserve the vaccine and to allow for stocks to be built back up.
One reason for the diminishing supply has been a high rise in cases in the Democratic Republic of Congo. According to Jon Abramson, chair of the WHO Strategic Advisory Group of Experts (SAGE) on Immunization: “Yellow fever outbreaks in Angola, Democratic Republic of the Congo and Uganda are placing unprecedented demands on vaccine supply for emergency vaccination campaigns to control the spread of the disease.” This was affirmed on the official WHO Twitter feed (@WHO): “Lower doses of #yellowfever vaccine – 1/5 of regular doses – could be used in emergencies: WHO advisory group of immunization experts #alert.”
