Yellow fever is a serious viral infection that is spread by a mosquito known as the Aedes aegypti mosquito. The causative agent is virus of the Flavivirus genus. Yellow fever mainly occurs in sub-Saharan Africa (countries to the south of the Sahara desert), South America and in parts of the Caribbean.
There are two forms of yellow fever: Urban and Jungle. Clinically and etiologically they are identical.
Urban yellow fever is an epidemic viral disease of humans transmitted from infected to susceptible persons by Aedes aegypti mosquitoes, which breed in domestic and peri domestic containers (e.g., water jars, barrels, drums, tires, or tin cans) and thus in close association with humans. In areas where Ae. aegypti has been eliminated or suppressed, urban yellow fever has disappeared. Urban yellow fever can be prevented by vaccinating human populations at risk for infection or by suppressing populations of Ae. aegypti mosquitoes so that they no longer perpetuate infection.
Jungle yellow fever can most effectively be prevented by vaccination of human populations at risk for exposure.
Incubation period of yellow fever is 3-6 days. Symptoms occur in 2 stages:
The first stage is also known as the 'acute phase', include:
A high temperature (fever) of 38ºC (100.4ºF) or above
Nausea and vomiting
Muscle pain, including backache
Loss of appetite
Second stage is more severe and is referred to as the 'toxic phase'. The symptoms can include:
A recurrent fever
Jaundice – a yellow tinge to the skin and whites of the eyes caused by liver damage
Bleeding from the mouth, nose, eyes or stomach, leading to blood in your vomit and stools (faeces)
Yellow fever is caused by a type of virus known as a flavivirus. The infection is transmitted by the bite of certain mosquitoes. If one is travelling, developing risks of yellow fever will depend on:
· Where you are travelling to and whether there is currently an outbreak of yellow fever in the area
· Whether you have been vaccinated for yellow fever
· Whether you are visiting jungle or forested areas