The worst outbreak of yellow fever seen for 20 years and the prospect of the virus taking a hold on the Arabian peninsula was the focus of the latest talk organized by WCMC-Q’s department for global and public health.
The lecture was held on 13 January and delivered by Aly Verjee, a senior researcher with the Rift Valley Institute based in Kenya.
Mr Verjee’s talk was based on the recent epidemic of yellow fever in Darfur in Sudan which began in September, peaked in October and November and is currently believed to be tailing off following a sustained immunization campaign by the Sudanese government, the World Health Organization (WHO) and non-governmental organizations (NGOs). It was the WHO that described the outbreak as the worst for 20 years.
In the 1930s it was not believed that yellow fever, which has a mortality rate of 20 per cent, was found in Sudan. But with the advent of air travel the country became a major transit post and the disease was discovered. A spraying campaign against the Aedes aegypti mosquito that transmits the disease, along with a vaccination program, brought the disease under control. But by the 1980s yellow fever had re-emerged and has remained in the region ever since due to re-infestations of the Aedes mosquito and a drop in vaccinations.
Until recently, however, the virus was not considered to be a major problem in the country but Mr Verjee suggested that the current socio-political situation in Darfur may have been a contributing factor as conflict and human displacement always have a negative effect on public health. There have also been no sustained vaccination programs.
But he added that the Sudanese government, with aid agencies, has reacted quickly to the outbreak of the epidemic and three million people have since been vaccinated with a further two million to follow. Reported cases of the virus have reached around 1,000 and there have been about 200 deaths although there may well be unreported outbreaks.
Mr Verjee also raised the prospect that the disease could one day reach the Arabian Peninsula, particularly the western coast of Saudi Arabia. The Aedes mosquito is already found in Jeddah and carries dengue fever but for some unknown reason no Aedes mosquitoes in Asia have been found carrying the yellow fever virus. With the mosquitoes now found in southern Egypt the potential remains for the disease to spread east.
Yellow fever is a viral, hemorrhagic fever of the same category as ebola although the disease is most closely related to dengue fever –the latter, however, has a mortality rate of only five per cent. The incubation period for yellow fever after being bitten by an infected mosquito is between three and six days with sufferers then experiencing a high fever, myalgia and vomiting. Most patients then recover but some – after a period of apparent remission – may then suffer jaundice, vomiting, hepatic fever and death.