East Africa: Who Revises Yellow Fever Guidelines for East Africa to Exclude … – AllAfrica.com
Christabel Ligami
7 August 2011
The World Health Organisation (WHO) has revised its recommendations for the Yellow Fever vaccination in Africa.
The new 2011 WHO report indicates that in East Africa, only Tanzania and part of Kenya from Nairobi to the coast are classified as low risk zones to the disease. But the whole of Uganda, Rwanda and Burundi remain high-risk areas.
Previously, the entire east and southern Africa were classified as Yellow Fever endemic and WHO recommended vaccination for all travellers aged nine months or older.
According to the new re-classification, travellers to and from these low risk areas will not require to produce proof of vaccination unless travellers' itineraries indicate potentially increased risk of exposure.
However, according to the international health regulations, countries with vulnerable populations and susceptible vector species can define their own yellow fever vaccine entry requirements.
In Kenya, only North Eastern Province, Kilifi, Kwale, Lamu, Malindi and Tana River in Coast Province have been classified as areas with low potential for exposure.
The new recommendations came up after recognition by travel medicine experts at WHO and Centre for Disease Control and Prevention (CDC) in 2008 of the need to harmonise both the classifications of geographical risk for yellow fever and vaccine recommendations.
WHO then convened a consultation group on yellow fever and international travel to discuss factors important for transmission of the virus, to establish criteria for the addition or removal of countries and geographical regions and to revise the yellow fever risk map and recommendations for vaccination.
The consultation group outlined four levels of yellow fever risk and classified geographical areas into four corresponding categories: endemic, transitional, low risk and no risk.
In Africa, the barren or sparsely vegetated lands of the Sahara desert are not suitable for the development of immature mosquitoes and were, therefore, not thought to harbour a risk for transmission.
The normalised difference in vegetation line was used to separate barren or sparsely vegetated zones as the criteria for the addition or removal of countries and geographical regions.
The following countries in Africa had no change to their prevalence classification: Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Congo (Brazzaville), Côte d'Ivoire, Equatorial Guinea, French Guiana, Gabon, Ghana, Guinea, Guinea-Bissau, Guyana, Liberia, Nigeria, Rwanda, Senegal, Sierra Leone, Suriname, The Gambia, Togo, and Uganda.
These countries repeatedly reported yellow fever infection in human beings or non-human primates and had inadequate surveillance systems to establish whether the virus was circulating at low levels in specific areas. These were therefore classified as endemic (high risk) regions.
The group agreed that countries with areas with only low potential for exposure be excluded from the list of countries with risk and such exemptions apply to Eritrea, Somalia, Tanzania, and Zambia.
Vaccination
Yellow fever is an acute haemorrhagic disease caused by the yellow fever virus transmitted by a bite of female mosquitoes mostly found in Africa and South America. The incubation period for the virus is between two and five days.
In Africa, transmission of the virus can also occur in an intermediate cycle between human beings or non-human primates.
Symptoms occur in severe cases and include jaundice, multi-organ failure, and distributive shock.
The yellow fever vaccine known as YF 17D vaccine has been regarded as one of the safest vaccines against the disease and lasts for four, five and 10 year interval between vaccinations.
Yellow fever vaccine is given for two reasons: to protect travellers visiting areas with risk of yellow fever virus transmission and to prevent international spread by minimising the risk of importation and translocation of the virus by viral endemic travellers.
Travellers immunised against Yellow Fever are issued with an internationally recognised vaccination certificate for inspection by immigration officials.
The international health regulations concerning Yellow Fever are equal worldwide and unvaccinated travelers may face denial of entry, or even quarantine in certain circumstances.
The International Certificate of Vaccination is then issued and becomes valid 10 days after vaccination and remains so for 10 years.
However, WHO maintains that the immunity from yellow fever vaccine remains the same and vaccination is mandatory for travellers to and from these high risk countries as stipulated in the International Health Regulations (2005) for individuals travelling to countries with a yellow fever vaccination entry requirement .
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