Yellow Fever is a serious viral haemorrhagic fever transmitted from monkey to monkey by mosquitoes’ bites in the forest canopy. Humans can get ‘into’ this cycle and become infected by mosquitoes as well. Transmission between humans can occur when a person with the yellow fever virus enters an area where there are also susceptible mosquitoes.
Many infections present mildly as a flu-like illness or, in its severe form, may cause headaches, nausea and vomiting, abdominal pain, bleeding, shock and collapse and signs of kidney and liver failure. The liver failure causes ‘yellow-jaundice’ hence the name ‘Yellow Fever’. Yellow Fever is mainly a disease of jungle areas but there are occasional outbreaks in towns and cities. The death rate is around 30%.
It occurs in exclusively in Africa, and South America. South American infections usually occur in rural workers, from occupational exposure in or near forests. In Africa, the Yellow Fever virus is transmitted in three regions: commonly in the moist savannah zones of West and Central Africa during the rainy season, occasionally in urban locations and villages in Africa, and rarely in jungle regions.
This is based on the typical illness and confirmed by special blood tests or post-mortem tests in fatal cases.
There is no specific treatment. Cases either recover spontaneously or die.
Every traveller’s first line of defence is to take personal protective measures against mosquitoes. The vaccine, though excellent, may not protect 100% against the disease. You are advised to wear mosquito repellent containing DEET (20-30% concentration is generally adequate), and stay in air-conditioned or screened rooms. Travellers can reduce the amount of skin exposure with appropriate clothing protection: e.g. socks, long pants and long-sleeved shirts. If you use a repellent containing DEET on children, do so with care – there is some evidence of a potential for neurological side effects associated with overdoses. Do not use strengths more than 10-20% without the advice of a travel health professional.
If you are to travel into rural regions, then take a bednet. We advise aerosol blasting any accommodation room with insecticides to kill indoor mosquitoes. Permethrin (a mosquito insecticide) can be applied to clothing and mosquito netting, for extra protection.
Prevention is by vaccination or immunisation with the Yellow Fever vaccine. This is a live vaccine, which gives almost 100% protection that lasts for 10 years. The vaccine is administered subcutaneously in a single dose. Immunity is attained after 6-10 days.
Regulatory authorities require:
A valid certificate 10 days prior to arrival at the destination.
Boosters at least every 10 years to maintain up to date protection.
Yellow fever vaccine should not be administered to any infant under 4 months of age: children 4-6 months should be considered only in unusual circumstances. Infants 6-9 months can receive the vaccine if they cannot avoid travelling to areas of risk and when a high level of protection against mosquito bites is not possible. Over 9 months of age vaccination, if required, is permissible.
Various authorities in many countries can prevent travel, if vaccination for Yellow Fever is not up to date. The international certificate is valid for 10 years, beginning 10 days after vaccination.
Yellow Fever vaccination is available only at designated yellow fever clinics. The D2 medical centre is one of these clinics with a license from the HSE
Reactions to this vaccine are generally mild and include fever, headache, and muscle ache. These reactions occur 5 to 14 days after immunisation. Serious side effects are unlikely, however there is a rare chance that serious problems or even death could occur after receiving any medicine or vaccine. Side-effects include redness and tenderness at the site of the injection, fever, mild headache, muscle aches, and a flu-like illness 3-7 days after vaccination. Those over the age of 60 years need to discuss particular reactions to the vaccination that could occur, with their travel health professional.
As with any serious medical problem, if the person has a significant or unusual problem after receiving the vaccine, call a doctor or bring the person to a health professional promptly.
After immunisation, an International Certificate of Vaccination is issued and is valid 10 days after vaccination to meet entry and exit requirements for all countries. The Certificate is good for 10 years. Take the Certificate with you, for travel to certain regions will require proof of having had the vaccination.
It is essential that travellers who have a medical reason not to receive the yellow fever vaccine obtain a medical waiver. Most countries will accept a such a medical waiver for persons with a valid reason not to receive the vaccine. Such a waiver will need a physician’s note clearly stating the medical reason not to receive the vaccine. It is essential that it be written on a surgery letterhead and bear the stamp used by the doctor writing the letter and preferably a stamp from the local health department or official immunization centre. This will assist in the validation of the waiver
Children younger than 4 months of age ( as noted above ), people who have had a previous severe reaction to the vaccine and those who are extremely allergic to eggs should not receive this vaccine.
People with AIDS or some other immune-suppression disease need to discuss the risks and benefits of this vaccine carefully with their travel health professional.
The vaccine can be administered in pregnancy only when the risk or contracting the disease far outweighs the risk of any side-effect, and the journey is essential. Wherever possible the travel should, however, be avoided until after the pregnancy is over. The vaccine may be given to nursing mothers