Chimpanzee by Bernard DUPONT

Yellow Fever: What You Need To Know

We are often asked about yellow fever by people coming on safari. Here we try to give you all the facts.

What Is Yellow Fever?

Yellow fever is a tropical disease transmitted by mosquitos. It is found in some areas of central and west Africa and South America, and is usually not severe. A small proportion of cases can progress to severe disease and death.

Yellow fever vaccination (and non-drug measures) are essential to minimise the risk of yellow fever transmission. It is important to remember that some countries (and this includes South Africa and Botswana) require proof of yellow fever vaccination from people travelling from, or who passed through in transit, yellow fever-endemic countries within the past 6 months.

Most countries visited on African Budget Safaris are not yellow fever endemic (like South Africa, Namibia, Botswana, Mozambique, Malawi and Zimbabwe). The areas visited by African Budget Safaris that do require vaccination and precautions are the western half of Kenya, Uganda, Rwanda and Ethiopia. Those that may require vaccination are the eastern of half of Kenya, Tanzania, and some parts of Zambia.

Check what's needed by all the countries you'll be visiting, well in advance of your trip! Also, if you have any underlying medical conditions, check with your doctor as to the safety of visiting a yellow fever area and vaccination.

Risk to Travellers

According to the CDC (Centres for Disease Control and Prevention, USA), during the period between 1970 and 2013, only 10 cases of yellow fever were reported in unvaccinated travellers from the USA and Europe. Five of these were from travellers to West Africa, and the other five to South America. There has only been one, non-fatal, case reported in a vaccinated traveller.

Risk depends on a number of factors, including vaccination status, areas visited, length of stay, and season.

Transmission

US Dept of AgricultureAedes aegypti Mosquito - US Dept of Agriculture

Yellow Fever is transmitted by mosquitos and has two hosts – primates and humans. It goes through three cycles:

Jungle Cycle: transmitted from primate (monkey) to mosquito and then to humans in the forested areas
Savannah Cycle: transmission from mosquito to human in jungle border areas, or human to human (via mosquito)
Urban Cycle: transmission between humans (via mosquito) in urban areas

Rod WaddingtonColobus Monkey - Rod Waddington

Symptoms

Initially, yellow fever presents as a flu-like illness – fever, chills, body pains, headache, nausea and/or vomiting. These initial symptoms are similar to malaria, so if you’ve been into endemic areas of either (or both), be sure to inform your doctor immediately, should you show any symptoms.

Most patients get better with symptomatic treatment, but some people (about 15%) – after a brief remission – progress to the more severe form. This form presents with jaundice (thus the name), bleeding and eventually shock and organ failure. Medical intervention is essential.

Yellow Fever Areas

CDCCDC Yellow Fever Vaccine Map Africa - CDC

Yellow fever is endemic in a large area of South America and across central and western Africa, and some parts of east Africa (see the CDC map, above). The areas visited by African Budget Safaris that require vaccination and precautions are the western half of Kenya, Uganda, Rwanda and Ethiopia.

Lower risk areas that may require vaccination are the eastern of half of Kenya, Tanzania, and some parts of Zambia.


Important: Certification Needed For Travel

It is important to remember that some countries (and this includes South Africa and Botswana) require proof of yellow fever vaccination from people travelling from, or who passed through in transit, yellow fever-endemic countries within the past 6 months.

Again, check the map – if you’re stopping off in, for example, Ghana or Brazil, on your way to South Africa, you’ll need proof of vaccination to be allowed in. Check all countries (Africa, above; South America, below) you’ll be visiting or transiting (or have transited within the past six months) well in advance of travelling, to allow time for vaccination.


Yellow fever-declared countries in Africa: Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Democratic Republic of Congo, Republic of the Congo, Cote d’Ivoire (Ivory Coast), Equatorial Guinea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Mali, Mauritania, Niger, Nigeria, Rwanda, Sao Tome Principe, Senegal, Sierra Leone, Somalia, Sudan, Tanzania, Togo, Uganda, Zambia

CDCCDC Yellow Fever Vaccine Map South America - CDC

Treatment

There is no specific treatment for yellow fever, only symptomatic and supportive treatment.

Prevention

Non-drug measures

missyMosquito Net - missy

The most important preventative measure is to avoid being bitten by mosquitoes in yellow fever-endemic areas. Following a number of simple steps can minimise your exposure to mozzies:

  • Sleep under a mosquito net
  • Cover up between dusk and dawn (long sleeves, long pants)
  • Treat clothing with permethrin
  • Use insect repellents on the skin

Vaccination

US Army Corps of EngineersVaccine - US Army Corps of Engineers

Yellow fever vaccination is also important and a requirement to enter countries in which yellow fever is present. It is important to remember, as stated above, that some countries (and this includes South Africa and Botswana) require proof of yellow fever vaccination from people travelling from, or who passed through in transit, yellow fever-endemic countries within the past six months.

The vaccine is a once-off injection which can be obtained from your local travel clinic. Immunity is conferred in most people by 10 days after vaccination, so be sure to get it well in advance of travel. Immunity lasts at least 10 years, if not life-long.

While some countries are changing their yellow fever vaccination requirement from needing a 10-year booster to no longer needing a booster, others aren’t. Check requirements for the countries you’ll be visiting to confirm.

CDCYellow Fever Certificate - CDC

Contraindications to Vaccination

There are a number of situations where vaccination for yellow fever is not advised. If the vaccine is contraindicated, it is wise not to enter a yellow fever endemic area. If travel is unavoidable, a medical waiver needs to be obtained.

Some of the conditions in which the vaccine is contraindicated include:

  • Infants younger than 6 months
  • Previous hypersensitivity to the vaccine, or its components ( this includes people with egg allergy)
  • Altered immune status (e.g. thymus disorder; HIV, if CD4 < 200; people on immunosuppressant drugs, e.g. post-transplant)

Precautions

Young Infants (6- 8 months old)

While the vaccine is contraindicated in infants under 6 months old, those between 6 and 8 months old should be vaccinated with caution – after weighing up potential adverse effects/risks with potential benefit – and only if travel is unavoidable.

Older Travellers

People over 60 years of age are also at higher risk for adverse reactions to the vaccine. Again, if travel to yellow fever areas is unavoidable, the decision to vaccinate must be made after weighing up the risks and benefits.

Others

A number of other conditions require careful thought and weighing up of risks and benefits with your medical practitioner before vaccination or request for medical waiver. These include

  • HIV Infection (CD4 > 200)
  • Pregnancy
  • Breastfeeding
  • Chronic conditions such as renal or hepatic disease

Safe Travel

Should you be unsure of any of the requirements regarding yellow fever (or anything else), contact one of our ABS consultants, and we'll be happy to help. 

For medical advice, and your specific health risks according to your medical history - discuss with your doctor and local travel clinic.


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