U.S Declares Global Health Alert Over African Yellow Fever Outbreak

Aedes aegypti feeding
Aedes aegypti feeding. Photo: James Gathany

Warnings have been issued by scientists in the United States that the current yellow fever outbreak that has killed 277 people in Angola, could start a world-wide health crisis.

The article, published in the Journal of the American Medical Association states:

Prior delays by the WHO in convening emergency committees for the Ebola virus, and possibly the ongoing Zika epidemic, cost lives and should not be repeated. Acting proactively to address the evolving yellow fever epidemic is imperative.

The disease is spread by the Aedes egypti and Haemogogus mosquito, the egypti is the same species responsible for spreading malaria, zika virus, dengue fever and chikungunya.

Yellow fever gets it’s name from the jaundice caused as the liver is attacked.

The spread of the virus is facilitated by mosquitoes who are not carrying the virus biting someone who has it. That mosquito then becomes a vector, spreading the disease to everyone else it bites. Other mosquitoes then bite one of these infected people and they too become carriers and spread it to everyone else they bite. It’s this mechanism that can turn a small outbreak into an epidemic.

Yellow Fever Virus
A TEM micrograph of the yellow fever virus (234,000X magnification). Photo: Erskine Palmer, Ph.D. – Centers for Disease Control and Prevention Publich Health Image Library.

The current outbreak has already spread to the Democratic Republic of Congo, Kenya, and even China as infected travellers carry the disease with them, get bitten and spread the fever.

The World Health Organisation states:

Once contracted, the yellow fever virus incubates in the body for 3 to 6 days, followed by infection that can occur in one or two phases. The first, “acute”, phase usually causes fever, muscle pain with prominent backache, headache, shivers, loss of appetite, and nausea or vomiting. Most patients improve and their symptoms disappear after 3 to 4 days.

However, 15% of patients enter a second, more toxic phase within 24 hours of the initial remission. High fever returns and several body systems are affected. The patient rapidly develops jaundice and complains of abdominal pain with vomiting. Bleeding can occur from the mouth, nose, eyes or stomach. Once this happens, blood appears in the vomit and faeces. Kidney function deteriorates. Half of the patients who enter the toxic phase die within 10 to 14 days, the rest recover without significant organ damage.

They are also reporting that emergency stockpiles of the only preventative measure against yellow fever, vaccination, ran out in April. This is not good news when only 6 million people in Africa, the majority of them in Angola, have been vaccinated since the start of the outbreak. Most Africans are not vaccinated against the disease and with a population of 1.11 BILLION people (2013 figures) this does not bode well.

Yellow Fever Mosquito
Adults of the yellow fever mosquito A. aegypti: The male is on the left, females are on the right. Only the female mosquito bites humans to transmit the disease.

PLOS report that the estimated number of deaths in Africa from Yellow fever is 78,000 per year with a 95% certainty index. This is an average year, a year without a major outbreak or uptick in cases.

All the usual advice regarding mosquitoes applies:

Wear long sleeves and long trousers at dawn and dusk if out and about
Use a decent repellant
Wear light colours as mosquitoes prefer dark ones
Always use mosquito nets at night if possible
If staying in a hotel or your home has air con turn it down mosquitoes like heat
Use a net over buggies or prams if you have a child with you
Skin so Soft (Avon) has proved to be effective on skin and in oil burners as a mosquito deterrent.
Use a Mos-Kill type plug in at home if you are in an endemic area (Africa, South America)
Make sure vaccinations are up to date if you are travelling to endemic areas.
With the major debacle with the Ebola outbreak lets hope that the WHO get on top of this quickly. Allowing it to spread to other countries, where mosquitoes are not currently infected would be an absolute disaster.

Take Care