What’s the big deal about yellow fever vaccine for travellers?

Dear doctor,

Every time someone is leaving the country, they are asked to show that they have been vaccinated against yellow fever. What’s the big deal about yellow fever? I have never seen or heard of anyone getting yellow fever.

Dave

Dear Dave,

Yellow fever is a viral disease that is spread by infected mosquitoes. After infection, there’s an incubation period of three to six days. Most people infected with yellow fever do not experience any symptoms and those who do may develop fever, muscle aches, back pain, headache, nausea and vomiting. About 24 hours after recovering from the initial symptoms, a small percentage develop severe symptoms, which may include high fever, abdominal pain, vomiting, heart problems, liver and kidney disease, dark urine and jaundice (yellowing of the eyes and other membranes, and the skin due to raised bilirubin levels), which is why the disease is called yellow fever. The individual may also develop seizures, delirium, coma and bleeding from the mouth, nose, eyes and stomach. Half of those who develop severe disease do not survive.

Yellow fever disease does not have specific treatment and management is through supportive care. While the patient is under treatment, they should be in bed under a mosquito net, both day and night, to avoid spreading the disease through mosquito bites. Disease prevention is through yellow fever vaccination, prevention of mosquito bites and vector/mosquito control.

There are some countries in South America and Sub-saharan Africa where yellow fever is endemic, meaning that the disease regularly occurs there.

Yellow fever can spread fast and widely, causing an epidemic. It can also lead to severe disease with high fatality rates. Because of this, it is a reportable disease. An infected person can spread the disease in a non-endemic country, if they are bitten by a mosquito that is able to transmit the virus, hence the travel requirements when traveling from or to a country that is endemic for yellow fever.

The best prevention for outbreaks is through vaccination of majority of the population. If someone gets yellow fever disease and recovers, they also develop immunity to the virus.

Dear doctor,

My son is three years old and he developed an itchy rash on the body and fever two days ago. Our neighbour says that his child has a similar problem, and he has measles, while at school there’s a classmate of his who has chicken pox. Which is which? How can we treat it?

Mercy

Dear Mercy,

Both measles and chicken pox are viral infections that can cause an itchy rash.

Measles is a respiratory infection that also presents with a rash, and it spreads easily through droplet and/or airborne transmission. Symptoms include fever, fatigue, running nose, cough and conjunctivitis. A rash develops about two weeks after exposure to the virus. It starts on the head and spreads downwards towards the lower limbs. An infected person is contagious from four days before to four days after the rash appears. Some people do not develop the rash. A few people develop complications with brain and/or lung disease, which can even lead to death.

There is no specific treatment for measles. Supportive treatment may include paracetamol, anti-histamines, fluids, rest and anti-itch skin lotions like calamine. Everyone who has measles should be given vitamin A supplement at the appropriate dose for age. The child should be isolated until he recovers. Urgent medical attention should be sought if there is high fever and/or other severe symptoms. The measles vaccine helps to prevent infection and in case someone gets infected, they are more likely to have mild disease.

Chicken pox is caused by the varicella zoster virus (VZV) and is very contagious. With close contact with an infected person, the disease spreads easily, leading to transmission to upto 90 per cent of those who are un-vaccinated or who have never had the disease before. After exposure, the disease develops in about two weeks. Chicken pox may cause fever, fatigue, aches and pains, headache and loss of appetite. The most common feature is a very itchy rash with fluid-filled blisters or lesions. The rash may start on the face, the chest or the back then spread to the rest of the body, including eyelids, inside the mouth and the genital area. After a few days, the blisters break open, dry out then form dark scabs. The person is contagious from two days before the rash starts to when the lesions form scabs and there are no new lesions in 24 hours.

For someone who is vaccinated, when exposed to chicken pox, they may either not get infected, or they may develop a milder form of the disease with no or few blisters, or develop a red rash and a mild fever. A few vaccinated individuals will develop the disease similar to unvaccinated persons.

Rarely, complications may develop, which include bacterial infection of the skin, blood infection, lung and brain disease and excessive bleeding.

To manage chicken pox, you can use ant-itch skin lotions like calamine lotion and bathe the child with cool water with added baking soda. Keep the child’s nails well-trimmed and filed to prevent scratching of the skin, and maintain hand hygiene to reduce risk of transmission. Other supportive treatments include hydration, rest and using paracetamol for fever and pain. Avoid use of aspirin because it may lead to Reye’s syndrome, a serious condition affecting the brain and liver. If there is high fever, or additional symptoms, then the child should be reviewed by a health care provider urgently.

Since measles and chicken pox are highly contagious, it is advisable to keep your child at home until he has recovered.

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