From the start of 2021 to the end of 2022, the World Health Organization received reports of 203 confirmed and 252 probable cases of yellow fever from 13 countries in Africa, with 40 deaths. Risk factors for the disease spreading and becoming more widespread include low immunity in the population, people moving around, the way the virus is transmitted, and environmental factors that have allowed the Aedes mosquito to thrive.
Recent efforts to increase immunity through vaccination campaigns may have helped to reduce the risk of yellow fever in certain countries, leading to a decrease in the number of reported cases in 2022. However, these countries are still at high risk for yellow fever. In 2022, 12 countries in Africa reported confirmed cases of yellow fever to the World Health Organization.
Yellow Fever Outbreak
These countries are Cameroon, the Central African Republic, Chad, Côte d'Ivoire, the Democratic Republic of the Congo, Ghana, Kenya, Niger, Nigeria, the Republic of the Congo, Sierra Leone, and Uganda. Four of these countries are newly reporting cases, while the other eight had ongoing transmission from the previous year. In 2021 and 2022, a total of 203 confirmed and 252 probable cases of yellow fever were reported, with 40 deaths and a case fatality rate of 9%.
Most confirmed cases were in people under 30, and children under 10 were disproportionately affected. Yellow fever vaccination coverage in the African region was 48% in 2021, lower than the 80% needed to provide immunity to the population. Past and ongoing vaccination campaigns have helped to increase immunity in certain countries. They may have contributed to the decrease in reported cases in 2022, but the risk of transmission remains high.
Yellow fever is a viral disease transmitted to humans through the bites of infected mosquitoes. It can have various symptoms, including fever, muscle and back pain, headache, loss of appetite, and nausea or vomiting. In some cases, the disease can progress to a more severe stage with symptoms such as high fever, abdominal pain, vomiting, jaundice, and dark urine, which can be caused by liver and kidney failure. Bleeding from various parts of the body can also occur.
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Symptoms and Diagnosis
The disease can be deadly, with a fatality rate of around 50% for those with severe symptoms. Fortunately, yellow fever can be prevented through vaccination. A single dose of the vaccine provides sustained immunity and long-term protection against the disease. It is effective within 10 days for most people who receive it and within 30 days for almost everyone who receives it. No booster doses are needed.
Most people infected with the yellow fever virus will either not have symptoms or mild symptoms and fully recover. The illness usually begins 3 to 6 days after infection for those who do develop symptoms. Initial symptoms may include a sudden onset of fever, chills, severe headache, back pain, body aches, nausea, vomiting, fatigue, and weakness. It's important to note that while most people infected with the virus will have mild or no symptoms, a small percentage of cases can progress to a more severe stage with potentially life-threatening symptoms.
There is no specific treatment for yellow fever, so the main focus is on providing supportive care to manage symptoms. This can include getting plenty of rest, drinking fluids to stay hydrated, and using over-the-counter pain relievers such as acetaminophen (Tylenol) to reduce fever and relieve body aches. It's important to avoid taking certain medications, such as aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, as they can increase the risk of bleeding.
Prevention: Vaccination
Instead, it's recommended to use medications specifically designed to reduce fever and relieve pain, such as acetaminophen. The most effective way to prevent yellow fever is through vaccination. A single dose of the yellow fever vaccine provides sustained immunity and long-term protection against the disease.
Yellow fever is transmitted to humans through the bites of infected mosquitoes, specifically the Aedes mosquito, which feeds during the day. The virus can spread quickly in urban settings and densely populated areas where these mosquitoes are present. To help prevent and control the spread of the disease, the World Health Organization (WHO) recommends closely monitoring the situation and actively coordinating and sharing information with neighboring countries that may also be at risk.
In addition, it's important to have enhanced surveillance in place, including the investigation and laboratory testing of suspected cases. As mentioned earlier, vaccination is the primary means of preventing and controlling yellow fever. WHO-approved yellow fever vaccines are safe, highly effective, and provide long-term protection against the disease.
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