Yellow fever is a mosquito-borne disease that is most prevalent in countries throughout South America and Africa. “Mosquito-borne” means that the primary means of transmission is via a mosquito bite, and from either a non-human primate to a human or an infected human to another human.
For some people, yellow fever is asymptomatic. In approximately 85% of cases in which individuals do develop symptoms, the symptoms are mild and resemble those of the flu. Common symptoms in this first stage of the virus include fever, body aches, chills, nausea, vomiting, headache and weakness. Most people recover within about one week. However, many do go on to experience months of weakness and fatigue.
In about 15% of symptomatic cases, individuals progress into the second stage of the illness. The first and second stages are broken up by a brief period of “recovery,” which lasts anywhere from a couple of hours to a couple of days. Following this period of remission, individuals develop intense and life-threatening symptoms. This first of these symptoms is a spike in fever. Shortly after the fever returns, organ damage begins to occur. The first organs affected are the liver and kidneys. In many cases, individuals develop jaundice, or yellowing of the skin. This symptom is the symptom for which the disease is named. Some infected persons begin to bleed from their mouth, nose, ears or eyes.
For individuals who never progress into the second stage of yellow fever, the mortality rate is almost non-existent. However, for persons who develop into the second stage, the mortality rate is high. Between 30% and 60% of individuals who progress into stage two end up dying within seven to 10 days of the onset of stage-two symptoms. Survivors live the rest of their lives dealing with and managing the symptoms of severe organ damage.
Yellow fever is contained mostly to certain South American countries and Africa. There are an estimate 200,000 cases that occur annually and on a global scale. Approximately 30,000 annual deaths are attributed to yellow fever. Of the 200,000 global cases, about 90% occur in Africa alone.
Yellow fever typically affects populations in South America and Africa. However, individuals can increase their risks of contracting the disease by traveling to these high-risk areas without taking proper precautions. The most effective preventative measure is the yellow fever vaccine, which has been around for nearly 100 years and, in that time, has proven itself to be both safe and effective. Additional precautionary measures include wearing mosquito repellent, allowing minimal skin to be exposed when outside, and using mosquito netting and screens to keep mosquitoes out.
Unfortunately, there is no cure for yellow fever. However, research has found that when individuals seek medical care at the onset of developing symptoms, they can improve their outcomes. For individuals who progress into stage two, managing dehydration and treating for kidney and liver failure early on can lead to more positive outcomes.