Identified: Signs of Fatal Yellow Fever

Researchers have recently discovered new signs that can help them identify when a patient is suffering from a potentially fatal infection of yellow fever. This could open up new treatment options and improve response and treatment that could save lives.

Yellow fever is a severe disease that can range from simple fever to full blown liver damage and even death. In most developed countries, the disease is only an imported threat, easily isolated and treated. However, according to the World Health Organization (WHO), 32 African countries are now considered at risk of yellow fever, with a total population of 610 million people.

The worst cases result in an estimated related 30,000 deaths each year, out of only 200,000 infections. And while that morality may seem a little high, it is in-part due to a lack of identification and early-treatment. The other cause, researchers report, is the fact that the virus seems to react differently to each victim, proving fatal for some, despite their age or well-being.

Now a research team has determined that the yellow fever virus replicates primarily in the liver, allowing them to target and search for indicators of an infection's severity, despite the fact that it may also cause other organ failure.

"Yellow fever is truly a neglected tropical disease," researcher Ilhem Messaoudi said in a statement. "Even though it continues to cause fatality, it remains understudied."

According to the researcher and her colleague, the disease is characterized by two phases.

During the first "acute phase," a patient has fever and a number of vague symptoms. These symptoms last about 48 hours.  While most people are able to resolve them, some enter remission followed by a toxic phase in which viral loads greatly increase.  Yellowing of the skin and the whites of the eyes (which is what gives the disease its name) is a consequence of this phase and is a key hint at liver failure.

"About 30 percent of unvaccinated people who contract the disease go through the toxic phase, which can be fatal," Messaoudi said.

According to the study, in this fatal 30 percent, the fever worked its poison in the liver to not only harm the patient, but alter gene expression in white blood cells, promoting inflation that likely causes organ damage in the rest of the body.

According to the team, identifying these radical genetic change is key, as it can alert physicians when they have a potentially fatal case of the disease on their hands.

"Supportive care would follow for all patients, but it would change the dynamics of how aggressive the treatment needs to be."

These results were published in PLOS Neglected Tropical Diseases.

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