Hemorrhagic fevers are a group of infectious illnesses caused by viruses. Also known as viral hemorrhagic fevers, these conditions are often associated with life-threatening internal bleeding, and they tend to have high mortality rates. The viruses that cause these illnesses typically live in rodents or insects, and they are commonly found in tropical areas of the world. The viruses can be transmitted to humans through contact with infected fluids or through handling infected animals. Vaccinations are available to prevent yellow fever, a major type of hemorrhagic fever, and an antiviral drug known as ribavirin may help shorten the duration of illness in some cases. However, there is currently no treatment for these conditions, and they can cause serious damage to the heart, lungs, brain, liver, and kidneys.
Yellow fever develops from a virus carried by Aedes aegypti mosquitoes. The majority of cases occur in tropical regions of South America and in sub-Saharan Africa. In mild forms of the illness, patients typically have a headache, nausea, vomiting, and a fever. However, a more serious form of the condition has a mortality rate of up to fifty percent. Symptoms typically begin around five days after infection, and patients may develop red eyes, sensitivity to light, back and knee pain, and dizziness. This acute phase could progress to a toxic phase in some individuals. In the toxic phase, patients are likely to experience jaundice, decreased urination, a slow heart rate, and liver and kidney failure. The patient may vomit blood, and they could also have bleeding from the mouth, nose, or eyes. Seizures have occurred, and patients may fall into a coma. To prevent yellow fever, doctors recommend for patients to receive a vaccination at least three to four weeks before traveling to an area where the disease is prevalent. In addition, patients should place mosquito nets over their beds at night, and the use of insect repellent is advised.