The topic of this final work is a tropical viral disease, called a yellow fever, one of the world's known contagious diseases. Yellow fever (lat. Febris flava) is caused by a virus from the genus Flavivirus, and the main carrier is an Asian typhus mosquito. These mosquitoes live in areas of Africa and South America, similar yellow fever viruses are the dengue virus, the Western Nile virus, and the Japanese encephalitis virus. These mosquitoes can not be fed and developed at temperatures below 23 ° C. Yellow fever most commonly affects people and monkeys, bitten by infected mosquitoes, so that the virus enters the bloodstream and circulates and retains in the glands of the pelvis. Therefore, there are three types of disease: urban (epidemic), rabies disease (which is a recurrent disease in limited enzootic areas) and the cycle of an acute, recently described, most common way of transmitting disease in Africa. Symptoms indicating a yellow fever virus In the acute phase, elevated body temperature (fever), headache, nausea, vomiting, loss of appetite, dizziness, muscle pain, eye redness, and in the toxic stage the symptoms may indicate heart, liver, kidney, brain, yellow skin problems bleeding. In the world there are about 200,000 cases of infection and about 30,000 deaths of this disease per year, the highest in Africa is 90% in sub-Saharan Africa and tropical South America. Yellow fever vaccination has been available for 70 years and deserves to reduce the number of people suffering from this disease (called kind 17D). The second dose is sufficient for lifelong protection. The treatment is supportive (adequate rehydration and pain relief with paracetamol drugs, if the disease is in severe form is hospitalization).