Yellow fever (febris flava) is a viral disease that can be infected by a person through a mosquito bite. In some patients, yellow fever is mild and resolves quickly, in others it leads to liver and kidney failure and even death. What else should you know about yellow fever? Certainly, you can protect yourself from this disease by being vaccinated against yellow fever.

Yellow fever(also calledyellow fever , in Latin also referred to asfebris flava) is a disease with which the human population has been dealing with for a long time - the first yellow fever epidemic to be described occurred in the 17th century on the islands of Barbados.

Yellow fever is not a disease that can be infected in Poland - it occurs in Africa and South America. Exact statistics on the incidence of yellow fever are not known (some cases of this disease are not simply reported), according to the assumptions of the World He alth Organization (WHO), there are as many as 200,000 cases of yellow fever in the world each year and up to 30,000 caused by her deaths. Both adults and children can suffer from yellow fever - this possibility is due to the cause of yellow fever.

Yellow fever (yellow fever): causes

Yellow fever belongs to the group of hemorrhagic fever and it is a disease caused by a viral infection. The etiological factor of this entity is yellow fever virus (abbreviated as YFV, where this abbreviation comes from the English term yellow fever virus), derived from the genusFlavivirusand belonging to the familyFlaviviridae .

Yellow fever virus occurs in primates, which include monkeys and humans. In humans, infection is caused by a mosquito bite, which is a carrier of the pathogenic virus. The main mosquitoes that can transmit the yellow fever virus are those of the genusAedesandHaemagogus . It is both possible for a mosquito to bite a human infected with yellow fever and transmit the virus to another person, and it is also possible for a mosquito to become a carrier of the virus after a monkey bite and then transmit the disease to a person.

Yellow fever (yellow fever): symptoms

Most of thempatients, the course of yellow fever is quite mild (sometimes the disease is completely asymptomatic). After the incubation period (the time it takes from infection with the yellow fever virus to the onset of disease symptoms), typically 3-6 days, patients may develop symptoms of yellow fever such as:

  • fever
  • headache
  • muscle pain
  • fatigue
  • chills
  • pains in the lumbar region
  • nausea
  • vomiting
  • loss of appetite

In this situation, the symptoms of yellow fever typically last for a few (3-4) days, then they disappear and the patient's condition returns to normal. However, the course of yellow fever is not so successful in all of them - in some patients (according to statistics, about 15% of patients), after the apparent stabilization of their condition - usually within two days of the first episode of fever - the reappearance of similar ones as before ailments, but also to the appearance of other, much more serious symptoms. In addition to fever, abdominal pain and nausea, patients may develop liver dysfunction, for example. Their effect, in turn, can be both jaundice and blood clotting disorders, leading to gastrointestinal bleeding, bleeding within the eyeball or mucous membranes. With bleeding from the gastrointestinal tract, the patient may vomit blood (hence the Spanish name of the disease, which is vomito negro - this term can be translated as "black vomit"). In addition to the already described, severe course of yellow fever may lead to renal failure, and in the worst cases, even shock, multi-organ failure and ultimately death.

Yellow fever (yellow fever): diagnostics

Yellow fever is suspected on the basis of the fact that the patient has stayed in the regions where the disease occurs, and also taking into account the patient's symptoms. It is possible to confirm that the patient's condition is infected with the yellow fever virus by means of laboratory tests. For this purpose, RT-PCR tests can be performed, thanks to which it is possible to detect the possible presence of a virus in the patient's blood. Another method is to isolate the virus from the blood of the sick.

In the diagnosis of yellow fever, serological tests can also be used - we are talking about the determination of specific antibodies in IgG and IgM classes. However, this diagnostic method for yellow fever has some limitations. They result, for example, from the fact that the statementantibodies in the patient's blood against the yellow fever virus may not be due to the disease caused by this microorganism, but may be due to vaccination against yellow fever. In addition, it happens that a patient gets positive antibody results, but they are not really due to yellow fever - this situation is related to the possibility of cross-reactions, which detect antibodies against other viruses in the patient. from the familyFlaviviridae- e.g. anti-dengue immunoglobulins In addition to diagnostics aimed directly at detecting pathogenic yellow fever-related virus, patients may also be subject to other laboratory analyzes in which it is possible detection of deviations typical of yellow fever. These include:

  • disturbances in the number of white blood cells (in the initial period consisting in a decrease in the number of white blood cells, i.e. leukopenia, in the later stage of the disease leukocytosis, i.e. an increase in the number of leukocytes, appears)
  • factors of coagulation disorders (e.g. thrombocytopenia, APTT prolonged)
  • hyperbilirubinemia
  • markers of liver dysfunction (e.g. increased levels of liver enzymes such as ALT and AST in the blood)

Carrying out a thorough diagnosis in patients with suspected yellow fever is important because the disease must be differentiated from several other entities, such as viral hepatitis, malaria, typhoid fever or leptospirosis.

Yellow fever (yellow fever): treatment

As in the case of other diseases belonging to the group of hemorrhagic fever, there are no methods of causal treatment of this individual in the case of yellow fever. In patients suffering from yellow fever, symptomatic management is implemented, based on hydration of the patients, as well as administering painkillers and antipyretics (e.g. paracetamol). It should be emphasized here that in the treatment of yellow fever, non-steroidal anti-inflammatory drugs (NSAIDs) should be avoided - these preparations have an effect that reduces blood clotting and if the patient develops clotting problems, the use of NSAIDs could aggravate them.

Yellow fever (yellow fever): prognosis

Overall, the prognosis of most patients who develop yellow fever is good. In patients with mild disease, as already mentioned, their condition stabilizes after a few days of illness. In a situation where the patient experiences yellow fever, Fr.severe course, its prognosis becomes much worse - death occurs in 20 to even 50% of all people experiencing this form of yellow fever.

Yellow fever (yellow fever): prevention

Fortunately, it is possible to prevent yellow fever - the prevention of this individual is to vaccinate against yellow fever. Such vaccination is the most available in Poland and it is recommended for those who travel to regions of the world where yellow fever is reported.

When planning trips abroad, it is worth finding out whether the country to which we are going does not require travelers to undergo any vaccinations. This is the case, for example, in the case of yellow fever, as some countries (e.g. Burkina Faso and Senegal) have introduced the obligation to undergo yellow fever vaccination before traveling to their territory.

Sources:1. Mary T Busowski, Yellow Fever, Medscape; on-line access: http://emedicine.medscape.com/article/232244-overviewa12. WHO materials, on-line access: http://www.who.int/mediacentre/factsheets/fs100/en/3. CDC materials, on-line access: https://www.cdc.gov/yellowfever/index.html

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

Category:

Infectious diseases