If you travel to South America or visit some African countries, you should be vaccinated against yellow fever in good time. The yellow fever virus is transmitted by mosquitoes and can be fatal, but the vaccine provides reliable protection against the disease. Yellow fever is notifiable in Germany. Everything important about the disease can be found here.
Transmission of yellow fever
Especially monkeys, but also snakes, birds and bats belong to their actual victims. The little mosquito Aedes aegypti infects these animals with the yellow fever virus during their blood meal. But humans are also stung and infected by the mosquito.
Most workers then find it in the wooded outskirts of the jungle in a number of countries in tropical Africa south of the Sahara and tropical South America, such as the Amazon. It is they who, on their return to the cities and villages, transfer the virus to other mosquitoes of this genus.
If the mosquito stings more people, the yellow fever virus spread epidemic-like in cities.
Yellow fever mosquito as a carrier of the disease
According to the World Health Organization (WHO), around 200, 000 yellow fever infections and around 60, 000 deaths each year are caused by the approximately 3, 000 mosquito species known worldwide (status: 2016).
At their sting, the viruses quickly enter the bloodstream and attack the phagocytes (macrophages) of the lymph nodes, spleen, liver and bone marrow. Here they multiply and get into the blood - for two to four days - and are then transferable via stitches.
Symptoms and course of yellow fever
The yellow fever virus belongs to the Flaviviruses. This family also includes the dengue virus and the hepatitis C virus. In it is the Latin word flavus - yellow, because it also comes to a yellowing (jaundice) of the skin and eyes. The cause is an increase in the concentration of the blood breakdown product bilirubin in the body. It results from the breakdown of red blood cells, a process that takes place constantly in the spleen, bone marrow and liver.
The incubation period lasts three to six days. Here, in the first phase of the illness, the following symptoms occur, which can disappear after three to four days:
- Headache and body aches
- Nausea and vomiting
These symptoms are similar to a "normal" infection and are not always taken seriously.
Subsequently, but only in about 15 percent of those infected, the second phase with high fever and internal and external bleeding, which ends in 20 percent of those affected deadly.
What is the prognosis for yellow fever?
By surviving the infectious disease, which usually heals without consequential damage, there is a lifelong immunity. The lethality of clinically observed cases is between 10 and 50 percent, with the highest mortality between 20 and 30 years.
Treatment of yellow fever
There is no drug for the virus. Only the complaints can be alleviated. In unfavorable course, the patient usually dies within the second week.
The last known death in Germany was, according to the Robert Koch Institute (RKI) 1999 - a man who had traveled the Ivory Coast and was not vaccinated.
The origin of yellow fever
The first yellow fever outbreaks of the New World are documented in 1648 by the peninsula of Yucatan (Mexico) and Havana (Cuba). Since then, numerous epidemics have occurred in Central and South America.
From England also the name "Yellow Jack" comes from yellow fever. Yellow fever patients were outfitted with yellow jackets and a yellow flag was raised above the quarantine area.
Vaccination against yellow fever
Although there has been a highly effective vaccine against yellow fever for decades, WHO has seen an increasing number of infected people in Africa and South America. The vaccine was developed in 1937 by the South African physician and scientist Max Theiler and is one of the best and safest vaccines. In 1951, Theiler received the Nobel Prize for his research.
The vaccine consists of attenuated, reproducible yellow fever viruses. 0.5 ml of the vaccine is injected under the skin - almost always in the upper arm.
A vaccination is already possible from the 6th month of life (according to WHO recommendation from the ninth month of life). The vaccine protection begins about ten days after the vaccination and lasts at least ten years. WHO even expects lifelong protection. The antibodies are detectable in 96 percent of the vaccinated.
Side effects of yellow fever vaccination
The vaccine against yellow fever is well tolerated, only allergic to chicken protein should inform the doctor before vaccination. Pregnant women and those infected with HIV, immunocompromised patients as well as patients who have just been vaccinated against other diseases should seek medical advice. For over-60s, the risk of serious side effects is increased.
The RKI has evaluations of yellow fever tolerance over a period of more than 35 years; after administration of more than 2.3 million doses, only 20 vaccine complications are described. According to the WHO, between 0.4 and 0.8 out of every 100, 000 vaccinees suffer from liver, kidney or nervous system damage.
The RKI recommends dispensing with alcohol for a week after the yellow fever vaccination and avoiding major sports efforts as well as sauna and solarium visits.
Typical vaccine reactions such as fatigue, fatigue, mild temperature rise, and redness at the site of injection are reported in five to ten percent of the vaccinees.
Do not forget the vaccination certificate
The vaccination is registered in the vaccination certificate - this is important for entry or transit in the countries affected by yellow fever. In South America, these include Bolivia, Brazil, Ecuador, Colombia and Peru, and in Burkina Faso, Ghana, Kenya and Nigeria. Inform yourself in good time before departure necessarily over the current regulations of the respective country.
The yellow fever vaccine belongs to the international travel vaccinations; it is only available to vaccination centers or certain vaccine doctors and is strongly recommended for the affected areas.