Yellow fever in Brazil: outbreaks caused by two mosquitoes

A survey by the Oswaldo Cruz Institute revealed that mosquitoes of the species Haemagogus leucocelaenus and Haemagogus janthinomys are responsible for the recent outbreaks of yellow fever in Brazil.

Both species were found in large quantities in cities in Rio de Janeiro, Minas Gerais and Espírito Santo. They are associated with cases of wild yellow fever , unlike the urban type, generally associated with aedes aegypti ( dengue mosquito ).

The identification allows to study the regions that have the presence of these species and thus to predict possible outbreaks in the future.

The study analyzed almost 18,000 insects between 2015 and 2018 and was published in the scientific journal Emerging Microbes & Infections .

Between 2016 and 2018, approximately 2,000 cases of yellow fever were registered in Brazil and 700 people died. The outbreak was strongest in the Atlantic rainforest region that had not registered the disease since the 1940s.

Understand yellow fever

Yellow fever is a viral disease transmitted by the bite of infected mosquitoes in humans.

The main symptoms are high fever and jaundice (or yellowing, hence the name). In addition to these, headache , nausea, weakness and body pain can also be indicative of the disease.

Symptoms can take up to 6 days to appear after contact with the virus.

When experiencing any suspicious signs, it is important to seek medical help for the correct diagnosis.

Urban or wild?

Yellow fever is divided into two types, according to the region of transmission:

  • Yellow Urban Fever (FAB) : is transmitted in an urban area. In Brazil, there has been no record of yellow fever transmission in large cities since 1943, according to the Ministry of Health.
  • Yellow Wild Fever (FAS) : is transmitted in rural areas, mainly in places close to rivers and forests. FAS can be transmitted to monkeys and other primates in addition to humans.

Vaccine is offered by SUS

Yellow fever is a disease that has a vaccine.

The first dose of the vaccine can be taken from 9 months of age. Babies between 9 and 6 months can receive immunization with a prescription. However, children under 6 months cannot be vaccinated.

Vaccination against yellow fever is distributed free of charge by the Unified Health System (SUS), and can be taken in basic health units throughout the country.

The vaccine takes about 10 days to take effect. A single dose is sufficient for total immunization against the disease.


Yellow fever is a disease that, in more severe cases, can kill. If you live in rural areas or travel to areas at risk, get the vaccine.

Presenting the symptoms and, if in doubt, consult a doctor.

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