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Scientists confirm circulation of Mayaro virus in humans in Roraima; understand the risks


The circulation of this pathogen is usually limited to animals and forest areas; In people it causes a disease with symptoms similar to dengue and chikungunya

A study carried out at the State University of Campinas (Unicamp) confirmed the circulation of the Mayaro virus (known by the acronym MAYV) among humans in the State of Roraima. The virus, transmitted by wild mosquitoes, causes “mayaro fever”, a disease with symptoms similar to those of dengue and chikungunya: fever, muscle pain, fatigue, as well as pain and swelling in the joints. The discovery of circulation between people, including in the urban area of ​​Roraima, raises an alarm about the possibility of spread throughout the country.

The research involved several research institutes in Brazil and abroad. The discovery was made by biologist Julia Forato, under the guidance of Professor José Luiz Módena, of Unicamp, and biologist Fabiana Granja, of the Federal University of Roraima (UFRR). At the Central Public Health Laboratory in Roraima, between 2020 and 2021, researchers analyzed serum samples from more than 800 febrile patients. The analysis revealed the presence of mayaro in 3.4% of the people tested.

In Brazil, the detection of marayo has historically been recorded in the states of the northern region, such as Acre, Pará and Amazonas. In Roraima, until then, the virus had only been detected in wild animals, in transition zones between rural and urban areas. The results therefore seem to indicate that the virus is spreading in different areas of the region.

Worrying data

For Rafaela Vieira Bruno, director of the Laboratory of Molecular Biology of Insects of the Oswaldo Cruz Institute (IOC/Fiocruz), despite the small percentage, the research data already raise concerns. “We still have a relatively low rate, but it is already important to stay alert. It is necessary to take preventive measures before this spread occurs,” she proposes.

The work is surprising because the disease caused by the Mayaro virus is considered a wild zoonosis. This means that it is an infection that originates and circulates primarily between disease vectors, such as mosquitoes, and animals, such as primates, birds and rodents.

In wild zoonoses, as underlined by the Ministry of Health, humans are considered an “accidental host”, that is, someone who can become infected only when they frequent the natural habitat of infected hosts and vectors. Therefore, as researcher Módena, from Unicamp, points out, those who are normally exposed to the virus are people who work in activities within the forest, such as loggers and fishermen.

It turns out that, according to the study, some of the people who tested positive for the virus had not reported doing any work in forest areas.

Módena points out that other recent studies have shown great potential for the virus to spread. According to him, there are already reports of Mayaro detection in states such as Mato Grosso and Goiás. The researcher believes that the pathogen could reach the southern and southeastern regions in the coming years.

Possible transmission via urban mosquitoes

Considered an arbovirus, transmitted by mosquitoes, marayo has as its vector the Haemagogus janthinomys, a mosquito known to spread yellow fever. As we were saying, it is present in wild areas. Therefore, the contamination of people in the cities of Roraima (including the capital, Boa Vista), raises questions about the possibility that other mosquitoes, those that populate the cities, are already infected with mayaro and act as vectors – such as Aedes a Egypti, which transmits dengue fever.

“This virus could circulate in urban areas and eventually be transmitted by mosquitoes other than that one Emagagogue. We couldn’t know which one [mosquito] in this study, but I think it opens up the prospect of exploring this,” says Módena.

Rafaela also stresses that the prospect of the virus being transmitted by other vectors is very worrying and needs to be tested.

Health impacts

Mayaro fever is a difficult disease to diagnose, as it is easily confused with dengue and chikungunya. However, compared to dengue, its main difference is that it is more likely to cause chronic joint pain and inflammation (conditions called arthralgia and arthritis, respectively. The condition affects a large percentage of people with chikungunya.

Módena explains that the pain and swelling in the joints caused by the disease can become permanent in most people who become ill, affecting their quality of life. “Chronic arthritis is very debilitating. People may no longer be able to do their jobs because they are in so much pain,” she explains. According to the researcher, for this reason the spread of the disease can have a strong impact on health and the medical field, as well as an important long-term economic impact.

The disease also causes other symptoms that can affect the well-being of infected people. According to the Ministry of Health, the main ones are:

  • Fever: With sudden (sudden) onset and temperatures between 39°C and 40°C;
  • Pain: headache, muscles and joints
  • Joint swelling (joint edema): a symptom that affects approximately 20% of infected subjects. They mainly occur on the wrists, fingers, ankles, and feet;
  • Chills;
  • Pain behind the eyes;
  • General malaise: weakness, tiredness and indisposition;
  • Rash (exanthema): Red spots on the skin that usually appear after the fifth day of symptoms;
  • Nausea and vomit;
  • Diarrhea

The acute clinical picture can last from one to two weeks.

Prevention

According to the Ministry of Health, there is not yet a vaccine against the disease. Therefore, to prevent infection, the agency recommends measures to minimize contact with the wild vector (the mosquito), such as:

  • Avoid exposure in unprotected forest areas, during the period of greatest activity of the mosquito that transmits the disease (from 9:00 to 16:00);
  • Wear long, repellent clothing;
  • Use of mosquito nets, especially in rural and wild areas;
  • Avoid exposure to the affected area (with active transmission).

According to the agency, there is no specific cure for mayaro fever. In case of infection, patients should remain at rest, minimizing symptoms with medications to relieve pain and fever.

The role of environmental impacts

Another scenario Rafaela hypothesizes has to do with the possibility that mosquitoes typically found in wild areas are moving to urban areas.

The infectious disease specialist attributes this, and the entire process of spreading the virus, to environmental changes. “The fact that we’re dealing with a lot of climate change, a lot of deforestation and a lot of natural disasters means that these viruses are starting to spread and leave their region,” he explains.

Source: Terra

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