Monkey pox. Understanding transmission, symptoms and the vaccine

The incubation time of the virus ranges from 5 to 21 days. The most characteristic symptom is the appearance of painful rashes and nodules on the skin.

The World Health Organization (WHO) declared monkey disease a public health emergency of international concern six days ago. Known internationally as monkeypox, the disease, which is endemic in parts of Africa, has already infected 20,637 people in 77 countries this year.

There are already 978 cases in Brazil, of which 744 are in Sao Paulo alone. Considering the importance of information to fight the progress of the outbreak, the Federal University of Rio de Janeiro (UFRJ) held a meeting this Thursday (28) where experts presented what is already known about the disease, as well as answering questions from the participants themselves. and online.

“We know this virus and we know how to deal with it. We have all the elements to eradicate it,” said Dr. Amilkar Tanuri, coordinator of the UFRJ’s molecular virology laboratory and consultant to the Ministry of Health.

According to him, since there are already many studies on monkeys, it is a different situation from Covid-19, which emerged as a new disease. However, the researcher warns that success in fighting the outbreak will depend on the commitment of public authorities.

Monkeypox is caused by a poxvirus of the orthopoxvirus subgroup, as well as other diseases such as vaccinia, cowpox, and chickenpox, which were eradicated by vaccination in the 1980s. The endemic pattern of the African continent is due to two different strains.

One of them, which is considered more dangerous because the mortality rate reaches 10%, is present in the Congo basin region. Another, with a mortality rate of 1% to 3%, was found in West Africa and is the one that caused the current outbreak.

However, according to the doctor, the virus in circulation has undergone a genetic rearrangement that has contributed to its ability to be transmitted around the world. “He had a disruptive evolution. He has undergone a drastic mutation.’ The researcher noted that serious cases are not repeated. The greatest concern concerns at-risk groups, which include immunocompromised children, children over 13 kg and pregnant women.


“The mortality rate is related to the local health system. No deaths have been reported outside endemic areas in the current outbreak. This shows that the monkeypox virus has a low mortality rate,” says virologist Clarissa Damaso, head of the Laboratory of Molecular Biology of Viruses at the UFRJ and WHO advisor.

Transmission and symptoms

The monkey was first described in humans in 1958. At that time the monkeys were also infected and they died. Hence the name of the disease. However, in the cycle of transmission, they become victims just like humans. In nature, wild rodents represent the animal reservoir of the virus.

“There are no described reservoirs in places outside of Africa. One of the biggest concerns in the current outbreak is preventing the virus from finding a reservoir in other countries. If that happens, containment will be much more difficult,” Clarissa assured.

Without an animal reservoir, worldwide transmission has occurred from person to person. Infection occurs from the patient’s wounds, body fluids and droplets. This can occur through close and prolonged contact without respiratory protection, contact with contaminated objects or skin, including sexual contact.


The incubation time of the virus ranges from 5 to 21 days. The most characteristic symptom is the appearance of painful rashes and nodules on the skin. Fever, chills, headache, muscle aches and weakness are also possible.

“The injuries are deep, the edge is well defined and there is progress. it starts as a red spot that we call a macula, it rises to become a papule, it becomes a pustule or pustule, and finally it ruptures, forms. the gut,” explained infectious disease expert Rafael Galliez, a professor at the UFRJ School of Medicine.

According to the WHO protocol, cases in which a patient has at least one skin lesion on any part of the body and meets one of these requirements in the last 21 days should be considered suspicious; travelers who have been in that country or intimate contact with strangers.

diagnosis and treatment

UFRJ’s molecular laboratory of virology has been established as one of the national centers for disease diagnosis. The first case in the state of Rio de Janeiro was detected on June 14, five days after the country’s first case was confirmed in São Paulo. After that, 117 positive results were registered in the state of Rio. Other states have also sent samples to the UFRJ for analysis.


These tests are performed directly on fluids collected from skin lesions using a swab. [cotonete estéril] dry It is expected that the population will soon have access to rapid antigen detection tests similar to those done for Covid-19.

Even in the most typical cases, research is important to confirm the clinical diagnosis. A challenge in detecting the disease is the similarity of its lesions to those caused by smallpox, a disease known as smallpox and caused by a different group of viruses. The change in symptom profile has also raised alarm from experts. Monkey eruptions tended to appear more or less together and progress at the same rate.

“We began to see solitary lesions, sometimes in the genital or rectal area, sometimes on the lip, sometimes on the hand. And we also see lesions appearing at different times, more like chicken pox. This pattern is different from what was studied about monkeys,” said Rafael, an infectious disease specialist.


Once diagnosed, treatment relies on clinical support and medication to relieve pain and fever. An antiviral drug called Tecovirimat, which blocks the spread of the virus, is already in use in some countries but is not yet available in Brazil.


According to the doctor, 10% of patients are hospitalized for pain control, usually when there are lesions of the anus, genitals, or oral mucosa that make swallowing difficult.

Prevention and vaccinations

Surveillance for rapid detection of new cases and isolation of those infected is essential to prevent the spread of the disease. It may take up to 40 days to resume social activities. Even if the patient feels better, he should continue as long as he has a rash. “With chicken pox, the crusted lesion no longer transmits the virus. In the case of monkey pox, this disease is transmitted,” emphasized Raphael.

The epidemiologist warned about the importance of avoiding contact with people belonging to risk groups. According to him, although there are few case studies involving pregnant women, the results are not good. “Child mortality is high. There is what we call vertical transmission, ie fetal involvement with serious damage: loss of placental structures and spontaneous abortions. From what little is known, it is considered a serious obstetric disease. Those suspected of being infected should be instructed to avoid contact with anyone who may be pregnant,” he warned.

UFRJ experts also noted that condom use does not prevent infection, as intense contact during intercourse and the exchange of bodily fluids provide several opportunities for the transmission of the virus. On the other hand, there are indications that people vaccinated against smallpox have protection against monkeys.

The immune system is also known to develop cross-protection against different orthopoxviruses. This means that anyone who has already been infected with, for example, smallpox or vaccinia, is likely to have immunity against the monkey. Based on this knowledge, the smallpox vaccine was created. Although aimed at fighting smallpox, which exclusively affected humans and had a high fatality rate of 30% to 40%, the immunizer was developed from vaccinia virus, a disease that commonly infects mammals and mammals.

With the eradication of smallpox, vaccination was suspended worldwide around 1980. In Brazil, stronger campaigns took place by 1975, but by 1979 the immunization was administered in health centers. Evidence shows that anyone born before that date and vaccinated is protected against mumps. The average age of the infected is below 38 years.

Although vaccines already exist to help combat monkeypox outbreaks, there is no provision for a mass vaccination campaign.

WHO leads the protection of health professionals and laboratory researchers. For other population groups, immunization should be administered after exposure. According to virologist Clarissa, it is about using a ring vaccination strategy. people who live with and have been in contact with a positive patient are vaccinated to try to block the spread of the virus. “This vaccine works very well after four days of infection,” he noted.

Clarissa adds that currently there is no vaccine for everyone and global production will take time. “Manufacturers did not have a production forecast for a disease that would affect the entire world. Production was exclusively for strategic stockpiles in countries with biodefense programs. Brazil, like many other nations, does not have that,” he explained. According to Raphael, studies have already shown the effectiveness of the ring vaccination strategy in certain outbreak scenarios.

Infection profile

The overwhelming majority of those infected are men under 40 years of age. Studies in the UK have shown that many victims self-identify as gay or bisexual. Experts warn, however, that monkeypox can affect anyone, not just sexually active men. In women and adolescents, this disease has already been diagnosed by the molecular laboratory of virology of the UFRJ.

WHO Director-General Tedros Adhanom Ghebreyesus this week advised men who have sex with men to reduce the number of sexual partners they have for now. At the same time, it warned that “stigma and discrimination can be as dangerous as any virus and can fuel an outbreak.”

According to Dr. Amilkar Tanuri, misinformation can leave the public unprepared to fight the outbreak. “This goes back to the history of AIDS and HIV. At first, there was a stigma that only hindered the prevention of the disease. This is because once a virus enters an initial group, it takes some time for it to spread to other groups. This is how HIV started. Then it turned out that hemophiliacs have HIV, children were born with HIV. There is no biological evidence that the monkeypox virus is sexually transmitted. Actually, I don’t know which virus has this feature,” he concluded.

According to Agência Brasil

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