Mpox is a zoonotic infectious disease caused by the mpox virus, which affects humans and other mammals. It was first identified in monkeys in 1958 and in humans in the Democratic Republic of the Congo in 1970. The virus has two distinct strains: the Congo Basin (Central Africa) strain and the West African strain. There are three recognized variants of the virus: Clade Ia, present in the Congo Basin, with a mortality rate of up to 10%, transmitted mainly by rodents and with little spread among humans; Clade IIa, which occurs in West Africa, with low mortality; and Clade IIb, which caused the 2022 outbreak. The new variant, Clade Ib, appears to be spreading more easily through routine close contact, such as among children.
The virus is transmitted mainly through direct contact with skin lesions (even scabs) or contaminated objects, respiratory secretions from infected wild animals, and bodily fluids such as secretions and blood from people. Anyone who has had close physical contact with someone who is sick is at risk of contracting the disease.
Mpox is not limited to sexually active individuals. Newborns, children, and immunosuppressed individuals are at higher risk of more severe symptoms, and healthcare workers are at higher risk of acquiring the disease due to increased exposure to the virus.
When do symptoms appear?
Symptoms of Mpox appear between 3 and 16 days, and can reach 21 days, after contact with the virus.
The initial symptoms of the disease are nonspecific, such as malaise, fatigue, fever, headaches and myalgia . Swollen lymph nodes appear, mainly in the neck region, and skin lesions appear. These skin lesions may appear before or after the fever and are characterized by being blistered or flat, with clear or yellowish fluid inside the blistered lesions. They can occur anywhere on the body, including mucous membranes such as the mouth, eyes, sexual organs and anus. However, they tend to be more concentrated on the face, palms of the hands and soles of the feet. They develop into scabs, which are still considered infected, and are only no longer transmissible after they fall off.
Pregnant women infected with the virus can transmit the disease to the fetus through the placenta and, after birth, to the child through skin-to-skin contact. Once the disease is suspected, laboratory confirmation of the diagnosis is performed through molecular tests or genetic sequencing performed on secretions or crusts from skin lesions. The tests must be performed on all patients who meet the definition of a suspected case. The samples must be sent to reference laboratories by the State Central Laboratory (Lacen).
There is no specific treatment for the disease. Medical care is used to relieve pain and other symptoms and prevent long-term consequences. Some antivirals have been used as tecovirimat .
What is prevention like?
The main control measures are the isolation of patients and suspected cases, the tracking and monitoring of the patient’s close contacts and family members, as well as the use of personal protective equipment by patients and health professionals or caregivers of cases (such as the use of masks, since contagion can occur through the respiratory tract). In addition, scratching of lesions should be avoided to avoid secondary skin infections and the spread of the disease. To prevent Mpox, it is therefore necessary to redouble daily care, even the simple act of washing your hands constantly.
There are two vaccines against Mpox: Jynneos and Imvanex. Although the smallpox vaccine also provides protection against Mpox, it is not yet known whether it is effective against the new variant. The two specific vaccines are currently intended for adults aged 18 or over and for people diagnosed with HIV, immunosuppressed, who have had direct contact with bodily fluids and secretions of suspected or confirmed cases of the disease (post-exposure), as well as laboratory professionals who work directly with the virus. Anvisa renewed the exemption from registration of the two vaccines mentioned.
The WHO (World Health Organization) has declared a public health emergency of international concern due to continued outbreaks of Mpox in Central and West Africa, the increase in cases and the circulation of the new variant of the virus in that geographic region.
As of August 2024, the Africa Centers for Disease Control and Prevention reported an additional 17,000 suspected cases across the continent, surpassing the number recorded in 2023, bringing the total to 14,000 confirmed cases and 524 deaths. The variant has spread to several African countries, including those that had never reported cases of Mpox, and across borders.
In Brazil, data from the Ministry of Health indicate that, up to the present moment in 2024, 706 cases and 16 deaths have been reported. In December 2023, São Paulo had the highest number of notifications in the country: 427, approximately 51% of the cases among Brazilian states.
(Text written by AnalÃria Moraes Pimentel, pediatric infectious disease specialist – CRM: PE 3280 – RQE 2596 – RQE 13484)
This content was originally published in Mpox: specialist explains transmission, symptoms and prevention measures on the CNN Brasil website.
Source: CNN Brasil
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