The monkeypox virus was first isolated and identified in 1958 from sick monkeys.
It was identified as a cause of human infection in the 1970s in the Democratic Republic of Congo in Africa. It is an endemic disease in certain parts of Africa.
The occurrence of clusters of monkeypox infection in several parts of the world where it is not endemic is now a public health concern.
The virus belongs to the same group (genus) as the virus that causes smallpox (variola virus) and the virus used in smallpox vaccine (vaccinia virus).
Under the microscope, the virus looks very similar to the variola and vaccinia viruses. These viruses also produce skin lesions that look the same. Smallpox has been eradicated through vaccination.
Transmission of monkeypox is through contact with an infected animal’s body fluids or through a bite. Human-to-human transmission also occurs through close contact with an infected person, through respiratory droplets, prolonged face-to-face interaction like within six feet for three hours or more, without personal protective equipment, or close contact with infected skin lesions.
Most cases of monkeypox in humans are mild, asymptomatic, and self-limited, meaning the illness resolves without medical intervention. The main treatment is supportive. If a person is dehydrated because of nausea, vomiting or loss of appetite, hydration is done. Bed rest and isolation are also observed.
Anti-viral drugs are considered in patients with severe disease and those who are at risk of developing severe disease like patients younger than eight years of age, pregnant or breastfeeding women, and patients on chemotherapy and other patients with very weak immune system. Anti-viral therapy may also be given if the monkeypox lesions are in the mouth, eyes or genital area.
Anti-viral drugs were approved for the treatment of smallpox based on animal studies and dose studies in healthy humans but are expected to have the same activity against human monkeypox. Hence, the use of these drugs in the treatment of monkeypox in humans is allowed but with strict supervision by experts.
Monotherapy with Tecovirimat is the treatment of choice. In July 2018, this drug which is available only through the United States Centers for Disease Control and Prevention was approved for the treatment of smallpox. It can be taken orally or is injected through a vein.
The duration of treatment is two weeks. Initial studies in humans showed that the drug is well tolerated. It reduced the period during which an infected patient sheds the virus (reduces spread of the virus) and shortened the duration of illness.
Another anti-viral agent Cidofovir has shown activity against monkeypox in laboratory studies and was shown to be effective against severe and deadly monkeypox in animal studies. There is still no clinical data showing its efficacy against monkeypox in humans.
Brincidofovir was approved in the U.S. for use in the treatment of smallpox. It can be taken orally but its availability for patient or clinical use is still not certain.
Data is limited regarding its use for the treatment of monkeypox in humans. In a clinical study, three patients who were given Brincidofovir 200 milligrams once weekly, treatment was discontinued because the patients’ blood tests showed signs of liver injury (elevated liver enzymes).
Prevention is through social distancing and avoidance of exposure to infected animals and infected humans. Prior smallpox vaccination protects against monkeypox infection.
Modified vaccinia ankara – trade names are Immune and Jynneos was approved in September 2019 for the prevention of smallpox and monkeypox.
Post-exposure vaccination or prophylaxis is also considered in close coordination with and under close supervision of public health and medical experts. Vaccination can be considered within four to 14 days after exposure.
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