How the spread of the virus can be limited

On May 9, the Ministry of Health in Singapore confirmed that a Nigerian who had arrived in the city on April 28 had the rare disease, monkeypox. The monkeypox virus is similar to human smallpox and belongs to the virus family Poxviridae. It is transmitted primarily through infected animals (rodents and primates). The man is suspected to have eaten bushmeat before arriving in Singapore, which could be the source of the virus.

Human-to-human transmission of monkeypox is possible but limited. The virus is transmitted to those in close contact through secretions of the respiratory tract and skin lesions. While the disease is largely self-limiting, in some cases it does cause complications leading to death. During monkeypox outbreaks, fatality varies from 1-10%, with most deaths seen in younger people.

The symptoms of monkeypox showed two days after the Nigerian arrived in Singapore, but he remained in his hotel till May 7. He was transferred to a public hospital on that day and tested positive for monkeypox the next day, when he was referred to the National Centre for Infectious Diseases, Singapore. According to the World Health Organization (WHO), he is now in a stable condition.

To limit the spread of the disease, Singapore has already identified 23 persons who were in close contact with the patient and offered smallpox vaccination. The WHO notes that prior smallpox vaccination is highly effective in preventing monkeypox. Data from Africa suggest that smallpox vaccine offers at least 85% protection against monkeypox if the vaccine is administered before exposure to the virus.

According to the Centers for Disease Control and Prevention, U.S., vaccination after exposure to monkeypox “may help prevent the disease or make it less severe”. In Singapore, at least 14 persons have been vaccinated. Close contacts have also been quarantined, while other contacts are under active surveillance.

Monkeypox occurs sporadically in Central and West Africa; cases have been reported from 10 African countries. It was first identified in humans in 1970 in the Democratic Republic of Congo, where the disease has now become endemic. There were three confirmed cases in 2016 from the Central African Republic. In late 2017, 61 laboratory-confirmed cases were reported from Nigeria. One confirmed case and 15 suspected cases were reported in 2018 from Cameroon. Outside Africa, the first case was reported from the U.S. in 2003. In 2018, monkeypox was documented in three people in the U.K. and in one person in Israel.

Since the majority of monkeypox virus transmissions to humans are from animals, the WHO advocates “restricting or banning the movement” of small mammals and monkeys from countries where the virus is prevalent to limit the spread of the virus.

The writer is the Science Editor of The Hindu