SINGAPORE – There was a spate of mpox cases in Singapore in the last four months of 2023, with 25 of the total 32 cases last year diagnosed from September to December.

Twenty of all the cases were locally transmitted, although not all sources of infection are known, said a Ministry of Health (MOH) spokesman. He said the “majority” of the 12 imported cases were local residents who had travelled to countries in South America and South-east Asia.

Of the known local transmissions, one case was linked to an imported case, and two cases were linked to an earlier local unlinked case. Both clusters are now closed, as there have been no new cases linked to them for the last 42 days, or two incubation periods. There were no family clusters, and the rest of the cases were unlinked.

Monkeypox was renamed mpox in Singapore in February 2023, in line with World Health Organisation guidelines that aim to avoid the stigma linked to the original name.

The MOH spokesman said: “Globally, there has been an increase in mpox cases, and Singapore is also seeing an increase in cases locally.”

Professor Paul Tambyah, a senior consultant in infectious diseases at the National University Hospital, speaking in his capacity as president of the International Society for Infectious Diseases, said: “We are in line with the rest of East and South-east Asia in that the mpox peak is a bit later than in Europe and the Americas, according to the World Health Organisation (WHO) data available.”

In October 2023, WHO recorded 668 cases from 29 countries; the following month, there were 906 cases from 26 countries.

Professor Hsu Li Yang, vice-dean for global health at the NUS Saw Swee Hock School of Public Health, said that although the mpox case count is still very low, the number of local transmissions with unknown sources “certainly could represent low-level endemicity in Singapore”. If that is the case, mpox infections will continue to emerge.

Singapore made the viral disease a reportable disease in mid-2022 following a global outbreak when the disease appeared in many countries where it is not endemic, including Europe, the United States and Australia, unlike in Africa where it originated.

Singapore recorded 18 cases in 2022 since reporting of the disease started at the end of June that year.

On July 23, 2022, WHO declared the outbreak of mpox to be a public health emergency of international concern, its highest available alarm. This is the seventh outbreak so designated by WHO since 2005. The one before this was Covid-19.

Although usually mild, mpox can prove fatal for some.

There are two clades, or groups of organisms. According to the US Centres for Disease Control and Prevention, mortality rate for Clade I (from Congo) is 10 per cent, while that for Clade II (from West Africa) is less than 1 per cent.

MOH said all the reported cases in Singapore were Clade II.

The disease can spread through exposure to respiratory droplets or direct physical contact with the blood, body fluid or lesion material from infected individuals or contaminated materials. So it can be transmitted when people talk to each other, or through any form of kissing or sex.

Mpox typically starts with a fever, muscle aches and sore throat, followed by a rash that begins on the face and spreads over the body, extending to the palms of the hands and soles of the feet, and evolves over two to four weeks in stages – macules, papules, vesicles, pustules. “Lesions dip in the centre before crusting over,” WHO said.

The rash can be both itchy and painful. Treatment is usually to alleviate symptoms, as the disease is often self-limiting. Antiviral medication may be used in more serious cases.

According to WHO, complications from mpox can cause serious illness and include pneumonia; corneal infection with loss of vision; pain or difficulty swallowing, vomiting and diarrhoea causing severe dehydration or malnutrition; sepsis (infection of the blood with a widespread inflammatory response in the body); inflammation of the brain, heart, rectum, genital organs or urinary passages; or death. 

The MOH spokesman said that anyone who has mpox symptoms should seek medical care early.

He added that the risk of mpox infection to the public remains low, “as the predominant route of disease transmission is through close physical contact, including intimate or sexual contact, with an infected person or contaminated materials”.