New Mpox Clade 1b worrying, can spread via physical contact, raise mortality rate

New Delhi: The new Clade 1b strain of Mpox (previously known as Monkeypox) is worrying as it can easily spread between people with just physical contact, and result in increased mortality rate even among children, said infectious disease experts on Monday.

Currently, confined to the Democratic Republic of Congo (DRC) in Central Africa, the new strain is different from the Mpox clade 2b that caused a global outbreak in 2022, consisting of 94,707 confirmed cases in 107 countries.

“The DRC has been seeing such endemic cases for a long time. Mpox clade 1 type which is more lethal and more prominent, has been there for decades. But now it has become more transmissible because of new variations, that is clade 1b,” infectious disease expert Dr. Ishwar Gilada, told IANS.

“Unlike Clade 1, the new strain Clade 1b, estimated to have jumped to humans around September 2023, has a high mortality rate and is not limited to men who have sex with men (MSM),” added Dr Rajeev Jayadevan, co-chairman of the Indian Medical Association’s National Covid-19 Task Force.

According to scientists from the University of Oxford in the UK, Clade 1B has a mortality rate of 5 per cent in adults and 10 per cent in children.

The new clade can affect men and women without sexual contact; and children; as well as cause miscarriages and stillbirths, they noted.

“The new strain of Mpox is worrying precisely because it may transmit more easily between people than the earlier strain,” Gautam Menon, Dean of Research and Professor of Physics and Biology, at Ashoka University told IANS.

Meanwhile, the Africa CDC reported an overall mortality rate of 6.7 per cent from 4,488 cases of suspected Mpox in 2024 in the DRC.

Seventy per cent of cases and 88 per cent of the total deaths were among children below 15. However, it is not known whether all of these cases were due to the new clade 1b strain or from the original clade 1 strain, Dr Rajeev told IANS.

“Estimating the true mortality rate is difficult because not all cases will be reported or counted. Another problem with the clade 1 strain of Mpox is that it can be confused with chickenpox, a common infection. Recent research conducted on doctors demonstrated difficulty in differentiating the two simply by looking at the lesions. Thus, there could be inaccuracies in the number of reported cases,” Dr Rajeev explained.

There are no indications yet of the spread of this new clade 1b strain in other countries.

But “if global travel carries this new strain to other parts of the world, person-to-person transmission could occur through sexual or physical contact or both. If that happens, the pattern of spread will be different from the 2022 outbreak, where women and children were not significantly affected,” Dr. Rajeev said.

“Until such data becomes available, there is no obvious risk to India at this time,” he added.

Yet, Dr. Ishwar, also Secretary General, People’s Health Organization-India, called for increasing vigilance with whole genome sequencing.

“There should be some kind of guidelines. We do not have any such case of Mpox currently in India, but we should be vigilant and we should keep on watching the global scenario,” he said.

Dr Gautam said that there are vaccines for Mpox and the virus fortunately “mutates more slowly than the virus causing Covid-19 and it still appears relatively hard to transmit. We should be watchful at this time but no more stringent measures are called for at this moment."