Why the latest mpox outbreak is raising alarm among health experts

An escalating mpox outbreak is causing alarm among some health experts, who warn that the latest strain of the virus could be more fast-spreading and deadly than an early 2022 outbreak.

The World Health Organization last week declared mpox a global public health emergency following the spread of an outbreak in the Democratic Republic of Congo (DRC) to neighboring countries.

Since the new outbreak, cases have been identified in countries where mpox is not endemic, such as Sweden, Pakistan and Thailand — although it’s unclear which strain has been identified in some of these nations.

Mpox is a viral infection which spreads through close contact and causes flu-like symptoms and lesions filled with pus. While usually mild, it can be fatal.

The WHO’s director for Europe, Dr. Hans Kluge, said Tuesday that the outbreak is “not the new Covid” and that it can be stopped with international cooperation.

But health experts have warned of the “many unknowns” surrounding the latest outbreak — and in particular a new subvariant — which could make it harder to contain.

“Clade 1b has recently emerged and there are many unknowns that need to be addressed,” said Trudie Lang, professor of global health research and director of The Global Health Network at the University of Oxford.

“There is emerging evidence of differences in transmission and symptoms; such as more commonly passed person to person and from mothers to their babies in pregnancy,” she said.

There are broadly two types of of mpox, known as clades, with the latest outbreak identified as clade 1. Compared with the 2022 strain, clade 2, the current strain, appears to spread more easily and has a higher fatality rate.

A newly identified clade 1b subvariant has been found to be particularly prevalent among young people and appears to be spreading through sexual networks, Jonas Albarnaz, a research fellow specializing in poxviruses at The Pirbright Institute, said.

However, he noted more data is needed to understand its transmission dynamics and to “inform the control strategies.”

Clade 1 is already known for causing more severe disease in young children, pregnant women and immunocompromised people. That has hastened the outbreak in countries where certain health conditions are more prevalent and those with poorer health-care systems.

“As mpox disease is more severe in immunocompromised individuals, it is also a concern that the current outbreak is taking place in a region where HIV prevalence is relatively high but access to antiretroviral drugs is poor,” said Brian Ferguson, associate professor of immunology at the University of Cambridge.

Ongoing conflicts in parts of Africa — such as the DRC, where a large number of displaced people have relocated to refugee camps — have also worsened sanitation…