The danger from the most dangerous strain of monkeypox

The new virus, called clade Ib, was first detected in a remote part of the Democratic Republic of Congo in September 2023, spreading to towns along the Rwandan border, near Burundi and Uganda.

Experts are concerned that clade Ib could cause a global outbreak, but they are not yet warning of a pandemic.

“The pandemic question is very difficult to answer. But I think we have to be really vigilant now and act to stop this as quickly as possible in the region,” Trudie Lang, director of the Global Health Network at the University of Oxford, UK, said at a press conference on June 25.

John Claude Udahemuka, a lecturer at the University of Rwanda, said the new strain of monkeypox was “the most dangerous of all known versions of the virus”, which can cause miscarriage and blindness.

New virus strain spreads easily

Monkeypox is spread through close contact, especially skin-to-skin contact. It can cause flu-like symptoms, with a painful, itchy rash that develops into pus-filled blisters and lesions that eventually crust over.

The earlier strains had limited transmission. Clade I was usually transmitted within households. Clade IIb has spread globally, primarily through sexual contact and affecting men who have sex with men. The new Ib strain is transmitted through both routes.

According to researchers, it initially spread sexually, through the local prostitution industry. In later stages, the virus circulated within households, between mothers and children. There were even cases of person-to-person transmission outside the household and without sexual contact.

Professor Lang said this was “really worrying”, because the virus was more likely to spread in the community than previous strains, and could even be transmitted via flights.

Clade I of the virus, where the new strain originated, also has a higher mortality rate than clade II. According to the WHO, some outbreaks have killed up to 10% of patients, compared to 1% for the older strain.

Tip of the iceberg

Leandre Murhula Masirika, health coordinator in Congo, said about 8,600 cases of monkeypox have been identified in the country since the beginning of the year, including 410 deaths.

“These are severe cases requiring hospitalization, so they are the tip of the iceberg,” Lang said.

Last week, Rosamund Lewis, head of the WHO’s monkeypox technical expert group, also warned of the urgency of handling cases in Africa.

Researchers say they need to understand more about the virus to determine the right safety measures and vaccines to prevent its spread. Scientists need to learn more about serology and immunology to propose a vaccine, Murhula Masirika said. In the meantime, he wants to vaccinate sex workers and local health workers in the hope of reducing the spread of the virus.

WHO said that from 2021-2023, the world recorded 92,000 infections and 167 deaths from monkeypox, mainly related to men who have sex with men and people with multiple sexual partners.

Initial cases were concentrated in the United States and several European countries, prompting the United Nations health agency to declare a public health emergency of international concern. This status was lifted in May 2022.

Vietnam detected its first monkeypox case in October 2022. By early this year, the Ministry of Health had recorded more than 68 monkeypox cases, 6 deaths, most of whom had a history of HIV infection. Since then, localities have still recorded sporadic cases of monkeypox.