A new and potentially more dangerous strain of mpox, known as ‘clade Ib’, has emerged in the Democratic Republic of Congo, raising serious concerns about a potential global health crisis. This strain, discovered in April 2023, is distinct from the one that caused the 2022 mpox outbreak, which primarily affected men who have sex with men. The new clade Ib strain exhibits different transmission patterns, spreading primarily through heterosexual contact, particularly among sex workers, who account for roughly 30% of recorded cases. It is also causing higher fatality rates, with approximately 5% of adults and 10% of children succumbing to the infection.
Unlike the previous mpox strain, which was primarily spread through close contact during sexual encounters, the new clade Ib strain is exhibiting unusual transmission patterns. Researchers have observed household transmission, as well as an outbreak in a school in Congo. This suggests that close non-sexual contact may also be a significant transmission route. Furthermore, the new strain is affecting women and men equally and has been reported to cause miscarriages.
The concerning aspect of the new strain is its increased efficiency in human-to-human transmission. Researchers believe the virus has mutated to become more transmissible, prompting worries about its potential for wider spread. With cases detected in towns near national borders, and sex workers from Rwanda and Uganda, a group known for its mobility, having been infected, the risk of international spread appears high. The dry season, which usually coincides with increased migration, further exacerbates these concerns, making it only a matter of time before the virus reaches neighboring countries and potentially spreads worldwide through close contact at international airports.
In response to this growing threat, the Africa Centres for Disease Control and Prevention have called for increased surveillance and contact tracing efforts. Some experts advocate for deploying the smallpox vaccine among high-risk groups, such as sex workers and healthcare workers, as it has been shown to offer cross-protection against mpox. However, the effectiveness of the smallpox vaccine against this new strain remains unknown. While uncertainties exist, Professor Trudie Lang, a global health research expert at the University of Oxford, suggests that the vaccine is safe, easy to use, and worth trying. Additionally, trials are underway for an antiviral drug called tecovirimat, with results expected next year.
The situation in the region is further complicated by ongoing war, displacement, and food insecurity, making containment efforts even more challenging. The likelihood of asymptomatic cases, where individuals are unaware of their infection but can still transmit the virus, adds another layer of complexity. Professor Lang highlights this, along with the prevalence of mild cases, as the biggest unknowns in the current outbreak.
To prevent this new mpox strain from escalating into a global health crisis, swift and coordinated action is crucial. Increased surveillance, contact tracing, and potentially the use of vaccines are essential to mitigating the spread of this potentially dangerous virus. The world must act decisively and collaboratively to contain the threat posed by this new strain before it becomes another global health emergency.
