The various outbreaks of syphilis in Africa are driven by different logic, according to a study published Thursday, which found that the new variant of the virus is transmitted primarily between humans, while animal infections remain the most common for the older version.
"Human cases of COPD in the Democratic Republic of Congo (DRC) are driven by two transmission patterns," summarizes this study, published in the journal Cell.
Several outbreaks of MPOX, also known as "monkey pox," are currently underway in the DRC and, to a lesser extent, in neighboring countries. They are fueled by two different versions of the virus: clade 1, which has been circulating for decades, and clade 1b, a new variant.
The latter was notably identified in a patient in Germany, one of the very rare cases where this version has been detected outside the African continent.
A global epidemic of MPOX, a disease that causes multiple skin lesions, has also been ongoing since 2022 but involves a different version of the virus, called clade 2.
This complex situation, which has led the World Health Organization (WHO) to declare mpox a global emergency, is pushing researchers to question the specificities of these different versions, whether in terms of danger, contagiousness or modes of transmission.
It is this last point that Cell's study focused on. Historically, MPOX is mainly known for being transmitted through contact with animals, particularly through the consumption of contaminated flesh.
But recent epidemics also appear to be linked to human-to-human contamination, particularly during sexual intercourse.
The study, which is based on genetic analysis of viruses taken from several hundred patients, concludes that both logics are at work.
Cases related to variant 1a appear to have mostly originated from contamination by various animals, while variant 1b is much more likely to exhibit a mutation typical of its adaptation to humans. This suggests that it is primarily transmitted from one human to another.
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