Mpox virus transmissible from mother to child during pregnancy

The Clade Ib variant of the mpox virus, which spreads through skin and sexual contact, can also be transmitted from mother to unborn child via the placenta. This has been revealed by research conducted by the Congolese National Institute for Biomedical Research (INRB) and the Institute of Tropical Medicine (ITM) in Antwerp. The transmission can lead to serious pregnancy complications, including miscarriage and stillbirth.

• This is the first evidence of mother-to-child transmission of the Clade Ib variant.
• The infection can lead to miscarriage, stillbirth or mpox in newborns.
• Targeted vaccination and treatment are needed to better protect pregnant women and their children in outbreak areas.

In the study, the scientists examined three pregnant women, each in a different trimester of their pregnancy, who became infected with the Clade Ib variant of the mpox virus during the recent outbreak in the Democratic Republic of Congo (DRC).

‘In all three women, the virus infected the foetus via the placenta,’ says Professor Laurens Liesenborghs, an expert in emerging infectious diseases at ITM. ’The infection led to a miscarriage, a stillbirth and, in one case, a newborn with mpox. We found lesions on the face and body of both the stillborn baby  and the newborn.’

Mpox had previously been linked to pregnancy complications, but evidence of mother-to-child transmission had been limited until now. This study adds mpox to the list of viruses that can affect the foetus, such as the rubella virus (which causes rubella), the varicella virus (which causes chickenpox) and the Zika virus.

This has important consequences, because in the current outbreak of the Clade Ib variant in the DRC, which is mainly spread through sexual contact, young women are very often infected. This increases the number of infections among pregnant women.

Professor Placide Mbala-Kingebeni, head of the Epidemiology and Global Health Department at the INRB, emphasises the urgency: ‘Every day, women are at risk of infection. We must take urgent action to better protect them and, in the event of pregnancy, their unborn children. It is also crucial to contain the outbreak in large parts of the DRC, including Kinshasa. Vaccination and safe, effective treatments are urgently needed.