The top way that monkeypox spreads is through prolonged skin-to-skin contact, especially when there are lesions, research finds.
Lesions are abnormal areas of skin that have been affected by disease or injury.
In monkeypox these can be rashes, scabs, pimples or bumps on the skin.
The other two main ways that monkeypox is spread is through touching contaminated objects and surfaces and by contact with respiratory secretions such as mucus.
However, simply brushing against someone or shaking their hand might not spread the virus.
Scientists are also not convinced that contaminated surfaces are strong vectors for the transmission of the virus.
Monkeypox has now spread to 90 different countries, with one-third of the cases occurring in the U.S..
Most cases have been among men who have sex with men, especially those who have more casual or anonymous sex.
Dr Michael Marks, co-author of a recent study on monkeypox, said:
“The more we understand about the monkeypox virus and how it spreads, the better we can diagnose and treat patients in order to get this outbreak under control.
One striking finding was that the viral load – the amount of virus present – was more than 1000 times higher in skin lesions than in lesions in the throat.
This, combined with the correlation between sexual contact type and location of lesions, suggests that transmission is most likely to have occurred by direct close contact during sex rather than through respiratory droplets.
This points to an increased risk of disease spread through sexual networks.”
The study examined 181 confirmed cases of monkeypox in Spain.
Skin-to-skin contact, mainly during sexual intercourse, emerged as the main method of transmission, certainly above airborne transmission.
Next researchers want to find out how the viral load changes over time, said Dr Marks:
“We now need to see how the viral load caries over time during the infection.
For example, whether the amount of virus in the throat is highest during early stages of illness, which could indicate how the risk of transmission may vary over the course of infection.”
The study was published in the journal The Lancet (Tarín-Vicente et al., 2022).