533 Mpox first skin lesion location: A reflection of mode of transmission?

Document Type

Conference Proceeding

Publication Date


Publication Title

Journal Of Investigative Dermatology


The 2022 mpox outbreak affected 84,318 individuals in 110 countries. Mpox is transmitted by multiple modalities, including direct contact, respiratory droplets, and fomites among others. Identifying skin lesions aids prompt diagnosis. Variation in initial skin lesion location is not well understood; it is hypothesized that mode of transmission may determine primary inoculation site and subsequent clinical presentation. This study sourced healthcare provider-reported data from the AAD/ILDS Dermatology COVID-19, Mpox, and Emerging Infections Registry to explore factors related to the location of the first skin lesion in mpox cases. Out 119 mpox cases,115 had primary lesion location data. 97% were male with a median age of 37. Most (83/115, 72%) patients had first skin lesions in the genito-anal area, and 32/115 (27%) had lesions elsewhere or had morbilliform rash. 74% of males had the first lesion in the genito-anal region compared to females (25%, p=0.03). Males in same-sex relationships had ano-genital lesions more often than men in other relationships (77% vs. 44%, p=0.03). The type of mpox exposure was also associated with first lesion location: 83% of patients who contracted mpox from a spouse or other sexual contact had ano-genital lesions as compared to a non-sexual contact (0%, p=<0.01). This analysis characterized factors associated with the first mpox skin lesion location, which can aid healthcare providers in diagnosis and shed light on transmission. This data suggests that type of exposure and mode of transmission may be associated with primary lesion location; patients who contracted mpox from sexual contact were more likely to have ano-genital lesions.





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