Sexual contact remains most common route of mpox exposure

Key takeaways:

• Mpox can spread multiple ways, but sexual contact remains the most common route of transmission.
• Better outreach and communication on prevention strategies may prevent some cases.

Mpox can spread a variety of ways — including through close face-to-face and skin-to-skin contact — but sexual activity remains the most common route of exposure, new study findings suggest.

The 2022 mpox outbreak disproportionately affected gay, bisexual and other men who have sex with men, but roughly one-third of patients did not report male-to-male sexual contact (MMSC), J. Danielle Sharpe, PhD, MS, an Epidemic Intelligence Service officer in the CDC’s Division of Global HIV and TB, and colleagues reported in MMWR.

Since the start of the outbreak, there have been more than 89,000 mpox cases reported globally, including nearly 31,000 cases and 50 deaths in the United States, according to the CDC.

WHO ended its global public health emergency for mpox in May after a 90% decline in cases over the previous 3 months.

Although the outbreak mostly affected people reporting MMSC, data showed a significant number of cases in cisgender women, children and men who do not report MMSC.

“Although a small proportion of mpox patients did not report MMSC, possible mpox exposures among these patients involved exposures or other behaviors know to potentially transmit Monkeypox virus, including sexual activity other than MMSC or other close skin-to-skin contact,” Sharpe and colleagues wrote in the study.

They analyzed data on 932 mpox cases reported to the CDC between Nov. 1, 2022, and Dec. 14, 2022, from six jurisdictions in the U.S. The researchers excluded patients without mpox, patients for whom MMSC was reported or could not be ruled out, or patients who were missing all exposure data for their diagnosis, leaving 52 mpox cases for further analysis.

Of the 52, the median age was 36 years and half were non-Hispanic Black or African-American. Additionally, 62% of the patients were cisgender men, 29% were cisgender women and 6% were transgender women.

Among 45 people who reported sexual orientation, 67% were heterosexual, 16% were gay or lesbian and 13% were bisexual.

Nearly all patients with available information reported having a rash during the infection, including nearly half who reported the rash started on their genitals. The legs, arms and trunk were the next most common areas where rashes started.

Eight patients had HIV and just three who were eligible for the vaccine received more than one dose of it.

The researchers found that 14 patients had a known exposure to somebody with mpox. Among them, eight reported sexual activity or other close intimate contact and six reported household contact.

Sharpe and colleagues described a household cluster linked to a cisgender heterosexual man who was arrested and detained in a jail cell with at least one person with mpox lesions on their arms, whom he shared a water fountain, bench and toilet with for 5 days. Upon returning home, he had sex with his female partner, and an adult woman and pre-school aged child later tested positive for mpox.

Two other cases outlined in the study included a property manager exposed to an mpox-positive client, and a source exposure at an indoor bar or restaurant without skin-to-skin contact or sharing of food or drinks.

Overall, however, 73% of cases included in the study had “no known exposure to a person with suspected or confirmed mpox,” the researchers wrote. Among those people, nearly half (45%) reported recent sexual activity and other close intimate contact, 37% reported close face-to-face contact, 29% reported attending a large social gathering, and 26% reported being in an occupational setting that involves close skin-to-skin contact.

“These findings suggest that sexual activity remains an important route of mpox exposure among patients who do not report MMSC,” Sharpe and colleagues wrote.

They suggested improving outreach and recommendations for people who either do not report MMSC or live in a household with somebody who has been diagnosed with mpox, including an emphasis on hand hygiene, adhering to cleaning and disinfection guidelines and avoiding touching potentially contaminated surfaces or sharing personal items such as bedding, clothing, towels or utensils.

Additionally, they wrote that people who do not engage in MMSC but live in a household with a person diagnosed or potentially exposed to mpox should consider vaccination, which has been shown to significantly decrease risk for the infection.

“The household mpox cluster described in this report involving three transmission events and possible transmission via contaminated household objects and surfaces underscores the need for public health agencies to consider outreach and mpox transmission prevention education for patients in household settings,” the researchers wrote.

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