As concerns mount about a type of mpox spreading across Africa that’s believed to cause more serious illness, infectious disease experts expressed cautious optimism that this branch of the virus would not spread as broadly in the U.S. or cause health impacts as severe.
The risk of this subtype of mpox to the U.S. could be mitigated by a number of factors, including immunity from vaccination and previous infection from the outbreak of a different variant that began in 2022; the lack of viral circulation in wild animals; and better health care access, living standards and public health.
On Wednesday, the World Health Organization reinstated the status of mpox (formerly monkeypox) as a public health emergency of international concern. This was in response to a large ongoing outbreak of clade I of mpox — a clade is an evolutionary branch — in the Democratic Republic of Congo, or DRC, that has spread to other African nations.
Clade I is generally considered more transmissible and more severe than clade II, which drove the global mpox outbreak that peaked in August 2022 and had a death rate of 0.2%. Immunocompromised people, in particular those with untreated, advanced HIV, have been at greatest risk of severe disease, hospitalization and death from clade II. The U.S. continues to see low-level clade II transmission.
Throughout the now-low-level clade II outbreak, mpox has overwhelmingly spread through sex between men. The CDC continues to urge men with multiple male partners to receive both Jynneos doses. Only an estimated 1 in 4 of those considered at significant risk of mpox in the U.S. have been fully vaccinated.
The DRC outbreak has seen substantial sexual transmission of clade I among both gay men and female sex workers. Children, however, have accounted for two-thirds of the approximately 20,000 suspected cases and three-quarters of the 975 suspected deaths in the DRC since January 2023, according to the CDC.
It’s possible that recent documented mutations in the virus may have made it more transmissible. Rimoin said close physical contact — whether sexual or nonsexual household contact — likely remains largely necessary for transmission.
People in rural DRC also likely contract mpox from an unknown wild animal host, perhaps a rodent. No animals in the U.S. are believed to carry the virus.
Differences in sexual behavior between gay men and heterosexuals in the U.S. might continue to limit mpox’s spread among the wider American population, Dr. Jeffrey Klausner, an infectious disease expert at the University of Southern California, said in an interview.
Unlike with heterosexuals, the overall population of gay and bisexual men has within it a smaller group that engages in behaviors that can sustain an mpox outbreak outside of Africa, Klausner wrote in a commentary in The Lancet Microbe on Aug. 7.
Klausner argued that infectious disease researchers have underestimated the rate of natural immunity from previous infection. For now, a combination of natural and vaccine-induced immunity, he argued, is sufficient among those engaging in sexual behavior patterns most likely to transmit mpox to largely prevent a substantial outbreak.
Obey
Article URL : https://www.nbcnews.com/health/health-news/new-mpox-threat-cause-significant-harm-us-rcna166937