As pride events are planned around the world in the coming weeks, U.S. officials are preparing for a return of mpox, the infectious disease formerly called monkeypox that has struck tens of thousands of gay and bisexual men worldwide in 2022. A combination of behavioral changes and vaccination has suppressed this epidemic. , but the majority of people at risk have not yet been vaccinated.
The Centers for Disease Control and Prevention on Thursday warned of a deadlier version of mpox ravaging the Democratic Republic of Congo and urged those at risk to get vaccinated as soon as possible. No cases of this subtype have been identified so far outside Africa. But Congo’s intensifying outbreak nevertheless poses a global threat, just as infections in Nigeria sparked the 2022 outbreak, experts say.
“This is a very important example of how an infection anywhere is potentially an infection everywhere, and why we must continue to improve disease surveillance globally,” said Anne Rimoin, epidemiologist at the University of California, Los Angeles.
Dr. Rimoin has studied mpox in Congo for more than 20 years and first warned of its potential for global spread in 2010.
The CDC is working to encourage Americans most at risk to get vaccinated before the virus resurgence. The agency’s outreach efforts include working with advocacy groups and social media influencers who have broad appeal within the LGBTQ community. In December, the agency urged clinicians to remain vigilant for possible cases in travelers from Congo.
There are two main types of mpox: Clade I, the dominant type in Congo, and Clade II, a version of which caused the 2022 global outbreak. (A clade is a genetically and clinically distinct group of viruses.) two clades have been circulating in Africa for decades, sporadically triggering epidemics.
People with mpox may have a fever, severe headache, and back pain, followed by a rash. Many patients also develop painful sores, often at the site of the infection. People with weakened immune systems, including those living with HIV, are most likely to become seriously ill and die.
The version of mpox that caused the 2022 outbreak, called Clade IIb, resulted in more than 30,000 cases in the United States that year. The epidemic subsided in 2023 with only about 1,700 cases, but is now showing signs of resurgence: the number of cases in the United States this year is almost double that of last year at this time.
In Congo, as of April 14, the Clade I virus has resulted in approximately 20,000 cases and nearly 1,000 deaths since January 2023. Clade I infection results in mortality of approximately 5 percent, compared to less than 0.2 percent. percent for Clade IIb.
More than three-quarters of deaths in Congo linked to Clade Impox concern children under 15 years old.
Even if the deadliest cluster were to emerge in the United States, American children would be less likely to be exposed to mpox and less vulnerable than those in Congo, experts say.
Most cases in children in Congo are thought to result from direct contact with infected animals such as monkeys, prairie dogs, squirrels and shrews, or from eating contaminated bush meat. Children may live in overcrowded households and be generally in poor health.
The country is troubled by armed conflict, flooding, poverty, malnutrition and multiple infectious diseases, including cholera, measles and polio.
“There’s just a difference in life in the DRC that likely favors higher spread among children,” said Dr. Jennifer McQuiston, deputy director of the Division of High-Consequence Pathogens at the CDC.
In Congo, adult cases have also been attributed to interactions with infected animals or close, sustained contact with infected people. But last year, for the first time, scientists discovered sexual transmission of Clade Impox among male and female sex workers and their contacts.
In an outbreak in Kamituga, a mining town in Congo, heterosexual prostitution in bars appeared to be the main form of transmission. Genetic analysis showed that around September, the virus had acquired mutations, allowing it to spread more easily among humans.
This chain of transmission appears to be a second distinct outbreak in the country, caused by a new version of the virus called Clade Ib, with cases split evenly between young men and young women, said Marion Koopmans, a virologist at the medical center. Erasmus from Rotterdam, Netherlands.
“I think there is more than one outbreak going on, and it’s important to continue to evaluate what that means,” Dr. Koopmans said. “We can’t assume” that all forms of mpox behave the same way, she said.
The development also alarmed scientists because minors and sex workers in the region are transient and could carry the virus to the neighboring countries of Rwanda, Burundi, Uganda and Tanzania.
In many of these countries, limited access to tests, vaccines and treatments gives the virus ample opportunity to thrive and evolve. A large majority of cases of mpox are diagnosed based on symptoms alone.
Some countries rely on tests that detect only Clade I or only Clade IIb. These tests may not detect Clade Ib, the new version that appeared in September, according to a recent study.
The finding prompted the World Health Organization to warn countries to review their testing procedures “and make sure they’re not missing a diagnosis,” said Dr. Rosamund Lewis, who leads the mpox response. the WHO.
In the United States, a test approved by the Food and Drug Administration detects all versions of mpox but cannot distinguish them. A positive result on this test should be followed by more specific tests to identify the clade, Dr. McQuiston said.
So far at least, available vaccines and antiviral drugs should be effective against all forms of the virus. The 2022 outbreak began in Europe in May and accelerated in the United States during Pride Month in June and thereafter.
Early in the outbreak, there was a shortage of the two-dose mpox vaccine, called Jynneos. But many gay and bisexual men, accustomed to heeding public health messages about HIV, curbed their sexual activity, precipitating a decline in cases even before vaccines were widely available.
However, the falling numbers may have created a false sense of security.
“A sense of complacency set in that it wasn’t really something that people had to continually worry about, and we saw those vaccination rates decline rapidly,” said virologist Dr. Boghuma Titanji. and an infectious disease physician at Emory University.
Behavioral changes are difficult to maintain, so vaccination is important for long-term control of the virus, Dr. Titanji said.
Two vaccine doses are more potent than one, with up to 90 percent effectiveness, according to an analysis conducted last month of 16 studies. Even when the vaccine did not prevent infections, it lessened the severity and duration of illness.
Yet fewer than one in four at-risk Americans have received two doses.
“We’ve continued to saturate the space with messaging, and adoption isn’t really changing that much,” Dr. McQuiston said, suggesting the need for more creative approaches.
In 2022, the vaccine was only available in the United States through federal agencies and faced delivery issues, limiting its availability; it is now commercially available. The WHO, which recommends vaccines to African countries, has been slow to approve them and has not even started the approval process.
Nonetheless, the WHO advisory group on immunization has recommended that, where available, the vaccine can be used to protect adults and children at risk of pox, Dr Lewis said.
In addition to preparing for the return of mpox to the United States, the CDC is supporting Congo’s efforts to obtain vaccines and medicines and contain the outbreak.
“It is best to help them bring this outbreak under control before it spreads to other regions and becomes a global risk,” Dr. McQuiston said. “And, ethically, it’s the right thing to do.”
News Source : www.nytimes.com
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