Pride events are scheduled around the world over the next few weeks, and U.S. authorities say the infectious disease, formerly known as monkeypox, will affect tens of thousands of gay and bisexual men around the world in 2022. , preparing for the recurrence of mpox. A combination of behavioral changes and vaccination brought the outbreak under control. However, the majority of people at risk have not yet been vaccinated.
On Thursday, the Centers for Disease Control and Prevention warned of a more deadly form of mpox that is rampant in the Democratic Republic of the Congo, and urged people at risk to get vaccinated as soon as possible. So far, no cases of that subtype have been identified outside of Africa. But experts said the outbreak in Congo remains a global threat, just as the outbreak in Nigeria triggered the 2022 outbreak.
Anne Rimoine, an epidemiologist at the University of California, Los Angeles, said: “This shows that infection can potentially be transmitted anywhere, and why we need to continually improve disease surveillance globally. “This is a very important example of what happens.”
Dr. Limoian has been studying mpox in Congo for more than 20 years and first warned of its potential for global spread in 2010.
The CDC is focused on encouraging Americans who are most at risk to get vaccinated before the virus spreads again. The agency's advocacy efforts include working with advocacy groups and social media influencers with broad appeal among the LGBTQ community. In December, the agency urged clinicians to remain vigilant about possible infection among travelers from Congo.
There are two main types of mpox. Clade I is the dominant type in Congo, and the other clade II is the type that caused his 2022 pandemic. (A clade is a genetically and clinically distinct group of viruses.) Both clades have been circulating in Africa for decades, causing sporadic outbreaks.
People with smallpox may develop a fever, severe headache, and back pain followed by a rash. Many patients also develop painful ulcers, often at the site of infection. People with weakened immune systems, including people with HIV, are at the highest risk of severe illness and death.
The version of mpox that caused the 2022 outbreak is called clade IIb and caused more than 30,000 cases in the United States that year. The epidemic subsided in 2023 with only about 1,700 people infected, but it is now showing signs of a resurgence. The number of cases in the U.S. this year is almost double what it was at this time last year.
In Congo, as of April 14, there have been approximately 20,000 infections and 1,000 deaths from clade I viruses since January 2023. The mortality rate for clade I infections is approximately 5%, compared to less than 0.2% for clade IIb.
More than three-quarters of deaths associated with clade I mpox in the Congo were in children younger than 15 years.
Even if a more lethal clade were to emerge in the United States, American children would be less likely to be exposed to mpox and less vulnerable than Congolese children, experts say.
Most infections among Congolese children are thought to result from direct contact with infected animals such as monkeys, prairie dogs, squirrels, and shrews, or from ingesting contaminated bush meat. Children live in crowded households and may have poorer overall health.
The country is plagued by armed conflict, flooding, poverty, malnutrition and multiple infectious diseases such as cholera, measles and polio.
“There are simply differences in the way people live in the Democratic Republic of Congo that are likely facilitating the spread of infection among children,” said Dr. Jennifer McQuiston, deputy director of the CDC's Division of High Impact Pathogens. Stated.
Adult cases in Congo are also thought to be caused by interaction with infected animals or close and sustained contact with infected persons. But last year, for the first time, scientists discovered sexually transmitted clade I mpox among male and female sex workers and their contacts.
In an outbreak in the Congolese mining town of Camituga, heterosexual prostitution in bars appears to have been the main mode of transmission. Genetic analysis revealed that at some point around September, the virus mutated, allowing it to spread more easily between people.
Erasmus Medical Center virologist Marion Koopmans said the outbreak appears to be the second separate outbreak in the country caused by a new version of the virus called clade Ib, with cases occurring in young men and women. He said it was almost evenly divided. Rotterdam, Netherlands.
“I think there are multiple epidemics going on, but it's important to continue to assess what that means,” Dr. Koopmans said. She said it “cannot be assumed” that all forms of mpox behave the same way.
The development also alarms scientists, as miners and sex workers in the region are temporary and could carry the virus to neighboring countries such as Rwanda, Burundi, Uganda and Tanzania. .
In many of these countries, access to testing, vaccines and treatments is limited, giving the virus ample opportunity to multiply and evolve. The majority of mpox cases are diagnosed based on symptoms alone.
Some countries rely on tests that detect only clade I or only clade IIb. Recent research suggests that these tests may not detect his Clade Ib, a new version that appeared in September.
Following the findings, the World Health Organization warned countries to reconsider their testing procedures and “make sure they don't miss a diagnosis,” said Dr. Rosamund Lewis, who heads the WHO's mpox response.
In the United States, tests approved by the Food and Drug Administration detect all versions of mpox but cannot differentiate between them. If that test yields a positive result, more specific tests that can identify the clade should be done, Dr. McQuiston said.
At least so far, the available vaccines and antiviral drugs are expected to be effective against all forms of the virus. The 2022 outbreak began in Europe in May and gained momentum during Pride Month in June and then in the United States.
Early in the outbreak, there was a shortage of the two-dose mpox vaccine called Jynneos. But many gay and bisexual men are used to heeding public health messages about HIV, refraining from sexual activity, and helping to reduce the number of infections even before a vaccine was widely available. .
But the decline in numbers may have created a false sense of security.
“This created a sense of complacency that people didn't need to continue to worry, and we saw vaccination rates drop rapidly,” said Dr. Bogma Titanji, a virologist and infectious disease physician at Emory University. Stated.
Dr. Titanzi said vaccination is important for long-term control of the virus because behavioral changes are difficult to maintain.
An analysis of 16 studies conducted last month found that two doses of the vaccine are more powerful than one, up to 90 per cent effective. Even if the vaccine did not prevent infection, it did reduce the severity and duration of the disease.
Still, fewer than 1 in 4 at-risk Americans have received both doses.
“We've continued to saturate the space with messaging, but uptake hasn't really changed that much,” Dr. McQuiston said, suggesting a need for more creative approaches.
In 2022, the vaccine was only available in the United States through federal agencies, but it was plagued by shipping issues and availability was limited. It is now commercially available. The WHO, which recommends vaccines for African countries, has been slow to approve them and has not even started the approval process.
Still, the WHO's Advisory Group on Immunization recommends that when a vaccine is available, it can be used to protect adults and children at risk of mpox, Dr. Lewis said. .
In addition to preparing mpox's return to the United States, the CDC is supporting Congo's efforts to obtain vaccines and treatments to contain the outbreak.
“It's much better to help get this outbreak under control before it spreads to other regions and becomes a more global risk,” Dr. McQuiston said. “And ethically, it's the right thing to do.”