The Democratic Republic of the Congo in Africa is in the midst of an mpox outbreak that has led to nearly 600 deaths, according to the World Health Organization. Unlike last year's global outbreak, this one involves a different type of mpox virus, known as Clade I, which causes more severe illness.
On December 7, the U.S. Centers for Disease Control and Prevention issued a health advisory alerting clinicians and health departments to be aware of the possibility of Clade I mpox in travelers who have been to the DRC, although no such cases have been reported in the United States so far. The CDC now recommends routine mpox vaccination for men who have sex with men, transgender people, and others at risk, even when an outbreak is not underway.
The DRC outbreak underscores the need for mpox vaccines and treatment worldwide, officials noted. Although widely available in the United States, they are not yet accessible in Africa.
"These tools are available and can't be limited only to wealthy countries. We need to do better," said Dr. Boghuma Titanji of Emory University in Georgia.
DRC outbreak
Mpox virus has two known types, Clade I, endemic in the Congo Basin region, and Clade II, endemic in West Africa. Last year's global outbreak, which was first identified in the United Kingdom in May 2022, involved Clade II. The virus soon spread rapidly among gay and bisexual men in European and U.S. cities.
That outbreak has declined dramatically, though sporadic clusters are still being reported. As of November 30, the CDC has identified 31,277 mpox cases in the United States, resulting in 55 deaths. WHO has tallied nearly 92,000 cases and more than 160 deaths worldwide, not including the ongoing DRC outbreak.
Prior to the global outbreak, mpox was historically known as an uncommon disease in western and central Africa, where it largely affected children. It was often associated with contact with wild animals and was not thought to spread easily between people. This changed with a 2017 Clade II mpox outbreak in Nigeria, in which most of those affected were men and sexual transmission appeared to play a key role.
The DRC did not report any cases during last year's Clade II outbreak, but a Clade I outbreak started there earlier this year. More than 12,500 suspected cases (meaning clinically diagnosed but not necessarily confirmed by laboratory testing) have been identified so far and — for the first time — this mpox strain also appears to be spreading via sex.
In March, a man tested positive for Clade I mpox in Kenge, a city about 100 miles east of the capital Kinshasa, after traveling in Europe, the WHO report stated. In the DRC, the man visited discreetly operated underground clubs frequented by gay men. While homosexuality is not illegal there, it is highly stigmatized. He reported sexual contact with six men and three women, and these individuals identified an additional 36 sexual contacts. Ultimately, four men and one woman tested positive for mpox.
In August, mpox cases were confirmed for the first time in Kinshasa. Four separate events were identified in which people exposed in other provinces traveled to the city, leading to local transmission clusters. In September, an outbreak in an eastern province grew to 80 suspected cases, including 20 sex workers. Overall, the DRC has reported 12,569 suspected Clade I mpox cases through mid-November, but due to limited access to diagnostics, only 1,106 received PCR tests, with 714 testing positive.
"This event is unusual and highlights the risk that [mpox virus] Clade I could also widely spread among sexual networks, as seen for Clade II during the 2022-23 global outbreak," the authors of the WHO report wrote. "The risk of mpox further spreading to neighboring countries and worldwide appears to be significant."
The DRC outbreak has led to 581 deaths, for a case fatality rate of 4.6%. In contrast, last year's global Clade II outbreak had a case fatality rate of only about 0.2%. The high death rate is likely attributable in part to Clade I mpox, which is known to cause more serious illness. Poorer health status and lack of access to care may also be a factor.
During last year's Clade II outbreak, people with advanced HIV were more prone to severe mpox complications and had a high mortality rate, although this was not the case for HIV-positive people with an adequate CD4 T-cell count. In the United States, around 40% of people diagnosed with mpox were living with HIV, but HIV-positive people accounted for more than 80% of those hospitalized, and most of the 55 people who died were Black gay men with AIDS.
The WHO report did not state whether the DRC mpox patients were HIV-positive or immunocompromised, but the country has a high rate of HIV among men who have sex with men and, due to the limited availability of care, many may be unaware of their status and remain untreated.
Vaccines recommended
Currently, there is no evidence that Clade I mpox is circulating outside central Africa. This strain has not been reported in the United States, and the CDC considers the threat to be low. But last year's global outbreak shows the potential for mpox to spread widely, especially within sexual networks of highly mobile gay and bisexual men.
The Jynneos vaccine and antivirals for mpox treatment are expected to be effective for both Clade I and Clade II virus, according to the CDC. What's more, a prior bout of Clade II mpox should provide some immunity that lessens the risk of Clade I infection and severe illness.
The CDC recommends that everyone at risk should receive two doses of the vaccine, regardless of whether an mpox outbreak is currently underway. Yet vaccination coverage remains low in the United States, with only one out of four people who are eligible having received both doses.
San Francisco has done considerably better. As the Bay Area Reporter previously reported, about 40% of people living with HIV and 65% of people on PrEP have received an mpox vaccine. However, a majority of city residents who recently contracted mpox were not fully vaccinated. Vaccine doses should be given at least 28 days apart, but if someone received their first dose months ago, they can still get the second one.
The San Francisco Department of Public Health recommends the vaccine for men, trans people and nonbinary people who have sex with members of the same groups, people living with HIV, people with recent sexually transmitted infections, people on PrEP, sex workers, and people who have had or expect to have sex with partners in any of these groups. In addition, because there is no vaccine shortage now, anyone who wants protection from mpox may receive it with no need to prove eligibility.
Unfortunately, this is not the case in the DRC, which currently faces the greatest threat from mpox.
"I am still able to offer vaccines for mpox at my clinic in Atlanta, although our case numbers have decreased dramatically in recent months," Titanji said. "Health care providers in the DRC should be able to do the same for communities there facing a far more deadly outbreak of the disease. It is shameful that this is still a debate after the global outbreak of mpox, which was an emergency when wealthy Western countries were affected."
For information about mpox vaccines in San Francisco, click here.
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