Photo: Different forms of the mpox virus particles shown under the microscope. (NIAID)
Understanding the resurgence of mpox
Jamie Hansen
September 12, 2024
Mpox has returned as a significant global health concern in recent months.
A relative of smallpox, mpox (formerly called monkeypox) has circulated in Central and West African countries for decades. In the last few years, a new offshoot of the virus emerged which spread more readily through close person-to-person contact.
In the summer of 2022, the World Health Organization declared mpox a "public health emergency of international concern" as it quickly spread through countries where it had not been seen before -- mainly via sexual contact between men. By May of 2023, cases had declined globally, and the WHO's declaration ended. While cases continued to occur in smaller numbers, the disease became endemic and was contained through public health measures.
Now, a new subtype, known as clade 1b, is spreading rapidly through Central and East Africa, prompting the WHO on Aug. 4 to once again declare it a public health emergency of international concern.
Abraar Karan, MD, a postdoctoral scholar of infectious diseases at Stanford Medicine, has been involved in public health response and research related to mpox since 2022. He helped the Department of Public Health for Los Angeles County, a hotspot at the time, track cases in vulnerable populations, and he has researched the virus's clinical presentations with colleagues at Stanford Medicine.
He emphasized the situation's dynamic nature as the virus evolves and as epidemiologists and health officials evaluate the risk posed by this new subtype.
"What the (new) clade 1b mpox outbreak is today, it won't be next week. This is a quickly and constantly changing situation," said Karan, who is affiliated with the Stanford Center for Innovation in Global Health.
Now is a critical time for health systems to prepare for mpox cases and to support African countries in mitigating its spread, he said. He discussed what we know and how the global health community can respond to the evolving challenge. This interview has been edited for length and clarity.
What concerns you about the mpox resurgence?
People have likely heard that a global emergency was declared. That's because a new version of the virus, which began circulating in late 2023 but was restricted to the Democratic Republic of Congo, has started spreading to nearby countries such as Burundi, Rwanda and Kenya.
The mpox virus is generally categorized into "clades," which are groupings of the virus that can include multiple strains. Clade 1 was known as the Congo Basin clade and mainly caused outbreaks in the Congo and other countries in the region for which it is named. Clade 1 viruses tend to cause more severe disease than the second grouping of viruses, known as clade 2, or the West African clade. Clade 2b, a subtype of this second grouping, caused the 2022 mpox pandemic.
Now, clade 1b has emerged and appears to be spreading with more casual contact, including in women and children. Consistent with other clade 1 viruses, it also seems to have a higher fatality rate than clade 2b, although it is difficult to assess the magnitude of this. We need more epidemiological data to fully understand the risks.
This summer's shift from a confined setting to intercountry spread caused major concern that something may have changed in terms of the virus's transmissibility, or that certain social factors -- such as sexual exposures involving female sex workers in a mining town -- may have amplified the virus's spread.
How great a public health risk does mpox pose globally?
The recent emergency declaration is meant to address the threat early so it doesn't become something worse. For people traumatized by COVID-19 and mpox in 2022, this news may bring up fears that mpox could create yet another pandemic, especially if it were to transmit more effectively between people.
But this is a different situation. Some people are concerned about airborne transmission, but this has been documented very rarely. A recent paper from the CDC looked at what happened when 113 infectious mpox patients traveled on commercial flights and found that none of the more than 1,000 contacts they followed were infected. Based on what we know today, mpox still spreads primarily through close physical contact, often sexual contact, and sometimes through contaminated objects such as blankets and needles.
Currently, this new strain has not been detected in the United States. At the same time, it's very likely we'll eventually see cases of clade 1b in the U.S, and it's important for clinicians and public health officials to be prepared.
What are the biggest challenges clinical systems face, and what can clinicians do?
While many clinicians may be familiar with the version of mpox we saw in 2022, the average health care provider may not be aware that there's a different clade to watch out for. This clade can affect populations beyond men who have sex with men and transmit more easily -- we may see cases in children and heterosexual adults. Health departments need to educate health care providers by providing information on the variability of mpox lesions and other symptoms -- and particularly how this clade differs from the earlier one.
The commonly used mpox tests may not effectively differentiate between clade 1b and 2b. Clinicians should alert the health department when they have a suspected case so they can do further testing. We need to watch for the introduction of clade 1b so we can understand epidemiologically how someone got it and respond with surveillance and other public health measures.
During the 2022-23 outbreak, we saw that many of the first Bay Area cases were detected in urgent care settings. We need to ensure that frontline providers in urgent care settings, in particular, understand there is a new outbreak and to be on the lookout for cases.
What tools are available to prevent and treat the virus?
Effective vaccines exist, but have been slow to arrive in Africa despite recent donations by multiple countries. Regulatory bottlenecks at the World Health Organization have seriously delayed the mpox vaccine used in the U.S. and Europe from reaching the DRC, and the first batch of 200,000 doses jut began arriving in the DRC on Sept. 5. The recent emergency declaration and a new, joint-continental response plan between the African CDC and WHO could help expedite the process of delivering the millions of needed vaccines.
Some antiviral medications, such as Tecovirimat and Brincidofovir, are available under the Food and Drug Administration's emergency use authorization, but we need more data on how effective they are -- especially against this new sub-clade. A recent placebo-controlled randomized trial indicated that Tecovirimat does not significantly improve symptoms in clade 1 infections. However, further investigations may help us understand if other factors, like how soon the drug is started, could make it more effective.
What did you learn from working on the L.A. County response, and what lessons can be applied here?
We saw that the people who became the sickest and died were those not adequately cared for in our health system. Lots of communicable diseases tend to spread well in crowded settings, especially where people lack access to high-quality health care or face other health-related challenges such as drug use, homelessness or poorly controlled HIV. That's what we saw with mpox. Treating vulnerable people was also more challenging: For instance, the antivirals must be taken with high-calorie meals, which can be difficult for those in unstable living situations. It underscored how important strong public health systems and social supports are for controlling epidemics.
What else do we need to know about mpox?
We're dealing with complex biological systems that are constantly changing. The virus is evolving to respond to evolutionary pressure and has complex hosts -- us. The public can expect health guidance and news about the virus to change as the situation evolves, and that's a good thing.
Contact
Lisa Kim
Senior Manager, Media Relations
Stanford Health Care | School of Medicine
Office of Communications
office: 650.723.6696 cell: 650.346.4454
email: likim@stanfordhealthcare.org
Source: SCOPE - Stanford Medicine - Stanford University
https://scopeblog.stanford.edu/2024/09/12/mpox-new-form-global-emergency/
"Reproduced with permission - "Stanford Medine - Stanford University "
Stanford Medine - Stanford University
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