Countries with endemic Mpox- Credit WHO
#17,804
Over the past 2 weeks we've looked at three separate reports (2 Risk Analyses, 1 EID Dispatch) on the explosion of Clade I Mpox cases in central Africa's DRC (> 12,000 cases & nearly 600 deaths in 2023), and the recent evidence of sexual transmission of the virus.
ECDC Risk Assessment On Transmission & Spread of Clade I Mpox From The DRC
Clade I Mpox (formerly Monkeypox) - which is endemic to central Africa (see map at top of post) - is far more severe than the Clade IIb Mpox virus which began its world tour in 2022. It appears more transmissible, can produce more disfiguring lesions, and is associated with a much higher fatality rate.
While we've seen no indication of international spread of the Clade I Mpox virus, the discovery of at least 2 clusters of sexual transmission (in MSM and sex workers) in the DRC raises concerns that - like Clade IIb - this more aggressive strain could eventually turn up outside of Africa.
Right now, it is mainly a theoretical concern, with the CDC stating: There is no known risk for Clade I MPVX in the United States at this time.
Earlier this week, the ECDC released a risk analysis where they said:`. . . the overall risk for MSM with multiple sexual partners stemming from this outbreak in the DRC is low. The overall risk for the general population is also assessed as low.
Yesterday the CDC issued a HAN Advisory - primarily for clinicians, healthcare personnel, state and local health departments, and testing labs - bring them up to speed on these recent developments. I've only posted some excerpts, so follow the link to read it in its entirety.
I'll have a bit more after the break.
Mpox Caused by Human-to-Human Transmission of Monkeypox Virus with Geographic Spread in the Democratic Republic of the Congo
Distributed via the CDC Health Alert Network
December 7, 2023, 10:45 AM ET
CDCHAN-00501
Summary
The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) Health Advisory to notify clinicians and health departments about the occurrence, geographic spread, and sexually associated human-to-human transmission of Clade I Monkeypox virus (MPXV) in the Democratic Republic of the Congo (DRC). MPXV has two distinct genetic clades (subtypes), and cases of Clade I MPXV have not been reported in the United States at this time (a clade is a broad grouping of viruses that has evolved over decades and is a genetic and clinically distinct group).
However, clinicians should be aware of the possibility of Clade I MPXV in travelers who have been in DRC. Clinicians should notify their state health department if they have a patient with mpox-like symptoms, which may include a diffuse rash and lymphadenopathy, and recent travel to DRC. Clinicians should also submit lesion specimens for clade-specific testing for these patients.
Vaccines (e.g., JYNNEOS, ACAM2000) and other medical countermeasures (e.g., tecovirimat, brincidofovir, and vaccinia immune globulin intravenous) are available and expected to be effective for both Clade I and Clade II MPXV infections. However, vaccination coverage in the United States remains low, with only one in four people who are eligible to receive the vaccine having received both doses of JYNNEOS. CDC recommends that clinicians encourage vaccination for patients who are eligible.
Background
MPXV has two distinct genetic clades (subtypes of MPXV), I and II, which are endemic to central and west Africa, respectively. Clade IIb MPXV has been associated with the 2022-23 global outbreak that has predominately affected gay, bisexual, and other men who have sex with men (MSM). Clade I MPXV is capable of human-to-human spread but has previously been associated with non-sexual routes of transmission; and Clade I has previously been observed to be more transmissible and to cause more severe infections than Clade II.
Since January 1, 2023, DRC has reported 12,569 suspected mpox cases (i.e., clinically diagnosed but not laboratory-confirmed) and 581 deaths (5% of suspected mpox cases). This is a substantial increase from the median 3,767 suspected mpox cases reported annually in DRC during the years 2016-2021. Clade I MPXV has been confirmed among cases for which testing was conducted. A recent World Health Organization (WHO) report noted that mpox cases in 2023 have been reported in more DRC provinces than in previous years (i.e., 22 of 26 provinces). This includes cases in urban settings where mpox does not normally occur (Kinshasa and South Kivu Province). In two provinces, outbreaks of Clade I MPXV associated with sexual contact, including among MSM, have been reported for the first time in DRC. Mpox vaccination is not generally available in DRC.
As part of surveillance for viral variants in the United States, CDC has tested a subset of positive MPXV or orthopoxvirus cases from commercial and state laboratories and performed clade-specific testing for 150 cases in 2023 (~12% of U.S. cases); no Clade I MPXV infections have been detected thus far. There are no direct commercial passenger flights from DRC to the United States, and the current threat for Clade I MPXV in travelers remains low. Clade II MPXV infections continue to occur in the United States. CDC encourages U.S. clinicians to continue to be alert for patients presenting with lesions consistent with mpox. Suspicion for Clade I MPXV should be high for people with travel to DRC within 21 days of illness onset, and clade-specific testing of MPXV should be performed in specimens from suspect mpox case-patients who report recent travel to DRC.
Most patients who have recovered from mpox (including infection with Clade II MPXV) or have been vaccinated with JYNNEOS or ACAM2000 are expected to have cross-protection to Clade I MPXV. However, clinicians are recommended to consider mpox as a possible diagnosis if a consistent clinical presentation occurs, even in those who are vaccinated or were previously diagnosed with mpox.
(SNIP)
Recommendations for the Public
There is no known risk for Clade I MPVX in the United States at this time. CDC continues to recommend people with risk factors for mpox be vaccinated with two doses of the JYNNEOS vaccine. If someone with risk factors for mpox has only received one dose, they should receive a second dose as soon as possible because two doses provide greater protection.
CDC has issued a Travel Health Notice for people traveling to DRC. People who have traveled to DRC should seek medical care at once if they develop a new, unexplained skin rash (lesions on any part of the body), with or without fever and chills, and avoid contact with others.
Small genetic changes could favor adaptation to a human host, and this potential is greatest for pathogens with moderate transmission rates (such as MPXV) (40). The ability to spread rapidly and efficiently from human to human could enhance spread by travelers to new regions.A 2016 study (see EID Journal: Extended H-2-H Transmission during a Monkeypox Outbreak) looked at a large 2013 outbreak of Monkeypox in the DRC and suggested that the virus's epidemiological characteristics may be changing (possibly due to the waning smallpox vaccine derived immunity in the community).
The DRC had reported a 600% increase in cases over both 2011, and 2012. The authors also cited a higher attack rate, longer chains of infection, and more pronounced community spread than have earlier reports.In 2017 Nigeria reported its first Monkeypox outbreak in nearly 40 years (clade II), and over the next 5 years we saw sporadic exported cases around the world (see here, here, here, and here).
We also looked at several cautionary reports - published before the 2022 outbreak - warning of the potential for Monkeypox to spread (including PLoS NTD: The Changing Epidemiology of Human Monkeypox—A potential threat?).
Earlier this year, in EID Journal: Monkeypox Virus Evolution before 2022 Outbreak, researchers suggested that` . . . the most likely scenario is that there has been silent and undetected circulation of MPXV, possibly including multiple non–MPXV-endemic countries outside Africa, since the 2017–2018 outbreak.'
Even though many voiced surprise when Mpox clade IIb began spreading internationally in 2022, we'd seen plenty of warning signs over the preceding decade. Most of which, were ignored.
While there are no guarantees that Clade I Mpox will follow suit, the warning signs are there. Just as they are for novel or avian flu, Lassa Fever, Nipah, MERS-CoV, and an increasing array of other emerging infectious diseases.
Nature is nothing, if not persistent.
And we continue to underestimate it at our own considerable peril.
