San Franciso Reports First Clade I Monkeypox Case
Meanwhile, a wastewater sample in Oahu, Hawaii has tested positive for the Clade I virus.
Last month, my colleague Mary Chastain reported that the New York City Health Department announced the city’s first case of the severe monkeypox strain, Clade 1.
I have been following the spread of this particular virus for some time. Clade I mpox is a more severe strain of the mpox virus endemic to Central Africa, associated with higher fatality rates (up to 10% historically) than Clade II. It includes sub-clades Ia (associated with animal-to-human transmission) and Ib (linked to recent, more rapid sexual transmission).
Now, a case is being reported in San Francisco.
San Francisco has confirmed its first case of clade I mpox in an unvaccinated adult who was in contact with someone who had traveled internationally. https://t.co/LOYgg3wXsE
— San Francisco Chronicle (@sfchronicle) April 16, 2026
On April 14, 2026, the first clade I mpox case in San Francisco (SF) was confirmed. The case occurred in an unvaccinated adult who was hospitalized and is improving. The individual reported close contact with someone who traveled internationally to an area where clade I mpox is circulating.
Clade I mpox is distinct from clade II mpox. The mpox outbreak in the United States that began in 2022 is due to clade II mpox and has led to 1066 cases in SF as of April 9, 2026. In contrast, an outbreak of clade I mpox in Central and Eastern Africa has been ongoing since 2023, with sporadic travel-associated cases reported in non-endemic countries and increasing reports of locally-acquired clade I mpox in Europe. Over the last two years, 15 clade I mpox cases have been reported in the United States, including 6 in California. Public health officials are monitoring cases to determine if clade I mpox is more severe than clade II mpox in the United States.
The patient appears to be recovering. However, it should be noted that a quarter of the Clade 1 cases in this country have been diagnosed over the last month.
The patient, who had not received the mpox vaccine, was hospitalized and is improving, according to SFPDH.
The agency said that this clade I mpox patient had reported close contact with another person who had traveled internationally.
The Centers for Disease Control and Prevention said that until now, 15 cases of clade I mpox have been detected in the U.S. since late 2024. Over a quarter of these cases were diagnosed in March 2026 alone.
According to the CDC, all U.S. cases of clade I mpox — which are not linked — were in people who had either recently traveled to areas associated with the outbreak in Central and Eastern Africa or parts of Western Europe with more recent outbreaks, or, like the San Francisco case, were linked to travel.
Meanwhile, a wastewater sample in Oahu, Hawaii, has tested positive for the Clade I virus.
The Hawai‘i Department of Health is reporting a wastewater sample from O‘ahu that has tested positive for clade I mpox. The sample was collected on April 13, 2026, from a wastewater treatment facility on Joint Base Pearl Harbor Hickam. This is the first time clade I mpox has been detected in wastewater in Hawaiʻi. To date, no clinical case of clade I mpox has been identified in Hawai‘i.
At this time, the risk for the general public is low. The presence of clade I mpox virus in wastewater does not confirm a clinical case or community spread. Instead, it serves as an indicator to be alert for possible mpox cases. People at higher risk of mpox infection should consider being vaccinated with two doses of the JYNNEOS (mpox) vaccine if not already protected.
The JBPHH facility serves not only on-base military housing and facilities, but public sites that receive large numbers of residents and visitors, including the Pearl Harbor National Memorial Museum.
DOH was notified of the initial detection on April 20, 2026, with positive confirmatory results received on April 24, 2026.
The Hawaii Department of Health today said a wastewater sample from Oahu has tested positive for clade I mpox.
Details: https://t.co/cSvvgP4sYI
— Star-Advertiser (@StarAdvertiser) April 28, 2026
While officials continue to reassure the public that overall risk remains low, the growing number of Clade I mpox detections, from major coastal cities to wastewater signals in Hawaii, suggests this is not a development to casually dismiss.
Public health agencies may prefer calm messaging, but vigilance, vaccination where appropriate, and transparent reporting will be key to ensuring this situation does not quietly escalate into a more serious issue impacting more Americans.
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Comments
“It includes sub-clades Ia (associated with animal-to-human transmission) and Ib (linked to recent, more rapid sexual transmission).”
Good grief. Can anything good come from Africa??
I avoided getting monkeypox by using this one weird trick.
It’s not rocket science folks. Our ancestors may not have known about the microscopic world but the moral framework they concocted works every bit as well as if they did.
Rule #1: Monogamous sexual relationships within marriages only.
Rule #2: Tab A goes into Slot B. Anything other than that subjects that organ to something it was not designed for and opens you up to severe, potentially fatal diseases.
Those two rules are not iron clad but will keep you out of trouble 99% of the time.
Oddly enough, similar basic measures apply to electronic viruses.
Don’t click on strange links. Don’t respond to claims that your bank account is overdrawn. (Call your bank on the number you usually use for them, and talk to someone.) Don’t install stuff on your computer – particularly if you didn’t initiate an install. Don’t fool around with people you don’t know on the internet. Etc.
And immorality laughs.
.
I wish I could give you more than one thumbs up!
The first one reported.
Or, are we implying SF pervs are smart enough to not go to Africa and pox monkeys?
“Last month, my colleague Mary Chastain reported that the New York City Health Department announced the city’s first case of the severe monkeypox strain, Clade 1.”
San Francisco is butthurt they couldn’t be the “first.”
San Francisco is butthurt
ISWYDT
In San Francisco!? No way! How could it possibly pop up there? Must be a big mystery that we’ll need to study. Whatever could be the connection???
Quarantine the entire states of Hawaii and CA, Nothing in or out. It’s the only way to be sure.
so lockdown blue cities!!??
wear condoms on their mouths????
NYC Health Department announced the city’s first case of Clade 1.
While Clade I is new to the city, the Clade II variant remains active, with 63 total mpox cases reported in NYC.
63 cases! We need a warning: “Gort, Claude II birada nikto”
In the USA getting new or older diseases are due to what as been let into our country in the last few years of illegal or “temporary” aliens. Also having many homeless on the streets with drugs.
Quarantine SF. They have no self control.
It spreads through friction on open sores.
It’s spreading to gay men unable to resist the sexual allure of other gay men covered in open sores.
It’s not the next pandemic.