In a recent Q&A on social media, Dr. Rosamund Lewis, technical lead on the monkeypox response for WHO, says The lack of clear understanding around disease severity is one reason why infectious diseases are so challenging.
“When people are exposed to infectious agents, they respond in different ways,” she said. Some won’t develop any symptoms or only mild problems like a low-grade fever. They get better and move on with their lives. Others, though, go on to develop very serious complications. “We’re seeing that now,” she said.
Lewis says WHO has asked every country for more information on the circumstances surrounding any monkeypox deaths.
Two previously healthy men die in Spain
Two recent cases in particular have raised an alarm.
Both men developed encephalitis, or swelling of the brain, which can be triggered by viral infections. They eventually fell into comas and died.
Andrea McCollum, an epidemiologist and pox virus expert at the US Centers for Disease Control and Prevention says encephalitis a very rare condition known to be associated with monkeypox. It has been reported in people with monkeypox in West Africa and in a patient in the US in 2003 during a small outbreak linked to imported prairie dogs.
“Why some of these patients have encephalitis is something we don’t know,” McCollum told CNN.
The severity of monkeypox disease probably depends on a person’s underlying health, the health-care resources they have access to and the strain of the virus they’re infected with.
In central Africa’s Congo Basin, McCollum says, about 11% of monkeypox cases are fatal, largely because the population hasn’t been vaccinated even against the related smallpox virus, which would protect against monkeypox
In West Africa, monkeypox turns fatal about 1% of the time, according to data that mostly comes from Nigeria. It also shows that people who die of monkeypox often have risk factors that lower their immune function, like poorly controlled HIV.
Babies are at higher risk of severe outcomes because they don’t have fully functioning immune systems, McCollum said. Pregnant women also have reduced immunity and may be at higher risk from a monkeypox infection.
The strain of the virus circulating in West Africa — the same strain circulating now in the US and other nonendemic countries — is thought to cause milder disease than the Congo Basin strain.
Outside of these endemic settings, not much is known about how and why cases can turn severe. Public health officials say they’re trying to learn on the fly.
Severe disease, but no deaths, in United States
“We are aware of a good number of patients here that have been hospitalized,” McCollum said. Doctors are reporting that some of the complications they’re treating are urogenital complications or infections that spread to the eyes , “so it still is a very serious illness,” she said.
McCollum says officials also are hearing that some patients need to be hospitalized for pain management. In other cases, people who have risk factors like lowered immunity are being admitted so doctors can keep a close eye on them.
In one case she recently consulted on, confluent lesions covered one area of the person’s body — “That’s when you have so many lesions, they just kind of all merge together.”
This can make the skin so disturbed that it causes problems with fluid loss, and the person has to be treated almost like a burn patient until their skin heals.
People at higher risk for severe monkeypox infections include: People with advanced HIV, since their immune function may be compromised; pregnant people; young children and infants; people with eczema or atopic dermatitis because they have many breaks in their skin that can cause the monkeypox rash to be much worse; those with at least one other complication, such as severe nausea and vomiting, diarrhea and dehydration, pneumonia, a secondary skin infection; or another disease at the same time