Officials at the Centers for Disease Control and Prevention on Friday opposed the idea that the monkeypox virus could spread through the air, saying the virus is usually transmitted through direct physical contact with a patient’s wounds or contaminated materials.
The virus can also be transmitted through the droplets of an infected patient who comes into physical contact with another person, they said. But it cannot be in the air over long distances.
Experts on airborne virus transmission disagreed, but some said the agency did not fully consider breathing drops, large or small, the possibility of breathing at a shorter distance from a patient.
The World Health Organization and several experts have said that although the transmission of the “short-out” monkey in the air is uncommon, it is possible because it needs measures. The UK also includes monkey pox in its list of “high-impact infectious diseases” that can spread through the air.
“Airborne transmission may not be the main or very effective means of transmission, but it can happen anyway,” said Linsey Marr, an expert on Virginia Tech airborne viruses.
“I think the WHO is right, and the CDC’s message is misleading,” he added.
In the United States, the incidence of monkeys has risen to 45 cases in 15 states and in the District of Columbia, CDC officials said at a news conference. The global number has risen rapidly since May 13, when the first case was reported, to more than 1,450. At least 1,500 cases are still being investigated.
Historically, people with monkeys have reported flu-like symptoms before a characteristic rash appeared. But some patients in the current outbreak have developed the rash first, and some have not had these symptoms at all, Dr. Agency director Rochelle Walensky said Friday.
No deaths have been reported in the current appearance, he said.
Questions about airborne Monkeypox virus are important because the answers will include recommendations for masking, ventilation, and other protective measures if the outbreak continues to grow.
The CDC said on Thursday that the monkey whale “is not known to last in the air and is not transmitted in the short shared airspace.” The statement came after an article in the New York Times on Tuesday described scientists as uncertain about the transmission of the virus.
“We know that those diagnosed with monkey pox in this case have described close and lasting physical contact with other people who were infected with the virus,” said Dr. Walensky said Friday. “This is in line with what we’ve seen in previous appearances and what we’ve known for decades about studying this virus and its closely related viruses.”
But the monkey has been misdiagnosed, according to other experts, and parts of the airborne transmission have been reported from time to time for a closely related smallpox virus. In a 2017 monkey outbreak in Nigeria, infections occurred in two health workers who had no direct contact with patients, scientists said at a recent WHO conference.
Some patients in the current outbreak do not know when or how they contracted the virus, CDC officials said.
The agency is right to reassure citizens that the outbreak is not a threat to most people because the monkeypox is not as contagious as the coronavirus, the doctor said. Donald Milton, an airborne virus transmission expert at the University of Maryland.
Airborne transmission will not be a danger to anyone other than immediate caregivers, Drs. Milton said he warned that denying the possibility was a “wrong way to do it.”
When a virus is in the saliva or in the airways, as this monkey’s mouth has shown, it can be expelled in the droplets when speaking, singing, coughing, or sneezing. Milton and other experts said.
Drops can be heavy and fall quickly on objects or people, or they can be small and light, in the air for long periods of time and long distances. The CDC’s assessment of whether the virus is present in large or very small droplets, called aerosols.
A similar controversy erupted at the beginning of the coronavirus pandemic, with agencies and the WHO targeting large drops as the main means of transmission. But aerosols were the main cause.
Monkeypox’s new CDC guidelines have described the drops of breath that patients emit as “secretions that come out of the air quickly.”
But the virus “can be found in respiratory particles of any size,” and not just in large drops, said Lidia Morawska, an air quality expert at Queensland University of Technology in Australia.
“In my opinion, there is no basis for saying that the virus is transmitted only by large drops and that it is only at close range and that there is a risk of infection,” he wrote in an email.
Patients in the current outbreak appear to have been infected through close and lasting contact, CDC officials said Friday. But that can be difficult to determine.
What to know about the Monkeypox virus
What is monkeypox? Monkeypox is an endemic virus in some parts of Central and West Africa. Baztanga is similar, but not so severe. It was discovered in 1958 after appearances in monkeys kept for research, according to the Centers for Disease Control and Prevention.
When people are in close contact, it may not be possible to tell if a virus has been transmitted by touch, spraying of large drops, or inhalation of aerosols. said Marr.
“Transmission in such situations does not define how the virus has spread from person to person,” he added. If the transmission can occur through the spraying of respiratory drops, “then almost certainly they also occur when inhaling aerosols.”
However, most experts agree that regardless of the contribution of inhaled aerosols, the monkey’s tail does not appear to cover the distances that coronaviruses or measles viruses can have.
“I agree that most monkey transmission occurs through touch, probably direct contact between mucous membranes,” said Dr. said Milton.
But “the CDC seems to be stuck with the old terminology,” he said. “We really need to talk about the terms of transmission using terms that clearly state: through touch, spray, or inhalation.”
The CDC itself recognizes this in its advice on clinical options for short-range air transmission. The agency recommends that patients wear masks and that health care workers use N95 respirators, which are necessary to filter aerosols.
He also warned that “procedures that can spread oral secretions should be performed in a room to isolate airborne infections.”
There is evidence that monkeys can survive in aerosols and that inhaled viruses can cause disease in monkeys. Airborne transmission may not be ideal for the monkeypox virus, however.
Patients may not have released many viruses in aerosols, the virus may not have been infectious for a long time, or the amount of virus inhaled may be too large to infect someone, Dr. said Marr.
If this is the case, it is likely that airborne transmission will only occur between people who have been around for a long time. However, health officials in the UK, like those in the United States, have said that many patients do not know when or where they could be infected.
If they had been infected without close contact, “air transmission may have occurred more than we thought,” said Dr. said Marr.