Scientists speculate that the monkeypox virus may have circulated for many years before it suddenly emerged in 26 countries.
Scientists at genetic laboratories and infectious disease experts are desperately searching for clues to help explain why a virus that has been discovered in West Africa for over 50 years and is not normally spread easily from person to person, made such a dramatic appearance in the last month.
“There may have been undetected transmitting for a while,” Dr. Rosamund L. Lewis, the World Health Organization’s technical leader for monkeypox, said during Wednesday’s briefing. We don’t know how long it may have taken. It’s not clear if it was weeks, months, or even a few years.
Marc Van Ranst, virology professor at the University of Leuven, Belgium, told NBC News that the sequencing of his virus genome revealed “limited” genetic mutations of this virus and that none of them were smoking guns.
Van Ranst stated that everyone is interested in more complete genomes. This will give an idea about a very important question: How long has this virus been under the radar? “I don’t believe anyone believes that this virus jumped out Africa just a few weeks ago.”
Scientists from University of Edinburgh recently sequenced samples of the outbreak. They posted their findings on May 30, 2018. They found that the samples were descended from a monkeypox variant, which was previously identified in Nigeria, Israel, Nigeria, and Singapore between 2017 and 2019.
Although investigators found an “unexpectedly large” number of genetic changes in the virus’s genome, experts don’t believe these shifts are responsible for the current outbreak.
Human cases of monkeypox in Africa have been mainly caused by exposure to infected animals, such as rodents, and not person-to-person transmission.
“What’s most likely happened is that an endemic infectious virus from Africa found its path into a social network and was then greatly aided through major amplification events such as raves in Belgium to spread around the globe,” Dr. Amesh A. Adalja said, a senior scholar at Johns Hopkins Center for Health Security.
Adalja said, “And then, because it’s transmitted through close contact during sexual encounters,” that many lesions may be mistakenly associated with other sexually transmitted diseases, which could delay diagnosis.
In recent weeks, detection rates have increased dramatically due to an increase in vigilance among public health officials, health care professionals and individuals around the world.
“When you look for a new disease in a population you will find many, many more cases,” Dr. David Heymann of the London School of Hygiene and Tropical Medicine, who was previously the WHO’s Programme on Emerging and Other Communicable Diseases, said to NBC News.
Heymann supports the idea that the disease could have been present for years in certain populations outside of the 11 Central and West African countries where it has become endemic. He suggested that there may be cases of the disease spreading stealthily to people other than the global gay community.
He stated, “The concern is not to look in one population but more generally.”
Infected individuals usually recover in three weeks. The infection can leave scarring and painful lesions all over the body. The majority of cases reported in Europe and the U.S. have been mild, some being so subtle that they were mistakenly thought to be other sexually transmitted diseases. They have also been seen in gay, bisexual, and other men who have had sex with other men. Experts emphasize that transmission is primarily due to close physical contact with sexual activity.
NBC News was told that some recent cases of monkeypox have been milder than what is seen in cases of African monkeypox. Dr. Sebastien Poulin, an infectious disease specialist at St-Jerome Hospital, Montreal, who diagnosed one of the first Canadian cases of the virus, said this: “Physicians should be aware of this.”
According to the Centers for Disease Control and Prevention, although monkeypox usually begins with fever, some recent cases in the United States have not experienced fever or any other signs before the lesions develop.
A Friday CDC study reported that cases could be mistaken for more common infections like varicella zoster and sexually transmitted diseases.
According to the World Health Organization, 66 people died from the disease in Africa in 2022. Since 2017, Nigeria has been fighting its own monkeypox epidemic, which may have helped to spread the disease worldwide.
The current outbreak has not resulted in any deaths in either Europe or the U.S. However, at least one person in the U.S. was admitted to hospital for severe pain due to lesions in their anal region. Capt. Jennifer McQuiston was the deputy director of High Consequence Parasites and Pathology at the CDC. She spoke during a briefing on Friday.
McQuiston admitted that there was a possibility of monkeypox cases being missed in the U.S. before, but she stated “not to a great extent” during the briefing. In the U.S., two cases were identified in 2021: one in Texas in July and another in Maryland in November. Both were recent Nigerian immigrants.
Van Ranst stated that the next days of the epidemic will be crucial for the control of the disease. According to WHO, there had been 643 confirmed cases as of June 1. He said that if the cumulative number of cases hits 4,000 by next week, then this situation is not under control.