Monkeypox cases are on the rise — here’s what we know so far

When experts in the UK confirmed the first case of monkeypox on May 7 this year, epidemiologist Andrea McCollum and her colleagues at the US Centers for Disease Control and Prevention followed closely.

Human monkeypox infection is rare, especially outside central and western Africa where the virus is endemic in animals and spreads primarily in densely forested areas. Since 2018, only eight cases have been confirmed in non-endemic countries including Israel, Singapore, the UK and the US – all travel-related, just like the May 7 patient, who traveled to Nigeria.

McCollum says that with cases with no known travel links to Africa emerging in many countries, alarm bells have gone off. “We haven’t really seen this kind of observation of monkeypox before, so this is particularly concerning,” she says.

Between May 13 and 24, at least 16 countries in Europe and North America, as well as Australia and Israel, reported more than 250 confirmed and suspected cases of monkeypox. The virus strain in West Africa appears to cause this infection. It causes flu-like symptoms followed by a rash on the face that can spread to other parts of the body. This rash turns from red spots to pus-filled blisters that flake and eventually fall off. These symptoms often go away on their own within a few weeks, but are fatal in about three percent of cases. Its counterpart, the Congo Basin monkeypox strain, causes more serious disease and kills nearly 10 percent of those infected. Smallpox virus, which was eradicated in 1979 and is close to monkeypox, was much more deadly, killing 30 percent of those infected.

“He. She [monkeypox] Completely different from COVID” Maria Van Kerkhove, an infectious disease epidemiologist at the World Health Organization, in an online public Q&A on May 23. “Transmission does happen from close physical contact, and skin-to-skin contact.” Monkeypox, unlike COVID-19 which spreads through tiny airborne droplets, does not spread easily.

“This is a containable situation,” Van Kerkhove said. There are potential antivirals for those infected and vaccines for those most at risk: those who are in close contact with infected individuals. This is amazing [vaccination] “It’s not something everyone needs,” she said.

Fortunately, so far, no one has died in this ongoing outbreak of monkeypox in many countries, but where it started and what caused its spread remains unknown.

For now, McCollum says, there are many open questions.

Here’s what we know so far.

cases so far

Since the May 7 patient was identified, the number of monkeypox cases in non-endemic countries has increased.

Public health officials are now contact tracing and searching for connections between cases to find clues. This may also help them identify undiagnosed cases that may be asymptomatic or have mild symptoms.

A large proportion of confirmed cases are currently reported from Europe, particularly the United Kingdom, Spain and Portugal. Most of these infections were among men, many of whom self-identified as men who had sex with men. In an interview on May 23 with the Associated Press, a key adviser to the World Health Organization said the main theory to explain the ongoing outbreak was sexual activity between men at two recent parties in Spain and Belgium.

How is the disease transmitted?

Although monkeypox can be spread through sexual contact, it is not a sexually transmitted infection, Andy Seal, consultant for the WHO’s HIV, Hepatitis and Sexually Transmitted Diseases Program, said in a public Q&A via Internet on May 23. This usually requires that the virus be infectious via semen or vaginal fluids, and there is no evidence to suggest this at present.

The disease is not limited to men who have sex with men. “Anyone can get monkeypox through close contact,” Sell said.

The disease is spread through an infected person’s body fluids – spit or pus – that can harbor the virus. Bed sheets or clothing contaminated with this virus-laden fluid can also be a potential source of infection.

Due to the widespread nature of the current outbreak, epidemiologists and virologists are trying to understand whether there is enhanced person-to-person transmission of this virus. Some experts are studying the genetic sequence of the virus obtained from infected patients to see if there are any mutations that could make the currently circulating virus more transmissible than any previous versions. They also check if the monekypox virus is present in semen or vaginal fluids, and if it is contagious, to make sure this is not a sexually transmitted disease.

Are there vaccines and treatments for monkeypox?

Not all monkeypox patients are hospitalized; Many get better on their own without treatment while isolating at home for three weeks. Some countries, including the United Kingdom, are advising those who have been in close contact with the affected individual to self-quarantine for 21 days. In the United States, President Biden has said such quarantines are unnecessary because vaccines are available to those exposed to the virus.

In 2019, the US Food and Drug Administration approved Bavarian Scandinavian The monkeypox vaccine called Jynneos, which can prevent the disease or make it less severe. Another vaccine called ACAM2000 that has been approved for smallpox may also be used. The United States and the United Kingdom, for example, provide the Jynneos vaccine to health care workers who treat or may have been exposed to infected patients. The CDC suggests getting a two-dose vaccine within four days of exposure.

However, no drugs have been approved to treat monkeypox. An oral antiviral drug called Tecovirimat was approved by the US Food and Drug Administration in 2018 to treat smallpox, but there is no data showing that it is effective in humans for any of these infections. For severe monkeypox, two other treatments may be used, the antiviral cidofovir and a monoclonal antibody called vaccine immunoglobulin.

How is monkeypox different from SARS-CoV-2?

Unlike SARS-CoV-2, the RNA virus that causes COVID-19, monkeypox is a DNA virus. Its genome is encoded at around 200,000 genetic units while the SARS-CoV-2 genome is much smaller: around 30,000 units. These DNA viruses tend not to mutate, tend to be fairly stable and less likely to generate variants, Rosamund Lewis, head of the WHO Smallpox Secretariat, said in an online public question and answer session May 23.

The two viruses also transmit somewhat differently. SARS-CoV-2 spreads rapidly through the air in tiny droplets when infected people talk, sneeze or cough. Monkeypox does not spread easily through the air and often requires close physical contact with an infected person or their contaminated clothing or bedding.

A short history of monkeypox

The virus was first discovered in 1958 in Denmark when researchers noticed a smallpox-like skin eruption on cynomolgus monkeys that came from Singapore and were housed in an animal research facility – hence the name monkeypox. In the following decade, more outbreaks were reported in the United States in captive monkeys imported from Asia, where monkeypox was not recognized. These primates were considered occasional hosts of the virus.

The first human case of monkeypox was documented in 1970 in the Equateur province of the Congo in a nine-month-old baby who was initially thought to have had smallpox – a nearly eradicated disease that resembled monkeypox. By 1985, the World Health Organization had recorded 310 cases of monkeypox in rural areas of West and Central Africa, mostly in the Congo.

This led to the search for the primary source of the monkeypox virus. A 1985 survey of 383 wild animals including monkeys, ferrets and bats in northern Congo revealed the presence of monkeypox-specific antibodies in the blood samples of two Thomas rope squirrel—a diurnal rodent, likely hunted and consumed for meat. One squirrel had a skin eruption and researchers succeeded in isolating monkeypox virus similar to viruses seen in humans from animal tissues.

In March 2012, another team of researchers isolated the virus from a species of monkey called the sooty mangabe in Côte d’Ivoire’s Tai National Park and In 2020 the western chimpanzee. Recently, another study that has not been peer-reviewed found evidence of the virus in shrews and some rodents. Living in the Congo Basin.

While rodents are suspected to be the primary reservoir for monkeypox, there is no direct evidence to show that these animals, which are hunted for meat or kept as pets, spread the virus to humans, says Joachim Marin, a disease ecologist at Belgium’s University of Antwerp. .

However, the infamous monkeypox outbreak of 2003 in the United States The first outside AfricaIt provides a glimpse into how this virus is transmitted from animal to human. At least 37 people From six states: Illinois, Indiana, Kansas, Missouri, Ohio and Wisconsin became ill after handling or petting infected prairie dogs. It was found that these rodents were very likely to have contracted monkeypox virus while present along with lilies and giant gambian rats that an animal distributor in Illinois imported from Ghana.

Why is the incidence of monkeypox rising?

In parts of Central and West Africa, where the virus is endemic, cases of monkeypox have been on the rise since the 1970s. A 2022 study estimated at least a 10-fold increase meGlobally confirmed, probable and probable case numbers for the past five decades. This increase is most dramatic in Congo, which recorded more than 28,000 cases between 2000 and 2019, and in Nigeria, where the disease re-emerged in 2017 after 40 years.

One of the main reasons for the escalation of monkeypox cases is the eradication of smallpox. In 1980, the World Health Organization declared smallpox eradication Vaccination against the virus has ended. But researchers have shown that the discontinued smallpox vaccine, which can have side effects, offers 85 percent protection against monkeypox.. A 2010 study from Central Congo found that vaccinated people had nearly five times lower risk The incidence of monkeypox is more than the unvaccinated.

Rising deforestation could also expose more people to the virus. Clearing forests to make way for farms and agriculture would likely bring humans closer to infected wild animals, increasing the virus’s chances of jumping species, as suggested for Ebola..

also 2014 study One copy of the Congo Basin monkeypox virus strain with a deleted gene that may be associated with adaptation to human-to-human transmission.

“We knew monkeypox was a disease that we needed to monitor closely due to its epidemic potential,” Laurens Liesenborghs, An infectious disease specialist studies the virus at the Institute of Tropical Medicine in Belgium. “However, what is happening now is a very strange thing.”

Is monkeypox caused by a more transmissible virus?

Another long-awaited question is whether the virus has evolved to spread more easily between humans. For poxviruses, which are DNA viruses, this usually means either losing or gaining genes that make them more transmissible, says Gustavo Palacios, a virologist at Icahn School of Medicine in Mount Sinai in New York.

Based on genome sequences of the virus taken from three newly infected monkeypox virus patients from Portugal, Belgium and the United States, there is no evidence of gene deletions or additions, he says. In fact, the draft of the Portuguese genome sequence provides a close match to the virus that was exported from Nigeria to Israel, Singapore and the United Kingdom in 2018 and 2019. The sequence of the draft gene from Belgium is very similar to that obtained from the Portuguese patient, says Philippe Selhurst, a virologist at Institute of Tropical Medicine in Belgium This makes sense, given that the Belgian man recently traveled to Portugal.

But to identify subtle changes in the genetic makeup of monkeypox, researchers need to sequence viral DNA from more patients and compare regions across the genome that may be different from sequences from previous outbreaks. The question is whether these differences, if any, live up to how the virus infects humans.

However, Selhorst’s concern is that even if the virus has not changed yet, it may have more opportunities to mutate, and the longer this ongoing outbreak continues.

Although monkeypox is not as contagious as COVID-19, Selhurst says, “It is never good when a virus that was in an animal reservoir is now spreading more and more among people.”

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