An unusual outbreak of monkeypox has now spread to at least 15 countries, with Australia registering its first two cases of viral illness on Friday.
Key points:
- More than 100 cases of confirmed or suspected smallpox have been detected outside Africa since May
- Smallpox is not easily transmitted from person to person and the outbreak suggests a possible change in the behavior of the virus.
- Experts say the risk to the general population remains low and there is no reason to panic
Smallpox, which is caused by the smallpox virus, a member of the same virus family as smallpox, is rarely seen outside of Africa and is not known to be easily transmitted from person to person.
Since the beginning of May, at least 120 confirmed or suspected cases have been detected outside Africa, including in Europe, the US, Canada, Israel and Australia, according to the World Health Organization (WHO).
Although monkeypox is considerably less infectious than respiratory diseases such as COVID-19, and the outbreak is not a cause for panic, the rapid spread of the virus seems to indicate a change in its behavior.
“Monkeypox is not on the same scale as COVID-19 … it doesn’t send many, many people to the hospital,” infectious disease expert Sanjaya Senanayake told ABC News Breakfast.
“But there are certainly some unusual aspects to this outbreak, and it involves several countries and it seems to be growing.”
What exactly is monkeypox?
Monkeypox is a viral zoonotic disease that was first discovered in monkeys in the 1950s and was first reported in humans in 1970 in the Democratic Republic of the Congo.
It causes flu-like symptoms and a rash or distinctive lesions, very similar to what has been seen in smallpox patients in the past, though much less severe.
The virus spreads through close physical contact with injuries, body fluids, respiratory drops, and contaminated materials such as bedding. Respiratory droplet transmission usually requires “prolonged face-to-face contact.”
Symptoms of monkeypox include fever, headache, muscle aches, swollen lymph nodes, and a rash or injury. (Reuters)
Smallpox is found mainly in the rainforest areas where the animals carrying the virus live, especially rats. It is endemic to parts of West and Central Africa.
There are two main strains or “clades” of the virus: the Congo Basin Clade and the West African Clade, the latter of which has been identified in the latest outbreak, says the epidemiologist and global expert on biosafety Raina MacIntyre.
“[The West African clade] has a 1% mortality rate, which is similar to SARS-CoV-2, while the Congo Basin Clade has a 10% mortality rate, “said Professor MacIntyre of the Kirby Institute in the Health Report.
To date, no deaths have been reported.
Why do experts care?
There are a few thousand cases of monkeypox in West and Central Africa each year, but it is unusual to see cases in places like Europe and North America, especially in people with no history of travel to endemic areas.
“Cases of smallpox found outside Africa are usually imported from infected travelers abroad or people exposed to infected animals brought into the country,” said Professor Senanayake.
“These human cases don’t usually infect other people, so the amount of person-to-person transmission we’re hearing seems to be more than expected.”
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The first known case of the outbreak was related to travel to Nigeria, but subsequent cases have not been related to travel or other previously confirmed cases, suggesting a certain level of community spread.
Because human-to-human spread is uncommon (previous research estimates that only about 3% of close contacts in a case of monkeypox will become infected), scientists have speculated whether the virus may have mutated to be more transmissible.
So far, the WHO says there is no evidence of this.
It has also been speculated that the monkey’s smallpox may spread asymptomatically; however, people with monkeypox are usually infectious while experiencing symptoms, and it is unclear whether asymptomatic people can transmit the disease.
Another unusual feature of the outbreak is that most, but not all, cases are being detected through sexual health services and between men who have sex with men, said Professor MacIntyre.
“There have been some links with popular events or big parties on a specific island in Spain.”
Monkeypox has not previously been characterized as a sexually transmitted infection, but can be transmitted through close physical contact during sex.
“The WHO and other organizations speculate that it has been sexually transmitted, but I think when you’re in very close contact, it’s hard to tell if it’s sexual contact by itself or just close contact,” Professor MacIntyre said.
In the past, smallpox outbreaks have been limited because the virus does not spread easily among people. (Getty Images: ROGER HARRIS / SCIENCE PHOTO LIBRARY)
Health officials say it is too early to say why more frequent cases have been reported among men who have sex with men, but that it can be reduced to “positive health research behavior” in this demographic.
“Monkeypox rashes can be similar to some sexually transmitted diseases, such as herpes and syphilis, which may explain why these cases are detected in sexual health clinics,” he said. WHO.
He added that the likelihood of seeing more cases in non-endemic countries, including other population groups, was high given the “unidentified transmission chains”.
Why are we seeing cases of monkeypox now?
According to the WHO, the widespread geographical spread of cases of monkeypox may indicate that transmission of the virus has been taking place for some time.
Early genomic sequencing of a handful of cases has also suggested that the strain that is currently spreading is similar to that identified in Europe in 2018, said Professor Senanayake.
“Potentially, it has been in Europe for a while and just under the radar, causing small outbreaks that have not made people too sick and have been missed,” he said.
“People are now moving closer, especially in the northern hemisphere, allowing it to spread.”
Outbreaks of smallpox have increased in recent years, which Professor MacIntyre said may be the result, at least in part, of declining levels of poxvirus immunity in the general population. smallpox.
“Smallpox was declared eradicated in 1980 and the last mass vaccination programs ceased in the 1970s,” he said.
“The smallpox vaccine protects against many of the orthopoxviruses, including monkeypox.”
Since the mass vaccination against smallpox ended 40-50 years ago, the proportion of people who are not vaccinated has grown to include most people under the age of 50, and the immunity of the elderly and vaccinated has declined.
What are the symptoms of monkeypox?
Smallpox is rarely fatal, especially in countries like Australia, where people generally have good access to health care.
If you get infected, there are usually two parts to the disease, with symptoms lasting two to four weeks, said Professor Senanayake.
“The first part is about five days of very high fever, very nasty headaches, muscle aches and pains,” he said.
“And then a rash begins, usually this rash affects the face and extends down and affects the palms. [of the hands] and alone [of the feet]. “
The rash, which includes pus-filled skin lesions (before they dry out and fall off), can also be found in the mouth, genitals, and eyes.
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Smallpox is usually self-limiting and symptoms go away on their own within a few weeks, but the disease can be severe in some individuals.
To control monkeypox outbreaks, epidemiological measures such as contact tracing and isolation of close contacts are often very effective, said Professor MacIntyre.
“There are effective antivirals that have been developed since smallpox eradication … and you can vaccinate your contacts [of cases]and that’s also protective. “
Health authorities abroad have already begun offering smallpox vaccines to some health workers and contacts who may have been exposed, which research suggests are about 85% effective against monkeypox.
However, the WHO says the outbreak does not require mass vaccinations, as measures such as good hygiene and safe sexual behavior will help control its spread.
To what extent should we be concerned?
Although health officials have called on doctors and nurses to be alert to possible cases, they say the risk to the general population remains low.
“While new groups of monkeypox cases in the UK and Europe need to be monitored, there is no reason to panic,” said Fasséli Coulibaly, an associate professor at the Biomedical Discovery Institute. Monash University.
“First, the mode of transmission of viruses in this family does not have the explosive power of respiratory viruses such as SARS CoV-2 and influenza virus.
“Second, monkeypox is caused by a virus that is not new.
“It has been known to infect humans since at least the 1970s and is closely related to the viruses we know how to fight.”
Maria van Kerkhove, WHO’s head of emerging diseases and zoonoses and technical head of COVID-19, said the situation was “manageable”, especially in Europe.
“But we can’t take our eyes off what is happening in Africa, in the countries where it is endemic,” said Dr. van Kerkhove.