প্রকাশ: 26/06/2022
The World Health
Organisation (WHO) has decided not to declare monkeypox a public health
emergency of international concern. This may change in the future.
However, WHO Director-General Tedros Adhanom Ghebreyesus
said he was "deeply concerned" about the evolving threat of
monkeypox, which he said had reached more than 50 countries.
There have been more than 4,100 confirmed cases globally,
including at least 13 in Australia.
The WHO also acknowledged there were many unknowns about the
outbreak.
Here are three things we know about monkeypox and three
things we want to find out.
1. Monkeypox is caused by a virus
Monkeypox is a large DNA virus belonging to the
orthopoxvirus family. Unlike the related smallpox virus, variola, which only
affected humans, monkeypox virus is found in rodents and other animals in parts
of Africa.
We know of two clades (virus groupings), and it is the less
severe of the two currently circulating outside Africa.
Orthopoxviruses are stable viruses that do not mutate much.
Multiple mutations, however, have been described in the virus causing the
current outbreak.
In the United States, at least two separate strains have
been circulating, suggesting multiple introductions into the country.
2. You can be infected for more than a week and not know
It takes an average 8.5 days from infection to showing
symptoms, such as enlarged lymph nodes, fever and a rash, which usually looks
like fluid-filled blisters that erupt. People are infectious while they have
the rash, and are usually infectious for about two weeks.
Children are most severely affected and have a higher risk
of dying from the disease. Historically, in the endemic countries of Africa,
almost all deaths have been in children.
The European epidemic is mostly in adult males, so this,
together with better access to care, may explain the low rate of deaths in
these countries.
3. We have vaccines and treatments
Vaccines work. Past vaccination against smallpox provides
85% protection against monkeypox. Smallpox was declared eradicated in 1980, so
most mass vaccination programs ceased in the 1970s.
Australia never had mass smallpox vaccination. However, an
estimated 10% of Australians have been vaccinated in the past, mostly migrants.
Vaccines protect for many years but immunity wanes. So
declining population-level protection is likely responsible for the resurgence
of monkeypox seen since 2017 in Nigeria, one of seven endemic hot spots in
Africa.
Mass vaccination is not recommended. But vaccines can be
given to contacts of confirmed cases (known as post-exposure prophylaxis) and
people at high risk of contracting the virus, such as some lab or health
workers (pre-exposure prophylaxis).
There are also treatments, such as vaccinia immune globulin
and antivirals. These were developed against smallpox.
1. How much do these new mutations matter?
The virus causing the current outbreak has several mutations
compared with versions of the virus circulating in Africa. However, we don't
know if these mutations affect clinical disease and how the virus spreads.
The monkeypox virus has a very large genome, so is more
complex to study than smaller RNA viruses, such as influenza and SARS-CoV-2
(the virus that causes Covid).
Experts wonder if the mutations have made it more contagious
or changed the clinical pattern to be more like a sexually transmitted infection.
A study from Portugal shows the mutations likely make the virus more
transmissible.
2. How is it spread? Is that changing?
Monkeypox has not been described as a sexually transmitted
infection in the past. However, the current transmission pattern is unusual.
There seems to be a very short incubation period (of 24 hours) following sexual
contact in some, but not all, cases.
It is a respiratory virus, so aerosol transmission is
possible. But historically most transmission has been from animal to human.
When there was transmission between humans, this usually involved close
contacts.
The rapid growth of the epidemic in non-endemic countries in
2022, however, has been all due to spread between humans. There may be many
more cases than officially reported.
We do not know why the pattern has changed, whether it is
sexually transmitted or simply transmitted due to intimate contact in specific
and globally connected social networks, or whether the virus has become more
contagious.
The virus is found in the skin rash, mouth and semen, but
this does not prove it is sexually transmitted.
3. How far will it spread? Does Covid make a difference?
Will this spread more widely in the community? Does the
Covid pandemic increase the risk? Possibly, yes.
We must also not drop the ball on surveillance in the wider
community or stigmatise the LGBTQI community.
Due to waning immunity from the smallpox vaccine globally
and the spread of monkeypox to many countries already, we may see the epidemic
spreading more widely.
If it does so and starts infecting large numbers of
children, we could see more deaths because children get more severe infection.
So we should monitor globally for clusters of fever and
rash, and misdiagnosis as chickenpox, hand foot and mouth disease, herpes
simplex or other diseases with a rash.
Another factor is Covid. As people recover from Covid, their
immune system is impaired. So people who have had Covid may be more susceptible
to other infections.
We see the same with measles infection. This weakens the
immune system and increases the risk of other infections for two to three years
afterwards.
If the epidemic becomes established in countries outside the
endemic areas, it may infect animals and create new endemic zones in the world.
It is important we do everything possible to stop this
epidemic.
- Reuters
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