PHOTOS: (TOP TO BOTTOM CDC/CYNTHIA S. GOLDSMITH/SCIE902 27 MAY 2022 • VOL 376 ISSUE 6596 science.org SCIENCEW
ith the COVID-19 pandemic still
raging, a second public health
threat has the world on high alert:
a global outbreak of monkeypox.
As Science went to press, two
dozen countries in the Americas,
Europe, North Africa, the Middle East, and
Australia had reported nearly 300 suspected
and confirmed cases of the disease, a much
milder cousin of smallpox, the deadly scourge
that the World Health Organization (WHO)
deemed eradicated in 1980. A disproportion-
ate number of cases are in men who have sex
with men (MSM), an unusual twist given that
researchers have never convincingly shown
sexual transmission occurs in monkeypox.
Monkeypox is endemic in West and Cen-
tral Africa, and the virus occasionally causes
outbreaks elsewhere in the world, but most
are quickly contained or peter out by them-
selves. This outbreak looks very different,
says Anne Rimoin, an epidemiologist at the
University of California, Los Angeles, who
has long studied monkeypox in the Demo-
cratic Republic of the Congo (DRC). “We get
concerned when we see a virus doing things
that we don’t normally see it doing,” Rimoinsays. “We now have to really reevaluate what
we know about monkeypox—which has all
been gleaned, essentially, from low-resource
settings in Africa—in very, very different
kinds of populations.”
“We should definitely be concerned about
this new situation,” agrees epidemiologist
Rosamund Lewis, head of poxvirus diseases
at WHO. Still, Lewis stresses that monkey-
pox, which causes skin lesions resembling
those of smallpox, is not easily transmitted,
and its spread can typically be limited by
isolating cases. “It’s not a concern for mostpeople,” she says. What’s more, several drugs
and vaccines developed for smallpox can also
treat and prevent monkeypox.
A WHO technical advisory group that
specializes in infectious hazards, chaired
by epidemiologist and monkeypox veteran
David Heymann of the London School of
Hygiene & Tropical Medicine, met last week
to develop recommendations covering ev-
erything from the need for more aggres-
sive surveillance to the use of vaccines. In a
23 May rapid risk assessment, the European
Centre for Disease Prevention and Control
warned there’s a “potential risk” for human-
to-animal transmission, which could enable
the virus to become established in Euro-
pean wildlife, as it is in Africa.
U.K. officials on 7 May were the first to
report a monkeypox case, a patient who had
arrived from Nigeria 3 days earlier. But that
person apparently did not transmit the vi-
rus to anyone else and is not the source of
the wider outbreak; public health officials in
Montreal say a man there had symptoms as
early as 29 April. At the time, he wasn’t tested
for monkeypox. Most doctors would not
think to do so because the disease is vanish-
ingly rare outside of Africa and its lesions can
resemble those of chickenpox and syphilis.
Given the torrent of cases reported over
the past 2 weeks, it’s possible the virus has
been spreading under the radar for months,
Heymann says. Rimoin says a much larger
outbreak could be underway in Nigeria and
nearby countries, from which the disease
might have been exported repeatedly to the
rest of the world. “We’re not looking for these
kinds of things, and if you don’t look for
them, you don’t find them,” she says.“MONKEYPOX” IS A MISNOMER; the virus was
discovered in 1958 in research monkeys,
but its natural hosts are likely rodents and
other small mammals. The virus first sur-
faced in humans in 1970 in what is now the
DRC, causing fever, headaches, and lymph
node swelling followed by an eruption of
pus-filled blisters. Outbreaks start when
someone comes in contact with an infected
wild animal. The biggest known outbreak in
the United States occurred in 2003, when
47 people were infected by pet prairie dogs
that had picked up the virus from rodents
imported from Ghana.
Most people recover within a few weeks.
The Congo Basin strain kills up to 10% of
those infected, but the current outbreak
appears to only involve the West African
strain, which in past outbreaks had a fatal-
ity rate of about 1%. Outbreaks “generally
fizzle out on their own,” Lewis notes, be-IN DEPTH
The monkeypox virus, shown here in a colored
electron micrograph, is related to the smallpox virus.Scabs cover the skin lesions developed by two people
who had monkeypox in the United States in 2003.Monkeypox outbreak questions
intensify as cases soar
Rapid emergence of hundreds of cases around the world
alarms public health officials and scientists
GLOBAL HEALTHBy Jon CohenCorrected 26 and 31 May 2022. See full text.