7 May 2022 | New Scientist | 9DOCTORS in the UK are
investigating whether an
adenovirus is behind an
unexplained outbreak of liver
disease in young children,
as case numbers rise in
countries including the
UK, the US and Israel.
As of 21 April, there had been
169 identified cases of hepatitis,
or liver inflammation, in
11 countries. Some people
have been quick to blame the
outbreak on either covid-19,
its vaccines or lockdowns. But
in the UK, which has had the
largest number of identified
cases, doctors said on 29 April
that the cause is still unknown.
Their leading hypothesis is
that the culprit is a usually mild
adenovirus, a common cause of
infection in children, along with
a second, undetermined factor.
By 29 April, there had been
145 cases of hepatitis in the UK
of unknown cause in under-16s,
mostly in children below the
age of 5. The covid-19 vaccine
can’t be responsible, as it isn’t
offered to the very youngest
children in the UK.
The condition has beenstriking children without
underlying health conditions.
Most of those affected have
recovered, but 10 children in the
UK needed a liver transplant
and so will need to take drugs
that suppress their immune
systems for the rest of their lives.The leading suspect at the
moment is an adenovirus called
41F, which usually causes
nausea, diarrhoea and fever.
Some kind of adenovirus was
found in 40 out of 53 of the
children who were tested for it
in England. Out of 11 cases where
adenovirus was detected in the
blood and could be identified,
all were the 41F type.
What could the unknown
second factor be? “It must
be in some way linked to the
pandemic,” says Deirdre Kelly at
the University of Birmingham,
UK. Of the 60 children with
hepatitis who were tested
for the coronavirus on arrivalat hospital, 10 were positive,
a rate of about 17 per cent.
A report from the UK Health
Security Agency (UKHSA) says
this “is not unexpected, given
the community prevalence
across the period of the
investigation”, but it is looking
into whether a previous
covid-19 infection could
be the second factor.
Another idea is that the
current cases are merely ones
that were “delayed” because
children had less chance to get
infected with the 41F adenovirus
over the past two years. When
England’s first lockdown began
in March 2020, infection rates
of all adenoviruses in 1 to 4-year-
olds plummeted. They returned
to previous levels in late 2021,
shot up to about three times
their former rate in February
and have since been falling.
However, the hepatitis
outbreak seems to have been
too sudden to just be delayed
cases. What is more, the 41F
adenovirus doesn’t normally
cause severe hepatitis like
this, even rarely, says Kelly.
The idea that the outbreak
is connected with lockdowns –
or rather, the return of social
mixing after a period when it
was lower than normal – is the
UKHSA’s leading hypothesis.
There have been fewer
childhood infections in
general going around during
the pandemic, not just
adenoviruses, and immune
responses against some
pathogens can give partial
protection against others.
“These children have not
encountered their normal
childhood viruses,” says Kelly. ❚Could low immunity
be leading to
hospitalisations?MedicineClare WilsonSE
BAST
IANROSE
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Y^ IMAGES169
Cases of hepatitis in children
worldwide in the outbreakAdenovirus is prime suspect
in child hepatitis outbreak
THE US hopes to fight criminal
use of drones with new rules that
will allow local law enforcement
agencies and other bodies to have
counter-drone systems.
At present, legal restrictions
in the US hamper efforts to tackle
such activity. The Federal Aviation
Administration bans anyone from
interfering with an aircraft in flight,
including drones, while the Federal
Communications Commission
forbids jamming radio signals,
a common anti-drone technique.
Only a few federal agencies are
allowed to shoot down drones in
extreme circumstances, such as
threats to critical infrastructure.
US police agencies have been
clamouring for counter-drone
systems in the face of increasing
criminal and careless use of
drones. Drones are routinely used
to smuggle drugs into the US from
Mexico and into prisons, and have
interrupted airport operations on
numerous occasions. Swarms of
drones have intruded over US
nuclear power plants and sites
believed to house nuclear weapons.
On 25 April, the White House
announced its Domestic Counter-
Unmanned Aircraft Systems
National Action Plan. It will expand
the authority of various federal
agencies and pilot the use by local
law enforcement agencies of
counter-drone systems. These will
probably include radio-frequency
jammers that block communication
between a drone and its operator.
“The creation of a nationwide
strategy is a good development
and the plans offer some positive
changes, especially around airport
protection,” says Zak Kallenborn
at the National Consortium for the
Study of Terrorism and Responses
to Terrorism in Maryland. But he
fears that the limited pilot scheme
will mean that many local law
enforcement agencies will still
struggle to tackle criminal drones. ❚TechnologyDavid HamblingUS to bolster its
ability to combat
lawbreaking drones