Vomiting humanoid helps research

Catherine Makison-Booth, research scientist at the Health and Safety
Laboratory, explains how measuring a manikin’s vomit is helping to
increase scientists’ understanding of contamination

One of the main symptoms of
Norovirus is projectile
vomiting and this can present
challenges for anyone faced with the
task of cleaning up. Following a large
outbreak of Norovirus in 2010, The
Health and Safety Laboratory (HSL)
developed a system that could help
identify how much of the environment
can become contaminated during an
episode of projectile vomiting.

‘Vomiting Larry’ was the result! As the
name might suggest, Larry is a
simulated humanoid vomiting system.

He consists of a manikin head
connected to a ‘stomach’ via a
simulated oesophagus.

Larry’s head is a training aid used by
medical students and has realistic
structures such as a tongue and teeth so
the trajectory of the projected fluid is as
realistic as possible. During a test, Larry
is primed with a vomit substitute in water
containing a fluorescent dye. Under UV
lighting the dye fluoresces help to
highlight small droplets and splash which
would otherwise be ‘invisible’.

Studies have shown that patients can
produce between 0.4 and 1.35 litres of
fluid during vomiting. Research has also
found that the main bulk of fluid from
projectile vomiting can travel 1.2 metres
from the source. However, HSL’s tests
have highlighted that this can increase up
to 3 metres once small droplets are
identifiable. This makes an effective
clean-up process difficult.

Once a test has been completed, the
area is cleaned under standard lighting
conditions. Wearing gloves, overalls and
shoe covers, the surrounding
environment is cleaned as per standard
practice, ie. from the cleanest areas
(smallest visible splashes) moving
towards the dirtiest areas (the main bulk
of the fluid). UV lighting is then used to
examine the results of the cleaning
procedure. This repeatedly shows
contamination of the hands, overalls and
soles of shoe covers. It also identifies
areas that have been missed during the
cleaning process.

It is estimated that as many as 1000,
000, 000 viruses can be present in one
litre of vomit so one small droplet can
easily contain many thousands of
viruses. The number needed to cause
infection with Norovirus can be as low
as 10 or 20. Couple this with the fact
that the virus is so robust that it can
survive for several days and even weeks
outside of its ‘host’, and it’s easy to see
the potential for transmission of the
virus during clean up.

HSL’s research has helped highlight
the need for improved methods of
cleaning and decontamination when
dealing with Norovirus sufferers. Many
disinfectant products, such as alcohols
and quaternary compounds are actually
ineffective against the virus.

Hypochlorite/bleach based products are
effective but they are often not suitable
for use with certain materials such as soft
furnishings and metal fixings. This
makes finding appropriate products for
disinfecting contaminated areas
challenging.

HSL is therefore now planning to
conduct research to identify methods
(and products) of best practice for
cleaning and disinfecting a variety of
environments and this will hopefully be
used to inform industry. For more
information on Norovirus, the Health
Protection Agency (HPA) has developed
guidelines for managing outbreaks at
www.hpa.org.uk/webc/hpawebfile/hpawe
b_c/1317131639453