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