What We Can Learn from Vomiting Larry

The robot’s name may be fanciful, but the task it’s tackling is quite serious. Researchers at the Health and Safety Laboratory in Derbyshire in Great Britain are using “Vomiting Larry” to learn more about how the infectious norovirus spreads. Vomiting Larry is a humanoid simulated vomiting system that expels a water and fluorescent liquid mixture enabling ultraviolet light to track the pattern and distance of expulsion, if you will.

That pattern is particularly important in understanding the spread of norovirus, a highly contagious virus that causes vomiting and diarrhea. In most cases, it is extremely unpleasant for a few days, but under some conditions it can be very dangerous or even fatal.

Named for an early outbreak at a high school in Norwalk, Ohio, norovirus is the leading cause of foodborne disease and the cause of half of all worldwide gastroenteritis outbreaks, according to the report Noroviruses: The Perfect Human Pathogens?  from the Centers for Disease Control (CDC). The CDC estimates that norovirus caused 21 million cases of acute gastroenteritis annually in the U.S. alone.

When norovirus invades human cells in the intestinal tract, it rapidly multiplies, and causes the violent emptying symptoms, referred to above. The expelled fluids contain billions of infectious doses of the norovirus, and many paths exist for transmitting those doses to a new host.

Noroviruses are notoriously robust, able to survive freezing and heating as well as many common chemical disinfectants, and can live on surfaces for up to two weeks. Among the ways infectious noroviruses can spread is through ingestion of airborne or aerosolized particles. With such potent doses of the virus carried in such small amounts of fluid, it’s critical that all surfaces and objects in range of those aerosolized particles be effectively disinfected, or discarded.

That’s why Larry is vomiting fluorescent fluid: to determine how far and wide expelled fluid can travel. Some of that fluorescent fluid has been traced more than three meters from Larry. So an object or surface about ten feet away from an incident that was contaminated two weeks ago could still cause transmission of the norovirus. The researchers intend to publish their more detailed findings in relevant journals and hope that the results can contribute to healthcare and procedure guidance in hospitals other medical facilities.

The robustness of the norovirus makes prevention and control of outbreaks particularly difficult. The CDC recommends rigorous hand hygiene (especially mechanical washing with soap and water), exclusion and isolation when possible, environmental disinfection (particularly with a high concentration of chlorine bleach), and thorough cooking of food whenever possible.

Meanwhile, let’s hope Larry is doing what he does, so we won’t have to.