By Renewable Cleaning Staff
June 6th, 2014
Antimicrobial Test Laboratories (ATL) – a contract microbiology lab founded in 2006 by microbiologist Dr. Benjamin Tanner – has provided the following information as a public service to prevent norovirus on cruise ships.
Norovirus (formerly called Norwalk virus) was first isolated in 1972 in Norwalk, Ohio. It is a relatively small virus that causes nausea, vomiting, and diarrhea. It is highly contagious. Scientists estimate that as few as 10 viruses are enough to cause illness. Symptoms usually last from 1-3 days. Fortunately, death from norovirus infection is rare. Noroviruses are relatively stable in the environment, meaning they can remain viable and infective on environmental surfaces for long periods of time.
- Cleaning and sanitizing ship and hand surfaces is critical to control norovirus outbreaks because studies show it is spread by close person-to-person contact as well as contaminated objects in the environment. Since norovirus is resistant to many ordinary disinfectants including most quaternary ammonium-based products, ship surfaces should be decontaminated with disinfectants specifically labeled for use against norovirus. Since contaminated hands are often involved in norovirus transmission, hand hygiene is also crucial. Alcohol-based hand sanitizers are minimally effective against norovirus. Handwashing with soap and water is most effective.
- The federal Vessel Sanitation Program (VSP) is a program administered by the Centers for Disease Control and Prevention (CDC) under the authority of the Public Health Services Act. It applies to all cruise ships that carry more than 13 passengers and have a foreign itinerary that includes at least one port in the United States. As part of this program, CDC maintains the VSP Operations Manual, which has specific guidelines for prevention and control of norovirus outbreaks. It covers norovirus outbreak surveillance, maintenance of potable and recreational water, food safety, pest management, childcare center hygiene, HVAC maintenance, and housekeeping. All ships covered by the VSP must keep a written outbreak prevention and response plan. If an outbreak is detected, cruise ships must use disinfectants specifically labeled for use against norovirus in accordance with manufacturer-specified use instructions, including contact time.
- The VSP requires housekeeping departments to have a plan for norovirus control, including defined "triggers" and steps taken at each trigger to control the outbreak. For example, studies indicate that a 0.45% daily infection rate is indicative of a pending outbreak, so housekeeping departments should take additional sanitation steps once that threshold is reached
- Ideally, housekeeping departments would incorporate disinfectants effective against norovirus into their ordinary, non-outbreak cleaning regiment to provide an additional layer of outbreak protection. In ATL’s experience, most cruise ships rely on quaternary ammonium disinfectants for routine disinfection. Studies have shown that quaternary ammonium disinfectants are not effective at controlling norovirus outbreaks. In some circumstances, quaternary disinfectants could contribute to the spread of norovirus to non-contaminated surfaces elsewhere in the ship. In addition to selecting agents for routine disinfection that are effective against norovirus, cruise ships should emphasize handwashing over the use of hand sanitizers, since it is more effective.
About Antimicrobial Test Laboratories (ATL)
Antimicrobial Test Laboratories (ATL) is an independent, GLP-compliant testing facility in Round Rock, Texas, whose mission is to improve public health by working seamlessly with customers through the antimicrobial research and development process.