Norwalk-Like Viruses are responsible for causing gastroenteritis outbreaks in many long-term care facilities. The transmission route is fecal-oral. The virus can be spread by food or water but is most frequently spread by the contaminated hands of healthcare workers. Environmental surfaces can also become contaminated, especially in areas where vomiting has suspended viral particles in the air.
The virus is from a family called Caliciviridae. This small virus is extremely infectious requiring only a small number of viral particles to produce symptoms. This virus can survive freezing, and heating to 60C, making it difficult to eliminate from food and water.
The incubation period is 12-48 hours and produces symptoms for 12-60 hours. The symptoms may include nausea, vomiting, abdominal cramps, diarrhea, headache, fever, chills and mylagia. The virus is present in vomitus and stool. Viral shedding begins a few hours before symptoms and may last a week or more even if symptoms are minimal. Immunity does occur after the infection but it will probably only last for six months.
There is no specific therapy available for treatment. The illness is self-limited requiring supportive care occasionally including fluid and electrolyte replacement. Facility outbreaks must be reported to DHS and public health. Control measures must be taken to interrupt the person to person transmission. Outbreaks should be detected early based on symptoms not lab test results.
DHS and some public health departments can provide PCR testing of stools free of charge in outbreak situations. MuirLab can provide stool testing through our reference lab. Specimens need to be obtained during early symptoms and sent fresh. Be sure to follow the lab directions for correct container and refrigeration requirements.