LONDON, Ont. - For the second time in less than a week, officials at the London Health Sciences Centre are dealing with an outbreak.

University Hospital and the Middlesex London Health Unit are reporting an outbreak of Norwalk virus on a unit on the 4th floor.

Four patients are currently experiencing Norwalk-like symptoms, and strict visitor restrictions have been put in place on the affected unit.

Symptoms typically involve an acute onset of nausea, vomiting and diarrhea. Headaches, fever and muscle pain are symptoms as well.

The virus is rarely severe or fatal in health adults, but patients in hospitals are susceptible and can become quite ill.

Last week, an Influenza A outbreak occurred on of the wings of the cancer in-patient unit at Victoria Hospital.

Until further notice, patients in the affected unit will be restricted to one visitor at a time.