Read the latest on this story | Health inspectors confident Calgary shawarma chain safe after 123 people fall ill

Alberta Health Services conducted a number of investigations at a chain of Calgary-based shawarma restaurants after receiving multiple complaints of illness, the health authority confirmed Thursday.

AHS said it received the first complaint related to Jerusalem Shawarma on Dec. 6, and then received more reports from 17 different groups who ate at multiple locations from Dec. 4 until Dec. 12.

The health authority conducted more than 25 inspections at all restaurant locations between Dec. 7 and Dec. 18, at which point it was determined norovirus was the likely cause of the illnesses.

"Public health inspectors discarded potential foods of concern (i.e. cut vegetables, sauces, et cetera), implemented enhanced handwashing procedures and increased disinfection levels and frequencies," reads a statement from AHS.

The restaurants were not closed down due to the outbreak being attributed to norovirus, according to AHS.

Norovirus is not a serious illness, AHS said, though some individuals may have symptoms such as nausea, vomiting, diarrhea and stomach cramping. Others may have chills, headaches or a low-grade fever, but symptoms generally subside within one or two days.

Those infected with norovirus can easily spread it to others, AHS said. The illness is spread through contaminated food and drink, and can also be spread when individuals touch surfaces that are contaminated and then place their hand in their mouth.

"Albertans are reminded to stay home when sick, refrain from preparing foods while sick with diarrhea or vomiting, and always wash hands well with soap and warm water before preparing foods or drinks or before eating or drinking," reads a statement from AHS.

AHS said it is continuing to work with Jerusalem Shawarma to ensure the outbreak is contained and doesn't pose any further risks.