One further guest and a further member of staff at the Beardmore Hotel in Clydebank have shown symptoms of diarrhoea and vomiting.
This takes the total number of guests affected to 25 and staff affected to four however none are giving cause for concern as a result.
None of those guests affected stayed at the hotel overnight but rather they were delegates at conferences held there last week.
All four members of staff will remain off work until fully recovered.
Dr Gillian Penrice, NHS Greater Glasgow and Clyde Public Health Consultant, said: "We have continued to monitor the situation closely and the clinical presentation of these individuals is very suggestive of Norovirus infection.
"Norovirus infection is a common viral illness present throughout the community and can spread rapidly in areas with a high concentration of people such as hotels, cruise ships, hospitals and schools.
"Our advice to other guests in the hotel who are not symptomatic and to those who are due to check in or attend any functions is to follow strict hygiene rules such as regular hand washing.
“Staff at the hotel have been exemplary in their cooperation with us and we are grateful to them for their efforts.
"We continue to be satisfied with the precautions that have been put in place to limit the spread of the illness and the hotel is still operational.
"I would advise anyone who has either stayed, attended or worked at the hotel and is experiencing either diarrhoea and/or vomiting and a fever and is concerned to contact NHS24 on 0845 4 242424 or their GP.”
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