The South Eastern Health Trust has been forced to close some wards to new patients because of increasing bed pressures caused by an outbreak of the norovirus.
Wards at the Lagan Valley and the Ulster Hospital have been affected, while the trust has also restricted visitors.
Some 33 members of trust staff have been affected by the bug.
In a statement the trust said there had been increased reports of vomiting and diarrhoea in healthcare facilities across the south-eastern area caused by |the virus.
It has advised that babies |and young children do not make hospital visits.
Charlotte McArdle, director of nursing, primary care and older people at the trust, said measures had been taken to limit the impact of the virus.
“When a patient has symptoms of that bug, we have to act very swiftly to try to isolate that |patient,” she said.
“On occasions that means we have to isolate all or part of a ward and restrict the entry to |that ward and that means we |have fewer beds available for |admissions.
“This bug escalates so quickly and is so contagious that it can be hard to manage.”
In a statement, the trust said it has experienced “significant increases in bed pressures”.
“This has resulted in some |patients experiencing a delay |in receiving a bed in a hospital ward,” it said.
“The trust has been working with the Health and Social Care Board and the Public Health Agency to address these difficulties and is currently opening |additional beds to deal with |the high numbers of in-patient admissions.
“The trust needs the support of patients, clients and carers and the public who may visit our hospitals.
“We would ask that individuals visiting patients in our facilities should avoid doing so if they have vomiting and diarrhoea, cold or flu symptoms.”
The trust has requested that members of the public attending accident and emergency departments inform staff if they have gastrointestinal symptoms.