Babies at Ninewells may have been exposed to the potentially fatal whooping cough, the hospital has warned.
Letters have been sent out to parents of babies who have visited the neonatal unit at the hospital recently, warning them to keep a close eye on the health of their offspring.
It is understood the alarm was raised after a night shift team member – who had been working with the babies in the unit – displayed symptoms of the illness.
The employee was subsequently sent home but bosses feared that the disease may have already spread to babies that came into contact with the staff member.
The letter recommends that parents contact the hospital if their baby is unwell or develops a cough illness in the next three weeks.
A spokesperson for NHS Tayside said: “The NHS Tayside Infection Control Team is currently investigating a confirmed case of pertussis, which is also known as whooping cough, in a staff member in ward 40 at Ninewells Hospital.
“The staff member affected is receiving appropriate treatment.
“Babies in the ward, their parents and other members of staff who may have been in contact with the staff member, are being offered treatment where necessary.
“We are taking the additional precaution of contacting the parents of a small number of babies recently discharged from the hospital who had brief contact with the staff member.
“All parents of babies who may have been affected have now been contacted directly. An information sheet is being offered to parents in the ward and nursing and medical staff will be on hand to answer any questions parents may have.
“The best way to protect your family from whooping cough is vaccination. All children are offered vaccination against whooping cough from the age of two months.
“Women can help protect their baby from getting whooping cough in the first weeks of life by having the whooping cough vaccine while they are pregnant – even if they’ve been immunised before or have had whooping cough themselves.
“Immunisation is recommended as soon as possible from week 16 of pregnancy. The ideal time is between weeks 16 and 32, but the sooner the better.
“If you are 16 weeks pregnant or more, talk to your midwife, practice nurse or GP and make an appointment to get immunised as soon as possible.
“If you have any concerns about whooping cough, or anything related to babies or children’s health, you can contact your GP or community midwife, or call NHS24 by dialling 111.”