Apple has confirmed to RTÉ News that the company is working with the Health Service Executive in relation to a case of rubella identified at its Hollyhill campus in Cork, where several thousand people are employed.
It is the first case of rubella in this country for more than a decade.
The HSE has said all precautionary steps have been taken to alert people who may have been in contact with the person who has been diagnosed with the disease.
The HSE confirmed it was informed of a case of the virus "in recent weeks".
However, the executive is refusing to comment on the specifics of the case or the identity of the person involved.
The case is understood to have come to light at the end of last month.
RTÉ News has also spoken to employee sources who have expressed concerns about precautions being taken at the plant, subsequent to staff being informed of the case.
An email to staff at the Hollyhill plant states that Apple has been informed by the HSE of a case of rubella "at our Cork Hollyhill campus".
The email continues: "Our employees' health and wellbeing is our top priority, and we want to ensure all members of the local team are aware of the situation and the resources available to you.
"The possibility of contracting rubella is low, and most cases are mild.
"HSE advice for pregnant women is to check your rubella immunity status with your GP however most likely this has already been checked by your antenatal team."
HSE South says its Department of Public Health has been in contact with GPs in the area, who have been asked to maintain increased surveillance. It is also encouraging people born after 1978 who have not been vaccinated to get the vaccine, which is free of charge and available from GPs.
Rubella is generally a mild condition, but it can harm the unborn babies of women who are pregnant.
Rubella is a notifiable disease, which means that medical practitioners must notify the HSE of suspected cases.
It is usually accompanied by a low grade fever and a red rash which starts on the face and progresses from head to foot. It may be fleeting but typically lasts about three days. It can be itchy. The rash is fainter than the measles rash and may be more obvious after a hot shower or bath, according to the HSE.
It says people with rubella are most infectious from one week before to one week after the onset of the rash. The incubation period is 14-17 days, with most developing a rash 14-17 days after exposure.
The last confirmed acute rubella case in Ireland was notified in 2009.
Last year the Department of Health here called on the public to ensure that they are up to date with the measles, mumps and rubella vaccination.
The appeal followed the release of figures by the World Health Organisation, which showed that measles cases rose 300 per cent worldwide to 112,163 in first three months of 2019, compared to 2018.
The best way to protect someone against MMR, according to the Department of Health, is to vaccinate directly, rather than rely on 'indirect' protection through herd immunity.
Rubella is not the same as measles, though the two illnesses do share some characteristics, including the red rash. However, rubella is caused by a different virus to measles, and is neither as infectious nor usually as severe as measles.