'As chicken pox is caused by the varicella zoster virus, which is transmitted by the airborne route, SM Goh's doctors decided to admit him to an isolation ward,' the statement said.

Mr Goh's condition is satisfactory and he is expected to be discharged in about a week's time, it added.

Chicken pox is a generally mild, contagious childhood illness that is characterised by a fever and the appearance of red spots on the body and face.

It spreads by direct contact or inhalation of air droplets from an infected person's coughing or sneezing.

It is not unusual for adults to be admitted for the disease as they might run into more complications, said Dr Leong Hoe Nam, a consultant infectious disease physician at SGH.

He noted that while it is less common for adults to get chicken pox, disproportionately more adults in Asia tend to succumb to the disease as they do not get it during childhood.

Once a person has had chicken pox, he is immune to the disease and very unlikely to catch it again. However, he or she may develop shingles.

One can get chicken pox within 10 days to 21 days of coming into contact with an infected person, according to the Health Promotion Board's website.

An infected person is usually infectious one or two days before the rash appears until about a week later, when the spots dry up and the body temperature falls back to normal.

Read the full story in today's edition of The Straits Times