Once it was famed as a calorie-burning Latin dance workout that celebrities swore by to lose as many as 30kg.

But the mention of Zumba now will send chills down many spines in South Korea, after more than 100 cases of community infection of the coronavirus were linked to it.

Netizens lashed out at a group of "crazy Zumba ajummas (Korean for auntie)" for spreading the virus in the western city of Cheonan, while Zumba instructors cried foul over a witch hunt that created the misconception that Zumba is an infectious dance.

This and more small cluster outbreaks of the coronavirus are triggering concern, as the number of cases continued to grow, reaching 8,799 yesterday. There were 147 new cases, and the death toll hit 102.

Prime Minister Chung Sye-kyun yesterday urged religious, sports and entertainment facilities to suspend operations, and people to avoid travel and socialising over the next 15 days, in order to curb the spread of the virus.

Social distancing also helps, as the virus can spread quickly in crowded, enclosed spaces, experts warned.

Infectious diseases professor Kim Woo-joo of Korea University Guro Hospital said people can reduce the risk of infection in crowded spaces by keeping a distance of 1m to 2m from others, and avoiding direct contact.

Cluster infections account for 80 per cent of South Korea's confirmed cases, the largest cluster being linked to a branch of the secretive Shincheonji Church of Jesus in the south-eastern city of Daegu.

The city has the highest number of cases, 6,344 as of yesterday.

Capital city Seoul has reported 314 cases, with another 321 in the surrounding Gyeonggi province.

Major clusters revolve around healthcare facilities, such as Daenam Hospital (119 cases) in Cheongdo, and religious organisations, including River of Grace Church (60) in Seongnam city.

Last week, Gyeonggi imposed a new administrative order on around 15,000 entertainment facilities, including Internet cafes, karaoke rooms and dance clubs.

They are required to abide by measures such as regular disinfection and maintaining good ventilation, or risk getting their business licence suspended.

The move came after a bout of small cluster infections emerged around the country.

In Seoul, there are 91 cases among telemarketers working at a call centre and nine linked to an Internet cafe. Other clusters include a coin karaoke room in South Gyeongsang province (seven cases) and a kindergarten in Busan (six cases).

In South Chungcheong province, Zumba dance "put Cheonan city in fear", according to JoongAng Ilbo newspaper.

The city's first two cases confirmed on Feb 25 are both linked to Zumba. The first is a 47-year-old woman who attended the class, and the second, a 50-year-old Zumba instructor who taught at three fitness centres and had 60 students.

By March 2, the cluster had grown to 77 cases, including family members of these Zumba instructors and students, from as young as a two-year-old child. Cheonan city closed 10 fitness centres and community centres offering Zumba lessons.

The final tally in the province, which includes Asan city, is now 103 cases. Most of them are women ranging in age from their 20s to 50s.

Zumba-linked infections have since spread beyond the region to Sejong , Seoul and Gyeonggi .

The health authorities said the virus could have spread so fast because Zumba classes tend to be conducted in small rooms with bad ventilation, with students standing a few centimetres apart.

Amid swirling animosity against the Zumba dance group, one woman has posted her experience on an online forum, calling for an end to hurtful comments.

Happymonjju said she attended a Zumba class at a fitness centre on Feb 19 but was told in a call to the coronavirus hotline that she did not need to go for a test as infections linked to the centre were traced to a Feb 21 class.

But her husband developed high fever on March 2 and tested positive for the coronavirus on March 4. She and her two children also tested positive the next day, even though they had no symptoms, she said.

"I regret not taking the virus test earlier, and I feel remorse for causing harm and being a threat to my neighbourhood," she wrote, adding that she was careful to stay at home and wore a mask when she went out to the supermarket and bakery.

But she still drew online comments that she was socially irresponsible and "went out a lot".

"I want to die because I think I caused too much damage... Even without hate comments, my mind is already experiencing hell."

• Additional reporting by Kim Yeo-joo