SINGAPORE - Four more suspected cases of Zika have been sent to the Communicable Disease Centre (CDC) at Tan Tock Seng Hospital, by another Sims Drive clinic on Monday (Aug 29).

They include three women, aged 32, 26 and 24, none of whom are pregnant. The last is a 44-year-old man.

All of them are Singaporean.

The cases were sent by TJ Medical & Surgery clinic at Block 48, Sims Place, which is across the road from Sims Drive Medical Clinic where doctors alerted authorities of Singapore's first known case of Zika.

Dr Tan Thai Keng of TJ Medical & Surgery told The Straits Times he had sent the four to CDC for confirmation, after they developed fever and rashes, "and a bit of joint pain, which is another symptom of viral infection".

The patients had gone to him earlier on Monday.

He said the clinic was more alert to potential cases following news of the Zika outbreak in the area. "Today we are on the lookout. That's why I wanted to send them to Tan Tock Seng to do their blood tests straightaway," he said.

The four were sent to the hospital in a taxi. It is not clear when the results will be out.

Dr Tan said that more women are visiting his clinic as news of the outbreak spreads. This includes a 32-year-old pregnant woman who was well but worried about the situation.

"She wanted to find out whether she had the virus in her blood or not. So we took her blood here, and sent it to the lab at Tan Tock Seng."

The latest four suspected cases follow on five earlier ones on Monday, which were referred to the CDC by Sims Drive Medical Clinic.