It was the second week of August when the three doctors at Sims Drive Medical Clinic became puzzled when they spotted a pattern emerging among patients.
Construction workers had come in with similar symptoms: rashes, joint pain and sore eyes. Then the symptoms showed up in other residents and office staff who had almost no contact with the workers.
Around 10 people a day were coming in with similar signs. But tests for dengue, chikungunya, measles and rubella all came back negative.
Unable to pin down the mysterious virus, Dr Tan May Yen, 37, Dr Lim Chien Chuan, 52, and Dr Chi Wei Ming, 47, had no choice but to provide them with general advice on how to treat their symptoms. But they still felt uneasy.
"I was uncomfortable because I owe my patients a duty of care," recalled Dr Lim. "They would want to know if their conditions were infectious, and what complications they were going to have."
The doctors considered the possibility of Zika, a viral infection transmitted by the Aedes aegypti mosquito.
Though generally a mild disease, it has been associated with congenital defects in babies born to women infected during pregnancy. But not one of them had travelled to an area that had been affected by Zika.
Concerned about the potential implications of the virus on vulnerable members of the community, the doctors contacted the Ministry of Health (MOH) on Aug 22 for help in identifying the mystery virus.
They alerted authorities to the possibility that Zika had come to Singapore and, days later, the first locally transmitted case was confirmed. It was one of the clinic's patients, a 47-year-old Malaysian working in the area.
Efforts were made to contain the spread of the virus. Those with symptoms were urged to go for testing and guard themselves against mosquitoes. MOH also offered to help the clinic provide free consultations at the Communicable Disease Centre for patients with symptoms.
The situation around the clinic was tense and regular patients avoided the clinic. But the doctors were more concerned about helping to contain its spread.
"The challenge was trying to educate the patients who were infected about precautionary measures that they could take, while telling them that they did not have to worry so much," said Dr Chi.
With the protocol put in place by the authorities, the infections dwindled. Fogging also helped to reduce the number of cases in the area.
After seven weeks, the Aljunied Crescent/Sims Drive cluster was closed on Oct 9, and kept under surveillance. The clinic saw more than 150 cases throughout that period.
Professor Duane Gubler, founding director of the emerging infectious diseases programme at Duke- NUS Medical School, said the collective effort by authorities and community managed to contain what could have been a major epidemic.