The number of people infected with dengue in Orchard Road has more than tripled to 64 in the past fortnight, making it the third-biggest cluster in Singapore.
The majority of those infected - 47 people - are construction workers at the Orchard Gateway.
The other 17 are people working in the area, near the Somerset MRT station.
The first case in the prime shopping belt surfaced on Sept 25. By Oct 23, 18 people had been infected, including 15 workers at the construction site.
Visits by National Environment Agency (NEA) officers to the area have uncovered only eight breeding spots - three of which are at the Orchard Gateway construction site. The contractor was given a six-day stop work order on Oct 25.
One of the breeding sites, in a nearby building, was a dust pan which had 30 larvae.
A spokesman for the NEA said it will continue to check and destroy any mosquito breeding in the area, adding: "There is no need to avoid this part of Orchard Road."
This year has seen Singapore suffering its worst dengue epidemic. About 19,000 people were infected and six have died from the mosquito-borne disease.
Although the number of infections is off its mid-year peak of more than 800 cases a week, dengue is still a major concern.
Last week, 495 people were diagnosed with it and between Sunday and 3pm yesterday, another 372 were down with it.
Associate Professor Leo Yee Sin, director of the Institute of Infectious Diseases and Epidemiology at Tan Tock Seng Hospital, said many factors can lead to increased dengue cases, including rain causing stagnant water where the Aedes mosquito can breed.
The NEA spokesman said the cooler weather at the year end usually results in fewer dengue cases, but warned that "there has been a rise in the number of cases in October".
Symptoms of dengue include sudden fever, headache and muscle aches and a red rash.