Singapore Singapore on Monday sent teams armed with protective suits, fogging machines and insecticide to wage war on mosquitoes after the discovery of dozens of Zika infections sparked alarm in the city-state.

Inspectors from the National Environment Agency checking for mosquito breeding sites visited homes in the suburban district where 41 cases — mostly foreign workers at a condominium construction project — were reported at the weekend.

Nearly all have recovered but five more suspected cases of Zika virus infection were reported Monday by a clinic, local media said.

The five, who include foreign workers, were undergoing further tests at the Communicable Diseases Centre.

Singapore, despite the highest health care standards in Southeast Asia, is a densely populated tropical island with frequent rain. Mosquitoes breed in stagnant water that collects in construction areas, open space and homes.

It is also one of Asia’s cleanest cities but has a chronic problem with dengue fever, which is spread by the same Aedes mosquito that carries the Zika virus.

Zika causes only mild symptoms for most people, such as fever and a rash, and has been detected in 58 countries particularly Brazil.

But in pregnant women, it can cause microcephaly, a deformation in which babies are born with abnormally small brains and heads.

“It’s quite frightening because I thought Zika is something happening on the other side of the world. But now it’s right here in my neighbourhood,” customer service manager Josephine Kwan, who lives in the affected suburb of Aljunied Crescent, said.

Singapore’s first reported case of Zika in May involved a man who had visited Sao Paulo in Brazil earlier in the year.

But all of the latest cases involved local transmission.

Neighbouring countries took steps to prevent the spread of the disease from Singapore.

Taiwan on Monday issued a travel advisory for Singapore, urging travellers to watch out for mosquito bites and cautioning pregnant women and those planning to conceive to postpone trips to all areas with Zika cases.

Malaysia, Indonesia and the Philippines have also said health officers will closely monitor arrivals from Singapore, which was visited by 15 million people in 2015.

In the city-state inspectors armed with insecticide spray cans on Monday visited high-rise public housing flats to check toilets and other areas for stagnant water.

Owners of homes found with such sites can be fined up to Sg$5,000 (Dh13,579).

Contractors in protective gear carried out insecticide fogging in public places, pumping a mosquito-killing mist over large areas on the ground.

The government Sunday confirmed a total of 41 Zika cases, of whom 36 are foreigners working at a condominium construction site.

Work was halted at the site on Saturday after environment agency officers found that housekeeping was “unsatisfactory with potential breeding habitats” for mosquitoes.

The latest global outbreak of the disease began in Brazil in early 2015.