A medical examination, including TB and HIV testing is required in these situations. Test certificates have to be presented on entry (“blood analysis for HIV serology”, performed by a physician registered in Singapore). Foreign certificates performed by clinics licensed for performing such tests are accepted.
There are no health checks at the border. Only obviously sick people are checked with more rigour.
HIV-positive spouses of Singaporean citizens are allowed to stay in the country.
Entering with antiretroviral medication for personal use: Prior approval by the Health Sciences Authority (HSA) is required, e-mail: hsa_info@hsa.gov.sg. In practice, such a permit will only be granted to HIV-positive spouses of Singaporean citizens. A declaration is not required at customs, however, the HSA permit needs to be presented in case of a routine check.
HIV-positive foreigners, including persons diagnosed with AIDS are immediately deported.
(Source: 1)