COUNTER-MEASURES the Ministry of Health has implemented in recent years may have slowed but not stopped or reduced the number of HIV/Aids cases. Raising awareness, screening pregnant women as a routine pre-natal procedure and, if a current proposal is adopted, testing men as part of hospital admissions are all sound steps.

But there obviously are high-risk individuals who show cavalier disregard for their partners in pleading ignorance about HIV infections they may have contracted. Health Minister Khaw Boon Wan disclosed in July that analysis of 3,000 anonymous leftover blood samples earlier this year showed that one in 350 public hospital patients had the virus.

This bears out a UNAids estimate of 0.3 per cent incidence among adults as a rough worldwide measure. That would notionally raise the Singapore incidence to 9,000 cases, as opposed to the 2,852 cases recorded. So, most of those infected do not know or do not want to know they are infected.

Why? More to the point, what is to be done? Such ignorance or denial is dangerous. If public health education or the matter of conscience fails to convince them to find out and to behave appropriately, criminal penalties might.

A proposed amendment to the Infectious Diseases Act now under public consultation will provide for up to 10 years' jail and/or a fine of as much as $50,000 for adults found guilty of having unprotected sex even if they do not know but have 'reason to believe' that they have or have been exposed to the virus.

The new provision tightens current law which requires proof that the accused knows he has an infection. It lowers the bar considerably but not completely. If trial is claimed, the prosecution will have to adduce evidence to prove the accused had 'reason to believe' - not an easy or practical task, if it requires surveillance to discover a pattern of private behaviour.

Nevertheless there is deterrence to the extent those who are ignorant or in denial need to be sure their partners, who probably are in a better position than law enforcers to know their conduct, do not testify against them. Also, some would rather avoid prosecution in the first place.

At the same time, the innocent need not fear as there presumably will be no enforcement if sexual activity does not result in infection. Those concerned about privacy protection might regard the amendment as intrusive, but there is the precedent of mandatory HIV/Aids notification of spouses.

There is no reason why the new measure cannot contribute to preventing risk-takers from turning the present low incidence into a serious epidemic that even cities less exposed to the virus than Singapore have experienced.