A possible labeling mix-up among about 135 people, whose blood were tested on the same day by PathWest, has a led to a re-test among 90 people as one of the patient's blood showed up HIV positive in an initial test in April.

The pathology center has conceded that it did not notify the right patient about the positive test, which means an infected person may have remained in the community for four months without knowing it.

The mix-up was revealed when one of the patients who had given blood test for HIV was initially told that he might have HIV, but a later test proved he was negative. This left the authorities with one positive HIV result, and in a bid to find the owner, the PathWest authorities re-tested all the patients who had originally asked for a HIV test, but found that all the people who had asked for HIV tests had actually received the correct results.