At least three inmates are apparently in isolation after testing positive for swine flu and extra measures have been introduced to help stop the spread of the virus using mechanisms to identify prisoners who might have influenza-like illnesses, test them, treat them, isolate them and visitors to jails are being asked to defer visits if they themselves have influenza-like illnesses.

Experts say the risk of outbreaks in institutions like prisons, hospitals, boarding schools and other institutions is high and diseases such as tuberculosis, influenza, and other respiratory viruses,are transmitted very easily in such closed settings.

They say in such situations caution regarding the movement of both inmates and staff must be exercised and vaccination too is important as well as the use of anti-viral drugs.

Though a number of companies are currently working on a H1N1 vaccine, nothing is expected to be available for some time.