Food and water samples are being collected and sent for laboratory tests to check for listeria bacteria, which causes the food-borne infectious disease listeriosis, the Epidemiology Unit of the Health Ministry said.

“A middle-aged woman’s death was reported from the Ratnapura hospital due to complications from listeriosis. The woman was working in Sri Pada (Adam’s Peak) area. There have been two suspicious deaths of pilgrims. However, it has not been confirmed that the duo died from listeriosis. Post-mortem examination is still being conducted," the unit said.

The unit said laboratory tests do not show a widespread outbreak hence there is no need for the public to panic.

Listeriosis is a foodborne infectious disease caused by a bacterium, Listeria Monocytogenes. It's most commonly caused by eating improperly processed meats and raw milk or for products prepared with raw milk or unpasteurized milk products like ice cream and yoghurt.

The unit said healthy people rarely become ill from listeria infection, but the disease can be fatal to unborn babies, newborns, pregnant women, people older than 65, and those with weakened immune systems.