MEDICAL experts are continuing investigations into cases of the tap water bug cryptosporidium in Bolton.

Seven cases have been reported to health chiefs in the past two weeks.

Most cases of the infection, which can lead to gastrointestinal illness with diarrhoea and vomiting, are associated with water consumption, animal contact, swimming pools or person to person contact.

One possible link health experts are considering is Thirlmere Reservoir, which supplies drinking water to Bolton.

Yesterday, the BEN was inundated with calls from residents suffering stomach bugs with similar symptoms to cryptosporidium.

Dr Robert Aston, consultant in communicable disease control for Wigan and Bolton Health Authority, said no further cases had been reported.

He said up to five per cent of the Bolton population suffers different types of stomach bug every week.

Dr Aston will meet with colleagues from the region on Monday to review their findings.

A further 84 cases have been reported in other towns and cities across the North-west. The cases come just weeks after North West Water promised to spend £300 million to cut any risk of infection after a major report concluded Thirlmere was responsible for more than 300 cases last year, including 67 from Wigan and Bolton.

After this latest outbreak of the water bug, regional epidemiologist Professor Paul Hunter said: "Thirlmere is a possibility but we are not totally sure what is causing the outbreak because there may be more than one."