Residents in Devon have been warned to boil tap water before drinking after “small traces” of a parasite which can cause sickness were found in a water supply in Devon.

Public Health identified 22 cases of sickness caused by the parasite in Brixham. Up to 100 people have also reported symptoms connected to the parasite known as cryptospodorium.

Infections are caused by drinking contaminated water or swallowing it in swimming pools or streams and can cause symptoms including diarrhoea, nausea, and low grade fever.

Symptoms have been reported since the start of the week, and the outbreak is expected to last another week as symptoms caused by the infection can take up to 10 days to show.

South West Water are investigating a reservoir and the wider Alston area as a potential cause for the outbreak, where about 40,000 residents get their water supply. They are asking residents to collect free bottled water as it searches for the “root cause”.

There is no effective antibiotic treatment for infections but most people recover.

The UK Health Security Agency said it is working with Torbay Council, SWW, NHS Devon and the Environment Agency to investigate the cause of the outbreak.