A Devon MP has said “heads are going to roll” following a waterborne parasite outbreak, as residents complain of a lack of contact from their water supplier.

Around 16,000 households and businesses in the Brixham area of Devon supplied by South West Water (SWW) have been told not to use their tap water for drinking without boiling and cooling it first.

The UK Health Security Agency (UKHSA) said on Friday that 46 cases of cryptosporidium, a disease which can cause unpleasant symptoms such as diarrhoea and vomiting, had been confirmed in the fishing town and that more cases were anticipated.

Conservative MP Anthony Mangnall, whose Totnes constituency includes Brixham, said it had been “an absolutely disastrous week and the anger is palpable”.

Speaking to LBC News on Saturday, Mr Mangnall said: “This is such a serious matter that yes, I think heads are going to roll over this, but it’s more important to get the system back up and running, make sure people have confidence in the network rather than pointing fingers.

“We do the investigation afterwards and we will make sure that those who are responsible are held to account.”

He added: “From starting this week with a denial from South West Water that it was anything to do with them, delaying the fact that the boil water notice came in, meaning thousands of people used the water network, to then issuing it on Wednesday, and there are a lot of people who are very ill.

“So, it’s been an absolutely disastrous week and the anger is palpable.”

SWW issued a “boil water notice” for Alston and the Hillhead area of Brixham after water tests showed “small traces” of the parasite.

SWW chief customer officer Laura Flowerdew said on Thursday a damaged air pipe in a field containing cattle was a potential source.

Dr Lincoln Sargeant, Torbay’s director of public health, said the initial contamination has been “more or less dealt with” but delays in symptoms developing may cause the number of cases to increase for “up to two weeks”.

He told BBC Radio 4’s Today programme on Saturday the waterborne disease was “unpleasant but self-limiting” for most people, while it was “vulnerable people who are at risk for more severe illness”.

Dr Sargeant added: “It’s important for listeners to recognise that in terms of the initial contamination that we think is more or less dealt with, so with the boiled water notice, with bottled water, we are pretty sure now that no one needs to continue to be affected by contaminated water.

“And we know that South West Water is now actively doing work to flush through the system to make sure that ongoing contamination does not occur.

“However, it’s important to recognise that people may continue to develop symptoms from that initial contamination up to 10 days, some people may even up to two weeks, so the numbers may increase – but that doesn’t necessarily mean that the situation is getting worse.”

Business owners in the fishing town have complained about the lack of contact from SWW.

Sally Dart, who runs homewares shop Flotsam 50 near Brixham Harbour, told the PA news agency business was “probably 30 to 40% down” and described the water company as “appalling”.

Ms Dart said locals first felt symptoms after a busy pirate festival held in the fishing town between May 4 and 6.

On SWW, she added: “They knew they had this problem – obviously the reservoir couldn’t cope for some reason or another, it was getting all the stuff off the field into it.

“No one was checking the quality of the water and we’ve all got sick and it’s stupid, really.”

A guest house manager said the disease has caused cancellations totalling “up to £1,000” and he had heard “nothing direct at all” from SWW.

Steve Price, who runs The Station Guesthouse in Brixham, told Today: “So for us at the moment, we are seeing guests actually cancelling.”

He said his business was “following all the guidance” to ensure visitors’ safety, adding: “So we’re trying everything we can to make sure that when guests do come that they feel comfortable and they feel safe.

“We’re also e-mailing all our guests at the moment to let them know we’re doing all this to try and put them at ease, to encourage them still to come and visit us because of course it’s a lovely area.”

Asked about what contact his business had with SWW, Mr Price said there had been “nothing direct at all”.

“We’ve had to instigate any contact, there has been notifications coming from Torbay Council about numbers to contact but it’s a shame for commercial businesses because we’ve had no one come round,” he added.

Asked how much his business had lost, he said: “So far, probably anywhere from up to £1,000 in cancellations so far, which is fairly substantial.”

Residents are being urged to boil water and let it cool before drinking it, preparing or cooking food or cleaning their teeth, although the company said water can continue to be used as normal for washing, bathing and flushing the toilet.

The disease can be picked up directly from the faeces of another person or animal, from swimming in or drinking contaminated water, or by eating contaminated food such as unwashed vegetables.