The most likely cause of the outbreak is raw milk from a vending machine at Low Sizergh Barn Farm.
The farm has suspended sales of raw milk to the public.
South Lakeland District Council and Public Health England are investigating the 56 illnesses.
Recall and sales stop
Low Sizergh Farm recalled its raw cows drinking milk due to six confirmed cases of Campylobacter infection in December.
It advised consumers not to have any of its raw milk that they have at home and dispose or return it for a refund.
The suspected vending machine has been shut down while extra tests are carried out.
Richard Park, farm owner, told BBC Radio Cumbria the safety and integrity of the milk was very important (from 1:21:36).
“One of the first things I did was investigate what I needed to do and sought advice from the authorities to what I needed to test for so for 18 months I was testing the milk and getting the right procedures in place.
“But Campylobacter wasn’t one of the bacteria that we were asked to test for so it did come as rather a shock when I got that phone call…”
Park added if things go smoothly it could be back selling the milk within a month.
An increase in cases was found after an online questionnaire was set up for visitors to the farm since 24 October.
FSA-led investigation
A council spokesman said: “The FSA is leading on the ongoing investigation at the farm and they are working to ensure measures are in place to prevent the public consuming unsafe products.
“Unpasteurised milk was removed from sale at the premises as soon as the Campylobacter results were confirmed.’’
The incubation period (time between eating contaminated food and start of symptoms) for Campylobacter is between two and five days but can be up to 10 days and symptoms usually last less than a week.
Normally, raw milk should be kept in the fridge (4°C) and used within five days of purchase.
The Food Standards Agency (FSA) said: “Long-standing FSA advice has been that vulnerable people - that’s older people, infants, children, pregnant women and those with weakened immune systems - are particularly vulnerable to food poisoning and that is why these groups should not be consuming raw drinking milk because it has not been heat treated.”
The number of registered raw cows' drinking milk producers in England, Wales and Northern Ireland has fallen from 570 in 1997 to around 100 in 2016. Raw drinking milk and cream is banned in Scotland.
Listeria in Australia
Meanwhile, a spike in Listeria cases has left one dead and at least another six in hospital in an Australian state.
Dr Finn Romanes, the Victorian Government's acting chief health officer, issued an active health alert.
The agency said it has seen an increase in notifications of listeriosis in pregnant women and the elderly in recent weeks but cases have not been linked to each other or to a certain food.
Time from infection to symptoms can range from eight to 90 days.
Martyn Kirk, associate professor at Australian National University, said Listeria is a rare infection, with 60-80 cases reported to health departments each year in the country.
“The majority of these infections occur in people who have weakened immune systems, or are elderly. The consequences are severe, with up to 20% of people dying following infection,” he said.
“For people in high risk groups (pregnant women and immunocompromised) they should not eat foods that are high risk for Listeria contamination, including pre-prepared fruits and salads, deli meats, pre-cooked and smoked seafoods, soft cheeses, pates and dips, soft serve ice creams, and unpasteurized milk products."