The cause of a campylobacter outbreak in Timaru is still unknown.
Village Milk Timaru shut its doors last week after Community and Public Health confirmed seven cases of people contracting campylobacter were linked to milk bought there on March 7 and 8.
Franchise owners Stu and Andrea Weir had previously hoped to reopen by today.
"There is more testing to be done. We don't know precisely what the cause of the original outbreak was. It could be from one of the introduced cows, or it could be part of the water supply was contaminated. We have to canvass every possible option," Stu Weir said.
"Hopefully, we will reopen by the end of the week. We appreciate our customers' support and patience."
Village Milk chief executive Mark Houston said the presumptive milk test results for last week's samples were still positive for campylobacter.
"We are now widening the search for a cause and have sent water samples away for analysis. We will not be able to reopen until we have a clear understanding of the cause of this problem and a solution that we can rely on to make sure the milk is safe to drink," Houston said.
The Ministry for Primary Industries has also launched an investigation into the source of the contamination.
"Any time there is an illness linked to a food source, any leftover food can be sent for testing by the investigating officer," an MPI spokesman said.
"In the case of raw milk, the product in question has almost always been consumed by the time people get sick, so there is nothing for investigators to test."
Campylobacter is the most common food-borne illness in New Zealand, with symptoms including diarrhoea, abdominal pain and fever within two to five days of being exposed to the organism.
South Canterbury Medical Officer of Health Dr Daniel Williams said there had been no further reported cases of campylobacter linked to raw milk consumption since last week, but that "does not mean no one else was affected".
"There would have been some people who got sick (from consuming the milk), but decided not to visit the doctor, or get tested for it," he said.
Williams said there were eight confirmed disease outbreaks linked to raw milk consumption last year, all of which occurred in the North Island.
- The Timaru Herald