Detection in the Chinese city of Wuhan of a bacteria that caused cholera in a student and was found separately in samples of softshell turtles at a food market has hit a sensitive nerve in ordinary Chinese, with some associating it with Covid-19.

The food market where samples of softshell turtles tested positive for the pathogen capable of causing cholera has been disinfected, local authorities said on Thursday. Although no cases of human cholera were found among people who came into contact with the softshell turtles, the specific store that sold them was ordered to close for three days.

Authorities said the Vibrio cholerae O139 strain for the student’s infection, announced Monday, and the contaminated samples are unrelated. Authorities are also tracking unspecified products from the same batch as the softshell turtles that were shipped elsewhere, the Hongshan District disease control authority in Wuhan said.

Despite the lack of solid signs of a cholera outbreak, netizens worried about another disease outbreak still made the issue one of the top news stories on China’s Twitter-like microblog Weibo on Friday, with 200 million readings. The first covid-19 infections in late 2019 were initially linked to a local market in Wuhan that also sold seafood and fish products.

The origin of the SARS-CoV-2 virus that causes covid-19 remains a mystery and a major source of tension between China and the United States. “Take the lesson of covid and hurry to search the sources for evidence!!!” wrote a weibo user. Cases of cholera, an acute watery diarrhea illness potentially fatal if not treated quickly and usually linked to contaminated food or water, are rare in mainland China, with five cases in 2021 and 11 in 2020 , but no deaths.

“The detection of Vibrio cholerae O139…reminds us again that wet markets, while culturally and economically important in Asia, are associated with them with various public health risks,” said Andrew Greenhill, Professor of Microbiology at Federation University Australia.

At this stage, there is no major cause for concern while continued surveillance is important, Greenhill said, adding that O139 has been detected in various other countries and large outbreaks of cholera are unlikely in places with safe drinking water and adequate sanitation.

“In fact, detecting the strain demonstrates that surveillance is underway, which can only be seen as a positive.”

Wuhan, with a population of more than 12 million, said on Monday that the cholera case in a local university student had not caused any other infections. Wuhan has not yet disclosed the sources of the bacteria for the student and the samples, or details on the progress of tracing the sources.