US fast-food chain Taco Bell is removing lettuce from its menu in some states after investigations found it could be linked to an outbreak of explosive diarrhoea caused by a parasite.

The decision was taken “out of an abundance of caution” following discussions with health officials, Taco Bell told the BBC.

The Centers for Disease Control and Prevention (CDC) says 1,645 people in five states that had “exposure” to Taco Bell have been infected by cyclosporiasis, a parasitic infection that spreads through contaminated food or water.

No deaths have been reported but 94 people have been hospitalised due to cyclosporiasis infections, which were first detected on 13 May, the FDA added.

“Do not eat food items with shredded iceberg lettuce from Mexico served at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio, and West Virginia,” the US Food and Drug Administration (FDA) said.

The company said lettuce from one of its suppliers is being removed indefinitely and will be replaced.

“While no official advisory has been issued, we believe public health is a shared responsibility among restaurants, their suppliers, and authorities,” the restaurant said.

It did not identify in which states lettuce will be removed from menus, but most of the infections have been reported in Michigan where more than 3,300 cases have been detected.

Taco Bell did not identify where the lettuce reportedly linked to the outbreak had come from, but US media have named the supplier as Taylor Farms in Mexico. US health officials said the FDA had traced the outbreak to a lettuce supplier in Mexico.

In a statement, Taylor Farms told the BBC it was “voluntarily removing all iceberg lettuce sourced from central Mexico from the U.S. market”.

It said the tracking by officials at the FDA pointed to one of its independent farms as the potential source of the outbreak.

Symptoms of infections by cyclosporiasis can take about two weeks to present.

Watery diarrhoea that lasts for days, sudden weight loss, and a loss of appetite are some of the more common symptoms.

Experts have told the BBC the parasite is notoriously difficult to trace, a task possibly complicated in part by cuts to federal health agencies.

“This isn’t like detecting a needle in a haystack. It’s like detecting a microscopic portion of a needle in a haystack,” said Steven Manderach, executive director of the Association of Food and Drug Officials.

Madeline Halpert, Kayla Epstein, and Grace Goodwin contributed to this report.