NEW: Federal and state health officials are investigating whether Taco Bell locations could be linked to a growing parasite outbreak.
The illness, cyclosporiasis, can cause weeks of severe stomach issues, including watery, "explosive" diarrhea.
While investigators haven't identified the source, signs posted at some Detroit-area Taco Bell restaurants say ingredients like lettuce and cilantro have been pulled because of a "national recall." So far, however, the FDA has not announced a recall involving Taco Bell or publicly linked the chain to the outbreak.
More than 2,600 cases have been reported in Michigan, and officials are still working to determine what's behind the outbreak. No deaths have been reported.
Taco Bell, Yum! Brands, the FDA and HHS did not immediately respond to Fox News Digital's request for comment.