Shredded lettuce served at Taco Bell has been linked to the massive cyclosposiaisis outbreak.

Investigators found that more than 1,644 people sick with the diarrhea-causing parasite reported eating lettuce at Taco Bell locations in five states.1

Nationwide, the outbreak has grown to an estimated 7,000 cases.2 Here’s what you need to know in the latest update.

Which Lettuce is Affected?

The identified source of cyclospora, the parasite that causes cyclosporiasis, is shredded iceberg lettuce sold at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio, and West Virginia.

“Based on ongoing conversations with public health officials, and out of an abundance of caution, Taco Bell has taken immediate action to voluntarily remove potentially impacted lettuce from a supplier in select states,” said Taco Bell Corp. in a statement.

On July 18, the Food and Drug Administration identified Taylor Farms as the supplier of the lettuce at Taco Bell. In response, Taylor Farms voluntarily recalled all iceberg lettuce sourced from central Mexico.

On July 19, Taylor Farms said the iceberg lettuce that tested positive for cyclospora was actually a false positive.3

However, in a press call on July 20, the FDA’s Acting Deputy Commissioner for Food Donald Prater said Taylor Farms is still the suspected supplier of the contaminated lettuce based on epidemiologic and traceback data, despite the false positive.

Is It the Only Source of Cyclospora?

Officials have not confirmed whether the shredded lettuce is the only source of the outbreak. Foods like fresh cilantro, raspberries, and snow peas have been linked to cyclosporiasis outbreaks in the U.S. and Canada in the past.4

It’s also unclear whether shredded lettuce caused the infections in states other than the five already identified.

“It is not 100% clear yet whether all or just some of the cases we are seeing reported right now represent a single outbreak or multiple simultaneous outbreaks,” Zoe Weiss, MD, director of clinical microbiology at Tufts Medical Center, previously told Health.

What You Should Do

If you live in the five affected states, do not eat shredded iceberg lettuce from Taco Bell. You can always avoid lettuce in general, but public health officials have not recommended that precaution yet.

Continue to use regular food safety practices, including washing your hands often during food preparation and rinsing all produce under running water.

Health officials also recommend cooking food to at least 158 degrees Fahrenheit, the temperature at which cyclospora dies, since washing alone cannot guarantee its removal.1

Contact a healthcare provider if you experience symptoms of cyclosporiasis, including watery diarrhea—the hallmark of the illness—as well as nausea, fatigue, abdominal cramps, flu-like symptoms, and loss of appetite.1

Stool testing can confirm if you have cyclosporiasis, and the infection is treatable with an antibiotic