The source of a spreading parasitic diarrheal outbreak in the United States has been identified, and officials urged people not to eat raw vegetables at Taco Bell outlets in five states, the Liberty Times reported.

The parasite spreads through uncooked fresh produce and is not reliably removed by washing when vegetables have been contaminated by water or soil. Infection causes diarrhea, fatigue and weight loss lasting days to weeks.

Why raw vegetables

Pathogens that die with cooking but resist washing inevitably surface in food eaten raw. That is why salads, lettuce and herbs recur as vehicles in cluster outbreaks.

When it happens at a national chain, as here, the reach widens: produce from one farm reaches hundreds of outlets across several states within days. An efficient distribution network is efficient for pathogens too.

What consumers can do

The advice is clear: avoid menu items with raw vegetables at the named chain in the named states. Anyone who already ate and has diarrhea lasting more than a few days should seek care; this infection is treated with specific drugs, not ordinary antibiotics.

At home, wash raw vegetables thoroughly under running water, and cook them if someone in the household is immunocompromised—while recognizing that washing alone cannot fully prevent infection.

Food-safety incidents are easily framed as one country's or one company's problem, yet this week Taiwan reported both a carcinogen scare over cooking oil and a study finding microplastics in baby food. Knowing what you are eating has become hard everywhere.