In developing countries, even cooked vegetables served hot can carry enteric pathogens.
Experienced travelers to developing areas usually know to avoid the water, the iced drinks, the unpeeled fruit, and the raw vegetables, but many get sick anyway. Does intestinal peril lurk even in cooked food?
Cooked and uncooked vegetables from 18 popular restaurants in Guadalajara, Mexico, were analyzed for bacterial content. Overall, 27 of 64 samples (42%) were contaminated with coliforms; in comparison, 17 of 67 samples (25%) from 32 Houston restaurants were contaminated. Similar contamination rates were reported in cooked and uncooked samples from buffets in both cities. However, cooked vegetables served at the table in Guadalajara were contaminated significantly more often than were those in Houston, and the number of colony-forming units in Guadalajara specimens was considerably higher, even if the vegetables were served hot. The coliforms isolated were most commonly Klebsiella and Enterobacter species; no standard enteric pathogens were found in any sample.
Comment: Using coliform counts as a marker for enteric risk, these researchers, who previously reported on contamination in guacamole and other tabletop sauces in the same cities (JW Jul 19 2002), have demonstrated why usual guidelines for safe travel eating sometimes fail. Travelers who follow the "peel it, cook it, boil it, or forget it" mantra might lower, but will not eliminate, their risk for diarrhea; in particular, eating only cooked vegetables is no guarantee of protection.
— Abigail Zuger, MD
Published in Journal Watch General Medicine July 24, 2008
Koo HL et al. Coliform contamination of vegetables obtained from popular restaurants in Guadalajara, Mexico, and Houston, Texas. Clin Infect Dis 2008 Jul 15; 47:218.