WEDNESDAY, Oct. 5 (HealthDay News) -- The death toll from an outbreak of listeria first linked to tainted cantaloupes has risen to 18, and a total of 100 people have been sickened across 20 states, the U.S. Centers for Disease Control and Prevention reported late Tuesday.
The agency said that even though the cantaloupes in question were recalled Sept. 14, more cases might still emerge since Listeria monocytogenes infection has a long lag time between diagnosis and laboratory confirmation "and also because up to two months can elapse between eating contaminated food and developing listerosis."
The listeriosis-linked deaths have occurred in Colorado (5), Kansas (2), Maryland (1), Missouri (1), Nebraska (1), New Mexico (5), Oklahoma (1) and Texas (2), the CDC said.
On Sept. 14, the agency announced that Jensen Farms, of Granada, Colo., had voluntarily recalled its Rocky Ford-brand cantaloupes and the produce is "now off store shelves." Consumers -- especially older adults, people with weakened immune systems and pregnant women -- should discard this brand of cantaloupe if it is in their refrigerator, the agency said. Other brands of cantaloupe are safe to consume, however.
According to the Wall Street Journal, the death toll from the current outbreak is on track to exceed that of the nation's worst listeria outbreak, in 1998, which was linked to hot dogs and killed 21 people while sickening 100 more.
In a news conference last Wednesday, CDC director Dr. Thomas R. Frieden called the cantaloupe-linked outbreak "the deadliest outbreak of a foodborne disease that we've identified in more than a decade."
The update from the CDC marks another step in health officials' attempts to contain listeria outbreaks over the past month. On Friday, Alaska regulators announced that chopped romaine lettuce shipped from California had been recalled because of concerns the salad greens might carry the potentially fatal bacteria.
The lettuce involved in the lettuce scare comes from True Leaf Farms, of Salinas, Calif., which was notified by the U.S. Food and Drug Administration that the pathogen was found in a random test sample, according to published reports.
True Leaf on Thursday announced a voluntary recall of chopped romaine lettuce distributed in 2-pound bags by Church Brothers, LLC in Alaska. The bags carry a use-by date of Sept. 29 and a code of B256-46438-8. Anyone who has the questionable lettuce should discard it, CBS News reported.
Unlike other bacteria, listeria can flourish in colder temperatures. So, "if you've got a contaminated cantaloupe in your refrigerator, the listeria will continue to grow," Frieden said. "That's one of the reasons why we may see continued cases from cantaloupe already in people's refrigerators in the days and weeks ahead."
Although listeria tends to infect fewer people, it is typically deadlier than other foodborne pathogens and inordinately affects the elderly, newborns, pregnant women and anyone with a weakened immune system. People can develop meningitis from the organism, but many people only experience milder diarrhea.
According to the CDC, some 1,600 cases are reported annually in the United States, resulting in 260 deaths.
Listeria bacteria are also particularly dangerous because they can thrive at both room temperatures and refrigerator temperatures.
And "the incubation period can be quite long, as little as three days but up to two months," said Philip Alcabes, a professor in the School of Public Health at Hunter College in New York City.
The bacterium tends to grow in soil and water. "The concern would be that the outside of cantaloupe is contaminated [and] when you slice into it, the knife can carry bacteria into the part that you eat," Alcabes explained.
But animals can also carry the organism and pass it on to humans through meats, dairy products and other foods of animal origins. Most listeria outbreaks are from animal products, not produce, the CDC said.
"Your grandmother told you to wash fruits and vegetables. It's probably not bad advice," Alcabes said.
The U.S. Centers for Disease Control and Prevention has more on listeria.
SOURCES: Oct. 4, 2011, news release, U.S. Centers for Disease Control and Prevention; Sept. 28, 2011, news conference with Thomas R. Frieden, M.D., M.P.H., director, U.S. Centers for Disease Control and Prevention, Margaret Hamburg, M.D., commissioner, U.S. Food and Drug Administration; and Philip Alcabes, Ph.D., professor, School of Public Health, Hunter College, City University of New York, New York City; Wall Street Journal, CBS News; Associated Press
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