Mar 28, 2008 (CIDRAP News) – Water quality officials in Colorado said today that the pathogen that contaminated the city of Alamosa's water system is Salmonella enterica serotype Typhimurium, which they said might suggest a wild animal source of the pathogen.
Steve Gunderson, director of Colorado's water quality control division, said officials don't know how the Salmonella entered the water supply, according to a report today from the Rocky Mountain News. He said health authorities are collecting bird and animal droppings from areas surrounding water facilities and will test them for Salmonella.
"Where we see animals and some sort of opening into the water system, we have been collecting samples," he told the News. "So far, the samples have been negative for Salmonella." He said officials are looking for any breaches in the water system, such as a hole in a water tank.
Craig Hedberg, PhD, an associate professor of environmental and occupational health at the University of Minnesota in Minneapolis, told CIDRAP News that S Typhimurium is the most common serotype of Salmonella and that its presence in Alamosa's water could have come from any of several potential sources.
"I wouldn't want to speculate on a source," he said.
At an Alamosa city council meeting on Mar 26, Robin Koons, emergency response director for the Colorado Department of Public Health and Environment, said there were three possible causes of the Salmonella contamination, according to a press release yesterday from the city of Alamosa. They include cross-contamination from the sewer system, a crack in a pipeline that would have allowed contamination to enter during low-pressure conditions, or contamination of a water storage site.
Rumors have been circulating in Alamosa that pigeons had been roosting in a ground-level covered reservoir, but Don Koskelin, the city's public works director, told the News there were no signs of birds in any of the city's water tanks.
As of yesterday evening, 286 possible Salmonella infections linked to the outbreak had been reported, including 73 confirmed cases, according to another Rocky Mountain News report. Eleven patients were hospitalized, but no deaths have been reported. Patients' ages range from 3 weeks to 89 years, though most are children, the News reported.
City officials were soaking the city's water system in 25 parts per million chlorinated water and planned to flush the system later with 10 parts per million chlorinated water, the Denver Post reported yesterday.
Local residents haven't received word yet on when they can resume using the water for drinking and cooking, the Post reported.
Firms recall Honduran cantaloupe
In other developments, over the past week seven US-based produce distributors have announced voluntary recalls of Honduran-grown cantaloupe that has been implicated in a nationwide Salmonella Litchfield outbreak.
On Mar 22 the Food and Drug Administration (FDA) blocked the importing of cantaloupe from Honduran grower Agropecuaria Montelibano after case-control studies suggested that the product was linked to 50 Salmonella cases in 16 states, along with 9 illnesses in Canada. The US Centers for Disease Control and Prevention (CDC) said today it did not have an update on the number of US cases.
The FDA said US distributors that have recalled their Honduran cantaloupe products include:
- Charlie's Produce, based in Spokane, Wa.: retail and foodservice fruit items that include fresh cut cantaloupe, distributed in eastern Washington, Idaho, and Montana
- Central American Produce, Inc., of Pompano Beach, Fla.: distributed nationwide, products include cardboard cartons of cantaloupe labeled "Mike's Melons" or "Mayan Pride"
- T.M. Kovacevich International, Inc. of Philadelphia: distributed in Georgia, Florida, Massachusetts, and New Jersey, products include whole cantaloupes with "Mike's Melons" stickers on them
- Tropifresh, based in Los Angeles: whole cantaloupes with "Mike's Melons" stickers on them that were distributed in 1,100-pound cardboard bins to wholesalers in southern California, Pennsylvania, and Canada
- Chiquita Brands International, of Cincinnati: cardboard cartons of cantaloupes labeled "Mike's Melons," "Mayan Pride," or "Chiquita" that were distributed throughout the United States and Canada
- Bounty Fresh, LLC, of Miami, Fla.; cantaloupes packed in sleeves or boxes and sold under "Chestnut Hill Farms" and "Perfect Melon" and distributed nationwide to grocery stores and wholesale outlets
- Simply Fresh Fruit, based in Los Angeles: fresh-cut fruit products containing cantaloupe that it received from Tropifresh (see above). The press release did not say where the products were distributed, other than that they were sold through retail and club stores and foodservice outlets.
Mar 27 city of Alamosa press release
Mar 22 FDA press release on Charlie's Produce cantaloupe recall
Mar 24 FDA press release on Central American Produce, Inc. cantaloupe recall
Mar 25 FDA press release on TM Kovacevich International cantaloupe recall
Mar 26 FDA press release on Tropifresh cantaloupe recall
Mar 27 FDA press release on Chiquita cantaloupe recall
Mar 27 FDA press release on Bounty Fresh cantaloupe recall
Mar 28 FDA press release on Simply Fresh Fruit cantaloupe recall