In the second week of March 2008, multiple residents of Alamosa, Colorado fell ill with severe gastrointestinal symptoms, including diarrhea and abdominal cramps. On March 17, 2008, the Colorado Department of Public Health and Environment (CDPHE) notified the Centers for Disease Control and Prevention (CDC) that 18 Alamosa residents who had fallen ill in the month of March 2008 had tested positive for Salmonella Typhimurium, and that 19 others were suspected to be suffering from gastrointestinal symptoms related to Salmonella Typhimurium infection.
During the same general timeframe, epidemiological investigation by CDPHE showed that the City of Alamosa’s public water facility was the likely source of infection amongst the 18 confirmed and 19 suspected Salmonella Typhimurium “cases.” Tests of randomly sampled water from the City of Alamosa’s public water facility soon confirmed that the water was, in fact, heavily contaminated by Salmonella Typhimurium, and was thus the source of illness in the developing outbreak.
Because Alamosa’s public water facility supplied potable water to many thousands of people, and thus constituted a grave threat to the health and lives of all Alamosa residents, as well as anybody who had come into contact with contaminated Alamosa water, either directly or indirectly, Colorado’s chief medical officer and CDPHE issued an order on March 19, 2008 requiring the City of Alamosa to advise its residents to drink only bottled water. As of that date, at least 79 people were believed to have been infected by the heavily contaminated public water supply; and that number was quickly rising.
Led by CDPHE, officials from a variety of local, state, and national health organizations, including the CDC, conducted a major investigation into the Alamosa water outbreak. Ultimately, 122 people were confirmed by stool or blood test as having been infected by the same strain of Salmonella Typhimurium as was isolated from Alamosa water in late March 2008. It is estimated, however, that as many as 2,000 people may have actually been infected and become ill in the outbreak. One person, Larry Velasquez Sr., died as a result of his Salmonella Typhimurium infection.
The Colorado Department of Public Health and Environment’s final report regarding the salmonella outbreak stated that animal waste most likely contaminated a concrete in-ground water storage tank. The tank was found to have several holes and cracks.