August 2008

From MMWR Weekly Report, August 29, 2008:

On May 22, 2008, the New Mexico Department of Health (NMDOH) notified CDC about four persons infected with Salmonella Saintpaul strains that were indistinguishable from each other by pulsed-field gel electrophoresis (PFGE) and 15 other persons with Salmonella infections whose isolates had not yet been characterized. In the following weeks, cases continued to be reported, and the outbreak expanded to include 43 states, the District of Columbia (Figure 1), and Canada. This report is an interim summary of results from seven epidemiologic studies, traceback investigations, and environmental investigations related to the outbreak. Further data collection and analyses are ongoing. As of August 25, 2008, a total of 1,442 persons had been reported infected with the outbreak strain. At least 286 persons have been hospitalized, and the infection might have contributed to two deaths. The outbreak began late in April 2008, and most persons became ill in May or June. The outbreak appears to be over; however, CDC and state health departments are continuing to conduct surveillance for cases of infection with the outbreak strain. Preliminary epidemiologic and microbiologic results to date support the conclusion that jalapeño peppers were a major vehicle by which the pathogen was transmitted and serrano peppers also were a vehicle; tomatoes possibly were a vehicle, particularly early in the outbreak. Contamination of produce items might have occurred on the farm or during processing or distribution; the mechanism of contamination has not been determined. These findings indicate that additional measures are needed to enhance food safety and reduce illnesses from produce that is consumed raw.

 


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The Salmonella Saintpaul outbreak may be winding down, but it is not over.   The Centers for Disease Control and Prevention (CDC) today updated its publicly available data for the first time since last Friday.   The outbreak, which began last April 16, continues this month with August 8 being the latest date for someone becoming a confirmed case.

The total number of confirmed cases during those four months now stands at 1,434.   CDC says 273 of the confirmed cases were treated at hospitals and Salmonella Saintpaul contributed to two deaths.  We continue to remind readers that various models for figuring the number of "unconfirmed" cases would now translate into 54,492.

Last year during this same period, CDC says there were a mere 18 Salmonella Saintpaul cases recorded in the USA.

Since we have not done so in some time, we are providing the complete CDC update.  From this point forward, its your tax dollars at work!


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Salmonella is a bacterium that causes one of the most common enteric (intestinal) infections in the United States – Salmonellosis. In some states (e.g. Georgia, Maryland), salmonellosis is the most commonly reported cause of enteric disease, and overall it is the second most common bacterial foodborne illness reported (usually slightly less frequent than Campylobacter infection).

The reported incidence of Salmonella illnesses is about 14 cases per each 100,000 persons (MMWR Weekly, 2006), amounting to approximately 30,000 confirmed cases of salmonellosis yearly in the U.S. (CDC, 2005, October 13). In 2005, just over 36,000 cases were reported from public health laboratories across the nation, representing a 12 percent decrease compared with the previous decade, but a 1.5 percent increase over 2004 (CDC, 2007).

As only about 3 percent of Salmonella cases are officially reported nationwide, and many milder cases are never diagnosed, the true incidence is undoubtedly much higher (Mead, 1999). The CDC estimates that 1.4 million cases occur annually (CDC, 2005, October 13). Approximately 600 deaths are caused by Salmonella infections in the U.S. every year, accounting for 31 percent of all food-related deaths (CDC, 2005, October 13; MMWR Weekly, 2001).

Theobald Smith, research-assistant to Daniel E. Salmon, discovered the first strain of Salmonella – Salmonella cholerae suis – in 1885. Since that time, the number of strains (technically termed serotypes or serovars) of Salmonella known to cause salmonellosis has increased to over 2,300. Salmonella typhi, the strain that causes typhoid fever, is uncommon in the U.S., while Salmonella enterica serotype Typhimurium and Salmonella enterica serotype Enteritidis have been the most frequently reported illnesses since 1993. Salmonella enterica serotypes Newport, Mississippi and Javiana have been increasingly identified as the source of illness (MMWR Weekly, 2006).

Symptoms of Salmonella Infection

An infectious dose of Salmonella is small, probably from 15 to 20 cells. Typically, non-typhoidal Salmonella produces a self-limiting febrile gastrointestinal illness that is indistinguishable from that caused by other bacterial enteric pathogens. Dehydration is the principal clinical concern. The incubation period – the time between ingestion of Salmonella bacteria and the onset of illness – varies from six to 72 hours (Mayo Clinic, 2007, April 12; MMWR Recomm Rep, 2001).

Salmonella can cause three different kinds of illness: gastroenteritis, typhoid fever, and bacteremia.

Symptoms of Salmonella gastroenteritis include diarrhea, abdominal cramps, fever, nausea, and/or vomiting. In mild cases diarrhea may be non-bloody, occur several times per day, and not be very voluminous; in severe cases it may be frequent, bloody and/or mucoid, and of high volume.

Fever generally occurs in the 100°F to 102°F (38°C to 39°C) range. Vomiting is less common than diarrhea. Headaches, myalgias (muscle pain), and arthralgias (joint pain) are often reported as well. Whereas the diarrhea typically lasts 24 to 72 hours, patients often report fatigue and other nonspecific symptoms lasting 7 days or longer.

Complications of Salmonella Infection

Typhoid fever, also known as enteric fever, is caused by Salmonella serotype typhi. The onset of symptoms usually occurs between 5 and 21 days after ingestion of Salmonela typhi bacteria. Symptoms may include constipation, cough, sore throat, headache, and a rash on the infected individual’s chest, as well as the slowing of the heartbeat and enlargement of the liver and spleen (Mayo Clinic, 2007, April 12).

Bacteremia is characterized by infection of tissues surrounding the brain and spinal cord (meningitis) and infection within the bloodstream (sepsis). This condition occurs when Salmonella enter and circulate within an infected individual’s bloodstream, and is accompanied by few symptoms (Mayo Clinic, 2007, April 12).


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