Seattle & King County is reporting an increase in shigellosis cases since mid-December in King County. Since the end of October, Public Health has received 40 total reports of Shigella infection, with 22 of those reported since December 14th. This compares to an average of 2-3 cases reported during a typical week this year. Public
“Shigella at a Wedding” – Instead of “I do,” should be “Hell No.”
On August 14, 2018, the Oregon Health Authority (OHA) and Yamhill County Health and Human Services (YCHHS) independently received reports of persons with gastrointestinal illness days after attending a wedding and reception in Yamhill County on August 11. Over the next…
The San Diego County Health and Human Services Agency is advising gay and bisexual men, homeless individuals, and people with compromised immune systems that they could be at an increased risk for the intestinal disease shigellosis.
According to the Centers for Disease Control and Prevention, young children and travelers to developing countries are also at…
In early September 2017, an over-30-year-old male who resides in northern Taiwan traveled to Bali, Indonesia with 18 tour group members. On the following day the case returned, he sought medical attention after developing symptoms, including fever, diarrhea and nausea, and was diagnosed with shigellosis. After a further investigation conducted by the health authority, a…
Ventura County Public Health was notified on Thursday, June 22nd, of an unusually high number of Shigella cases in the county. Shigellosis is an infectious disease caused by a group of bacteria called Shigella (shih-GEHL-uh), which most often causes diarrhea and fever. It is highly contagious.
Through a series of interviews with those affected, it…
Between May 2014 and February 2015, a drug-resistant strain of shigella has infected 243 people across the US, according to the US Centers for Disease Control and Prevention (CDC). The CDC’s findings were first published in the agency’s
Wife of active duty U.S. Navy diver is one of 275 people who became ill with Shigellosis
Attorneys Bill Marler and Drew Falkenstein of Marler Clark, the nation’s only law firm dedicated to representing victims of foodborne illness, have filed a lawsuit in the Circuit Court of Benton County, Arkansas on behalf of married couple…
Researchers have launched an early-stage human clinical trial of two related candidate vaccines to prevent infection with Shigella, bacteria that are a significant cause of diarrheal illness, particularly among children. The Phase I clinical trial, funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, will evaluate…
Scientists have found new genetic information that shows how harmful bacteria cause the acute diarrheal disease shigellosis, which kills more than a million people worldwide each year.
The research, which could lead to the development of future treatments, was published today in the journal PLoS ONE. The study was led by Ohio University scientist Erin…
Shigella are Gram-negative, non-motile, non- sporeforming, rod-shaped bacteria. Shigella species, which include Shigella sonnei, S. boydii, S. flexneri, and
S. dysenteriae, are highly infectious agents. Some strains produce enterotoxins and Shiga toxin. The latter is very similar to the toxins produced by E. coli O157:H7.
Humans are the only host of Shigella, but it has also been isolated from higher primates. The organism is frequently found in water polluted with human feces.
In terms of survival, shigellae are very sensitive to environmental conditions and die rapidly. They are heat sensitive and do not survive pasteurization and cooking temperatures. In terms of growth, shigellae are not particularly fastidious in their requirements and, in most cases, the organisms are routinely cultivated in the laboratory, on artificial media. However, as noted in subsequent sections, the relative difficulty of cultivating this organism is dependent, in part, on the amount of time within which stool or food samples are collected and processed.
Shigella species are tolerant to low pH and are able to transit the harsh environment of the stomach. These pathogens are able to survive and, in some cases, grow in foods with low pH, such as some fruits and vegetables. They are able to survive on produce commodities packaged under vacuum or modified atmosphere and can also survive in water, with a slight decrease in numbers.
The illness caused by Shigella is shigellosis (also called bacillary dysentery), in which diarrhea may range from watery stool to severe, life-threatening dysentery. All Shigella spp. can cause acute, bloody diarrhea. Shigella spp. can spread rapidly through a population, particularly in crowded and unsanitary conditions.
S. dysenteriae type 1 causes the most severe disease and is the only serotype that produces the Shiga toxin, which may be partially responsible for cases in which hemolytic uremic syndrome (HUS) develops. S. sonnei produces the mildest form of shigellosis; usually watery diarrhea.
S. flexneri and S. boydii infections can be either mild or severe. In developed countries, S. sonnei is the Shigella species most often isolated, whereas S. flexneri predominates in developing countries.
• Mortality: In otherwise healthy people, the disease usually is self-limiting, although some strains are associated with fatality rates as high as 10-15%. (See Illness / complications section, below.)
• Infective dose: As few as 10 to 200 cells can cause disease, depending on the age and condition of the host.
• Onset: Eight to 50 hours.
• Illness / complications: In otherwise healthy people, the disease usually consists of self- limiting diarrhea (often bloody), fever, and stomach cramps. Severe cases, which tend to occur primarily in immunocompromised or elderly people and young children, are associated with mucosal ulceration, rectal bleeding, and potentially drastic dehydration. Potential sequelae of shigellosis include reactive arthritis and hemolytic uremic syndrome.
• Symptoms: May include abdominal pain; cramps; diarrhea; fever; vomiting; blood, pus, or mucus in stools; tenesmus (straining during bowel movements).
• Duration: Uncomplicated cases usually resolve in 5 to 7 days. Most of the time, the illness is self-limiting. In some circumstances, antibiotics are given; usually trimethoprim-sulfamethoxazole, ceftriaxone, or ciprofloxacin.
• Route of entry: The fecal-oral route is the primary means of human-to-human transmission of Shigella. With regard to foods, contamination is often due to an infected food handler with poor personal hygiene.
• Pathway: The disease is caused when Shigella cells attach to, and penetrate, colonic epithelial cells of the intestinal mucosa. After invasion, they multiply intracellularly and spread to contiguous epithelial cells, resulting in tissue destruction. As noted, some strains produce enterotoxin and Shiga toxin similar to those produced by E. coli O157:H7.
A recent Centers for Disease Control and Prevention (CDC) report on foodborne illnesses acquired annually in the United States revealed that about 15,000 laboratory-confirmed isolates are reported each year, with estimates of actual occurrence ranging from 24,511 to 374,789 cases (average of 131,243). About 31% of these are estimated to be foodborne. Estimates of foodborne illness episodes (mean) caused by 31 pathogens placed Shigella as the sixth most frequent cause (after norovirus, Salmonella species, Clostridium perfringens, Campylobacter, and Staphylococcus aureus, in that order).
Episodes of shigellosis appear to follow seasonal variations. In developed countries, the highest incidences generally occur during the warmer months of the year.
Most cases of shigellosis are caused by ingestion of fecally contaminated food or water. In the case of food, the major factor for contamination often is poor personal hygiene among food handlers. From infected carriers, this pathogen can spread by several routes, including food, fingers, feces, flies, and fomites.
Shigella is commonly transmitted by foods consumed raw; for example, lettuce, or as non- processed ingredients, such as those in a five-layer bean dip. Salads (potato, tuna, shrimp, macaroni, and chicken), milk and dairy products, and poultry also are among the foods that have been associated with shigellosis.
Diagnosis is by serological or molecular identification of cultures isolated from stool. Shigella may be more difficult to cultivate if stool samples are not processed within a few hours.
6. Target Populations
All people are susceptible to shigellosis, to some degree, but children 1 to 4 years old, the elderly, and the immunocompromised are most at risk. Shigellosis is very common among people with AIDS and AIDS-related complex.
7. Food Analysis
Shigellae remain a challenge to isolate from foods. A molecular-based method (PCR) that targets a multi-copy virulence gene has been developed and implemented by FDA. Improvements in the bacterial isolation method continue and should be available in the near future.
The window for collecting and processing Shigella from foods, for cultivation, may be days (rather than hours, as is the case with stool), depending on the food matrix and storage conditions; e.g., temperature. Shigella species can be outgrown by the resident bacterial populations found in foods, which may reflect the usual low numbers of the organism present in foods and, in some foods, a very large number of non-Shigella bacteria. Another factor that reduces the chance of isolating Shigella from foods may be the physiological state of the pathogen at the time of analysis. Environmental conditions could affect its ability to either grow or survive in any food matrix.
8. Examples of Outbreaks
The CDC’s Morbidity and Mortality Weekly Reports provide information about Shigella outbreaks.
9. Other Resources
• Loci index for genome Shigella spp.
• GenBank Taxonomy database
• More information about Shigella and shigellosis can be found on the CDC website.