Health Advisory
INCREASE IN SHIGELLA INFECTIONS ASSOCIATED WITH MULTI-STATE CLUSTER

The Delaware Division of Public Health (DPH) is reporting an increase in shigellosis in New Castle County. This advisory contains recommendations for community control, information about the increase, and information about shigellosis.

Recommendations for Community Control

Outbreaks of shigellosis occur periodically in Delaware. Documented outbreaks occurred in 1985 and 2002. Childcare facilities have played an important role in several of these outbreaks. While difficult to control, strict adherence to the following recommendations is believed to shorten the duration of community wide Shigella outbreaks.

• Proper hand hygiene, disposal of soiled items (e.g., diapers) and disinfection of soiled surfaces is important to limit the spread of Shigella. Anyone with diarrhea must be educated about washing hands after using the bathroom, and before preparing food. Young children should be supervised using the toilet and instructed to wash their hands. Special care should be taken when handling diapers of infected children.
• Because of the small infective dose, patients with known Shigella infections, and their ill contacts, should not be employed to handle food or to provide child or patient care until 2 successive fecal samples or rectal swabs (obtained at least 48 hours after the last dose of antibiotic and at least 24 hours apart) are found to be Shigella-free.
• Children and staff with confirmed Shigella infection should have two negative stool cultures, obtained at least 48 hours after the last dose of antibiotic and at least 24 hours apart, prior to returning to the childcare facility. Older, school age children may return to school once symptom-free of both diarrhea and fever for 24 hours.
• Secondary attack rates in households with infected children are high. Stool specimens from household contacts who have diarrhea also should be cultured.
• Healthcare professionals should always obtain stool cultures from anyone presenting with diarrhea if they participate in childcare, whether there is a recognized outbreak of gastrointestinal illness or not in the facility. Other bacterial infections (e.g., Salmonella, Campylobacter) also occur in this age group and need to be identified as they are also subject to similar restrictions.
• All symptomatic persons with confirmed Shigella in their stool should receive appropriate antimicrobial therapy when warranted, such as to protect contacts in childcare centers. The choice of antibiotic depends on susceptibility data of individual isolates as well as local antimicrobial susceptibility patterns. The susceptibility pattern of 12 of the recently reported cases is as follows:
  • Ampicillin:  0% susceptible (one of the 12 did not report ampicillin susceptibilitiy)
  • Flouroquinolone:  100% susceptible
  • Trimethoprim sulfa:  58% susceptible

The Recent Increase in Shigellosis

Since January of this year, 29 cases of Shigella sonnei infection have been reported to DPH, compared to 5 during this same time period in 2008. Twenty six of this year’s cases are in New Castle County and 23 of these cases have been reported since the middle of April. Of these 23 cases, at least eight are associated with childcare facilities in New Castle County. All of these Shigella cases are linked by Pulsed Field Gel Electrophoresis to an ongoing multi-state cluster identified by the Centers for Disease Control and Prevention.

About Shigella Infection

• Clinical Features – Watery or bloody diarrhea, abdominal pain, fever, and malaise are typical. Most clinical infections are self-limited (48-72 hours).
• Incubation Period – Usually 1-3 days.
• Transmission – A small inoculum (10 to 200 organisms) is sufficient to cause infection. As a result, spread can easily occur by the fecal-oral route.
• Diagnosis – Cultures of feces or rectal swab specimens. 
• Infectious Period – Usually within 4 weeks after illness onset.
• Treatment – Although antibiotics are not required for this generally mild disease, they are often prescribed to shorten the duration of illness and reduce the infectious period, particularly in childcare center attendees and food handlers.80% of isolates have been found to be resistant to ampicillin and 47% to TMP/SMX; 38% resistant to both drugs.,  Resistance to fluoroquinolones such as ciprofloxacin has also occurred.  Antidiarrheal agents such as loperamide (Imodium) or diphenoxylate with atropine (Lomotil) can prolong illness.

More Information and to Report Cases

• DPH, Bureau of Epidemiology at (302) 744-4541 or 1-888-295-5156 for information and to report cases
• CDC: http://www.cdc.gov/nczved/dfbmd/disease_listing/shigellosis_gi.html#3

General References Used in Preparation of this Advisory:

• Red Book, American Academy of Pediatrics, 26th edition.
• Control of Communicable Diseases Manual, American Public Health Association, 19th edition.

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