Shigella Bacteria Diarrhea in Children: Should WHO Guidelines Be Modified?

Shigella bacteria

A review study of Shigella bacteria diarrheal infections in children in developing countries investigated whether current WHO management guidelines should be modified.

Shigella bacteria infections are a leading cause of childhood diarrhea in developing countries. The infections can be life-threatening, with fatality rates of up to 28% in children with severe illness. Symptoms include stomach cramps, fever, diarrhea, and in some severe cases, dysentery. Dysentery occurs when there is an inflammation of the colon (the lower gut) which causes diarrhea with blood, pus, and mucus. Shigella bacteria infections are a common cause of dysentery, but it can also be caused by other gut infections.

What are the WHO Guidelines?

Current World Health Organization (WHO) diarrhea guidelines for treating Shigella bacteria infections focus on rehydration of the patient and recommend reserving antibiotic treatment for children with dysentery. In developing countries it can be difficult to access laboratory testing to determine the precise cause of infection, and dysentery is a useful indicator of Shigella bacteria infection. However, not all severe cases of Shigella infection cause dysentery. Relying on this symptom to identify Shigella bacteria infection may mean that some children who could benefit from antibiotic treatment are missed. Researchers at the University of Washington, Seattle (USA) reviewed the available evidence to evaluate whether current guidelines should be modified. They recently reported their findings in Lancet Global Health.

The researchers performed three detailed reviews of published studies looking at evidence on: Shigella-associated mortality and dysentery-associated mortality; the diagnostic value of dysentery for identifying Shigella infection; and the efficacy of antibiotics in children with Shigella or dysentery or both. Sixty studies were included in the analysis, with 13 on mortality rates, 27 on the diagnostic value of dysentery, and 20 on antibiotic treatment.

Dysentery is not a Reliable Indicator of Shigella Infection

Shigella infection was associated with mortality in children with diarrhea. Combining data from several studies, the researchers found that Shigella infection (with or without dysentery) had a stronger association with mortality that dysentery. The presence of dysentery did not reliably identify children with Shigella infections.

That is, Shigella is common in children with dysentery, but most children infected with Shigella do not have dysentery. The sensitivity of dysentery for identifying Shigella seems to have declined over time. This may be related to the changing prevalence of different strains of Shigella bacteria. Most antibiotic trials for confirmed Shigella infection were conducted in  children with dysentery. There were few differences in the effectiveness across a range of antibiotics. As the antibiotic studies were done in different settings it was not possible to draw any useful conclusions.

The researchers concluded that while current WHO guidelines outline effective management of dysentery they might miss children infected with Shigella who do not have dysentery. Doctors should be aware that the absence of dysentery does not exclude Shigella as a cause of diarrhea, or mean there is a low risk of mortality. They should be particularly vigilant in vulnerable children, such as those under two years or with malnutrition. Clinical trials are urgently needed to help develop treatment strategies for non-dysenteric Shigella bacteria infections.

Written by Julie McShane, Medical Writer

Reference: Tickell K, Brander R, Atlas H, et al. Identification and management of Shigella infection in children with diarrhea: a systematic review and meta-analysis. Lancet Global Health 2017;5:e1235-48.

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