Dysentery

When possible, patients presenting with signs and symptoms of dysentery should have stool specimens examined by microscopy to identify Entamoeba histolytica. Care should be taken to distinguish large white cells (a nonspecific indicator of dysentery) from trophozoites. Amebic dysentery tends to be misdiagnosed.

Shigellosis

If a microscope is unavailable for diagnosis, or if definite trophozoites are not seen, persons with bloody diarrhea should be treated initially for shigellosis. Appropriate treatment with antimicrobial drugs decreases the severity and duration of dysentery caused by Shigella and reduces the duration of pathogen excretion. The selection of an antimicrobial treatment regimen is often complicated by the presence of multiresistant strains of Shigella. The choice of a first-line drug should be based on knowledge of local susceptibility patterns. If no clinical response occurs within 2 days, the antibiotic should be changed to another recommended for that particular strain of shigellosis. If no improvement occurs after an additional 2 days of treatment, the patient should be referred to a hospital or laboratory for stool microscopy. At this stage, a diagnosis of resistant shigellosis is still more likely than amebiasis.

Drugs of choice. Treatment guidelines for shigellosis are listed below.

For strains resistant to these regimens, alternative treatment with nalidixic acid or tetracycline is indicated.

The fluoroquinolones (e.g., ciprofloxacin and ofloxacin) are highly effective for the treatment of shigellosis, but are expensive and have not yet been approved for treatment of children or pregnant or lactating women with shigellosis.

Because multiresistant strains of Shigella have become widespread and because Shigella strains can rapidly acquire resistance in endemic and epidemic settings, it is advisable that periodic antibiotic susceptibility testing be performed by a reference laboratory in the region. Note: WHO does not recommend mass prophylaxis or prophylaxis of family members as a control measure for shigellosis.

Amebiasis and giardiasis

Treatment for amebiasis or giardiasis should not be considered unless microscopic examination of fresh feces shows amebic or Giardia trophozoites, or two different antibiotics given for shigellosis have not resulted in clinical improvement.

Treatment guidelines for amebiasis are as follows:

Treatment guidelines for giardiasis are as follows:

References

  1. United Nations High Commissioner for Refugees. Handbook for emergencies. Geneva, 1982.

  2. Cairncross S, Feachem RG. Environmental health engineering in the tropics: an introductory text. New York: John Wiley & Sons Ltd., 1983:28-33.

Selected Reading

World Health Organization. A manual for the treatment of acute diarrhoea. Geneva: Diarrhoeal Diseases Control Programme, 3rd. ed., 1990.

CDC. Shigella dysenteriae Type 1 Guatemala, 1991. MMWR 1991;40:421,427-8.

Keusch GT, Bennish ML. Shigellosis: recent progress, persisting problems and research issues. Pediatr Infect Dis J 1989;8:713-9.

Smith M. Water and sanitation for disasters. Trop Doct 1991;21(suppl 1):30-7.

World Health Organization. Guidelines for cholera control. 1991;80.4;Rev. 2.


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