Shigellosis

The incubation period for Shigella is 1 to 4 days. The most common presentation, watery diarrhea, is indistinguishable from other bacterial, viral, and protozoan infections that induce secretory activity of intestinal epithelial cells. Fever may be present.

In adults, initial symptoms of shigellosis may be

These episodes recur with increasing severity and frequency. Diarrhea becomes marked, with soft or liquid stools containing mucus, pus, and often blood. Rectal prolapse and consequent fecal incontinence may result from severe tenesmus.

However, adults may present without fever, with nonbloody and nonmucoid diarrhea, and with little or no tenesmus.

The disease usually resolves spontaneously in adults—mild cases in 4 to 8 days, severe cases in 3 to 6 weeks. Significant dehydration and electrolyte loss with circulatory collapse and death occur mainly in debilitated adults and children < 2 years.

Rarely, shigellosis starts suddenly with rice-water or serous (occasionally bloody) stools. The patient may vomit and rapidly become dehydrated. Infection may manifest as delirium, seizures, and coma but with little or no diarrhea. Death may occur in 12 to 24 hours.

In young children, onset is sudden, with fever, irritability or drowsiness, anorexia, nausea or vomiting, diarrhea, abdominal pain and distention, and tenesmus. Within 3 days, blood, pus, and mucus appear in the stools. The number of stools may increase to ≥ 20/day, and weight loss and dehydration become severe. If untreated, children may die in the first 12 days. If children survive, acute symptoms subside by the 2nd week.

Diagnosis of shigellosis is facilitated by a high index of suspicion during outbreaks and in endemic areas and by the presence of fecal leukocytes on smears stained with methylene blue or Wright stain. Stool cultures are diagnostic and should be obtained; for severely ill or at-risk patients, antimicrobial sensitivity testing is done. PCR testing is also available.

In patients with symptoms of dysentery (bloody and mucoid stools), the differential diagnosis should include enterohemorrhagic E. coli Infection by Escherichia coli O157:H7 and Other Enterohemorrhagic E. coli (EHEC) The gram-negative bacteria Escherichia coli O157:H7 and other enterohemorrhagic E. coli (EHEC) typically cause acute bloody diarrhea, which may lead to hemolytic-uremic syndrome... read more , Salmonella Overview of Salmonella Infections The genus Salmonella is divided into 2 species, S. enterica and S. bongori, which include > 2500 known serotypes. Some of these serotypes are named. In such cases, common... read more , Yersinia Plague and Other Yersinia Infections Plague is caused by the gram-negative bacterium Yersinia pestis. Symptoms are either severe pneumonia or large, tender lymphadenopathy with high fever, often progressing to septicemia... read more , and Campylobacter Campylobacter and Related Infections Campylobacter infections typically cause self-limited diarrhea but occasionally cause bacteremia, with consequent endocarditis, osteomyelitis, or septic arthritis. Diagnosis is by culture... read more infections; amebiasis Amebiasis Amebiasis is infection with Entamoeba histolytica. It is acquired by fecal-oral transmission. Infection is commonly asymptomatic, but symptoms ranging from mild diarrhea to severe dysentery... read more ; and Clostridioides difficile infection Clostridioides (formerly Clostridium) difficile–Induced Diarrhea Toxins produced by Clostridioides difficile strains in the gastrointestinal tract cause pseudomembranous colitis, typically after antibiotic use. Symptoms are diarrhea, sometimes bloody... read more .

The mucosal surface, as seen through a proctoscope, is diffusely erythematous with numerous small ulcers. Although leukopenia or marked leukocytosis may be present, white blood cell count averages 13,000/mcL (13 × 10⁹/L). Hemoconcentration is common, as is diarrhea-induced metabolic acidosis.

Fluid loss due to shigellosis is treated symptomatically with oral or IV fluids Intravenous Fluid Resuscitation Almost all circulatory shock states require large-volume IV fluid replacement, as does severe intravascular volume depletion (eg, due to diarrhea or heatstroke). Intravascular volume deficiency... read more .

Antidiarrheal drugs (eg, loperamide) may prolong illness and should not be used.

Antibiotics can reduce the symptoms and shedding of Shigella but are not necessary for healthy adults with mild illness. However, certain patients, including the following, should usually be treated:

For adults, the following antibiotic regimens may be used:

For children, the following antibiotic regimens may be used:

Many Shigella isolates are likely to be resistant to ampicillin, trimethoprim/sulfamethoxazole (TMP/SMX), and tetracyclines, but patterns of resistance vary by geographic region.

Hands should be washed thoroughly before handling food. Soiled garments and bedclothes should be immersed in covered buckets of soap, water, and disinfectant until they can be washed in hot water. Appropriate isolation techniques (especially stool isolation) should be used with patients and carriers.

A live oral vaccine is being developed, and field trials in endemic areas hold promise. However, immunity is generally type specific so presumably the vaccine would need to be polyvalent or contain an antigen common to multiple serotypes.