Bacilliary dysentery is a diarrhoeal illness caused by Shigella infection.
There are four species of Shigella known to cause diarrhoeal illness:
· Shigella sonnei (75% of UK infections) cause most of the mild infections.
· Shigella flexneri and Shigella boydii (travellers) cause intermediate infections.
· Shigella dysenteriae is the most serious.
Shigella is a human pathogen without an animal reservoir. Spread is by person-to-person contact, faecal–oral route or contaminated food. The incubation period is usually 2 days. The organism attaches to the mucosal epithelium of the distal ileum and colon causing inflammation and ulceration.
Acute watery diarrhoea with systemic symptoms of fever, malaise and abdominal pain develops into bloody diarrhoea. Other features include nausea, vomiting and headaches. Complications include colonic perforation, septicaemia, arthritis and convulsions.
Diagnosis is made on stool culture. Sigmoidoscopy if performed reveals an inflamed mucosa with ulceration similar to that seen in inflammatory bowel disease.
Treatment is symptomatic. Severe cases may be treated with trimethoprim or ciprofloxacin. Outbreaks may occur and require notification and source isolation.