Other important diarrhoeal illnesses

Question 1

Bacillary dysentery - Shigella: Which organisms, how many affected, which parts of the world?

Answer 1

• Shigella are gram-negative rods and humans are the only important reservoir
• Transmission is faecal-oral: P2P, food, water, flies
• There are >150 million cases/year with >1 million deaths, mainly kids
• There are 4 types that each contain multiple serotypes:
• S. Dysenteriae causes epidemics
• S. Flexneri causes endemic dysentery in developing countries
• S Boydii is common in the Indian subcontinent
• S Sonneii is a common cause in the industrialised world
• Infection confers serotype-specific immunity
• Vitamin A and Zinc reduce mortality

Question 2

Bacillary dysentery - Shigella: Clinical features

Answer 2

Bloody stool

Incubation is 1-7 days

• Varies from asymptomatic carriers to fulminant colitis or toxic megacolon
• Typically causes a bloody mucoid diarrhoea with septic features
• In children this may be proceeded by a meningoencephalitis.
• Death is usually due to dehydration but also blood loss, sepsis
• HUS can occur

Question 3

bacillary dysentery - Shigella: How is it diagnosed and how is it treated?

Answer 3

Investigations

• “Redcurrant jelly” stool
• Bacilli are scant in stool and may not be seen
• Rapid antigen testing for s. dysenteriae type 1 only (major cause of outbreaks)

Treatment

• Adequate hydration and nutrition as always
• WHO guidelines: all bloody diarrhoea should receive prompt antibiotic treatment that is effective against Shigella. Ciprofloxacin is first line – resistance is common
• Antibiotic sensitivity testing is essential in outbreaks
• Vitamin A and Zinc supplement for 2/52 especially in children
• No available vaccines

Question 4

Bacillary dysentery - Balantidium Coli: features

Answer 4

Question 5

Traveller’s diarrhoea: cause

Answer 5

Question 6

Others

Answer 6