Cluster of Acute Watery Diarrhoea in a Peri-Urban Settlement

The officer should treat this as a suspected cholera outbreak until proved otherwise. The reasoning is epidemiological: acute watery diarrhoea in a defined area, a cluster on two streets sharing a broken water line, and a case fatality of about 7% (3/43) are enough to act immediately; waiting for laboratory confirmation would cost lives.

Priorities:

• Save lives now: open oral rehydration points at the clinic and in the affected streets, ensure staff can assess dehydration and give oral rehydration salts or intravenous fluids for severe dehydration, and keep a small stock buffer.
• Find cases actively: start a line list with name, age, address, date of onset, dehydration category, treatment and outcome; search households for unreported cases and deaths.
• Stop transmission: advise boiling or chlorinating water, protect wells, and arrange emergency repair or alternate water supply; provide soap and handwashing points.
• Confirm the cause without delaying action: collect stool or rectal swabs from early cases into Cary-Blair transport medium and arrange culture; a negative rapid test would not stop the response.
• Coordinate: designate one incident lead, brief the two nurses, and plan referral for severe cases.

The school-closure demand and radio interview should be handled the same day, but they are communication decisions, not the first clinical priority.

A practical suspected-case definition is: any person living in or visiting the affected settlement from the start of the outbreak who has acute watery diarrhoea, with or without vomiting. A confirmed case would be a suspected case with Vibrio cholerae O1 or O139 isolated from stool. A death should be recorded as a suspected cholera death if it follows acute watery diarrhoea in the same setting, even without laboratory confirmation.

The judgement is to favour sensitivity over specificity during an outbreak. If the definition requires laboratory confirmation, many cases will be missed because testing is unavailable and transport is slow. If it requires severe dehydration, mild cases that sustain transmission will be missed. Including all ages is appropriate here because adults have died, although in some outbreaks the standard definition focuses on people aged 5 years and older; the local epidemiology should guide that choice. A false-positive case in the line list is less harmful than a missed case, provided the data are reviewed. The definition must specify place and time so that cases outside the settlement are not counted indiscriminately. It should be updated if culture confirms another pathogen.

The officer should acknowledge the community leader's concern but explain that school closure alone is unlikely to stop a waterborne outbreak. The reasoning is that the main exposure appears to be contaminated water on two streets, not person-to-person spread in classrooms. Closure has costs: children may lose education and may gather elsewhere without supervision. A short closure or modified school day is reasonable if the school has no safe water or handwashing facilities, or if several pupils or staff are already ill. The decision should be reviewed in 48–72 hours.

For the radio interview, the officer should:

• state what is known and not known, without blaming any group;
• give three practical messages: treat or boil drinking water, seek care immediately for watery diarrhoea especially in young children and older adults, and use oral rehydration salts early;
• explain where oral rehydration points are and that treatment is available;
• correct misinformation, including the idea that the outbreak is a punishment or that antibiotics prevent illness;
• avoid promising that the outbreak is over.

A single designated spokesperson should speak, and the same messages should be repeated through community leaders and the clinic.