Antimicrobial-resistant epidemic Shigella dysenteriae type 1 in Zambia: modes of transmission.

To determine the modes of transmission of an epidemic caused by Shigella dysenteriae type I (Sd1) in Zambia, a case-control study was conducted. Case-patients were more likely to have recent contact with a person with dysentery (P = .03) and to have a family member with preceding dysentery (P = .01). Case households were more likely to share their latrine (P = .06). Stored drinking water was obtained by hand-dipping a cup into wide-mouthed vessels or by pouring from narrow-mouthed vessels; case households were more likely to obtain drinking water only by hand-dipping (P = .03). Case-patients were more likely to have eaten relish (a cooked meat or vegetable dish; P = .03) purchased from a vendor. Evidence from this study suggests that Sd1 was transmitted by person-to-person spread, by water stored in vessels that permitted hand-dipping, and by prepared foods sold by vendors. Preventive measures should be directed at these risk factors.