Typhoid outbreak investigation in Dzivaresekwa, suburb of Harare City, Zimbabwe, 2011
Introduction: Typhoid fever is a systemic infection caused by a Gram negative bacterium, Salmonella typhi. Harare City reported 1078 cases of suspected typhoid fever cases from October 011 to January 2012. We initiated an investigation to identify possible source of transmission so as to institute control measures.
Methods: An unmatched 1:1 case-control study was conducted. A questionnaire was administered to study participants to identify risk factors for contracting typhoid. A case was a resident of Dzivaresekwa who presented with signs and symptoms of typhoid between October and December 2011. Water samples were collected for microbiological analysis.
Results: 115 cases and 115 controls were enrolled. Drinking water from a well (OR= 6.2 95% CI (2.01-18.7)), attending a gathering (OR= 11.3 95% CI (4.3-29.95)), boiling drinking water (OR= 0.21 95% CI (0.06-0.76)) and burst sewer pipe at home (OR= 1.19 95% CI (0.67-2.14)) were factors associated with contracting typhoid. Independent risk factors for contracting typhoid were drinking water from a well (AOR=5.8; 95% CI (1.90-17.78)), and burst sewer pipe at home (AOR=1.20; 95% CI (1.10-2.19)). Faecal coli forms and E. coli were isolated from 8/8 well water samples. Stool, urine and blood specimens were cultured and serotyped for Salmonella typhi and 24 cases were confirmed positive. Shigella, Giardia and E coli were also isolated. Ciprofloxacin, X-pen and Rocephin were used for case management. No complications were reported.
Conclusion: Contaminated water from unprotected water sources was the probable source of the outbreak. Harare City Engineer must invest in repairing water and sewage reticulation systems in the city.
Key words: Typhoid, outbreak investigation, contaminated water, Zimbabwe