A nosocomial outbreak of malaria associated with contaminated catheters and contrast medium of a computed tomographic scanner

OBTECTIVE: To identify the risk factors associated with an unexpected outbr eak of malaria that occurred among seven patients in a general teaching hos pital in Taipei in October 1995. DESIGN: A three-stage case-control study was conducted to identify risk fac tors. PATIENTS: We identified all 7 patients who were diagnosed as malaria cases and 69 controls from those undergoing computed tomography (CT) examination. METHODS: Malaria was diagnosed by demonstrating the presence of Plasmodium falciparum on either thick or thin blood smears. Clinical characteristics a nd exposure information were collected from medical records and patient int erviews. RESULTS: The index case was infected by malaria when he visited Nigeria in early September and was diagnosed when he was hospitalized in hospital A in October. Among 10 patients examined with the Imatron scanner after the ind ex case, all 6 who were injected with contrast medium were infected, but no ne of 4 examined without contrast medium were infected (P=.005). CONCLUSIONS: This nosocomial outbreak of malaria was most likely due to tra nsmission via a contaminated catheter and contrast medium used for CT scann ing. Use of disposable catheters may avoid such nosocomial outbreaks in the future.