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 outbreak of malaria that occurred among seven patients in a general teaching hospital in Taipei in October 1995. DESIGN: A three-stage case-control study was conducted to identify risk factors. 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 and exposure information were collected from medical records and patient interviews. 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 index case, all 6 who were injected with contrast medium were infected, but none of 4 examined without contrast medium were infected (P=.005). CONCLUSIONS: This nosocomial outbreak of malaria was most likely due to transmission via a contaminated catheter and contrast medium used for CT scanning. Use of disposable catheters may avoid such nosocomial outbreaks in the future.