Reducing the delay in initiation of treatment improved clinical outcomes in patients with imported malaria

Although imported malaria poses a grave public health threat in Japan, diagnostic methods and disease management among patients and primary care providers has rarely been reported. Here, we retrospectively reviewed medical records of patients diagnosed with imported malaria in our hospital from 1991 to 2010. Thirty-four malaria cases were identified, corresponding to approximately 2% of the total number of cases in Japan. Falciparum malaria has become predominant in the last 2 decades, and compared with patients in the earlier decade (1991-2000), patients in the latter decade (2001-2010) showed significantly shorter delays in consulting medical facilities. The overall hospital delay also tended to be shorter in the latter decade, although delayed referral of patients by a week or more was still observed in more than one-third of the cases. The prevalence of risk factors for severe malaria among patients on the day of the referral visit was also lower in the latter decade. Further, the number of WHO-defined cases of severe malaria was smaller, and the length of the hospital stay was not prolonged during that decade. These findings indicated that a shorter delay in seeking medical treatment could reduce the risks of severe malaria.