Epidemiology of Travel-associated Pandemic (H1N1) 2009 Infection in 116 Patients, Singapore
Pratik Mukherjee, Poh Lian Lim , Angela Chow, Timothy Barkham, Eillyne Seow, Mar Kyaw Win, Arlene Chua, Yee Sin Leo, and Mark I-Cheng Chen
Author affiliations: Tan Tock Seng Hospital, Singapore (P. Mukherjee, P.L. Lim, A. Chow, T. Barkham, E. Seow, M.K. Win, A. Chua, Y.S. Leo, M.I-C. Chen); National University of Singapore, Singapore (A. Chow, M.I-C. Chen); Duke–National University of Singapore Graduate Medical School, Singapore (M.I-C. Chen)
Figure 2. Travel duration and illness onset relative to arrival in Singapore for 116 patients infected with pandemic (H1N1) 2009 virus identified during epidemiologic weeks 21–25, 2009. A) Distribution of travel duration by epidemiologic week; B–E) timing of illness onset by travel duration in case-patients who did not have symptoms before embarkation (n = 87). Black, travel duration <3 h; white, 3–5.9 h; red, 6–14.9 h; blue, >15 h. Mean time from arrival to illness onset was 3.5 days (95% confidence interval [CI] 1.9–5.2), 1.7 days (95% CI 0.9–2.4), 1.0 days (95% CI 0.4–1.6), and 0.8 days (95% CI 0.0–1.5), respectively. The percentage of patients with symptom onset before arrival was 0%, 14%, 29%, and 33%, respectively. Week 21, May 24–30; week 22, May 30–June 6; week 23, June 7–13; week 24, June 14–20; week 25, June 21–27.
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