Estimates of short- and long-term incubation periods of Plasmodium vivax malaria in the Republic of Korea.
With the current epidemic of vivax malaria closely associated with the demilitarised zone along the border between North and South Korea, it has been suggested that the incubation period tends, in part, to be prolonged. Based on the detailed travel history of cases from 2000 to 2003 who reside in non-malarious areas, statistical estimates of the incubation periods were obtained. The data suggest that cases fall into two categories with short- and long-term incubation periods, respectively. Of 416 cases with available information, 72 and 79 successfully met our criteria for inferring the durations of short- and long-term incubation periods. The mean short- and long-term incubation periods were estimated to be 26.6 days (95% CI 21.0-32.2) and 48.2 weeks (95% CI 46.8-49.5), respectively. The maximum likelihood method was used to fit gamma and normal distributions to the short- and long-term incubation periods, assisting prediction of the frequency distribution of the overall incubation period, which exhibited a bimodal pattern. We postulate that the observed distribution reflects adaptation of the parasite to the seasonal population dynamics of the vector, Anopheles sinensis, ensuring continued transmission of vivax malaria in this temperate zone.
Nishiura
Hiroshi
H
Department of Medical Biometry, University of Tübingen, Westbahnhofstrasse 55, Tübingen, Germany.
Lee
Hyeong-Woo
HW
Cho
Shin-Hyeong
SH
Lee
Wook-Gyo
WG
In
Tae-Suk
TS
Moon
Sung-Ung
SU
Chung
Gyung Tae
GT
Kim
Tong-Soo
TS
D000293:Adolescent; D000328:Adult; D000818:Animals; D006801:Humans; D007723:Korea / Q000453:epidemiology; D016780:Malaria, Vivax / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission; D008875:Middle Aged; D010966:Plasmodium vivax / Q000502:physiology*; D011159:Population Surveillance; D013997:Time Factors; D014195:Travel