Infect Chemother.  2013 Jun;45(2):184-193. 10.3947/ic.2013.45.2.184.

The Long and Short Incubation Periods of Plasmodium vivax Malaria in Korea: The Characteristics and Relating Factors

• Kim SJ
• Kim SH
• Jo SN
• Gwack J
• Youn SK
• Jang JY

• KMID: 2284999
• DOI: http://doi.org/10.3947/ic.2013.45.2.184

Abstract

BACKGROUND
The cases of Plasmodium vivax malaria in Korea are mixed with long and short incubation periods. This study aims to define clinico-epidemiologic chracteristcs of Plasmodium vivax malaria in Korea.
MATERIALS AND METHODS
We selected the civilian cases infected with P. vivax malaria in Korea from the epidemiological investigation data of 2001 to 2010, whose incubation periods could be estimated. The long and short incubation periods were defined by duration of infection and onset time, and the cases were compared by demographic factors and clinical symptom, infection and onset time. The correlation was analyzed between the proportion of cases in the infected region with the long incubation period and meteorological factors along with latitude.
RESULTS
The length of the mean short and long incubation periods for the cases were 25.5 days and 329.4 days, respectively. The total number of the study subjects was 897, and the number cases of short and long incubation periods was 575 (64.1%) and 322 (35.9%), respectively. The aspect of incubation period showed a significant difference by region of infection; there was a higher proportion of long incubation period infection cases in Gangwon-do than in Gyeonggi-do and Incheon. The proportion of long incubation period cases showed significant correlation with latitude and temperature of August and September of the infected regions.
CONCLUSIONS
Incubation period of P. vivax malaria in Korea showed significant difference by infected region, infection and onset time and the proportion of long incubation period cases showed significant correlation with latitude and meteorological factors of the infected regions.

Keyword

Malaria; Plasmodium vivax; Incubation period; Epidemiology

MeSH Terms

Demography
Korea
Malaria
Malaria, Vivax
Meteorological Concepts
Plasmodium
Plasmodium vivax

Figure

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  Figure 1 Major risk areas of P. vivax malaria in Korea (2010-2011). In 1990s, initial stages of re-emergence, it occurred mostly in regions near the Demiliatarized Zone (DMZ), but it rapidly spread to the east and west. Recently, the incidence of malaria has increased in Northwestern region of Gyeonggi-do, such as Gimpo-si, Paju-si, Goyang-si, and Incheon.

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  Figure 2 Study population.

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  Figure 3 Distribution of the short and long incubation periods of P. vivax malaria cases, 2001-2010.

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  Figure 4 Yearly proportin of malaria infected regions and patients with short incubation period, 2001-2010. Gagnwon-do: Goseong-gun,Yanggu-gun,Inje-gun, Cheorwon-gun, Chuncheong-gun, Hwacheon-gun. Gyeonggi-do: Gapyeong-gun, Goyang-si, Gimpo-si, Dongducheon-si, Yangju-si, Yeoncheon-gun, Uijeongbu-si, Paju-si, Pocheonsi. Incheon: Ganghwa-gun, Seo-gu, Jung-gu, Dong-gu, Ongjin-gun.

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  Figure 5 (A) Monthly distribution of cases with P. vivax malaria by infection time, 2001-2010. (B) Monthly distribution of cases with P. vivax malaria by disease onset time, 2001-2010.

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  Figure 6 Correlation between proportion of P. vivax malaria with long incubation period and latitude in infected regionsa, 2001-2010. aGoseong-gun, Inje-gun, Cheolwon-gun, Chuncheon-gun, Hwacheon-gun, Gapyeong-gun, Goyang-si, Gimpo-si, Dongducheon-si, Yeoncheon-gun, Paju-si, Pocheon-si, Ganghwa-gun, Seo-gu, Jung-gu, Ongjin-gun.

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