Since the late 1970s∼early 1980s, malaria cases had not been reported in South Korea,
except for imported cases. One vivax malaria case was reported in 1993, then the
number of cases sharply increased to 25 in 1994, 107 cases in 1995, 356 in 1996, and
1724 cases in 1997. Undoubtedly, all cases were neither imported nor induced. The
majority of them were soldiers infected in Paju-gun, Yonchon-gun, and adjacent
counties located within 10km from the demilitarized zone (DMZ), the border of South
and North Korea.
The question is where the source of infection was, as there had been no malaria
cases for more than 15 years. The only possible source of infection was the infected
mosquitoes which few down across the DMZ from North Korea. Though we do not
know about the epidemiology of malaria in North Korea, it is certain that the
epidemiological, entomological, and socioecological factors in North Korea are
significantly different from those in South Korea. The living standard of people is
extremely low because of the economic crisis and top priority of the military
strengthening policy. Therefore, it is assumed that malaria endemicity had been
maintained at very low level until 1993. The precipitation records of Inchon and Seoul
from 1993∼1996 are shown in Table 1; because the meteorological data of North Korea
is not available, the data from Seoul and Inchon meteorological offices located near
Whanghae-do, North Korea are cited. There was heavy rainfall in July 1993 (438mm in
average of two areas that is 102 mm heavier than usual) and August 1995 (704 mm in
average that is 454 mm heavier than usual), causing that all rice fields were flooded.
The damage was particularly severe in North Korea and these floods provided extensive
breeding places for the vector mosquitoes, Anopheles sinensis. Malaria epidemics might
have started then. Variations in climatic conditions influence greatley the transmission
and seasonal incidence of malaria; particularly excessive rainfalls or drought. An.
sinensis is highly zoophilic; 97.3% of the females feed on cows and pigs. However, there
are very few numbers of cows and pigs in North Korea, so that most females of this
vector species have no choice but to feed on humans.
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