For the present, there is no report of dengue occurring in Korea5
. Six cases of imported dengue were first reported in 20015)
. As increasing numbers of international travelers visit dengue endemic areas, the incidence of imported dengue has increased. Choi et al9)
reported the characteristics of 17 adult cases with dengue fever by collecting domestic literature from Korean bibliographic databases. Park et al10)
reported the case of a 15 year-old male with dengue fever complicated by rhabdomyolysis. This is the first report that prospectively estimated international travel experiences and dengue fever in Korean children who visited a pediatric infectious diseases clinic at a university hospital.
Dengue fever is a reportable infectious disease (group 4) in Korea. The KCDC reported 169 cases of dengue from 2003 to 20075)
. The destinations of imported dengue patients were mostly Asian countries except in one case where the patient was infected in Brazil. The most common destination where Korean travelers were infected with dengue was the Philippines (36.7%, 62/169). Among 169 cases, 13 cases (7.7%, 13/169) occurred under 20 years of age. Of note, we diagnosed 4 pediatric dengue cases in 2008 in our clinic.
The data from the Korea national statistical office showed that 13.33 million people accounting for 22.3 percent of the total population traveled abroad and 11.3 percent of all primary school students had international travel experiences in 200711)
. In this study, about one third of children who visited the pediatric infectious diseases clinic (29.8%) had international travel experience during the 12 months of the survey period from January 2008 to December 2008. Although the patients who visited our clinic may not represent all Korean children in a general population considering the socioeconomic differences among cities and provinces, this study still shows that Korean children are at risk of acquiring dengue fever from travel abroad and Korean pediatricians should be more prepared for such patients. Although small in numbers, this study is the first report to describe the clinical features of dengue fever in Korean children.
Dengue may present symptoms 3-14 days (usually 4-7 days) after exposure to the virus and the infection may range from subclinical to fever, retro-orbital headache, arthralgia and sometimes a quite florid maculo-papular rash usually within 3-5 days following the onset of the fever3)
. Patients with dengue fever sometimes may have hemorrhagic manifestations. Laboratory findings commonly include thrombocytopenia, leukopenia with lymphopenia, mild to moderate elevations of hepatic aminotransferases and lactate dehydrogenase, and hyponatremia2)
. The capillary leak results in dengue hemorrhagic fever and in its severe or fatal form dengue shock syndrome, which are complications defined by the WHO6
. Although infection with one serotype confers life-long protection against that serotype, reinfection with another serotype of dengue virus may predispose a person to the development of dengue hemorrhagic fever or dengue shock syndrome which have more serious outcomes2)
. Therefore those who have suffered from dengue fever previously should be more careful when traveling to endemic areas.
The spread of dengue is attributed to expanding geographic distribution of the four dengue viruses and their mosquito vectors, A. aegypti
and A. albopictus14
. Of note, although Korea is not a dengue endemic country, the A. albopictus
("Asian tiger mosquito") mosquitoes have been discovered throughout Korea5
. These mosquitoes are well adapted to life in urban settings2)
. Global air travel has allowed introduction and cocirculation of different serotypes of the virus in new regions. Consequently, dengue has developed into a disease of pandemic proportions16)
. Although A. albopictus
is native to tropical and subtropical regions, they are successfully adapting to cooler regions and have been expanding globally at an alarming rate6
. Having vectors capable of transmitting dengue in Korea has a very important implication on the nation's dengue surveillance since there is the possibility for a domestic dengue case by the Aedes albopictus mosquito in the future5
Many countries where dengue is endemic are popular tourist destinations and the disease is an increasingly serious problem encountered by international travelers. Many Korean children visit dengue endemic areas, may return home with dengue fever and there are no vaccines or drugs against dengue yet.
Dengue fever is not a familiar disease to Korean pediatricians which makes its diagnosis harder. Fever in the returned traveler can be a manifestation of a minor, self-limited process or can develop into a progressive and life-threatening illness. The clinician's lack of familiarity with the types of infections that the patient may have encountered while traveling is often an obstacle for the assessment of these patients. A systematic approach to the evaluation of febrile patients should include basic information about the geographic distribution of infectious diseases in the locations where the person has lived and traveled20
In conclusion, dengue fever should be suspected in Korean children who have a travel history to endemic areas and febrile illness.