INTRODUCTIONThe scientific identification of lymphatic filariasis (LF), which includes elephantiasis, was conducted for the first time in Korea in 1927 . While it was originally thought that LF was caused by Wuchereria bancrofti, in 1943, Senoo  clarified that LF in Korea was caused by Brugia malayi instead. The first nationwide survey on patients with LF was conducted in the 1950s, which involved an analysis of 5,001 night blood smears in 25 randomly selected villages in Jeju-do . The study showed that 12.1% (604/5,001 cases) of the samples were positive for microfilaria caused by B. malayi. Three subsequent epidemiological studies indicated the following positive rates: 9.2% (19/206 cases) , 11.4% (26/229 school children), 22.2% (79/356 inhabitants) [5,6], and 8.6% (184/2,139 inhabitants) . These data strongly suggested that there were three major endemic foci of LF in Korea: the northeastern part (inland) of Gyeongsangbuk-do, and the western coastal areas of Jeollanam-do and Jeju-do. Jeju-do was found to be highly endemic, whereas the other two areas were found to be moderate-to-low endemic. During the early 1970s, chemotherapy was implemented in several regions endemic for LF with satisfactory results. In Yeongju-si, one of the main LF foci in Gyeongsangbuk-do, a remarkable decrease in LF prevalence was achieved, which resulted in complete disappearance of the disease during the observation period . However, western remote islands, such as Heuksan-do, were identified as new endemic areas of LF during the 1980s . A recent epidemiological study, however, revealed that this area is now LF-free [10,11].In this study, we report the epidemiological data of the follow-up on 83 patients who were identified in the past as affected by LF during the LF elimination survey program of the Korea National Institute of Health between 2002 and 2010 in previously endemic areas.
MATERIALS AND METHODSPeripheral blood (20 mL) was collected by capillary from the ear lobe or finger of villagers during house-to-house visits between 20:00 and 02:00. The commercially available dipstick kit Brugia RapidTM (Malaysian Bio-Diagnostics Research Sdn Bhd., Selangor Darul Ehsan, Malaysia) was used to detect anti-B. malayi antibodies. The kit was prepared with a goat anti-mouse antibody control line and B. malayi recombinant antigen test line. The presence of anti-filarial antibodies in subjects’ sera was tested according to the manufacturer’s instructions using the filarial antigen and colloidal gold-conjugated monoclonal anti-human immunoglobulin G4 provided in the kit. Blood from patients with elephantiasis was stained with Giemsa and examined under a light microscope.
RESULTSIn this study, we examined subjects who were previously diagnosed with elephantiasis of the lower or upper extremities due to LF; some of them had shown causative LF symptoms until 2010. The subjects were 60-to-98-years-old. A total of 52 subjects had a negative test result, while 31 had moved to a different city, were hospitalized for a reason other than LF, or had died (Table 1 and Figure 1).Most of the subjects still exhibited edema in the lower legs or arms, and some complained of redness and swelling in the legs or ankle joints. However, we could not find microfilaria in their blood and found that the redness and swelling in their legs and/or ankle joints were due to other diseases such as rheumatoid arthritis or cellulitis.
DISCUSSIONElephantiasis of the lower extremities was traditionally called Soojongdari or Darijeongeung (leg dropsy or king leg, respectively, translated to English). In Korea, when lymphangitis and lymphadenitis is associated with fever and transient joint swelling, this disease is called Pinaerim (blood down-flow), Pijeong (blood disease), or Gakmomsal (malaise with arthralgia) . Korean elephantiasis mainly affects the lower extremities and occasionally the arms; however, it has not been reported to involve the external genitalia .In the past, LF has been diffused in mainly coastal areas of Korea, such as Jeollanam-do and Jeju-do. However, a continuous effort of the Korean government, such as installation of mosquito nets and sanitation of houses, has resulted in the elimination of LF in Korea . This survey and follow-up study for patients who previously had filariasis confirms that LF has been completely eliminated in Korea.