hookworm is one of important soil - transmitted helminthes ( sth ) for humans around the world .
human infection by hookworms induces blood loss , iron - deficiency anemia , and other anemia associated - symptoms and signs .
necator is rather prevalent in tropics and southern subtropics while ancylostoma is in subtropic or northern temperate zones .
worldwidely , n. americanus accounts for the predominant etiology of human hookworm infection , whereas a. duodenale occurs in more scattered focal environments ( 2 ) . until the 1970s , sths were highly prevalent in korea , and the population of infected people far outweighed those uninfected .
infections of sth were decreased , however , by a national mass control program in the 1970s to 1990s ( 3 ) .
only clonorchiasis and sporadic tissue parasitic helminthiases are recognized at present in korea ( 4 ) . among sths ,
hookworm disappeared first , and thus anemia and malnutrition by hookworm infection became negligible in korea in 1980s .
the hookworm egg positive rate in korea was 10.7% in 1971 , but decreased to 3.7% in 1978 , 0.08% in 1985 , and 0% in 2004 ( 3 , 5 ) .
of human hookworms , a. duodenale was predominant in korea but n. americanus was recognized in a few localities ( 6 - 8 ) .
the last case of n. americanus infection in korea was reported in 1978 ( 8) .
later , in 1992 , an imported case of a. duodenale was reported ( 9 ) .
herein , we describe a case of an 82-yr - old woman who suffered from severe chronic iron deficiency anemia by necator americanus infection in korea .
an 82-yr - old woman was transferred to the national police hospital , seoul , on october 22 , 2007 , complaining of shortness of breath and dizziness which lasted for years .
she lived in uljin - gun ( county ) , a remote rural area of eastern mountain of gyeongsangbuk - do , korea .
she had resided in uljin - gun throughout her entire life and had no history of overseas traveling .
, she had been treated for anemia including two transfusions in 2006 at a general hospital in seoul .
she also visited another general hospital complaining exertional dyspnea , and was treated for pulmonary tuberculosis . on physical examination at admission , she was pale , ill - looking , and undernourished , but her vital signs were stable .
laboratory results revealed overt anemia : rbc 1.6610/l ( normal 4.0 - 5.410/l ) , wbc 3.810/l ( normal 4 - 1010/l ) , hb 3.4 g / dl ( normal 12 - 16 g / dl ) , hct 12.4% ( 36 - 48% ) , mcv 74.7 fl ( normal 79 - 95 fl ) , mch 20.5 pg ( normal 27 - 33 pg ) , mchc 27.4 g / dl ( normal 32 - 36 g / dl ) , platelet count , 16210/l ( normal 130 - 40010/l ) , fe 9 g / dl ( normal 37 - 145 mg / dl ) , total iron - binding capacity 318 mg / dl ( normal 228 - 428 mg / dl ) , ferritin 10 ng / ml ( normal 10 - 130 ng / ml ) , neutrophils 56% , lymphocytes 25% , monocytes 11% , and eosinophils 8% .
stool examination was negative for occult blood , but was not examined for parasite eggs .
other biochemistry examinations , including electrolytes , liver and renal functions were within normal limits .
serum elisa against tissue invading helminthiases was negative for clonorchis , paragonimus , cysticercus , and sparganum .
gastroduodenoscopy found hyperemic mucosa and numerous 10-mm long slender reddish moving roundworms in the duodenum ( fig .
a total of 7 worms were removed by endoscopic biopsy forceps and 5 of them were transferred to the department of parasitology and tropical medicine , seoul national university college of medicine .
the worms were round - cylindrical in shape and blood - tinged , and the 5 worms ( male : 3 , female : 2 ) measured 10.5 mm ( range ; 8 - 11 mm ) long and 0.5 mm ( range ; 0.4 - 0.5 mm ) wide ( fig .
the buccal cavity at the anterior end was characterized by one pair of cutting plates .
two male worms showed the copulatory bursa at the posterior end , the dorsal costa of which had a deep notch .
after the diagnosis , she was treated with packed rbc transfusion , iron supportive therapy and albendazole medication , 400 mg twice per day for two days .
repeated tests two months after the treatment found her hemoglobin level to be 10.6 g / dl ( 12 - 16 g / dl ) and gastroduodenoscopy found normal mucosa and no n. americanus worms in her duodenum .
the present case constitutes evidence of local transmission of hookworm infection in korea in 2007 .
the patient had no history of overseas travel and stayed at home for long periods of time .
the patient 's home is at an isolated remote mountainous village in uljin - gun ( county ) , gyeongsangbuk - do , and she cultivated a small dooryard farm there .
the environment of her door - yard must have been favorable for active transmission of hookworm .
this transmission of n. americanus may be residual of the past endemicity of hookworm in the locality .
however , it is a surprising finding for the recent epidemiology of helminthiasis in korea because most parasitologists and physicians regard that sths were eradicated .
the morphological characteristics of the present hookworms were clear and definite enough to identify them as n. americanus .
most human hookworms in korea in the past have been a. duodenale , but n. americanus has also been found in remote agricultural localities in chungcheong - do or gyeongsang - do ( 6 - 8 ) . since sths , including hookworm , heavily infected throughout korea in the past , whole rural villages were endemic for the helminthes .
uljin - gun has been also an endemic area of those helminthes , and n. americanus must have been prevalent there .
upgrades of environmental sanitation and mass anthelminthic chemotherapy successfully eliminated sths and their associated diseases in the whole of korea ( 3 , 5 ) .
however , the present case allows for the possibility that some remaining endemic foci of sth transmission may be scattered in remote mountainous localities . in the village where the present patient lived , ascaris or trichuris
it is necessary to screen infection status of sths in such remote isolated villages in the mountainous zones of korea because other similar cases may live there .
clinical findings of the present case included anemia , dyspnea , and undernourished condition , which are known to be associated with hookworm infection ( 10 ) .
the severe anemia may have been due not only to the hookworm infection , but also to undernourishment and low hematopoietic activity due to her old age .
the physician observed hundreds of worms on the duodenal mucosa by endoscopy but recovered only 7 of them . picking out
in addition to endoscopy visuals , the laboratory hematological findings also suggested that the present patient was infected by at least hundreds of hookworms , because n. americanus suck less blood than a. duodenale do ( 1 , 2 ) .
in general , infection by a few hookworms is not sufficient to induce clinical anemia .
this fact confirmed that the anemia of the present case was caused by heavy infection of the hookworm , n. americanus .
reviewing her medical records , it was unfortunate that her fecal specimen was not examined properly throughout her whole past medical history .
she had visited several hospitals but no doctors had suspected hookworm anemia and her feces had not been properly checked for more than 2 yr . the present patient suffered from this disease for at least 2 yr because the possibility of hookworm anemia in this case was completely neglected by physicians .
this is the first case of hookworm anemia in korea to be diagnosed by endoscopy .
although most of past endemic sths have disappeared in korea , it is still necessary for physicians to be mindful of the possibility of sths .
 this report describes clinical and parasitological findings of an 82-yr - old female patient who lived in a local rural village and suffered from severe chronic anemia for several years . 
 she was transferred to the national police hospital in seoul for management of severe dyspnea and dizziness . at admission , 
 she showed symptoms or signs of severe anemia . gastroduodenoscopy observed hyperemic mucosa of the duodenum and discovered numerous moving roundworms on the mucosa . 
 endoscopy isolated seven of them , which were identified as necator americanus by characteristic morphology of cutting plates in the buccal cavity . 
 the patient was treated with albendazole and supportive measures for anemia , and her physical condition much improved . 
 this case suggests the possibility that hookworm n. americanus is still transmitted in a remote local mountainous area in korea . 