nematode parasites of the genus thelazia are clinically important , causing insect - borne zoonoses in humans .
more than 10 species have been reported in various parts of the world . among them , thelazia callipaeda , the oriental eye worm , is widespread in domestic and wild animals in asian countries , italy , france , and germany , and it is sometimes found in humans in china , india , thailand , indonesia , japan , and korea [ 1 - 4 ] . in the republic of korea , a total of 37 human infection cases were reported in the literature since the first one by nakada ( 1934 ) [ 5 - 32 ] .
recently , we found 2 cases of human thelaziasis ( ht ) that occurred in gyeongsangnam - do , and we analyzed characteristics of the overall 39 korean ht cases , including the present 2 cases .
a 58-year old woman , residing in hadong - gun , gyeongsangnam- do , came to gyeongsang national university hospital ( gnuh ) complaining of foreign body sensation and itching of the right eye in march 2000 .
she had a trabeculectomy in her right eye in gnuh about 10 years ago , and lost the sight of the right eye about 1 year ago . at ordinary times , she engaged in farming and gathered wild vegetables in the mountains .
many dogs were raised in her residential village , and she used the vally water as drinking water .
thread - like worms were found in the lower conjunctival sac of the right eye , and total 6 thelazia callipaeda adult worms ( 2 males and 4 females ) were extracted at gnuh ( fig .
a 80-year old man , residing in jinju - si , gyeongsangnam - do , came to gnuh complaining of foreign body sensation , itching , and pain of the right eye in december 2007 .
he had climbed a mountain 1 month before . at 10 days after the mountain climbing ,
1 worm was incidentally found and reissn moved by a physician in a local hospital in jinju - si , gyeongsangnam- do . a total of 4 worms ( 3 females and 1 dead and degenerated ) were extracted from his right eye . at 1 month later , 1 female worm was also removed from his right eye at gnuh .
a 58-year old woman , residing in hadong - gun , gyeongsangnam- do , came to gyeongsang national university hospital ( gnuh ) complaining of foreign body sensation and itching of the right eye in march 2000 .
she had a trabeculectomy in her right eye in gnuh about 10 years ago , and lost the sight of the right eye about 1 year ago . at ordinary times , she engaged in farming and gathered wild vegetables in the mountains .
many dogs were raised in her residential village , and she used the vally water as drinking water .
thread - like worms were found in the lower conjunctival sac of the right eye , and total 6 thelazia callipaeda adult worms ( 2 males and 4 females ) were extracted at gnuh ( fig .
a 80-year old man , residing in jinju - si , gyeongsangnam - do , came to gnuh complaining of foreign body sensation , itching , and pain of the right eye in december 2007 .
he had climbed a mountain 1 month before . at 10 days after the mountain climbing , 1 worm was incidentally found and reissn moved by a physician in a local hospital in jinju - si , gyeongsangnam- do .
a total of 4 worms ( 3 females and 1 dead and degenerated ) were extracted from his right eye . at 1 month
among 10 worms collected , 6 females and 1 male were fixed with 10% hot formalin , cleared in alcohol - glycerin solution , mounted in glycerin - jelly , and observed under a light microscope ( lm ) with a micrometer . to observe the surface ultrastructure , remainders , 2 females and 1 male ,
were washed several times with 0.2 m cacodylate buffer ( ph 7.2 ) and fixed with 2.5% glutaraldehyde at 4. after washing 3 times with the buffer , they were dehydrated through a graded alcohol series ( 50% , 70% , 80% , 90% , 95% , and absolute alcohol ) , dried with hexamethyldisilazane , coated ( jfc-1100e ion sputtering device ) with gold , and observed with a scanning electron microscope ( philips xl-30s , einthoven , the netherlands ) at an accelerating voltage of 20 kv . the male worm was 12.40.44 mm in size , had a scalariform buccal cavity ( 0.0250.033 mm ) , a long muscular esophagus ( 0.65 mm long ) , and a coiled tail . in the scanning electron microscopic ( sem ) study , the cephalic part ( about 0.0280.044 mm ) with the buccal cavity , 2 cephalic papillae , and a body papilla which located at anterior 1/10 in a longitudinal groove , were characteristically observed in the anterior portion .
folded transverse striations were arranged on the anterior surface from just behind the cephalic part .
their densities were about 375 rows per 1 mm length of the cuticle ( fig .
cuticular transverse striations arranged in the middle and posterior portions were about 220 and 240 rows per 1 mm length , respectively .
a spicule and dome - shaped papillae , 7 pairs of preanal , and 2 pairs of postanal papillae were observed in the coiled tail part ( fig .
females were 17.0 - 18.50.39 - 0.49 mm ( 17.70.44 mm on average ) in size , had a scalariform buccal cavity ( 0.0280.033 mm ) , a long muscular esophagus ( 0.70 mm long ) and a conical tail .
vulva openings were located at 0.52 - 0.6 mm ( 0.57 mm on average ) from the anterior end and at more anterior portion than the esophago - intestinal junction .
numerous coiled larvae were contained in the proximal part of the uterus , and lots of eggs were present in the distal part of the uterus . in the sem study of the body surface , folded transverse striations arranged on the anterior surface were about 250 rows per 1 mm length .
cuticular transverse striations arranged in the middle and posterior portions were about 170 and 375 rows per 1 mm length , respectively .
in the present study , 2 cases of ht were reported for the first time in gyeongsangnam - do . therefore , including the present 2 cases , a total of 39 cases of ht have been documented in the republic of korea . among them , 28 cases ( 71.8% ) occurred in seoul and gyeonggi - do ( province ) , and the remainders ( 11 cases ) occurred in chungcheongbuk - do ( 2 cases ) , jeollabuk - do ( 1 case ) , gyeongsangbuk - do ( 1 case ) , daegu ( 1 case ) , gyeongsangnam - do ( 2 cases ) , busan ( 1 case ) , and other areas ( 3 cases ) .
it is interesting to note that all 5 cases reported from southeastern parts ( gyeongsangbuk - do , daegu , gyeongsangnam- do , and busan ) occurred after 2000 , whereas all cases of seoul and gyeonggi - do occurred before 2000 ( table 1 ) .
the plenty of ht cases in seoul and gyeonggi - do may be related to an abundance of academic facilities and manpowers which can aware and report the parasitic disease , as well as to the increase of outdoor activities of residents .
however , it is meaningful to see that ht cases are now being reported chiefly in southeastern parts after 2000 . in china , a total of 371 ht cases had been reported by 2005 , and most of them occurred in rural populations unlike in korea .
total 3 cases were reported before the 1960s . among them , 2 cases occurred in the northern part of korea , hwanghae - do and pyeonganbuk - do [ 5 - 7 ] .
there were no reports during the 1960s , 6 ( 15.4% ) in the 1970s , 11 ( 28.2% ) in the 1980s , 13 ( 33.3% ) in the 1990s , and 6 ( 15.4% ) after 2000 .
a total of 21 ( 53.8% ) cases were males and 18 ( 46.2% ) were females . by age groups ,
19 cases ( 48.7% ) occurred below 30 years of age , 16 cases ( 41.0% ) in 31 - 60 years , and 4 cases ( 10.3% ) at over 61 years ( table 1 ) . on the other hand , a review on the analysis of 179 chinese ht cases revealed 51% from females and 49% from males , and showed that the majority ( 64.2% ) of patients were children younger than 6 years .
the highest incidence of 17 cases ( 43.6% ) occurred in autumn ( 6 cases in september : 5 in october , and 6 in november ) . in the summer season , total 7 ( 17.9% ) cases ( 1 case in june , 3 in july , and 3 in august ) occurred .
a total of 5 ( 12.8% ) and 3 ( 7.7% ) cases were encountered in winter ( 4 cases in december and 1 in january ) and spring ( each 1 case in march , april , and may ) .
there was no case in february , and the occurrence date was unknown in 7 ( 17.9% ) cases .
the prevalence ( 69.2% ) of the second half year , from july to december , is much higher than that ( 12.8% ) of the first half year , from january to june .
therefore , seasonal tendency may be related to increasing outdoor activities of humans and increase of the vector population .
a total of 146 worms ( 44 males , 62 females , and 40 unknown ) were recovered from all 39 korean cases .
the individual worm burden was 1 - 15 worms per patient ( 3.7 on average ) . in the case of the maximum worm burden ( 15 worms ) ,
the infection recurred at 25 days after the primary worm recovery ( 10 worms ) .
kim and shin   removed 14 worms at once from the right eye of a 7-year old girl in july 1989 .
a total of 21 cases ( 52.5% ) had infection in the right eye , 16 ( 40.0% ) in the left eye , 3 ( 7.5% ) unknown , and only 1 case had infection in both eyes . only in 2 cases ( 5.1% ) , worms were found in the intraocular sites , whereas in the most of cases ( 94.9% ) , worms were detected in the conjunctival sac .
the chief complaints of korean cases with t. callipaeda , especially conjunctival sac infections , were foreign body sensation ( 78.8% ) , itching ( 48.5% ) , and lacrimation ( 36.4% ) .
they sometimes complained of hyperemia and hemorrhage of the eyes , mild visual disturbances , blurring sensation , and pain as the minor symptoms .
the visual disturbance , floaters , myodesopsia , and vitreous opacity were manifested in intraocular cases . for diagnosis of ht , identification of worms extracted from the eye
therefore , many researchers observed morphological characteristics , including surface ultrastructure , of worms recovered from human cases [ 21,23,27,33 - 35 ] .
we also examined the morphologies of t. callipaeda worms recovered from a case to provide more clear and profitable information in this study .
internal structures , such as the scalariform buccal cavity , muscular esophagus , esophageal nerve ring , intestine , rectum , anus , spicule , vulva opening , vagina , and larvae and eggs in uteri , were well visualized in light microscopic observations .
surface ultrastructures , including the cephalic part , cephalic papillae , body papilla , transverse striations by body portions , spicule , and preanal and postanal papillae , were well revealed by the sem study .
the morphological findings observed in this study were well coincided with those of the previous studies .
however , the fine and clear lm and sem images obtained in this study will be helpful to identify t. callipaeda from ht cases [ 21,23,27,33 - 35 ] .
 the present study was performed to describe 2 cases of human thelaziasis ( ht ) which occurred in gyeongsangnam- do and to briefly review the previously reported korean cases . 
 a 58-year old woman , residing in hadong - gun , gyeongsangnam - do , came to gyeongsang national university hospital ( gnuh ) complaining of foreign body sensation and itching of the right eye in march 2000 . 
 total 6 adult nematodes of thelazia callipaeda ( 2 males and 4 females ) were detected in her right eye . 
 a 80-year old man , residing in jinju - si , gyeongsangnam - do , came to gnuh complaining of foreign body sensation , itching , and pain of the right eye in december 2007 . 
 a total of 5 worms ( 4 females and 1 degenerated ) were removed from his right eye . 
 we analyzed characteristics of the total 39 korean ht cases reported to date , including the present 2 cases . 
 most of the cases ( 71.8% ) occurred in seoul and gyeonggi - do before 2000 , and 21 cases ( 53.8% ) were males and 18 ( 46.2% ) were females . 
 the prevalence was higher in younger ages below 30 years ( 48.7% ) than 31 - 60 years ( 41.0% ) and over 61 years ( 10.3% ) . 
 the seasonal prevalence showed a higher incidence in autumn ( 43.6% ) than in other seasons . 
 most of the cases ( 94.9% ) were conjunctival sac infections and only 2 ( 5.1% ) were intraocular cases . 
 the present 2 ht cases are the first reported cases in gyeongsangnam - do 
 . some characteristics of korean ht cases were analyzed . 
INTRODUCTION
CASE RECORD
Case 1
Case 2
DESCRIPTION OF WORMS
DISCUSSION