praziquantel ( pzq ) is the drug of choice for treatment of parasitic infections by trematodes or cestodes .
it is estimated that about one hundred million people take pzq over the world every year .
pzq is safe enough for the global use even though it has some known adverse effects , such as abdominal pain , diarrhea , sleep disorder , dizziness , and headache .
these adverse effects are common but mild and transient , and require no specific medical intervention .
in addition to the common adverse effects , rather severe reactions to pzq have been recognized .
the severe reactions are drug eruptions , including skin rash or urticaria , dyspnea , and hypotensive shock .
these serious symptoms or signs are induced by hypersensitive or anaphylactic reaction of individuals to most of drugs . at present ,
4 cases of pzq hypersensitive reactions have been reported worldwide [ 2 - 5 ] .
the present case report describes clinical findings of a clonorchiasis patient who had hypersensitive reactions after pzq ingestion in korea .
the patient was a 54-year - old - female who was running a dairy farm in gyeongju , korea .
she had eaten raw trout a few times and cooked freshwater fish frequently but not enjoyed eating raw freshwater fish .
she was found to pass eggs of clonorchis sinensis through her feces when she was examined by a program of parasitic infection survey for dairy farmers in 2009 .
on 25 august , 2010 , she took the first dose of pzq ( distocide , shin poong pharmaceutical co. ltd . ,
seoul , korea ) , and felt an itching sensation and noticed skin rashes on her hands and then on her entire body about 2 hr after the ingestion .
the patient assumed that these symptoms had been caused by some kinds of food and the symptoms subsided during sleeping .
she realized that pzq might have caused the skin rash , and visited a local clinic . according to the record of the local clinic , the symptoms slightly subsided compared from the beginning but body itching and skin rashes persisted .
blood pressure was 116/64 with heart rate 64 , and she was diagnosed as acute gastritis with distocide allergy .
the doctor prescribed chlorpheniramine maleate 0.5 ample ( anti - histamine ) followed by bepotastine besilate 10 mg ( second generation anti - histamine ) , methylprednisolone 4 mg , and metoclopramide hcl 3.84 mg for 2 days .
she was examined of her feces at department of parasitology and tropical medicine , seoul national university .
her feces were confirmed to pass a few eggs of c. sinensis on 9 september , 2010 .
the present case demonstrated skin rashes and other symptoms of nausea , dizziness , and dyspnea after pzq ingestion , which were compatible with those by hypersensitive reactions .
both pzq and parasites are foreign bodies and become potential allergens for a human body . in schistosomiasis , dead parasite bodies and eggs were recognized to induce the hypersensitive reaction after pzq medication .
pzq kills s. japonicum in the blood vessel , and the disintegrated dead worms may suddenly release much amount of allergens into the blood .
nonetheless , the present case is regarded as a patient of hypersensitive reaction which was induced by pzq itself .
that was a case of reaction to pzq not to the worms . since c. sinensis
live in the intrahepatic bile duct , pzq which is metabolized in the liver and excreted into the bile can kill the worms . since tmax of pzq is 2 hr after ingestion in humans
furthermore , c. sinensis live in the bile duct and pass down to the intestine through the bile duct lumen after paralysis or death of worms by pzq .
since most of the dead worms of c. sinensis are discharged from the body , they have little chance of allergic stimulation within 2 hr after pzq medication .
contrary to this , allergens from the dead worms of schistosoma or paragonimus are directly exposed to immune cells in the blood or tissue . in this context , it is evident that the present case showed hypersensitive reactions to pzq not to the parasite .
although she denied ingestion of the pzq before , she had been exposed to pzq in an unnoticed occasion .
since the present case was unable to finish whole dosage of pzq therapy , she was examined and found still positive for c. sinensis eggs .
desensitization is a good choice for cure of those hypersensitive or allergic patients of a certain drug .
they have been unnoticed by physicians and therefore not reported . only the cases of serious reactions
there have been only 4 reported cases as hypersensitive or anaphylactic reaction to pzq although it has been globally used for more than a billion people during the last 30 years . in conclusion , pzq is a safe anti - helminthic but hypersensitive reaction may rarely occur .
 praziquantel is the drug of choice for clonorchiasis . 
 since clonorchiasis is endemic in most river basins , praziquantel has been widely used for 30 years in korea . a 54-year - old korean woman suffered from hypersensitive reactions , such as nausea , dyspnea , rash , and urticaria after taking the first dose of praziquantel to treat clonorchiasis . 
 she ingested one dose again and the same symptoms appeared , and she was treated at a clinic with anti - histamines . 
 she tried one more dose with anti - histamines but found the same symptoms . 
 later , she was found to pass eggs of clonorchis sinensis and medicated with flubendazole . 
 the hypersensitive reaction to praziquantel is rare but occurs . 
 this is the 5th case report in the world . 
INTRODUCTION
CASE REPORT
DISCUSSION