Cross-reactivity of Toxocariasis with Crude Antigen of Toxascaris leonina Larvae by ELISA.

Roundworms of Toxocara canis and Toxascaris leonina are common gastrointestinal helminths of canids over the world. Humans are infected with T. canis larvae through ingestion of infective eggs in contaminated environments or larvae by consumption of raw or uncooked meat or livers. Recently, patients of clinically diagnosed toxocariasis are increasing and require correct diagnosis in Korea. The present study investigated serological cross-reactivity between crude antigens of T. canis (TCLA) and T. leonina (TLLA) larvae. We collected serum specimens from 177 toxocariasis patients who were clinically suspected in the Seoul National University Hospital and 115 healthy controls. An ELISA method for toxocariasis was used to evaluate diagnostic efficacy of TLLA for serodiagnosis of human toxocariasis. The IgG ELISA using TLLA gave 14 (14.3%) positives of 98 TCLA positive specimens among 177 suspected toxocariasis patients. Most of them showed high absorbances with TCLA. In conclusion, there is a partial cross reaction between serum specimens of toxocariasis and TLLA.

Serodiagnosis of toxocariasis by ELISA using crude antigen of Toxocara canis larvae.

Toxocariasis is a worldwide zoonosis caused by larvae of ascarid nematodes of dogs or cats, Toxocara canis or T. cati. Diagnosis of human toxocariasis currently relies on serology that uses T. canis excretory-secretory antigen to detect specific IgG antibodies by ELISA. We investigated the serodiagnostic efficacy of ELISA using crude antigen of T. canis larvae (TCLA). Serum specimens of 64 clinically confirmed toxocariasis, 115 healthy controls, and 119 other tissue-invading helminthiases were screened by ELISA using TCLA. The ELISA using TCLA showed 92.2% (59/64 patient samples) sensitivity and 86.6% (103/119) specificity. Its positive diagnostic predictivity was 78.7% and negative predictivity was 97.8%. No serum of healthy controls reacted but that of anisakiasis (45.5%), gnathostomiasis (19.2%), clonorchiasis (15.8%), sparganosis (11.1%), and cysticercosis (6.3%) cross-reacted. Immunoblot analysis on TCLA recognized antigenic proteins of 28- and 30-kDa bands in their dominant protein quantity and strong blotting reactivity. The present results indicate that the ELISA using our TCLA antigen is acceptable by the sensitivity and specificity for serodiagnosis of human toxocariasis. ELISA with TCLA is recommended to make differential diagnosis for patients with any sign of organ infiltration and eosinophilia.

Serodiagnostic applicability of recombinant antigens of Clonorchis sinensis expressed by wheat germ cell-free protein synthesis system.

We evaluated the diagnostic applicability of recombinant proteins from Clonorchis sinensis, the human liver fluke. Four recombinant proteins, 7-kDa protein (Cs7P), 28-kDa cysteine protease (Cs28CP), and 26- and 28-kDa glutathione s-transferases (Cs26GST and Cs28GST), were expressed by wheat germ cell-free protein synthesis system. In ELISA, crude antigen showed the highest sensitivity (92.7%). However, sensitivities of r7P (47.3%), r28CP (30.9%), r26GST (21.8%), and r28GST (14.5%) were dramatically lower. The overall specificities of the crude antigen, r7P, r28CP, r26GST, and r28GST, were 100%, 94.5%, 96.7%, 94.5%, and 98.9%, respectively. Taken together, r7P and r28CP showed moderate sensitivities and high specificities, whereas r26GST and r28GST revealed low sensitivities and high specificities. We demonstrated that recombinant antigens, when used as a single antigen for ELISA, are not sensitive enough to diagnose clonorchiasis. Cocktail or chimeric antigens may be useful to increase the sensitivity of each antigen and may improve the serodiagnosis of clonorchiasis.

Tissue parasitic helminthiases are prevalent at Cheongjin, North Korea.

We investigated a small-scale serological survey to screen tissue-parasitic helminthiases of North Koreans as one of research programs for re-unification of Korea. Soil-transmitted helminthiases were found highly prevalent among North Korean residents at the border with China. ELISA using 4 tissue-parasitic helminth antigens was applied to 137 residents living in Cheongjin-shi, Hamgyeongbuk-do, North Korea and 133 female refugees in South Korea in 2004-2005. Among a total of 270 samples, 31 (11.5%), 25 (9.3%), and 11 (4.1%) were positive for specific IgG antibodies to antigens of Clonorchis sinensis, Taenia solium metacestode, and sparganum, respectively. The overall positive rate was 21.5%; 38.2% in males and 15.8% in females. The present finding suggests that tissue parasites, such as C. sinensis, T. solium metacestode and sparganum are highly prevalent in some limited areas of North Korea. These foodborne tissue-parasitic helminthiases should be considered for future control measures of parasitic diseases in North Korea.

Collection of Clonorchis sinensis adult worms from infected humans after praziquantel treatment.

A cohort was established for evaluation of cancer risk factors in Sancheong-gun, Gyeongsangnam-do, Korea. As one of the cohort studies, stools of 947 residents (403 males and 544 females, age range: 29-86 years) were screened for Clonorchis sinensis eggs using both Kato-Katz method and formalin-ether sedimentation technique. The overall egg positive rate of C. sinensis was 37.7% and individual EPG (eggs per gram of feces) counts ranged from 24 to 28,800. Eight egg positive residents voluntarily joined a process of collection of the passed worms after praziquantel treatment. A total of 158 worms were recovered from 5 of the 8 treated persons, ranged from 3 to 108 in each individual. The worms were 15-20 mm x 2-3 mm in size, and showed brown-pigmented, red, or white body colors. This is the first collection record of C. sinensis adult worms from humans through anthelmintic treatment and purgation. The adult worms of C. sinensis may be paralyzed by praziquantel and then discharged passively through bile flow in the bile duct and by peristaltic movement of the bowel.

A case of anaphylactic reaction to praziquantel treatment.

A 35-year-old Chinese man was administered praziquantel for clonorchiasis, and 30 minutes later he experienced a sudden onset of itching urticaria over his entire body with dyspnea, palpitation, and dizziness. The patient had no recent medication history except for the praziquantel. He was diagnosed as having an anaphylactic reaction with skin eruptions induced by praziquantel. His symptoms subsided after a stomach wash and the administration of anti-anaphylactic medication in emergency department of a regional hospital in the People's Republic of China. The immediate type of hypersensitive reaction to praziquantel is plausible, and this reaction should be considered for praziquantel therapy.

Status of intestinal helminthic infections of borderline residents in North Korea.

The present authors investigated intestinal parasitic infections among North Korean residents and refugees in China in 2003. The Kato-Katz method was applied to 236 residents and soldiers in a town on the North Korea-China border and to 46 people at a refugee camp in China. Only eggs of Ascaris and Trichuris were detected, with egg positive rates of 41.1% and 37.6%, respectively. The total egg positive rate was 55.0% and most of those who were egg positive were only lightly infected. Women of 61.2% and men of 53.1% were egg positive. The refugees from rural areas showed higher egg positive rates than those from urban areas. The present investigation confirmed high prevalence of soil-transmitted intestinal helminths in rural borderline areas of North Korea.

[Genetic identification of Acanthamoeba sp. CJY/S1 and CJY/S2 isolated from soil].

Two isolates of Acanthamoeba sp. CJY/SI and CJY/S2 were received from soil in Yanji of Jilin Province. Full 18S rDNA gene was amplified using PCR, cloned and sequenced. The results were analyzed by software Clustal X. The full length of CJY/S1 and CJY/S2 is 2255 bp and 2252 bp respectively, both belong to T4 genotype.