Effect of reducing agents on Toxocara canis eggs viability and establishment of coproantigen detection for diagnosis of toxocariasis

• Main Authors: Hsin Chieh Lin, 林心潔
• Other Authors: Hong-Kean, Ooi
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/91198487235358507936

碩士 === 國立中興大學 === 獸醫微生物學研究所 === 91 === Abstract Toxocara canis is an important zoonotic parasitic disease. Its infection in human through the ingestion of the eggs can result in a disease called visceral larval migrans. Besides treatment with high temperature, no other chemical reagents are known to be able to completely destroy the eggs. Thus, it is very important to identify or test for reagents that can inhibit the development of the T. canis eggs. It could be used as an ovicidal chemical compound against the dog roundworm eggs. By comparing the efficacy of the various reducing reagents that includes sodium sulfite potassium bisulfite, sodium thiosulfate, and magnesium oxide in inhibiting the development of the T. canis eggs, it was found that sodium sulfite ( Na2SO3 ) was the most efficacious. When T. canis eggs were treated in vitro with sodium sulfite at 0.1%, 1 % and 2%, it was observed that 35%, 27.5% and 5%, of the eggs embryonated, respectively. This phenomenon of egg growth inhibition was not observed for Ascaris suum eggs that were similarly treated. On the other hand, it is also the aim of this study to develop a diagnostic method for dogs infected with T. canis but were not shedding any parasite eggs. A coproantigen detection method, which is basically a sandwich ELISA that detect the excretory-secretory (ES) antigen of the worm in the dog feces, was developed. The capture antibodies used were polyclonal antibody against the ES antigen of T. canis that were raised in rabbits. Cross-reactivity studies using fecal samples of dogs that were infected with other helminth parasites showed that the coproantigen test developed in this study is sufficiently specific enough to be applied to the field. Partial characterization of the detected T. canis coproantigen using chemicals such as formalin, acetone, sodium metaperiodate and Triton X-114 as well as using enzymes such as proteinase K andα-amylase, suggests that it possesses a hydrophobic moiety with glycoprotein at its epitope.