Released August 2007 - The Indian Society for Parasitology

10Agrawal and Banerjeeexcretions and secretions were found to protect the triclabendazole, recommended against Fasciolaanimals against re-infection with varying degree of species, killed S. incognitum to a significant (p < 0.05)success. Most of the work has been carried out using S. level. These works of Shrivastava and Agrawal (1999)incognitum as it is easy to grow this parasite in emphasized the need of the trial of drugs in differentlaboratory animals, though S. spindale has also been doses and combinations in other helminthic infectionsused in heterologous immunological trials (Agrawal as well.and Shah, 1989). There is a success story of usingvaccine containing irradiated larvae against lungSome recent work has shown the development ofworms of sheep produced by Indian Veterinarydrug-resistance by H. contortus against not onlyResearch Institute (IVRI) workers (Dhar and Sharma,benzimidazole group of drugs but also against1981). Some work was also carried out usinglevamisole and ivermectin etc. warranting moreirradiated larvae against H. contortus infection inattention on the subject and to discouragesheep (Sood, 2003b). However, the work could not beindiscriminate use of anthelmintics by commercialextended in domestic animals against schistosomosis;dairy farms (Yadav et al., 1995; Singh et al., 2002).production of vaccine against lung worms wasLikewise, there is little work on the use of combinationdiscontinued by IVRI. It seems that presently noof drugs for synergistic effect or for studyingIndian institute is continuing the work on vaccinepharmacokinetics of a particular drug against aproduction against any helminthic disease.common helminthic infection in two different hostspecies. Sanyal (1995, 1996) has demonstratedNo doubt, the future vaccine work cannot be continued different pharmacokinetics of triclabendazole inwith irradiated larvae or live cercariae but pure buffalo and cattle, thereby suggesting the requirementantigenic molecules have to be identified by of higher therapeutic dose in buffaloes for killing F.employing genetic engineering techniques, which will gigantica. Similar type of work is needed on otheralso help in their production in large quantities. Here it drug and host combinations.may be pertinent to mention that research onimmunodiagnosis of fluke infections has led toThere are some interesting efforts made in selfidentification of antigenic molecules responsible formedication system for integrated management ofproducing antibodies, which are helping in diseasegastrointestinal parasites in dairy animals and in-feeddiagnosis. It will be worthwhile to investigate if theseformulations for ovine and caprine parasiticantigens, some of which are common to other flukesgastroenteritis (Sanyal, 1998). However, research onalso, may be used as vaccine candidates. Unlike India,new drug molecules against helminthosis is lackingmore work is going on in other countries on thedue to apathy on part of pharmaceutical companies.development of sub-unit/molecular vaccines againstThough clinical research is taking shape in humanhelminths and it will be beneficial to collaborate withmedicine, it will take some more time to cash this ideasuch research groups.in veterinary practice in India.CONTROLA critical analysis of drug industry reflects either theyare not interested in drug research againstConsiderable attention has been paid to treat helminthosis due to lower market demand or have nohelminthosis and new drugs have been tried as soon as research facilities to that magnitude. Also, therethey become available. Work on the comparison of the appeared little social concern by the drug industryefficacy of different drugs has also been undertaken with no attention on molluscicides or even marketingwith different dosages. Whereas there are effective the well established molluscicides in India to combatdrugs against fasciolosis, amphistomosis, snail population, responsible for all the flukegastrointestinal nematodiasis, apparently, there is no infections.effective drug against Indian schistosomes as lithiumantimony thiomalate has proved to be of doubtfulControl of helminthosis has largely been dependent onefficacy. Even praziquantel, recommended by Worldchemotherapy. However, as it is confined to individualHealth Organisation for human schistosomosis couldtreatment or at the most treating a group of animals, itnot kill significant number of S .incognitum worms.has not influenced helminth population in theLooking at the doubtful efficacy and the cost of theenvironment. Control measures, besidedrug, it is difficult to recommend this drug for thechemotherapy, have still been confined to laboratorytreatment of bovine schistosomosis. Interestingly,and no organization has come forward either to