ReviewVaccination Against Cysticercosis and Hydatid Disease
Section snippets
Existing measures for parasite control
General improvement in the economic situation of countries or regions is likely to lead to decreased transmission of both cystic hydatid disease and cysticercosis. Improvements in public education about sanitation and the availability and use of prepared dog foods impact on transmission of hydatid disease. Similarly, improvements in public health education and sanitation, the provision of latrines and the industrialization of pig raising decrease transmission of T. solium. Such measures, not
The need for vaccines
Numerous countries have had active control programmes for hydatid disease for many years, based on public education and dog control. However, few control programmes have had a major impact on disease transmission. It is difficult to change people's behaviour even in affluent, well-educated populations. In dogs, little or no immunity develops to E. granulosus, and so to ensure that E. granulosus transmission cannot occur, dogs need to be treated with anthelmintic drugs, such as praziquantel,
Vaccination against hydatid disease
Osborn and Heath13 showed that sheep could be vaccinated against infection with E. granulosus by immunization with non-living antigens obtained from the parasite oncosphere. Recombinant DNA methods provided the necessary tools for these antigens to be produced on a scale suitable for practical application. Oncosphere RNA was cloned and expressed in Escherichia coli and the product of one clone, designated EG95, was found to induce host-protective immunity in sheep14. Subsequent vaccine trials
Vaccination against cysticercosis
Most progress has been made with vaccination against cysticercosis caused by T. ovis in sheep and T. saginata in cattle. Native oncosphere antigens were identified as a source of host-protective antigens16, 17. Specific host-protective molecules were identified for T. ovis and recombinant DNA techniques were used successfully to clone and express the genes encoding three different antigens, each of which was able to induce almost complete immunity against experimental challenge infection in
Protective oncosphere antigens contain a fibronectin sequence motif
DNA sequence comparisons between the clones that produce the various protective recombinant antigens of T. ovis, T. saginata and E. granulosus do not identify all antigens as having significant homology. However, analysis of the predicted amino acid sequence has revealed the presence of a conserved motif as part of all the host-protective recombinant antigens described to date (Fig. 1). This relationship exists despite the antigenic clones having been isolated independently and their having no
Future challenges
The focus of this review has been on the potential for control of the zoonotic infections, cysticercosis and hydatid disease, by vaccination of livestock animals. The benefits to human morbidity and mortality of such an approach are indirect. A more direct approach would be to use protective vaccines against cysticercosis and hydatid disease in humans. Viewed from this perspective, the vaccination trials that have been so successful against hydatid disease in sheep can be regarded as a model
Acknowledgements
Financial support is acknowledged from the National Health and Medical Research Council; Meat Research Corporation; Melbourne Water; European Community; International Development Research Centre, Ottawa; National Council for Science and Technology, México; and Programa de Control de la Hydatidosis, Chubut, Argentina.
References (46)
Hydatid disease in China
Parasitol. Today
(1991)Australasian contributions to an understanding of the epidemiology and control of hydatid disease caused by Echinococcus granulosus – past, present and future
Int. J. Parasitol.
(1990)Mass chemotherapy for intestinal Taenia solium infection: effect on prevalence in humans and pigs
Trans. R. Soc. Trop. Med. Hyg.
(1997)- et al.
Hydatidosis and cysticercosis: the dynamics of transmission
Adv. Parasitol.
(1983) - et al.
Immunisation of lambs against Echinococcus granulosus using antigens obtained by incubation of oncospheres in vitro
Res. Vet. Sci.
(1982) Vaccination trials in Australia and Argentina confirm the effectiveness of the EG95 hydatid vaccine in sheep
Int. J. Parasitol.
(1999)- et al.
Successful vaccination of lambs against infection with Taenia ovis using antigens produced during in vitro cultivation of the larval stages
Res. Vet. Sci.
(1971) - et al.
Immunisation of calves against Taenia saginata infection using antigens collected by in vitro incubation of T. saginata oncospheres or ultrasonic disintegration of T. saginata and T. hydatigena oncospheres
Res. Vet. Sci.
(1981) Identification and cDNA cloning of two novel low molecular weight host-protective antigens from Taenia ovis oncospheres
Int. J. Parasitol.
(1996)Taenia saginata: vaccination against cysticercosis in cattle with recombinant oncosphere antigens
Exp. Parasitol.
(1996)