Scientific Studies and Reports on Echinocossus Granulosus and Hydatid Disease
Release and survival of Echinococcus eggs in different environments in Turkana, and their possible impact on the incidence of hydatidosis in man and livestock
This is research by T. M. Wachira, C. N. L. Macpherson and J. M. Gathuma
The abstract is below. The entire research is behind a pay wall.
Abstract: In Turkana, Kenya, a prevalence of hydatidosis of nearly 10% has been recorded among the pastoralists yet their livestock have a much lower prevalence of the disease. The present study investigated the release from dogs and subsequent survival of Echinococcus eggs in Turkana huts, water-holes and in the semi-arid environment. The results were compared with the survival of eggs of Taenia hydatigena and T. saginata. The study was repeated under the cooler and moister conditons found in Maasailand where livestock have a greater incidence of hydatid disease than in Turkana but where the incidence in man is ten times lower. The average number of Echinococcus eggs per proglottid is 823. Nine percent of these remain in proglottids 15 minutes after release from a dog and the released eggs lose their viability in less than two, 48 and 300 hours in the sun, huts and water in Turkana respectively; the major influencing factor being temperature. The greater survival of eggs in the houses, coupled with the fact that dogs congregate for most of the day in the small houses facilitating a close man:dog contact, provide ideal conditions for the trasmission of the parasite to man. The hostile environmental conditions and lack of contact between dogs and livestock contributes to the lower infection rate in livestock. Conversely in Maasailand, Echinococcus eggs survive in the environment for longer than three weeks and in addition, dogs are used for herding. This partly explains the higher infection rate among Maasai livestock but the low human infection rate remains arcane and requires further study. The rapid mortality of the majority of Echinococcus eggs in Turkana suggests that control measures aimed at dog control and a decreased man:dog contact should have a profound effect on the incidence of the disease in an area intrinsically unsuitable for the parasites’ survival.
Influence of Temperature on the Infectivity of Eggs of Echinocossus Granulosus in Laboratory Rodents. Christina W. Colli and J.F. Williams.
This is a study. The link is to a preview. The entire study is behind a pay wall. The abstract is below.
Abstract: A comparison was made of the susceptibilities of Mongolian jirds (Meriones unguiculatus) and CF1 mice to infection with embryos of Echinococcus granulosus administered either intraperitoneally or orally. Optimal infectivity was obtained in both hosts using a dose of 1,000 eggs by the intraperitoneal route. This procedure was subsequently used in a series of experiments on the effects of exposure to subfreezing temperatures or moist heat on the survival and infectivity of eggs of E. granulosus. Eggs were found to survive for 24 hr at -30 C with no detectable effect on infectivity. One animal became infected after receiving eggs exposed to -50 C for 24 hr. No infections developed in animals inoculated with eggs subjected to -70 C. After 5 min incubation at 55 C the infectivity was significantly reduced, and incubation for an identical period of time at higher temperatures was sufficient to inhibit cystic development completely. These findings are discussed in relation to available information on the survival of taeniid eggs exposed to extremes of temperature.
Viability and infectiousness of eggs of Echinococcus granulosus aged under natural conditions of inferior arid climate – Paula Sanchez Theveneta, Oscar Jensen, Ricardo Drut, Gloria E. Cerrone, S. Greno?vero, Hector M. Alvarez, Hector M. Targovnik, Juan A. Basualdo
267-Page Study on E.G.
R.C.A. Thompson and D.P. McManus
The control of any infectious agent requires a sound knowledge of the taxonomy and transmission cycles which perpetuate the agent in nature. This is essential for surveillance and predictive epidemiology, and in determining the aetiology and appropriate treatment regimes in cases of disease. In this chapter, the biology of the causative agents of various forms of echinococcosis are described and details provided of the major cycles of transmission which are known to maintain the parasites in different geographic areas. Emphasis is given to the extent and nature of variability within the genus Echinococcus which reflects considerable inter- and intraspecific heterogeneity which has a profound influence on the epidemiology of echinococcosis. The identification of species and strains within the genus is an essential prerequisite to the establishment of local control programmes and appropriate molecular biological tools are now available for this.
From Iowa State University, the Center for Food Security and Public Health, information on E.G. and quite a bit about transmission and viability of E.G. eggs.
A letter sent to the Montana Environmental Quality Council in March of 2010, contains a translated letter from experts in hydatid disease in Russia that was a warning to the citizens of one particular region about human hydatid disease. Click this link for a PDF download of 4 pages.
Human Echinococcosis Mortality in the United States, 1990–2007 – An eighteen year study examining the echinococcosis-associated deaths of humans in the United States.
Hydatid disease: medical problems, veterinary solutions, political obstacles
From the Medical Journal of Australia, this editorial deals with the struggles in dealing with hydatid disease. Contains referenced resources.
Genetic variation and epidemiology of Echinococcus granulosus in Argentina.
This is a link to an “Abstract” found in the U.S. National Library of Medicine.
Hydatids – when a dog is not man’s best friend
Published by the Australian Academy of Science, this piece deals with the life cycle of hydatid disease, how it is spread and more specifically what role your pet dog can play.
Manipulative parasites in the world of veterinary science: Implications for epidemiology and pathology
A full 18-page review by Clément Lagrue *, Robert Poulin, Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054 New Zealand
Echinococcus granulosus in the wolf in Italy
This is a link to an “Abstract” of a study. You may have to join or purchase the full study.
The Distribution of Echinococcus Granulosus in Moose: Evidence for parasite induced vulnerability to predation of wolves?
This link contains the first page, including the Abstract, of a study that suggests that moose infected with hydatid cysts makes them more susceptible to fall prey to wolves. (You will have to purchase the entire report.)
Hydatid (Echinococcus) Disease in Canada and the United States
This link to the Oxford Journals, American Journal of Epidemiology, contains a report by Thomas B. Magath and published in 1936. His work documents recorded cases of human hydatid disease in Canada and the U.S. from 1921 – 1936, with additional cases that had not been previously recorded prior to 1921.
The full text of the report is available through a subscription and fee.
Survival of Protoscolices of Echinococcus Granulosus at Constant Temperatures
Ferron L. Anderson and Raymond M. Loveless of Department of Zoology, Brigham Young University, Published in the Journal of Parasitology, Vol. 64, No. 1, Feb. 1978
Contains the first page, including Abstract. Full text of the study can be purchased.
Echinococcus Granulosus: Variability of the Host-Protective EG95 Vaccine antigen in G6 and G7 genotypic variants
Conan Chow, Charles G. Gauci, Gulay Vural, David J. Jenkins, David D. Heath, Mara C. Rosenzvit, Majid Fasihi Harandi, Marshall W. Lightowlers,*
Received 19 November 2007; received in revised form 20 January 2008; accepted 28 January 2008
Available online 2 February 2008
Oncospheral penetration glands are the source of the EG95 vaccine antigen against cystic hydatid disease
A. JABBAR, D. J. JENKINS, S. CRAWFORD, A. K. WALDUCK, C. G. GAUCI and M.W. LIGHTOWLERS
(Received 30 March 2010; revised 9 June 2010; accepted 10 June 2010; first published online 21 July 2010)
Immunohistochemistry and immunogold labelling techniques were used to localize the EG95 vaccine antigen in Echinococcus granulosus oncospheres. In non-activated oncospheres, the cytoplasm of 2 pairs of bilateral cells exhibited specific positive labelling for the presence of EG95. No surface localization was seen in non-activated or recently activated oncospheres. Besides the staining of 2 pairs of bilateral cells, there was also a generalized distribution of specific staining for EG95 throughout the parenchyma of activated oncospheres. Immunogold labelling of non-activated oncosphere revealed specific reactivity for EG95 involving 2 pairs of bilateral cells and the ultrastructural characteristics of these cells were consistent with them being penetration gland cells. No other oncospheral structures stained specifically for the presence of EG95. The absence of surface location of EG95 in oncospheres suggests that the parasite may not be susceptible to vaccineinduced antibody and complement mediated attack until some post-oncospheral development has occurred. Further studies would be required to determine when the EG95 antigen associates with the parasite’s surface, thus making them susceptible to immune attack.
Key words: hydatid disease, vaccination, antigen, EG95, oncospheres, location.
Hydatid disease (Echinococcus granulosus) in Australian Wildlife – FACT SHEET
From the Australian Wildlife Health Network