• "WHO classification": the draft was given in the last issue of EchinoNews.

Future of the group : for a scientific publication : application of the proposed classification to a significant number of cases (as it was done for PNM classification in AE) ; evaluation of the usefulness of the classification in a joint study with the networks on long term evaluation of chemotherapy, surgery and PAIR

® collection of cases + 5 years follow-up : round-table in Lisbon, 1997

® booklet on PAIR : publication by WHO in April 2000

® common publication

• study of the 10-year follow-up
• collection of all side-effects

® a list of people involved in the "Classification" Network as well as in the PAIR Network will appear in the "PAIR booklet"

® precision on the "resuscitation kit" will be given in the booklet

® PCR for E.granulosus ?

experience of teams working on E.multilocularis would be useful to teams working on E. granulosus

• After the meeting in Cyprus, contacts were established between the Australian – New Zealand teams which developed the vaccines and various teams involved in echinococcosis control, especially in China and South America ; and results of field trials are now available.

• Results of these field trials were given at Session I of the Congress by M. Lightowlers, D. Heath and O. Jensen and can be summarized as follows :

MW Lightowlers, DD Heath, E Fernandez, JA Iriarte

Three years have passed since the publication that described the successful vaccination of sheep against infection with Echinococcus granulosus (Lightowlers et al. 1996). In the intervening period new research collaborations have been established through which numerous vaccine trials have been undertaken. These trials have sought to confirm and extend our knowledge about the potential that the EG95 vaccine may have to assist in the control of transmission of hydatid disease. The results of many of these trials will be described in this and the subsequent two presentations at this Congress. Here, an overview is given of progress with the EG95 vaccine and a proposal is presented for the extension of research to include clinical trials towards development of a human vaccine for prevention of hydatid disease.

The EG95 vaccine consists of a sterile solution containing a purified, recombinant protein and an adjuvant. For use in sheep, and injection consists of 50 micrograms of protein and one milligram of Quil A adjuvant. Two subcutaneous injections of vaccine 2-6 weeks apart leads to a prominent 1gG antibody response to the EG95 protein (Woollard et al. 1998). Protection induced by the vaccine correlates with the appearance of complement-fixing antibodies which have been shown to kill E. granulosus oncospheres in in vitro culture (Heath et al. 1996 ; Lightowlers et al. 1996).

The two initial trials of the EG95 vaccine were performed in New Zealand using Romney and Dorset breeds of sheep and an isolate of E. granulosus which was derived from sheep/dog transmitted parasites in New Zealand. The parasite isolate had been maintained experimentally in sheep and dogs at the Wallaceville Animal Research Centre at Upper Hutt. In these two trials, EG95 induced 96-98% protection in lambs against experimental challenge infection with E. granulosus eggs. Since these trials, new experiments have been completed in Australia, Argentina and China as well as further trials in New Zealand. Results of a series of trials carried out in Australia and Argentina were published in May this year (Lightowlers et al. 1999). These trials confirmed the effectiveness of the EG95 vaccine and showed that the vaccine was effective in different breeds of sheep (merinos) against isolates of E. granulosus from different regions of the world (New Zealand, Australia and Argentina) and against parasites which were involved in a different host-parasite transmission cycle (dingo/wallaby). The three independent trials recorded 96%, 99% and 100% protection against the development of hydatid cysts following experimental infection with E. granulosus eggs. Not only was there a reduction in the average number of hydatid cysts which established in the sheep, many of the vaccinated animals were completely protected against infection. Collectively, 86% of the sheep in the three vaccine trials had no viable hydatid cysts when examined one year after the experimental infection.

Other vaccine trials have been completed in China and Argentina which are the subject of the following presentations at the Congress.

DD Heath, Qi Pusheng, Z Zhuangzhi, W Jincheng, F Jinglan, MW Lightowlers

Control programmes for echinococcosis have invariably the aim to reduce or eliminate the infection in human populations. The desired outcome is a satisfactory decrease in prevalence in the 1-20 years old age group. Several geographically-isolated countries (Iceland [Schabe, 1994] ; New Zealand [Gemmel et al. 1986 ; Heath and Kasper, 1991] ; Cyprus [Papadopoulos, 1985 ; Polydorou, 1992 ; Economides 1994 ; Economides et al. 1998]) have procedures in place to eradicate the parasite. Others, such as Tasmania, (Schantz et al. 1995) or the Falkland Islands, (Reichel 1994) are content with the degree of control obtained.

In contrast, countries forming part of large continents and that have seriously attempted hydatid control, for various reasons have not always achieved the satisfactory level of control where human disease becomes infrequent (Chile, Argentina, Uruguay, Algeria, Morocco, Spain, Greece, Sardinia). In many endemic areas, effective control has not been achieved or even attempted (Schantz et al. 1995). Apart from political instability, the major difficulties appear to be (a) movement of definitive and intermediate hosts across borders (b) difficulty in gaining access to definitive hosts (c) the need in some countries to feed dogs on dead livestock and offal and (d) the need to maintain regular monthly or 6-weekly anthelmintic treatment of all dogs for up to 20 years. (Falkland Islands – 19 years [Reichel, 1994] ; New Zealand – 23 years [Health & Kasper, 1991].

The concept of recombinant vaccines against acquisition of the metacestode stage of cestodes has been discussed by Heath (1991) and Lightowlers et al. (1992). A vaccine to prevent intermediate host becoming infected with Echinococcus granulosus is now a feasible addition to control programmes (Heath, 1995 ; Heath & Lightowlers, 1997). As with most vaccines, young animals need to be vaccinated twice, with a month interval between vaccinations. Thereafter, annual vaccination will be required. Domestic livestock are usually handled at least once a year, and vaccination can fit into normal farm practice.

The protective molecules of E. granulosus have been studied in sheep by Heath & Lawrence (1996). The oncosphere, which is the invasive stage of E. granulosus, emerges from the egg and penetrates the epithelium of the small intestine (Heath, 1971). After entering a portal venule or lymphatic lacteal, the oncosphere is carried to the liver or lungs. Post-oncospheral development is characterised by the proliferation of microvilli from the plasma membrane, with base-material for this rapid expansion of surface area being apparently supplied by granules stored in two large cells within the oncosphere that have ducts to the plasma membrane (Harris, Heath, Lawrence and Shaw, 1989). Within 2-3 days the microvillar layer of the oncosphere is sloughed as the metacestode tegument develops (Holcman, Heath & Shaw, 1994). This early epithelial microvillar layer apparently stimulates a strong antibody response, which is protective. Concomitant immunity, related to the development of the laminated layer, results in the metacestode developing while further invading oncosphere are destroyed by an antibody-dependent complement-mediated lysis (Heath et al. 1994). The base-material stored in the two large cells of the oncosphere apparently serves as a source of protective antigen (Osborn and Heath, 1982) and vaccination with oncosphere secretions can induce 99% protection against a challenge infection, as can vaccination with oncosphere homogenate (Heath and Lawrence, 1996). When 10 million oncospheres were dissolved in sodium dodecylsulphate and the proteins preparatively separated using a Briorad Prep-Cell, one fraction was able to confer 92% resistance to a challenge infection when injected into sheep (Heath and Lawrence, 1996). Antibody to the 25 kDa fraction was used to screen a cDNA library prepared from oncospheres, and a series of Escherichia coli clones expressing parts of the molecule were tested for protective potential by vaccinating sheep and then challenging them with E. granulosus eggs. One clone (Eg95) gave 96% protection (Lightowlers et al. 1996). The 14 kDa molecule was expressed as a fusion with glutathione-s-transferase of Schistosoma japonicum (26 kDa) and could be purified on a glutathione-agarose column (Smith & Johnson, 1988).

A further trial, designed to evaluate adjuvants gave 97% protection with the best adjuvants (Lightowlers et al, 1996). Preliminary scale-up experiments have shown that the fusion protein can be expressed as an inclusion body, and solubilisation of the inclusion bodies yields a partially-purified antigen.

A vaccine to protect sheep and goats against hydatid disease caused by the cysts of Echinococcus granulosus was prepared as a recombinant fusion protein expressed as inclusion bodies in E. coli. A series of experiments were carried out in Xinjiang Province, People’s Republic of China. Solubilised inclusion bodies were injected, together with QuilA, on two occasions subcutaneously into merino lambs or cashmere kids at 2 and 3 months of age. Some lambs received a third injection 6 or 12 months after the second. Safety and efficacy were tested initially, with challenge infection of E. granulosus eggs being given either 1, 6 or 12 months after the second immunisation.

The vaccine proved to be safe and well tolerated, and after 2 injections protected kids against an artificial challenge infection by 100% at 1 month and 83% at 6 months. Lambs were protected by 91% at 1 month, 84% at 6 months and 97% at 12 months. A third injection given at either 6 or 12 months induced a high (99%) and long-lasting protection against artificial or natural challenge infection.

Field trials against natural challenge infections were set up with two breeds of sheep (Mongolian sheep and Xinjiang merino). Lambs were protected against natural infection 81% or 85% in their first year, and 94% after a third injection, increasing to 98% after exposure to a field challenge that infected all unvaccinated controls.

Longevity of immunity was tested by vaccinating lambs twice at an interval of 1 month, and then challenging them 12 months after the second injection. A group of these lambs were given a third injection, 6 months after the second. The immunity still present 12 months after 2 injections was 97.4% and 99.1% in the group that received 3 injections. Numbers of cysts in controls ranged from 6-40.

This vaccine should provide the basis for a successful hydatid control programme, especially in those countries that practice seasonal pastoralism.

Because Echinococcus multilocularis is a significant cause of echinococcosis in humans and domesticated livestock in some parts of the world (Craig et al, 1991), it would be useful if this vaccine was also able to prevent infection with E. multilocularis. Preliminary studies have shown an homologous gene to Eg95 in E. multilocularis (MW Lightowlers and C Gauci, personal communication).

Although much developmental research is required to register a bulk-produced vaccine for use in animals, this research is now on-going.

In order for a vaccine to be totally user-friendly, it would be preferable to have one shot conferring life-long immunity. Although this is not possible with current technology, we are actively pursuing single-shot vaccines for young animals and methods for extending the protective period. However, the two-shot vaccine will be available in the foreseeable future, and in many situations will be a cost-effective method of achieving the degree of control required.

It should be emphasized that the vaccine has no effect on established cysts. In countries where echinococcosis is hyper-endemic and there is little increase of prevalence with age, the vaccine will need to be given to young animals only, in the first year. In the second year, those animals will be re-vaccinated, and also the current crop of young animals. In the third year, three age groups will be vaccinated, and so on until a fully immune population has been built up. Because the older stock will be infected for the average lifetime of the stock, dogs will still be able to be infected from the older stock until all old stock have been killed or have died. This poses a risk to humans of becoming infected during the time of the average lifetime of the stock.

It would be advantageous to vaccinate humans as well as livestock, but the time needed to register a version of the vaccine for human use is not available. Therefore, to prevent human infection during the immunisation period, dogs should receive anthelmintic treatment wherever possible, and accelerated removal of old stock should be contemplated.

Similar field trials were performed in Argentina ("Chubut 1 trial, 1995-1996 ; Chubut 2 trial 1996-1998 ; Chubut 3, 1997 ; Chubut 4, 1997). Report on these trials in Spanish is availble in "Archivos Internacionales de la hidatidosis" Ed. E. Larrieu, S. Romeo, C. Mercapide. Consejo Pronvicial de Salud Publica, Provincial de Rio Negro, Argentina (e-mail : Prof E. Larrieu, see above).

Personal contact : Dr Oscar Jensen : Veterinario Jefe; Programa de Control de la Hidatidosis, Sistema Provincial de Salud, Provincia del Chubut, Uruguay 48, 9020 Sarmiento Chubut Argentina

Future work : perspectives in humans ? a preliminary evaluation should be done. Rationale for such investigations is given in the Network Documents section.

1. There is not much progress in the preparation of a test with recombinant oncospheral antigen for screening and clinical cases purposes. There is also not much progress in preparing a simple quick test for detection E. granulosus specific antigen in cyst fluid in humans. The reason behind is funding and low interest from research clinical and/or screening centers.
2. Information is still being collected about the early stages of cystic echinococcosis in humans (small, sterile cysts) and their occurrence in various groups of people examined.
3. Longitudinal observation on development of the cysts in humans in individual cases will be possible only if a "wait and observe" approach becomes more popular in early cystic echinococcosis.
4. Some samples of hydatic fluid are frozen from biopsies but participants in the Network are not aware of collection the material on occasion of PAIR. Please, inform Z. Pawlowski, J. Eckert if this material is available for immunological and chemotherapeutic studies.
5. Several occasions (meetings in Ulm, Berlin, Gdynia, Olsztyn), have been used to publicise a scheme of the natural history of E. granulosus infection in the liver (Pawlowski, 1997) and relate the differential diagnosis and optimal treatment to that scheme. Still not enough attention is given to small non-parasitic cysts present in human liver especially at population screening. It is strongly suggested that at any screening the number of detected cases of non-parasitic simple cyst should be notified in order to find out the proportion of echinococcal and non-parasitic cysts. The seminar on "asymptomatic" patient management at XIX Congress of Hydatidology in Bariloche has been a good forum for discussion on the early stages of cystic echinococcosis in humans.

A meaningful paper is now available on this subject, written by B. Frider et al. and published in the Journal of Hepatology in 1999. Because of its stimulating results, the abstract is given below :

B Frider, E Larrieu, M Odriozola

J Hepatol, 1999, 30, 228-231

Background/Aims : The aim of this study was to determine the outcome of asymptomatic liver hydatid cysts in a cohort of 33 out of 59 carriers by evaluating clinical and ultrasonographic (US) changes 10-12 years after initial diagnosis.

Method : We compared US features and cyst size with the original descriptions from 1984-1986. Patients were questioned about hydatid-related symptoms and signs.

Results : Thirty-three of the 59 carriers could be re-evaluated, five (15.2%) of whom had undergone surgery without presenting symptoms, while of 28 unoperated cases, 21 (75%) remained asymptomatic. Of the unoperated cases evaluated by US, in 8/14 (57.1% there were no modifications in cyst size during the 10-12 year period, in five (35.7%) growth was slight (< 3 cm) and in one (7.1%) the cyst grew 4 cm. Mean cyst growth in all 14 cases was 0.7 cm.

Conclusions : Despite the limited number of cases, our results show that most asymptomatic liver hydatid cases (75%) remain symptom-free for more than 10 years, regardless of cyst size or type. We believe that such carriers are at low risk of developing complications, so that it is difficult to establish specific rules for their therapy, if any. Longitudinal follow-up of larger series of asymptomatic hepatic hydatidosis cases is essential to gain a deeper insight into the natural history of such patients, and to draw up comprehensive guidelines for treatment.

Future work : Prospective study with a follow-up of small cysts

• found in clinical settings

• found at screening

These prospective studies will be of major interest

1. to elucidate the "natural history of the US image"… and perhaps salve the debate on the so-called "pathognomonic features of CE cysts"
2. to give some rationale to therapeutic strategies (wait and see, versus puncture, versus chemotherapy, versus surgery).

To participate in these studies, please contact :

This new Network was initiated in 1999

Forms have to be prepared and teams which volunteer to participate in the study should get in touch with

Two complementary studies will be designed :

® follow-up of patients operated on 10 years ago (retrospective study)

® prospective study

Comparisons of outcomes in surgical patients from different countries/continents should e of major interest, especially regarding side-effects of surgery and long-term recurrence.

This Network was initiated at the end of 1998 but the study has not begun yet. You will find enclosed (in the "Network Documents" Section) the proposal of a standardized form to collect information on patients'follow-up by Antonella Teggi. All interested teams should contact her for further discussion and work on the study's protocol.

The chapter on the socio-economic impact of cystic echinococcosis (CE) for the last version of the WHO Guidelines on Echinococcosis (J. Eckert ed) was prepared. For this contribution, papers, unpublished documents and personal communications of participants in the network were utilised. Human CE was considered in terms of medical expenses and of social damage ; in livestock the costs are mainly analysed with regard to lowered production and to condemned viscera. The following costs of control were discussed : education, dog control and treatment, detection and destruction of infected viscera of livestock, diagnosis and therapy in humans and costs of programme administration and evaluation. Examples of some important costs were given.

In collaboration with A. Teggi and C. Franchi (Network "Long-term evaluation of chemotherapy of CE") an evaluation of the costs of diagnosis and chemotherapy with albendazole of CE of the liver in out-patients was done, according to the actions scheduled at the Department of Infectious and Tropical Diseases of the University "La Sapienza", Rome (1998). The present value of the individual mean cost of diagnosis and chemotherapy, considering a 10-year period of follow-ups post-diagnosis, and considering that a relapse occurs in nearly 25% of the patients, was evaluated to average 1,800-2,00 EURO, at different discounted rates. Nearly 70% of these costs are supported by the patient.

In the period 1998-April 1999, contributions of the Italian team of the network were given to workshops and courses (organized by WHO/FAO Collaborating Centre for Veterinary Public Health, Rome, WHO Mediterranean Zoonoses Control Centre, Athens, and other Institutions) concerning occupational biological risks, animal-man relationships in normal and disaster situations, and medical-veterinary cooperation. Echinococcosis was one of the major zoonoses discussed, with special reference to socio-economic and epidemiological aspects in the Mediterranean Region.

Future work : A comparative study of the actual cost of CE in different areas in the world, using an identical methodology is planned :

• Europe (Italy, Spain, Portugal)
• North Africa (Morocco)
• South America (Argentina or Uruguay)
• China (Sichuan)

G. Batelli will contact the teams which have already proposed their participation (M. Kachani, Morocco; Wang Jiang, Sichuan) . All other interested teams should get in touch with him :

Achievements of the Network were presented at Session 7 of the International Congress of Hydatidology by DA Vuitton, and as free communication at several European and International meetings (see the "meeting section" in "News from the teams"...)

• Definition of "cases": abortive/progressive/serological
• PNM staging

are given in the "Network Documents" section

Future work :

® standard form for follow-up ("evolution") classification

® publication of the evaluation of the PNM system of staging on 100 patients files collected in Germany (Ulm) and France (Besançon)

Because of problems with his administration, Luis Colon Garcia was unfortunately not able to coordinate the Network and the planned work was not done.

C. Palmas and M. Kachani accepted to coordinate the Network and have prepared a questionnaire to collect all educational materials designed by the teams working on Health Education. This questionnaire is included in the "Network Documents" section. Please send them back to

However, in terms of prevention, knowledge is not behavior, and evaluation is mandatory to assess the relevance/efficacy of the proposed educational material. The scientific goal of the Network will be "evaluation", and all teams which have experience in evaluation procedures and/or agree to participate in such studies should contact M. Kachani and C. Palmas.

The main objectives are :

1. Establishment of a "standard" serum for Echinococcus serology in humans.

Prof Janitzchke in Berlin has developed a "German national control serum" for E. multilocularis serology. A "German national control serum" for E. granulosus has been available since 1983. Contact with Prof Janitschke will be very useful to the participants in the Network.

The ultimate goal would be to agree upon an international "100% positive standard serum", approved by WHO, both for E. granulosus and E. multilocularis

2) Development of "fast tests"

• for serology
• for antigen detection

especially for the diagnosis of small cysts at puncture ; cf. report of the "Natural history of small cysts" Network