Immunological responses of the mammalian host against tapeworm infections. IV. Species specificity of hexacanth embryos in protecting sheep against Echinococcus granulosus

Eighty lambs were divided into four groups, each comprising twenty animals. Half the lambs in each group were vaccinated with viable eggs and half with the activated embryos of Echinococcus granulosus, Taenia hydatigena, T. ovis or T. pisiformis. These lambs together with ten control animals were subsequently challenged with eggs of E. granulosus.

Only a few hydatid cysts were established from the challenge infection in the lambs immunized with the homologous eggs or embryos. Only one acephalocyst in one animal survived. The metabolism of this cyst was of a low order compared with that of most of those in the controls.

Hydatid cysts were established from the challenge infection almost as frequently in the animals vaccinated with eggs or embryos of the sheep metacestodes T. hydatigena and T. ovis, as in the controls. Fluid accumulated in only a few hydatid cysts from the challenge infection in those sheep vaccinated with the activated embryos of these heterologous species.

The injection of viable eggs or activated embryos of the rabbit metacestode T. pisiformis induced no resistance to the establishment or to the survival of the challenge infection of E. granulosus.

     

Detection ofEchinococcus coproantigens by enzyme-linked immunosorbent assay in dogs,dingoes and foxes

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection ofEchinococcus coproantigens in fecal samples from dogs, dingoes or foxes infected with eitherE. granulosus orE. multilocularis. The ELISA was based on protein-A-purified polyclonal antibodies [anti-E. granulosus excretory/secretory (E/S) antigens]. The specificity of the assay as determined in 155 samples derived from carnivores that were free of helminth infection (n=37) or infected with non-Echinococcus cestodes (n=76) or with various nematodes (n=42) was found to be 98% overall. The diagnostic sensitivity was strongly dependent on the homologous worm burden. All 13 samples from foxes harboring >1,000E. multilocularis worms and 13 of 15 (87%) samples from dogs or dingoes containing >200E. granulosus worms were ELISA-positive, whereas 34 of 46 samples from foxes harboring <1,000E. multilocularis and 9 of 10 samples from dogs or dingoes bearing <200E. granulosus tested negative. Experimental prepatent infections of dogs withE. granulosus revealed positive ELISA reactions within the prepatent period (10–20 days post-infection) for six animals bearing >1,000E. granulosus each; a low worm burden (<1,000 tapeworms/animal) resulted in ELISA positivity in only 2 of 3 animals at 30 days post-infection at the earliest. All five dogs that had been experimentally infected withE. multilocularis tested positive in the coproantigen ELISA as early as on day 5 post-infection.Dedicated to Prof. K.T.F. Friedhoff on the occasion of his 60th birthday     

Observations onEchinococcus multilocularis in the definitive host

Six dogs were found to be susceptible to experimental infections with a European isolate ofEchinococcus multilocularis from southern Germany. Two cats were only poorly susceptible. Adult worms were not evenly distributed throughout the small intestine and the majority of parasites were found in the posterior region. The mode of attachment ofE. multilocularis in the dog was similar to that forE. granulosus with the adult worm extending its rostellum deep within a crypt of Lieberkühn. In cats only few worms were found to have penetrated deeply between the villi.E. multilocularis was found to possess a modified group of rostellar tegumental cells, morphologically and functionally identical to those described inE. granulosus and previously referred to as the “rostellar gland”. By studying development in vivo and in vitro, the time required for the production of shelled eggs was demonstrated to be only 28 days. Concurrent experimental infections in dogs withE. multilocularis andE. granulosus revealed that both species will develop together in the same host. Their development was not retarded in any way by the presence of the other and both species were able to coexist in the same area of the intestine.     

Prévalence du téniasis échinococcique chez les chiens errants dans la région de Constantine,Nord-Est algérien

In North Africa, the domestic dog is regarded as the main reservoir for infection by Echinococcus granulosus of domestic livestock and man. In Algeria, there is very little data on the rate of infestation of dogs, while the prevalence of E. granulosus in the definitive host is a very reliable marker of the potential risk of transmission of cystic tapeworm to humans and livestock. To find out this information, a survey was conducted to assess the prevalence of infection with E. granulosus in stray dogs in the region of Constantine (North-East Algeria). We autopsied and examined 120 stray dogs, 22 (18.3%) of which were infected with E. granulosus, with an average intensity of infestation of 249 worms. The prevalence in the area of survey was evaluated: 15.5% (14/90) and 26.6% (8/30) dogs were parasitized by E. granulosus in urban and rural areas respectively. The influence of age on the rate of infection was very marked. In addition, the appreciation of the prevalence of parasitism by cestodes as a whole showed that 56 (46.6%) animals out of 120 were infected. Facing such a situation of endemic tapeworm parasitism, with a potential risk of transmission to humans, there is an urgent need to take measures to control and break the epidemiological cycles of the parasite.     

Immunological responses of the mammalian host against tapeworm infections: III. Species specificity of hexacanth embryos in protecting sheep against Taenia ovis

Sixty lambs were divided into three groups each comprising twenty animals. Half the lambs in each group were vaccinated with the viable eggs and half with the activated embryos of Taenia ovis, T. hydatigena or T. pisiformis. These lambs together with ten control animals were subsequently challenged with eggs of T. ovis.

Only one of the lambs in the group immunized with T. ovis completely resisted the challenge infection, but almost all of these lambs developed a solid resistance to the challenge infection, preventing it from reaching maturity at the site of election.

No lamb in the group vaccinated with T. hydatigena completely resisted the challenge infection of T. ovis, but some animals harboured significantly fewer cysticerci of T. ovis than control sheep or those vaccinated with T. pisiformis.

The injection of viable eggs or activated embryos of T. pisiformis induced no resistance to either the establishment or the subsequent survival of the challenge infection of T. ovis.

     

Echinococcus granulosus of camel origin: development in dogs and parasite morphology

The developmental characteristics ofEchinococcus granulosus of camel origin were studied in four dogs artificially infected with protoscolices originating from hydatid cysts isolated from the lung of a camel (Camelus dromedarius). Two dogs each were necropsied 34/35 and 41 days post-infection (p.i.); one dog had a low worm burden and the others were heavily infected (27,625–41,150 worms). At day 35 p.i., 20% of the parasites had developed three segments and the uterus of the vast majority of the total population was full of developing eggs in the terminal segment. At day 41, up to 58% of the parasites contained mature eggs (embryonated eggs with fully developed, thick-shelled embryophores). Morphological studies revealed the following major characteristics for 35 day-old worms: the mean length of the terminal segment accounted for 54% of the total worm length; the position of the sexually mature segment was always terminal; the female reproductive system possessed an elongated ovary with compact lobules; the female ducts were also compact; the Mehlis' gland was covered by the vitelline gland and the testes were distributed throughout the segment, with 1 row posterior to the vitelline gland. The camel isolate can readily be distinguished from the horse and sheep strains, but it is similar to the cattle strain in some respects, particularly in its precocious development. However, the camel isolate differs from the cattle strain in the position of the sexually mature segment, arrangement of the testes and structure of the female reproductive system. As in the cattle strain, the metacestodes in the principal intermediate host are mostly localised in the lung and have a high fertility rate. Detailed morphological characteristics and biological features of the sheep, cattle, horse and camel isolates ofE. granulosus are presented.Increasing evidence is being accumulated that local populations ofEchinococcus granulosus may vary in morphological and biological features and that the occurrence of intraspecific variants or strains can play an important role in the epidemiology of echinococcosis (Rausch 1986; McManus and Smyth 1986; Thompson 1986; Thompson 1988; Thompson and Allsopp 1988; Eckert and Thompson 1988), because strains differ in their infectivity to final and intermediate hosts and their transmission patterns. Moreover, the pathogenic significance of strains to humans may also vary.The camel is an important host ofE. granulosus and is commonly infected throughout Africa and the Middle East (Schwabe 1986). The camel has attracted much interest as an intermediate host ofE. granulosus, particularly in its role as a reservoir of infection in humans. In addition, it has been proposed that the camel form ofE. granulosus may be a different subspecies or strain (Pandey et al. 1986). However, very little comparative work has been carried out to characterise isolates ofE. granulosus from camels (Thompson and Lymbery 1988).The aim of the present work was to study the morphological and biological characteristics of intestinal stages ofE. granulosus of camel origin obtained from artificially infected dogs. In addition, data were collected on the metacestodal stage.     

The evagination of Echinococcus granulosus scolices from lung cysts of bovine origin

Summary The present report deals with a study on the evagination of Echinococcus granulosus scolices from lung cysts of bovine origin, as compared to the results of an earlier one on scolices from liver cysts of equine origin. Considerably lower percentages of evagination were noted, and even the well known stimulation by a pepsin-HCl pre-treatment did not appear very effective. These slow reactions were connected with the fact that E. granulosus is obviously not fully adapted to cattle as intermediate hosts. The existence was concluded of a physiological difference between the scolices from lung cysts of bovine origin and scolices from liver cysts of equine origin, which would be related with the nature of these hosts. Finally, this difference is considered as supporting a proposed subspeciation of the European E. granulosus.

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Zusammenfassung Es wird über die Evagination von Scolices von Echinococcus granulosus aus Lungencysten der Rinder berichtet, die mit früheren Beobachtungen an Scolices aus Lebercysten vom Pferd verglichen werden. Es wurden erheblich geringere Anteile von Evaginationen beobachtet. Die wohlbekannte Stimulation durch Pepsinsalzsäure-Vorbehandlung erwies sich hier nicht als sehr wirkungsvoll. Diese langsame Reaktion geht wohl darauf zurück, daß E. granulosus offensichtlich nicht voll an das Rind als Zwischenwirt angepaßt ist. Daraus wird ein physiologischer Unterschied zwischen den Scolices aus Lungencysten von Rindern und solchen aus der Leber des Pferdes abgeleitet, der mit der Natur dieser Wirte in Beziehung steht. Diese Unterschiede werden als Ausdruck einer möglichen Entwicklung zu Unterarten des europäischen E. granulosus angesehen.

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Résumé Dans cet article nous avons étudié l'évagination de scolex d'Echinococcus granulosus provenant d'hydatides pulmonaires bovines et nous l'avons comparée aux résultats de notre travail antérieur sur des scolex provenant d'hydatides hépatiques équines. Nous avons noté des pourcentages d'évagination beaucoup plus bas. Même le traitement préalable à la pepsine-HCl n'a pas son effet stimulateur habituel. Ces résultats incitent à croire que le séjour dans le boeuf comme hôte intermédiaire n'est pas aussi favorable au parasite que son dévelopement dans le cheval. Ceci et les données d'autres auteurs nous font conclure qu'il existe une différence physiologique entre les scolex d'origine chevaline et ceux d'origine bovine, différence qui donnerait appui à notre hypothèse d'une subspéciation dans l'espèce de l'E. granulosus européen.

     

Immunity to Escherichia coli in pigs: IgG immunoglobulin in passive immunity to E. coli enteritis

IgG immunoglobulin was isolated in large quantities from sows' colostrum. The sows were vaccinated intramammarily with a live, formalinized Escherichia coli vaccine. A four-stage batch method with DEAE-A50 Sephadex was used in the isolation procedure. Antibacterial tests, heat labile enterotoxin neutralization tests and pig protection tests were employed to investigate the presence of any protective immunity in colostral IgG when compared with whole colostrum.

In antibacterial tests, no bactericidal activity was found in colostral whey or colostral IgG from vaccinated or non-vaccinated sows. There was, however, a significant decrease in the rate of multiplication of E. coli organisms in tests containing colostral whey or IgG from vaccinated sows when compared with similar preparations from non-vaccinated sows.

In enterotoxin neutralization tests using ligated intestinal segments of pigs, the neutralizing effects of colostral whey and IgG on the enterotoxin preparation were significant, whereas only colostral whey afforded significant protection against the vaccine strain of E. coli.

In pig protection tests, the mean survival time of two groups of 5-day-old gnotobiotic pigs fed colostral whey or IgG was significantly greater than that of the untreated control group. There was no significant difference between the two treated groups.

     

Immunological responses of the mammalian host against tapeworm infections: I. Species specificity of hexacanth embryos in protecting sheep against Taenia hydatigena

Ninety sheep, comprising three groups each of thirty animals, were vaccinated intramuscularly with the eggs or activated embryos of Taenia hydatigena, T. ovis or T. pisiformis. These, together with ten controls, were subsequently challenged with eggs of T. hydatigena.

Each of these three groups of thirty animals were subdivided into three sub-groups of ten animals. In the ten animals comprising the first sub-group in each group, the vaccine was injected as activated embryos, in those comprising the second sub-group as viable eggs and in those of the third sub-group as eggs which had been killed by deep-freezing at –70°.

The ten sheep injected with activated embryos of T. hydatigena developed a solid immunity to the establishment of the challenge infection.

None of the ten sheep injected with viable eggs of T. hydatigena developed a solid resistance to the establishment of some cysticerci from the challenge dose of eggs of T. hydatigena, but eight of the ten animals in this sub-group resisted the subsequent growth of the cysticerci to the infective stage. In the remaining two sheep only one cysticercus reached maturity in each animal.

None of the sheep injected with the activated embryos of T. ovis or T. pisiformis developed a solid resistance to the establishment of the challenge infection with T. hydatigena, but most of those animals injected with the activated embryos of the former and some of those injected with those of the latter cestode developed a solid resistance to the long-term survival of the challenge infection with T. hydatigena.

No significant resistance was observed either to the establishment or to the subsequent growth of the challenge infection of T. hydatigena in those sheep previously injected with either killed eggs of T. hydatigena or viable or killed eggs of T. ovis or those of T. pisiformis.

     

Brucella : Studies on the Mechanism of Non-Specific Resistance to • Induced in Mice by Vaccination with BCG

Mice vaccinated with living or killed BCG become resistant to infection with Brucella abortus, as evidenced by a lower bacterial count in the spleen and liver as compared to controls. Some of the observed resistance is attributed to the ability of the treated mice to mobilize quickly a large number of macrophages in the abdominal cavity, since these macrophages could phagocytose and subsequently kill a proportion of the injected bacteria. However, the main antibacterial effect appears to take place in the spleen and liver. These organs contained most of the Brucellae found in the animal at 6 hours after challenge and showed the most significant differences between vaccinated and non-vaccinated animals.

Sera of BCG-treated mice contain a factor capable of conferring to normal animals some protection against challenge with Brucella.

     

Epidemiological studies on Echinococcus in Pampas fox (Lycalopex gymnocercus) and European hare (Lepus europaeus) in Buenos Aires province, Argentina

In Argentina, hydatid disease caused by Echinococcus granulosus is widespread. The south of Buenos Aires province, Argentina, is one of the three regions where hydatidosis is endemic. Although domestic dogs and sheep are considered to be the main hosts for E. granulosus, the potential role of wildlife in the local transmission of E. granulosus has not been investigated. The aim of this study was to estimate the hydatidosis/echinococcosis prevalence in European hare (Lepus europaeus) and Pampas fox (Lycalopex gymnocercus), two abundant species with a strong predator–prey relationship in rural areas of Buenos Aires province using different diagnostic tests. A total of 61 fox intestines were examined, finding that 52 (85.2 %) harbored at least one helminth species. However, no adult or immature form of Echinococcus sp. was found in the intestinal contents. Coproparasitological analysis and Copro–ELISA followed by Copro–PCR were used as supplementary diagnostic tests. Only one (1.7 %) of 59 fecal samples was positive to Taeniidae eggs by coproparasitological analysis, but this same sample was negative by the Copro–ELISA test. The analysis by Copro–ELISA showed 6 of 57 (10.6 %) positive samples, but the Copro–PCR tests carried out on these samples were negative to E. granulosus. A total of 6,808 lungs, 3,576 livers, and 3,542 hearts of hunted hares were examined and palpated, but no structure resembling hydatid cysts were detected. Our results suggest that hares and Pampas foxes are not currently important wild reservoirs of E. granulosus in the studied area.     

Immunological responses of the mammalian host against tapeworm infections: II. Species specificity of hexacanth embryos in protecting rabbits against Taenia pisiformis

Rabbits vaccinated by intramuscular injection with the viable eggs or the activated embryos of Taenia pisiformis, T. ovis or T. hydatigena, were subsequently challenged per os with eggs of T. pisiformis.

A single intramuscular injection of viable eggs or activated embryos of T. pisiformis induced a relatively solid immune response to the establishment and also to the long-term survival of the challenge infection of T. pisiformis.

A single intramuscular injection of the activated embryos of both T. ovis and T. hydatigena also induced some resistance to the establishment and long-term survival of a challenge infection with T. pisiformis but no significant immune response to a similar challenge infection was detected in those rabbits vaccinated with the viable eggs of these two sheep metacestodes.

     

Detection of Echinococcus multilocularis in the Definitive Host: Coprodiagnosis by PCR as an Alternative to Necropsy

Recently, extensions of the range of Echinococcus multilocularis in Europe and North America and drastic increases in fox populations in Europe put an increasing proportion of the human population at risk of alveolar echinococcosis. To obtain data on the local infection pressure, studies of the prevalence of the parasite in the animals that transmit the parasite, foxes, dogs, and cats, are urgently required. Such investigations, however, have been hampered by the need for necropsy of the host animal to specifically diagnose infection with the parasite. In this study, a nested PCR and an improved method for DNA extraction were developed to allow the sensitive and specific diagnosis of E. multilocularis infections directly from diluted fecal samples from foxes. The target sequence for amplification is part of the E. multilocularis mitochondrial 12S rRNA gene. The specificity of the method was 100% when it was tested against 18 isolates (metacestodes and adult worms) of 11 cestode species, including E. granulosus. The sensitivity of the method was evaluated by adding egg suspensions and individual eggs to samples of diluted feces from uninfected foxes. The presence of one egg was sufficient to give a specific signal. To confirm the PCR results, an internal probe which hybridized only with E. multilocularis amplification products but not with the DNA of other cestodes was constructed. In order to investigate the applicability of this method for epidemiological studies, 250 wild foxes from a area in southern Germany where echinococcosis is highly endemic were examined by both necropsy and PCR of rectal contents. The sensitivity correlated with the parasites’ number and stage of maturity. It ranged from 100% (>1,000 gravid worms) to 70% (<10 nongravid worms). On the basis of positive PCR results for 165 foxes, the sensitivity of the traditional and widely used necropsy method was found to be not higher than 76%. We therefore present this PCR system as an alternative method for the routine diagnosis of E. multilocularis in carnivores.     

Efficacy of Emodepside plus Praziquantel Tablets (Profender? Tablets for Dogs) against Mature and Immature Cestode Infections in Dogs

The efficacy of a novel flavoured tablet formulation of emodepside plus praziquantel (Profender? tablets for dogs) against intestinal cestodes was investigated in four randomised, blinded placebocontrolled dose confirmation studies in dogs experimentally infected with Echinococcus granulosus or E. multilocularis and in dogs naturally infected with Dipylidium caninum or Taenia spp. The tablets were used at the minimum recommended dose of 1 mg emodepside and 5 mg praziquantel per kg body weight. The studies demonstrated 100% efficacy against mature and immature E. granulosus and E. multilocularis and mature Taenia spp. and D. caninum. Additionally, one of the studies demonstrated non-interference of emodepside with the efficacy of praziquantel against D. caninum. No side effects of the treatment were observed. It is concluded that emodepside plus praziquantel tablets are safe and effective against mature and immature stages of E. granulosus and E. multilocularis and mature stages of Taenia spp. and D. caninum.     

Reaginic antibodies in dogs infected with Echinococcus granulosus

Serum samples from twenty dogs infected with Echinococcus granulosus were tested for the presence of homocytotropic skin-sensitizing antibodies. Five of the twenty sera were positive in this test, while none of the sera from twenty normal dogs was positive. The antibody was thermolabile and susceptible to 2-mercaptoethanol reduction.

Reaginic antibodies to cestode antigens have not been described previously in dogs, though they are frequently associated with helminth infection in other animals and may play a role in acquired resistance.

     

In vitro and in vivo treatments of Echinococcus granulosus with Huaier aqueous extract and albendazole liposome

The aim of this study was to investigate the in vitro and in vivo efficacies of chemotherapy employing albendazole liposome (L-ABZ), Huaier aqueous extract, and a Huaier aqueous extract/L-ABZ combination against Echinococcus granulosus. Protoscolices of E. granulosus were incubated in vitro with the two drugs, either separately or in combination, at the following final concentrations: 2 mg/mL Huaier aqueous extract, 10 μg/mL L-ABZ, and 2 mg/mL Huaier aqueous extract + 10 μg/mL?L-ABZ. Huaier aqueous extract and L-ABZ displayed slower protoscolicidal activity when applied separately than when used in combination. The maximum protoscolicidal effect was found with the combination Huaier aqueous extract + L-ABZ. Despite the low Huaier aqueous extract + L-ABZ concentrations used, protoscolex viability dropped rapidly. In vivo studies were performed on mice injected with protoscolices of E. granulosus. Huaier aqueous extract and L-ABZ were administered three times a week for a period of 4 months by the oral route. Huaier aqueous extract in E. granulosus-infected mice was effective. Combined application of both drugs did increase the treatment efficacy. In conclusion, the outcomes obtained clearly demonstrated that in vitro and in vivo treatment with Huaier aqueous extract and L-ABZ is effective against E. granulosus.     

Polymerase chain reaction for detection of patent infections of<Emphasis Type="Italic"> Echinococcus granulosus</Emphasis> (“sheep strain”) in naturally infected dogs

Polymerase chain reaction (PCR) for the identification of eggs of the tapeworm Echinococcus granulosus (sheep strain) was evaluated with primers derived from mitochondrial sequences. Specificity of these primers was confirmed by investigating DNA of other strains of E. granulosus and of 14 helminth species which inhabit the intestines of dogs. This PCR assay was used to investigate 131 purged dogs from Kazakhstan. Eighteen dogs harboured Echinococcus worms, ten of them in mixed infections with Taenia spp. Coproantigen detection was positive in 15 and taeniid eggs could be recovered from 13 of these specimens. Eight of the egg-containing samples were positive in the PCR for E. granulosus and four in a Echinococcus multilocularis -specific PCR revealing one mixed infection. Egg-containing faeces from two dogs harbouring both Taenia spp. and Echinococcus spp. were negative in both PCRs. The combination of egg isolation and PCR will also be of value in epidemiological studies when investigating environmental samples.     

Copro-DNA test for diagnosis of canine echinococcosis

Echinococcosis is one of the most important parasitic zoonotic diseases in the world. The life cycle of Echinococcus granulosus is dependent to the dog–sheep cycle and is actively transmitted in all pastoral regions where sheep, cattle and camels predominate. DNA approaches are now being used routinely for accurate identification of Echinococcus and Taenia species, subspecies and strains. In this study, faecal samples were collected from 50 stray dogs from Mashhad city in the northeast of Iran during June 2011. All samples were frozen at least for 1 week in ?80°C. The embryophore layer of the eggs was broken by freezing–thawing method after egg concentration by the formalin-ether method. DNA was extracted using a DNA isolation kit (MBST, Germany/Iran) according to the manufacturer’s instructions. After PCR, by the primers expressed in the following it became, clear that about 20 % of stray dogs are infected with E. granulosus. In this study, we describe a modified method for DNA isolation from faeces for coprodiagnosis of Echinococcus spp.     

Molecular characterization of Echinococcus granulosus in a hyperendemic European focus,the Republic of Moldova

Cystic echinococcosis is a zoonosis caused by the tapeworm Echinococcus granulosus sensu lato. The lifecycle of the parasite is mainly domestic, requiring dogs as definitive hosts and livestock species as intermediate hosts. Although human cystic echinococcosis is a high public health priority in the Republic of Moldova, the rare animal data available concerns only infection in cattle. A preliminary slaughterhouse survey was conducted to assess prevalence and perform the first molecular characterization of E. granulosus sensu lato in sheep and cattle. For the survey, 40 sheep and 19 cattle were inspected. Very high prevalence in sheep (82.5 %) and in cattle (78.9 %) was found. Molecular analyses identified genotypes G1 and G3 of E. granulosus sensu stricto in all the liver and lung samples. Based on the concatenated sequences of cox1?+?nad3 (701 bp), 23 different haplotypes were obtained. Mixed infections by different haplotypes/genotypes were frequently identified in both sheep and cattle. The relatively high (20.0 %) cyst fertility observed in cattle argues for the potential contribution of cattle to the lifecycle of E. granulosus sensu stricto, unlike previous observations in Europe. The hyperendemic situation of Moldova can be explained by a high majority of animals slaughtered at home usually without veterinary inspection. Further extensive slaughterhouse surveys with molecular identification also involving pigs and goats are needed to obtain a better overview of the epidemiological situation of E. granulosus sensu lato in this hyperendemic focus in the Republic of Moldova.     

Cystic Echinococcosis

Echinococcosis is one of the 17 neglected tropical diseases (NTDs) recognized by the World Health Organization. The two major species of medical importance are Echinococcus granulosus and Echinococcus multilocularis. E. granulosus affects over 1 million people and is responsible for over $3 billion in expenses every year. In this minireview, we discuss aspects of the epidemiology, clinical manifestations, and diagnosis of cystic echinococcosis or cystic hydatid disease caused by E. granulosus.