Epidemiology and strain characteristics of Echinococcus granulosus in the Benghazi area of eastern Libya

The incidence of surgically confirmed cystic echinococcosis in eastern Libya was estimated to be at least 4.2 cases/100,000, with significantly more female cases than male. The prevalences of infection with Echinococcus granulosus among 1087 sheep, 881 goats, 428 camels and 614 cattle from the same region, determined postmortem in abattoirs, were 20%, 3.4%, 13.6% and 11%, respectively. Infection in the livestock was age-dependent and, generally, the female animals were more often infected than the male. The measurements of rostellar hooks on protoscoleces collected from sheep and cattle were similar but significantly different from the corresponding measurements of parasites of human or camel origin. However, when a portion of the cytochrome c-oxidase subunit I (cox1) gene from each of 30 protoscolex samples from Libya (12 from cattle, three from humans, five from camels and 10 from sheep) was sequenced, the sequences were all found to be identical to that published for the common sheep strain of E. granulosus.     

Prevalence of hydatidosis in slaughtered animals from North Jordan

The prevalence of hydatid disease was investigated in 704 sheep, 391 goats, 280 cattle and 68 camels slaughtered at two abattoirs in North Jordan. The infection rates for these animals were 4.0, 3.6, 11.4 and 8.8%, respectively. In general, older animals had higher infection rates than younger ones. The percentage of infected animals that had fertile cysts was 66.7% in camels, 34.3% in cattle, 28.6% in goats and 7.1% in sheep. Out of 143 single cysts recovered from cattle, 52.4% were fertile; 29.2% of cysts in goats, 14.7% of cysts in camels and 8.0% of those in sheep were fertile. However, infected sheep had more fertile multiple cysts than other animals. The lung was the predominant location for hydatid cysts in camels. In cattle and goats more hydatid cysts were found in the lung than in the liver, while in sheep the reverse was true.     

Cystic echinococcosis of livestock and humans in central Sudan

New information was collected on cystic echinococcosis in livestock (camels, cattle and sheep) and humans in the central region of Sudan. The livestock data were collected in abattoir-based surveys in the towns of Omdurman, Tamboul and Wad Madani, between 1998 and 2001, and covered a total of 8205 animals. The highest prevalence of infection was found in the camels (44.6% of 242 infected), followed by the sheep (6.9% of 5595) and cattle (3.0% of 2368). Records were made of the sizes of the 1320 hydatid cysts detected in the livestock (907 in sheep, 71 in cattle, and 342 in camels), whether or not each cyst was fertile, and where it occurred in the body of the host. Cysts collected from cattle and camels where much more likely to be fertile (22% and 24%, respectively) than those from sheep (1%). Camels and cattle therefore appear to be the principal intermediate hosts for Echinococcus granulosus in central Sudan, whereas sheep apparently play a marginal role in transmission. In 2002, as a preliminary assessment of the public-health impact of the disease, 300 residents of a rural village 60 km west of Wad Madani were surveyed using a portable ultrasound scanner. Only one (0.33%) of the villagers investigated was found infected. The implications of these finding are discussed in terms of the various strains of E. granulosus and the role of each in human disease.     

Study of cystic echinococcosis in slaughtered animals in Al Baha region, Saudi Arabia: Interaction between some biotic and abiotic factors

The variation in cystic echinococcosis (CE) prevalence and mean intensity was studied in relation to site, season and host age and sex. A total of 12,911 slaughtered animals, 140 camels, 2668 cattle, 6525 sheep and 3578 goats were inspected for hydatid cysts in Al Baha region, Saudi Arabia, in three study areas during four seasons from June 2008 to May 2009. The prevalence of infection was 32.85%, 8.28%, 12.61% and 6.56% in camels, cattle, sheep and goats respectively. The prevalence of the parasite varied significantly in relation to site, season and host age classes and sex in most host species. Spring showed the highest prevalence in camels, cattle and sheep. A significant association was found among host age classes and likelihood of infection in all examined hosts and the oldest age class was significantly more likely to be infected. The main effects in parasite intensity were host sex and age in most examined host species. A positive correlation was found between intensity of CE and host age class in all animal species examined. The most commonly infected organs were liver and lungs which constituted 48.75% and 32.83% respectively, of the total infected organs. There was a significant difference among host species in fertile cysts (P < 0.0001). The higher percentages of fertile cysts were in sheep (47.67%) and goats (23.99%) indicating that sheep and goats are the most important intermediate hosts for Echinococcus granulosus. Examined hydatid cysts of the liver had a higher fertility rate (38.79%) than those of the lungs (25.13%). Cysts size ranged from 1 to 8 cm in diameter. The mean cyst diameter was found in the lungs higher than that in the liver in all hosts. The range in the number of cysts was 1-33 in infected animals. The mean number of cysts was higher in lungs than that in liver in all examined animals. The viability rate of protoscoleces of liver fertile cysts (62.20%) was significantly higher than that of lung cysts (52.73%). In conclusion, these findings of infection, mean abundance and fertility rates of CE in slaughtered animals, prompt plans for further epidemiological studies and control programmes.     

The immunodiagnostic potential of protoscolex antigens in human cystic echinococcosis and the possible influence of parasite strain

The results of ELISA, SDS-PAGE and western blotting indicated that the protoscolex antigens of Echinococcus granulosus (of 10-125 kDa) included antigens recognized by sera from human cases of cystic echinococcosis (CE). Some of the latter antigens (of approximately 79, 59, 45, 38, 31 and 29 kDa) exhibited cross-reactivity with sera from humans with other parasitic infections, including alveolar echinococcosis, cysticercosis and African trypanosomiasis. The 31-kDa antigen recognized by IgG antibodies in human CE sera only appeared to be present in the extracts of protoscoleces from sheep, and not in the corresponding extracts from horse or camel cysts. In contrast, the human CE sera recognized a 45-kDa protoscolex antigen only present in the horse cysts and a 125-kDa antigen present in the camel and horse (but not sheep) cysts. Extracts of protoscoleces from different species of hosts might therefore provide a source of strain-specific diagnostic antigens for human CE.     

Using morphometry of the larval rostellar hooks to distinguish Iranian strains of Echinococcus granulosus

Human cystic echinococcosis is widely distributed throughout Iran, where sheep, cattle, goats, camels and other animals act as intermediate hosts. It appears that morphometry of the rostellar hooks on the protoscoleces of the causative parasite, Echinococcus granulosus, can be used to separate the strains or variants of the parasite to be found in humans and livestock in Iran. Multivariate statistical procedures, including principal-component analysis and discriminant-function analysis (DFA), were used to explore the morphometric data obtained from the larval hooks of Iranian samples of E. granulosus. Although five physical variables were initially considered, the results of the PCA indicated that just two factors (based on the length of hooks and number of hooks) accounted for 91.6% of the variance observed in the hook measurements. The results of the DFA allowed the correct classification of all the samples. The presence in Iran of the sheep and camel strains of the parasite was confirmed. The sheep strain was the most common variant encountered, being recovered from sheep, cattle, goats, humans and occasionally camels. Most of the metacestode samples from camels and a few of those from cattle (five of 30), sheep (one of 27) and humans (two of 23) were found to be of the camel strain. These results indicate that larval-hook morphology is a valid method for identifying E. granulosus strains in Iran, and one that is potentially useful for epidemiological studies.     

Molecular characterization of human and animal Echinococcus granulosus isolates in Isfahan, Iran

Cystic hydatid disease (CHD) is one of the most important zoonotic diseases in different parts of Iran. While it causes major health problem, there is limited information about its transmission cycles and reservoirs of human infection. Therefore we aimed to characterize the existence Echinococcus granulosus cysts in humans and animals in the province of Isfahan, central region of Iran. We collected hydatid cysts from the liver and lungs of patients who underwent surgery procedure and also cysts were obtained from domestic animals at slaughterhouses. DNA was extracted from the protoscoleces and examined by polymerase chain reaction (PCR) of rDNA internal transcribed spacer1 (ITS1-PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP). In addition, fragments of the genes coding for mitochondrial cytochrome c oxidase subunit 1 (CO1) and NADH dehydrogenase 1 (ND1) were sequenced. Among the two different identified strains/genotypes (sheep and camel), the sheep strain was shown to be the most common genotype of E. granulosus affecting humans, sheep, cattle, goats and occasionally camels. Nine out of 26 camel samples were infected with sheep strain. However the camel genotype was observed in humans, camels and cattle. Seventeen out of 26 camel isolates, 6 out of 31 human and 5 out of 14 cattle samples were infected with the camel genotype. The camel genotypes had PCR and RFLP patterns which were different from the PCR and RFLP patterns of the rest of isolates (sheep strain). The results of this study showed that the ‘camel’ strain was actual source of infection to humans which circulates between intermediate hosts including camels and cattle, and it confirms the camel–dog transmission cycle in Isfahan.     

The abattoir condemnation of meat because of parasitic infection, and its economic importance: results of a retrospective study in north-eastern Iran

In nine districts in the north of Khorasan province, in north-eastern Iran, a 5-year retrospective study was carried out to determine the prevalences, in livestock slaughtered in abattoirs, of the parasitic infections responsible for the condemnation of the animals' carcasses and viscera (and the economic importance of such infections in terms of lost meat and offal). Between 20 March 2005 and 19 March 2010, 436,620 animals (45,360 cattle, 275,439 sheep, 115,674 goats and 147 camels) were slaughtered in the study area and the livers of 30,207 (6.9%), the lungs of 23,259 (5.3%) and the carcasses of 1072 (0.2%) of these animals were condemned. Almost all (92.4%) of the condemned livers, most (68.9%) of the condemned lungs but only 10.8% of the condemned carcasses were rejected because of parasitic infection. The parasitic lesions observed in the condemned livers were attributed to Echinococcus granulosus, Fasciola hepatica and/or Dicrocoelium dendriticum (cattle, sheep and goats) or entirely to E. granulosus (camels). All the parasitic lesions observed in the condemned lungs (which also came from cattle, sheep, goats and camels) were attributed to E. granulosus. Sarcocystis cysts and/or Taenia cysticerci were found in ovine muscle while only Taenia cysticerci were detected in bovine muscle (no parasitic lesions were observed in the muscles of the goats and camels). Parasites were responsible for 80.8% of the condemned organs or carcasses, and the value of the food lost because of parasite-related condemnation (based on market prices in 2010) was estimated to be U.S.$421,826 (U.S.$47,980 for cattle, U.S.$316,344.0 for sheep, U.S.$57,372 for goats and U.S.$130 for camels). The parasites contributing most to the condemnation of otherwise marketable organs and muscles were E. granulosus (52.2%) and D. dendriticum flukes (29.5%). These parasites clearly remain too common and cause considerable economic loss in Khorasan and, presumably, other areas of Iran.     

Hydatidosis-echinococcosis in Greece

Hydatidosis/echinococcosis (Echinococcus granulosus infection) is considered to be a serious problem for both public health and the livestock economy in Greece. The present paper reviews and summarizes all data available on this disease since 1970. The disease was widely prevalent long before the 1970s. At that time the annual surgical incidence rate was 12.9 per 100000 inhabitants. As a result of the seriousness of the disease, the Greek Department of Veterinary Services initiated an anti-echinococcosis campaign in 1984. When the program started, the prevalence of infection in farm animals was 82% in cattle, 80% in sheep, 24% in goats and 5% in pigs. Data obtained in a survey in Northern Greece in 1994, recorded the prevalence of CE as 100% in sheep, 56.6% in cattle, 15.4% in goats and 9.3% in pigs; sheep had not only more cysts but significantly higher rates of fertile cysts (e.g. contained viable protoscolices) than intermediate host species examined. Serologic surveys (specific IgG) in humans carried out between 1988 and 1999 had shown seroprevalence up to 29%. Surveillance in livestock species, since 1998, carried out as part of an European Union (E.U.) project, have documented the prevalences of CE in sheep (31.3%), in goats (10.3%), in pigs (0.6%) and in cattle (0%). The official campaign against this zoonosis in Greece is ongoing. It is concluded that since hydatidosis/echinococcosis is still present, surveillance and intervention measures should be continued to track the course of the infection and to eliminate risk to humans.     

Studies on the parasitic helminths of slaughtered animals in Iraq. I. Parasitic helminths of the liver of herbivores

The livers and lungs of 580 sheep, 160 goats, 418 cattle, 50 camels and 48 buffaloes slaughtered in Baghdad in April-July, 1981 were examined for helminth parasites; 14.3% of the sheep, 0.6% of the goats, 18.2% of the cattle, 72.0% of the camels and 8.3% of the buffaloes were infected with trematodes and cestodes. Dicrocoelium dendriticum is reported from the livers of sheep in Iraq for the first time.     

18kDa抗原诊断泡型包虫病的评价

目的：评价１８ｋＤａ抗原在泡型包虫病（ＡＥ）诊断中的价值。方法：用免疫印渍法检测３３例泡型包虫病、６９例囊型包虫病（ＣＥ）、３０例囊虫病和８２例健康人血清对泡型棘球蚴（Ｅｍ）和囊型棘球蚴（Ｅｇ）原头节１８ｋＤａ抗原的抗体反应。同时用羊包囊液抗原常规ＥＬＩＳＡ法检测上述血清。结果：ＥＬＩＳＡ试验,ＡＥ血清阳性率为９３．９％、ＣＥ为８５．５％、囊虫病为５０％、健康人为６．１％。显示３种患者血清存在较强的交叉反应。免疫印渍试验,两种原头节的１８ｋＤａ抗原对ＡＥ血清阳性反应均为９０．９％、ＣＥ分别为１０．１％和１３％、囊虫病患者为１３．３％和１６．７％。与健康人血清不发生反应。结论：１８ｋＤａ抗原可以有效的鉴别两型包虫病。     

Rapid dot-ELISA for the detection of specific antigens in the cyst fluid from human cases of cystic echinococcosis

A rapid dot-ELISA was developed for the detection of specific antigens in samples of cyst fluid from human cases of Echinococcus granulosus infection, permitting the confirmation of cystic echinococcosis (CE). Peroxidase-conjugated antibodies against antigen B (derived from the fluid in the cysts of sheep infected with E. granulosus) were used to test cyst-fluid samples from 22, surgically confirmed cases of human CE and 21 domestic animals (horses, sheep, buffalo, a cow and a camel) with CE. All of these samples were found to be strongly positive in the dot-ELISA, by direct reading with the naked eye. In contrast, fluid samples from seven, non-parasitic liver cysts of human origin were all negative, and a sample taken from the residual cavity left in a patient after previous CE surgery showed a weakly positive reaction. The antigen-detection assay, which can be completed within 10 min, may be a useful 'bedside' test for the differential diagnosis of cysts during surgery or percutaneous treatment for suspected CE.     

Development of Em18-immunoblot and Em18-ELISA for specific diagnosis of alveolar echinococcosis

Extensive experience has documented that Em2(plus)-ELISA, Em10-ELISA and Em18-immunoblot and Em18-ELISA are reliable serologic methods for detection of alveolar echinococcosis (AE) caused by the metacestodes of Echinococcus multilocularis. Among these, tests based on detection of antibodies to the specific Em18 antigen, either immunoblot or ELISA, appears to be the most specific for AE. Between 90 and 97% of AE cases with characteristic hepatic lesions detectable by image analysis have been positive in Em18-serology. In contrast Antigen B (8 kDa)-immunoblot is the most sensitive for all forms of echinococcosis, although it can not differentiate AE from cystic echinococcosis (CE). Primary serologic screening for echinococcosis, especially for CE using hydatid cyst fluid of Echinococcus granulosus appears to be highly sensitive in endemic areas. Glycoproteins (GPs) purified from cyst fluid of Taenia solium are highly specific for diagnosis of T. solium neuorcysticercosis (NCC). Using currently available antigens it is not difficult to differentiate these three larval cestodiases serologically. We recommend that (1) primary screening of CE in endemic areas should be carried out using hydatid cyst fluid of E. granulosus prepared from cysts in either sheep, human or mouse for immunoblot and from sheep or mouse for ELISA, (2) both primary screening and confirmation of AE in endemic areas should be carried out using Em18-ELISA, Em18-immunoblot or Em2(plus)-ELISA. Serodiagnosis in areas where both AE and CE are endemic, such as in China, should be carried out as a combination of (1) and (2), and (3) serology of NCC should be carried out using GP-ELISA or GP-immunoblot. All samples showing antibody to Em18 are exclusively from echinococcosis cases. There have been no false positive test reactions with sera from other diseases. Strongest Em18 responders are all from patients with AE but some weaker responses may be found in sera of persons with advanced complex lesions of CE. These highly reliable serodiagnostic methods using native, recombinant and synthetic antigens are briefly summarized and experiences with these methods in Japan is reviewed. We believe that use of these specific antigens in screening and confirmation programs for AE in Japan will improve specificity and reduce the confusion, anxiety and expense in persons whose sera give false positive reactions with crude echinococcal antigens.     

Crimean hemorrhagic fever-Congo (CHF-C) virus antibodies in man, and in domestic and small mammals, in Iran.

A Crimean hemorrhagic fever-Congo (CHF-C) virus antibody survey was carried out in Iran with sera from man and several animal species; this survey was done by means of agar gel diffusion precipitation (AGDP) test with the following results (percent positive of number tested): men, 13% of 351; sheep, 38% of 728; goats, 36% of 135; cattle, 18% of 130; camels, 0% of 157; small mammals, 3% of 274. A number of sera were tested by complement-fixation (CF), neutralization (N), and hemagglutination-inhibition (HI) tests in addition to the AGDP test. A good correlation was found in the results with 105 sera tested by AGDP, HI, and N, with approximately 70% to 75% positive in all three tests; by CF, only 20% were positive. Of 55 human sera, of which 15 could be tested by N test, about half were positive by AGDP and only 10% by HI at low titers; none was positive by N and CF tests. These results suggest that any one of the three serological tests (N, HI, and AGDP) can be used to survey the antibody prevalence in sera from domestic animals; the CF test, not unexpectedly, was less suitable. Our results, however, are inconclusive in regard to the human sera.     

5种抗原检测囊型包虫病血清学评价

目的 评价细粒棘球蚴纯化囊液粗抗原、天然抗原B（nAgB）及其3个重组亚基检测囊型包虫病的效能。 方法 从新疆源细粒棘球蚴原头节中提取总RNA,通过RT-PCR获得编码AgB8/1、AgB8/2和AgB8/3基因片段并克隆入pGEX-3X表达载体,IPTG诱导表达分别得到重组蛋白rAgB8/1、rAgB8/2 、rAgB8/3;羊细粒棘球蚴囊液经透析沉淀获得纯化囊液粗抗原（HCF）、此纯化囊液粗抗原经煮沸离心弃沉淀得到天然抗原B。用制备的5种抗原分别作为包被抗原,应用ELISA法检测囊型包虫病人及其它寄生虫病人和健康人血样中抗体。结果 HCF、nAgB、rAgB8/1、rAgB8/2和rAgB8/3应用于ELISA法检测囊型包虫病人血清的敏感性依次为90.8%（79/87）, 87.4%（76/87）, 67.8%（59/87）, 78.2%（68/87） 和 59.8%（52/87）;特异度依次为96.0%, 96.0%, 96.0%, 98.0% 和 97.0%。纯化HCF、nAgB、rAgB8/1、rAgB8/2和rAgB8/3的诊断效能分别为93.5%, 91.9%, 82.8%, 88.7% 和 79.6%。纯化HCF和nAgB检测的敏感度高于 rAgB8/1、rAgB8/2和rAgB8/3（P<0.05）;rAgB8/2检测的敏感度高于rAgB8/1、和rAgB8/3（P<0.05）;5种抗原检测的特异度之间均无统计学差异（P>0.05）。结论 天然抗原应用ELISA法检测囊型包虫病的效能总体优于重组抗原。     

Prevalence of cystic echinococcosis in pigs from Slovakia, with evaluation of size, fertility and number of hydatid cysts

The regional occurrence of cystic echinococcosis in slaughtered pig from Slovakia was studied in the period of 2000–2008, along with the quantitative parameters associated with the establishment of cysts (intensity of infection, fertility, size). From 103 pig livers collected from abattoirs in 35 sites Slovakia as suspected for Echinococcus infection, 63 were positive for cystic echinococcosis, whereas in 40 livers cysticercosis was diagnosed. Fertile cysts with echinococcal protoscoleces were recorded in 25.4 % of positive pigs, with the 8.9 % fertility rate and the intensity of infection reaching value of 5.9 cysts per liver. The average size of fertile cysts was more than three times larger than diameter of sterile cysts (diameters of 4.67 cm vs. 1.37 cm, respectively). No significant differences in relative amounts of fertile and sterile cysts were found among counties (P = 0.15). The annual prevalence of E. granulosus in pigs in 2000–2 008 has ranged from 0.02 % to 0.13 % (average rate 0.08 %), with the decreasing tendency over the period, especially after 2005. The most heavily affected areas with cystic echinococcosis over 2006–2008 were indicated in Prešov (eastern Slovakia, 0.68 % prevalence) and Komárno districts (southwestern Slovakia, 0.26 % prevalence). Obtained data are relevant in designing regional control strategies to suppress the occurrence of disease in livestock and risk for humans to be infected.     

Coxiella burnetii in Humans,Domestic Ruminants,and Ticks in Rural Western Kenya

We conducted serological surveys for Coxiella burnetii in archived sera from patients that visited a rural clinic in western Kenya from 2007 to 2008 and in cattle, sheep, and goats from the same area in 2009. We also conducted serological and polymerase chain reaction-based surveillance for the pathogen in 2009–2010, in human patients with acute lower respiratory illness, in ruminants following parturition, and in ticks collected from ruminants and domestic dogs. Antibodies against C. burnetii were detected in 30.9% (N = 246) of archived patient sera and in 28.3% (N = 463) of cattle, 32.0% (N = 378) of goats, and 18.2% (N = 159) of sheep surveyed. Four of 135 (3%) patients with acute lower respiratory illness showed seroconversion to C. burnetii. The pathogen was detected by polymerase chain reaction in specimens collected from three of six small ruminants that gave birth within the preceding 24 hours, and in five of 10 pools (50%) of Haemaphysalis leachi ticks collected from domestic dogs.     

Crimean-Congo hemorrhagic fever virus in ticks collected from humans, livestock, and picnic sites in the hyperendemic region of Turkey

During June and July 2007, about 3125 adult ticks were collected from humans, animals, and vegetation in a hyperendemic region (Sivas and Tokat) of Turkey. A total of 2193 ticks were pooled in 225 pools and screened for the Crimean Congo hemorrhagic fever virus (CCHFV) presence by antigen-capture enzyme-linked immunosorbent assay. Infection rates were calculated as the maximum likelihood estimation with 95% confidence intervals (CI). The dominant tick species was found to be Hyalomma marginatum with the following infestation rates in human, cattle and sheep, respectively: 47.43%, 66.07%, and 30.12%. Maximum likelihood estimation values of CCHFV in H. marginatum ticks collected from human, cattle, and sheep were 0.91% (CI 0.05-4.42), 2.10% (CI 1.12-3.64), and 3.11% (CI 1.18-6.87), respectively. CCHFV antigens were also demonstrated in Hyalomma excavatum, Haemaphysalis parva, and Boophilus annulatus ticks collected from cattle and Rhipicephalus bursa ticks from sheep. Our results suggest that the studied area might maintain its endemic properties in the near future unless effective tick control measures are implemented.     

细粒棘球蚴原头节18 kU纯化抗原ELISA的建立及其对两型包虫病鉴别诊断的意义

目的用细粒棘球蚴原头节18ku纯化抗原建立ELISA诊断方法,用于两型包虫病的鉴别诊断.方法用18ku纯化抗原ELISA方法对44例泡型包虫病(AE)、70例囊型包虫病(CE)、29例囊虫病和30例健康人血清中特异性抗体进行检测,同时用羊包囊液抗原(Bu)常规ELISA法检测上述血清做比较.结果18ku纯化抗原检测不同血清的阳性率为AE90.91%、CE11.43%、囊虫病和健康人血清均为阴性;Bu抗原分别为AE97.73%、CE88.57%、囊虫病51.72%和健康人10.0%.18ku-ELISA对AE血清诊断敏感性为90.91%、特异性93.80%、阳性预示值为83.33%、阴性预示值96.80%.结论两型包虫病患者体内18ku抗体水平存在明显差异,纯化抗原18ku-ELISA可用于两型包虫病的鉴别诊断,较免疫印渍法简便快速.     

An immunoassay for the detection of circulating antigens in human echinococcosis

An immunoassay (double-antibody-sandwich-ELISA) was developed to detect circulating antigens (CAg) in patients with cystic (Echinococcus granulosus) echinococcosis. Echinococcus antigens derived from heterologous intermediate hosts were used to immunize rabbits and to purify the rabbit-IgG-fraction obtained by affinity-chromatography, thus avoiding major interference with host components. The purified rabbit anti-hydatid IgG was immunosorbed with bovine and human sera. One part of the resulting IgG served as coating agent in a double antibody sandwich-ELISA; the other part, coupled to alkaline phosphatase, as detecting conjugate. The specificity of the antibody reaction was demonstrated by immunoelectrophoresis. Sera of 21 patients with cystic echinococcosis were examined with this test system. In seven of the patients' sera CAg were detected in concentrations ranging between 310 ng and 680 ng protein per ml serum. Comparing pre- and postoperative serum samples obtained from nine patients operated on for cystic echinococcosis, four sera were found to be CAg-positive before and three after operation.