Human cystic echinococcosis (CE) is a chronic, complex and neglected infection causing severe disease in humans. Hepatic CE cysts are detected and classified mainly by using ultrasound. Expert opinion and published data suggest that uncomplicated inactive liver cysts do not require treatment and only need to be monitored over time (“Watch and Wait”). Here we update our findings as published in 2014 on the “Watch and Wait” approach applied to inactive, asymptomatic cysts of the liver to keep the medical community informed. Clinical data of patients who accessed the World Health Organization Collaborating Center for CE at the University of Pavia-San Matteo Hospital Foundation from January 1991 to October 2017 were analyzed. Inclusion criteria were presence of one or more inactive uncomplicated cysts in the liver (CE4 or CE5), without any history of previous treatment, and an ultrasound-based follow-up of at least 24 months. Fifty-three patients with 66 inactive cysts fulfilled the inclusion criteria. Of these, 11 patients are newly described here; 37 were part of our previously described cohort and the follow-up for 17 of them was further extended; and five were excluded from the previously published analysis as their follow-up was too short, but could be included now. Without the need for treatment and without development of complications, 98.5% of cysts remained inactive over time. In only one patient (1.9% of patients), a reactivation of one cyst (1.5% of cysts) was observed.

The diagnosis of cystic echinococcosis (CE) is based on imaging. Serology supports imaging in suspected cases, but no consensus exists on the algorithm to apply when imaging is inconclusive. We performed a retrospective analysis of serology results of patients with untreated hepatic CE and non-CE lesions, seen from 2005 to 2017, to evaluate their accuracy in the differential diagnosis of hepatic CE. Serology results of three seroassays for echinococcosis (ELISA RIDASCREEN, indirect hemagglutination (IHA) Cellognost, and Western blot LDBIO) and clinical characteristics of eligible patients were retrieved. Patients were grouped as having active or inactive CE and liquid or solid non-CE lesions. Sensitivity, specificity, and diagnostic accuracy were compared between scenarios encompassing different test combinations. Eligible patients included 104 patients with CE and 257 with non-CE lesions. Sensitivity and diagnostic accuracy of Western blot (WB) were significantly higher than those of the following: 1) IHA or ELISA alone, 2) IHA+ELISA interpreted as positive if both or either tests positive, and 3) IHA+ELISA confirmed by WB if discordant. The best performances were obtained when WB was applied on discordant or concordant negative IHA+ELISA. Analyses performed within “active CE (n = 52) versus liquid non-CE (n = 245)” and “inactive CE (n = 52) versus solid non-CE (n = 12)” groups showed similar results. Specificity was high for all tests (0.99–1.00) and did not differ between test combination scenarios. WB may be the best test to apply in a one-test approach. Two first-level tests confirmed by WB seem to provide the best diagnostic accuracy. Further studies should be performed in different settings, especially where lower test specificity is likely.

The differential diagnosis of hepatic cystic echinococcosis (CE) may be challenging. When imaging is insufficient, serology can be applied, but no consensus diagnostic algorithm exists. We evaluated the performances of nine serological tests commercialized in Europe for the diagnosis of “echinococcosis”. We performed a diagnostic accuracy study using a panel of sera from patients with hepatic CE (n = 45 “liquid” content stages, n = 25 “solid” content stages) and non-CE focal liver lesions (n = 54 with “liquid” content, n = 11 with “solid” content). The diagnosis and staging of CE were based on ultrasound (gold standard). Nine commercial seroassays (5 ELISA, 2 WB, 1 Chemiluminescence Immunoassay [CLIA] and 1 Immunochromatographic test [ICT]) were the index tests. Sensitivity (Se) ranged from 43 to 94% and from 31 to 87%, and specificity (Sp) from 68 to 100% and from 94 to 100%, when borderline results were considered positive or negative, respectively. Three seroassays (2 ELISA, 1 WB) were excluded from further analyses due to poor performances. When tests were combined, Sp was 98–100%. The best results were obtained using the WB-LDBIO alone (Se 83%) or as a third test after two non-WB tests (Se 67–86%). A validated WB or two non-WB tests, read with stringent criteria (borderline = negative and considered positive only if concordant positive), possibly confirmed by the WB, appear sensible approaches.

Cystic echinococcosis (CE) is one of the most widespread helminthic zoonoses and is caused by the tapeworm Echinococcus granulosus complex. CE diagnosis and monitoring primarily rely on imaging techniques, complemented by serology. This is usually approached by the detection of IgG antibodies against hydatid fluid (HF), but the use of this heterogeneous antigenic mixture results in a variable percentage of false positive and negative results, and has shown to be useless for follow-up due to the long persistence of anti-HF antibodies in cured patients. To improve test performances and standardization, a number of recombinant antigens mainly derived from HF have been described, among them the B2t and 2B2t antigens. The performance of these antigens in the diagnosis and follow up of patients with CE has been so far evaluated on a limited number of samples. Here, we evaluated the performances of tests based on B2t and 2B2t recombinant antigens compared to HF in IgG-ELISA and immunochromatography (IC) for the diagnosis and follow-up of patients with CE in a retrospective cohort study. A total of 721 serum samples were collected: 587 from 253 patients with CE diagnosed by ultrasonography (US), 42 from patients with alveolar echinococcosis and 92 from healthy donors from Salamanca (Spain). The highest overall sensitivity was obtained with HF in ELISA (85.5%), followed by IC containing HF and 2B2t-HF (83.0% and 78.2%, respectively). The lowest sensitivity was obtained with B2t and 2B2t in ELISA (51.8%). The highest specificity was obtained with IC containing 2B2t-HF (100%), and the lowest with HF-ELISA (78.0%). The lowest cross-reactivity with sera from patients with alveolar echinococcosis was detected with the recombinant antigens in ELISA (9.5% - 16.7%) and the highest with the HF-IC (64.3%). The results of B2t and 2B2t-ELISA were influenced by cyst stage, as classified by US according to the WHO-Informal Working Group on Echinococcosis (WHO-IWGE), with low sensitivity for inactive (CE4 and CE5) cysts, and by the drug treatment, with higher sensitivity in patients after drug treatment compared with patients not subjected to drug treatment. The two recombinant antigens in ELISA provided promising results for monitoring patients in follow-up, although their use is limited to patients with positive serology against them at the beginning of the follow-up. Potential biological reasons behind the low sensitivity of the recombinant antigens and possible strategies to enhance the performance of CE serology are discussed. Cystic echinococcosis (CE) is a helminthic zoonosis caused by Echinococcus granulosus sensu lato. CE diagnosis and monitoring is of paramount importance for the clinical management of patients and primarily rely on imaging techniques, complemented by serology. CE serology is usually based on the detection of antibodies against hydatid fluid (HF), but the use of this heterogeneous antigenic mixture shows several drawbacks, including false positive and negative results, unsatisfied predictive values, and long persistence of detectable antibody levels in cured patients. As an alternative, to improve test performances and standardization, several recombinant antigens have been described, but these have been so far evaluated only on a limited number of samples. Here, two recombinant antigens derived from one of the immunodominant HF antigens (antigen B2) have been tested in enzyme-linked immunosorbent assay (ELISA) and in immunochromatographic strips (IC) against 721 serum samples. Although more specific than the HF, the recombinant antigens in ELISA showed low sensitivity for patients with inactive (CE4 and CE5) cysts and for patients not subjected to drug treatment. This limited their use for follow-up, although promising, to those patients with positive serology at the beginning of the follow-up period. These results will aid in the future development of a serological test with enhanced performance in the diagnosis and follow-up of patients with CE.

Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of the cestode Echinococcus granulosus. The parasite typically infects dogs and ungulates, with humans acting as dead-end hosts. Information on the epidemiology of CE is lacking from Central Asia, including from Kazakhstan where CE cases are reported centrally. This study presents data from the Kazakhstan Scientific and Practical Center for Sanitary and Epidemiological Evaluation and Monitoring on CE patients treated surgically, with a diagnosis confirmed by pathology. Evaluation of data from 2007 to 2016 indicated that the CE incidence rate decreased during this time period in most areas of Kazakhstan (country-level incidence rate of 5.6 versus 4.7 cases/100,000 population in 2007 and 2016, respectively). Cystic echinococcosis had a higher incidence in southern Kazakhstan, with an incidence rate between 7.0 and 10.5 cases per 100,000 population, whereas northern regions had rates less than 4.0 cases per 100,000 population. Moreover, despite the overall decrease, CE incidence continues to increase in the south. Cystic echinococcosis surveillance is needed, particularly in the south, to help inform policymakers and orient disease control efforts.