The diagnosis of patients with cystic echinococcosis (CE) by means of serology has a limited support in clinical practice due to cross-reactivity with other helminthes leading to overestimation of the parasite's true prevalence. A wealth of reports on the diagnostic performance of antigen B (AgB) has been produced. This study was designed to comparatively assess the diagnostic efficacy of crude sheep hydatid cyst fluid (HCF), AgB and its subunit (12 KDa) to detect IgG or IgG4 antibodies in CE patients' sera using enzyme-linked immunosorbent assay (ELISA).The best diagnostic performance was obtained with anti-HCF IgG ELISA which gave 92.4% sensitivity and 92.6% specificity. Despite the low sensitivity of anti AgB IgG ELISA (84%), it gave the best specificity (94.4%) with less cross-reaction with sera of subjects infected with other parasites. In conclusion, it is recommended to use anti-HCF IgG ELISA for initial screening in large seroprevalence studies. Further analysis of positive serum samples with anti AgB IgG ELISA would allow the confirmation of true positives. Specific IgG4 ELISA may represent a complementary assay, useful as secondary confirmatory tests for patients with suspected CE and negative for total IgG ELISA.

This is the first study dealing with the correlation between HLA antigens and cystic echinococcosis (CE) in Egyptian patients. The potential immunogenetic predisposition for susceptibility and resistance to unilocular echinococcosis was investigated by HLA-DRB1 typing; first by HLA-DRB1 amplification using PCR then using the allele-specific probing technique based on the reverse hybridization principle. The study was carried out on 35 patients with confirmed CE, and 100 apparently healthy individuals. A statistically significant positive association was found between HLA-DR3 and HLA-DR11 and the occurrence of CE. HLA-DR3 antigen was positively associated with the occurrence of isolated pulmonary cysts, multiple cysts, cysts >5 cm in size, non-cured disease and with a common radiological picture of hydatid cyst. A significant positive association of HLA-DR11 with the occurrence of cysts <5 cm in size was detected. This study demonstrates that carriers of DR-3 and DR-11 are at high risk for CE, and that those with DR-3 are more liable to complications.

Genetic polymorphisms of encoding antigen B2 gene (AgB2) in Echinococcus granulosus were studied using PCR-RFLP and DNA sequencing among 20 Egyptian isolates. Five isolates from different host origins (humans, camels, pigs, and sheep) were collected and used. All examined isolates of each host group gave very similar patterns of PCR-RFLP after restriction enzyme digestion with AluI, with the gene size of approximately 140 bp and 240 bp for sheep and human isolates, and approximately 150 bp and 250 bp for pig and camel isolates. No digestion pattern was obtained after incubation of all studied isolates with EcoRI. These results reveal high intra-group homogeneity. DNA sequence analysis highlighted that human infecting strain showed 100% identity with respect to sheep infecting isolate, 96% and 99% with pig and camel infecting isolates, respectively.