HLA class II alleles: susceptibility or resistance to cystic echinococcosis in Yemeni patients.

This is the first study dealing with the association between HLA alleles and cystic echinococcosis (CE) in Yemeni patients. The present study aimed to detect the association of HLA-DRB(1) alleles and susceptibility or resistance to CE in Yemeni patients by HLA-DRB(1) typing; first by HLA-DRB(1) amplification using PCR then using the allele-specific probing technique based on the reverse hybridization principle. This case-control study was carried out on 66 unrelated patients with confirmed CE and 66 apparently healthy individuals. The association of class II HLA-DRB alleles was examined in the patients with CE and compared with control subjects. Frequency of HLA-DR16 allele was 18.2% among patients and was statistically significant (higher) than in the control group [3%; odds ratio (OR) = 6.5, chi (2) = 7.1, P = 0.011]. Frequencies of HLA-DR1, DR8, and DR52 alleles were decreased in the patient group (0.0%, 0.0%, and 56%, respectively) than in the control group (19.7%, 9.1%, and 74.2%, respectively) (OR = 0.0, 0.0, 0.443 and P < 0.0001, 0.04, 0.05, respectively). HLA-DR16 allele was found to be statistically positively associated with the occurrence of isolated hepatic CE, single cysts, and cysts >5 cm in size. In contrast, HLA-DR1 and DR52 alleles were found to be statistically negatively associated with the occurrence of isolated hepatic CE. This study demonstrates that susceptibility to CE in Yemeni patients is statistically significantly associated with the HLA-DR16 allele and resistance to CE is statistically significantly associated with HLA-DR1, DR8, and DR52 alleles. Thus, this study has identified that carriers of HLA-DR16 are at high risk for CE, so appropriate preventive measures and quick and careful treatment should be applied to those patients.

Larvicidal, miracidiacidal and cercaricidal activities of the Egyptian plant Iris pseudacorus.

The larvicidal properties of Iris pseudacorus leaves ethanol extract against second-instar larvae of two mosquito species, Culex pipiens and Aedes caspius (Diptera: Culicidae) were studied. It was observed that the larvicidal effect of this extract was dose-dependent. The LC50 values of I. pseudacorus against C. pipiens and A. caspius were 10.36 and 16.43 mg/l within 24 hr, and 7.36 and 10.1 mg/l within 48 hr, respectively. The miracidiacidal and cercaricidal properties of I. pseudacorus extract were directly tested against Schistosoma mansoni miracidia and cercariae and a time-concentration relationship was observed. The concentrations needed to kill all miracidia (LC100) within 5 min., 30 min. and an hr of exposure were 2.7, 1.6 and 0.9 mg/l respectively. The concentrations needed to kill all cercariae (LC100) within 5 min. 30 min. and an hr of exposure were 1.5, 1.0 and 0.6 mg/l respectively.

Diagnostic potentials of copro-antigen detection based ELISA, compared to microscopy in intestinal amoebiasis.

Ninety three patients clinically presumed to have intestinal amoebiasis were chosen and stool samples were collected from all of them. Stool samples were subjected to microscopic examination and Entamoeba copro-antigens detection using Entamoeba and Entamoeba II tests. Out of 93 clinically positive samples, 51 (54.8%) were found positive by microscopy, while 49 (52.7%) were detected by Entamoeba test as having antigens specific for E. histolytica/E. dispar (88.24% sensitivity). Among 49 specimens, 4 were demonstrated as microscopy negative (90.48% specificity). Entamoeba II test demonstrated 16 specimens having antigens specific for the pathogenic E. histolytica among 49 positive by Entamoeba test, while 33 were detected as positive for nonpathogenic E. dispar copro-antigens. Copro-antigen assay using ELISA has shown to be more sensitive and specific than microscopy in different-tiation between pathogenic and nonpathogenic Entamoeba species. Extensive use of this technique allowed for revising the epidemiology of the true pathogenic E. histolytica and obviate the need for unnecessary chemotherapy with its costs and risk of side effects.

Selective identification of the pathogenic E. histolytica in fresh stool samples using polymerase chain reaction (PCR).

Stool samples from 93 individuals clinically presumed to have intestinal amoebiasis and subjected to microscopic examination and DNA extraction. The PCR amplification was performed using two sets of primers that differentiate between pathogenic and nonpathogenic Entamoeba DNA. Of 93 clinically positive cases, 51 (54.8%) were positive by microscopy, while 53 (56.9%) were detected by PCR as having DNA specific for either E. histolytica / E. dispar. A specificity of 85.71% and a sensitivity of 92.15% were with PCR compared to microscopy. Among 53 PCR positive specimens, three different DNA sequences were demonstrated: 8 specimens had DNA sequences specific of E. histolytica, 31 with DNA specific for E. dispar and 14 specimens have mixed DNA sequences for E. histolytica and E. dispar. PCR is a sensitive and a specific tool. PCR application is better the epidemiology in endemic areas through keeping indefinite DNA records for prospective and retrospective studies.

Detection of IgA anti-Entamoeba histolytica in the patients' saliva.

E. histolytica is a protozoan parasite with worldwide distribution. The diagnosis of this parasite still depends on the microscopic examination. Determination of the sIgA in the different body fluid proves to be of diagnostic value in many pathogens. To find out the potentials of salivary sIgA in diagnosis of intestinal amoebiasis, 30 patients with parasitologic proved E. histolytica and 30 cross-matched negative controls were selected for levels of salivary sIgA using radial immunodiffuion technique. The result showed a high significant increase in the mean concentration of salivary sIgA in patients rather controls. However, six negative controls gave positive sIgA. So, salivary IgA concentration has a predictive diagnostic values of intestinal amoebiasis, when the stool examination is practically impossible as well as in tissue amoebiasis.

Incidence of Parastrongylus cantonensis larvae in different fresh water snails in Dakahlia Governorate.

Samples of snails were collected from different water bodies in Dakahlia governorate to assess a survey on the naturally infected snails and their infection rate with the Parastrongylus cantonensis larvae. The nematode P. cantonensis is associated in the etiology of eosinophilic meningeoencephalitis of man. Lanistes carinatus showed the highest rate of infection with 19-400 larvae per snail. Biomphalaria alexandrina, B. glabrata, Bulinus truncatus, Lymnaea cailliaudi (natalensis), L. alexandrina, and Cleopatra cyclostomoides were found naturally infected with the larvae of P. cantonensis for the first time in Egypt. The number of larvae per infected snail varied depending on the snail type. The highest rate (39.2%) of infected snails was collected from the end canals at Tanneekh and the lowest in the river Nile (12.5%).