Efficacy of some laboratory methods in detecting giardia lamblia and cryptosporidium parvumin stool samples

Abstract

Background: Giardia duodenalis and Cryptosporidium parvum are the most prevalent intestinal parasites of human. It also infects a wide range of mammals .Two genotype of G.duodenalis (A and B) were commonly reported among humans with different frequency of distribution in different geographical locations. Methods :total of 434 stool samples were collected from peoples in kikrkuk city during October 2012toAugust 2013. Zinc sulphate flotation technique was applied on 226 positive stool, serological methods involve Giardia ELISA-corpo antigen, Direct fluorescent assay (DFA), and lateral immune-chromatography assay(Triage panel) .Extractions of Giardia genome DNA from stool samples were performed using QIAamp Stool Mini kit with a modified protocol. PCR- one step procedure was used to amplify a fragment of Giardia lamblia genome using k725 gene locus,(Mixture primers of human A and B assemblages) Results:The overall rate of intestinal parasitic infection was 52.07%,Giardia lamblia rate was 24.65%.Common isolated parasites were Cryptosporidium parvum ,Blastocystishominis, other intestinal protozoan parasites and nematode helminthes:7.60 & 5.76 %,7.37 and 6.68 % respectively. Sensitivity and specificity of PCR method and direct microscopy were higher than other four methods used for detecting giardiasis. Triage panel method exert high rate of giardiasis than revealing of Cryptosporidium and Entamoeba histolytica. From the application of five methods for Cryptosporidium diagnosis, DFA and modified Ziehl-Neelsen(MZN) methods show high sensitivity and specificity than other three methods. Application of PCR single step using mixture primers assemblages A and B, show high rate of sensitivity than other methods in detecting giardiasis.Amplified Giardia genome length extended from 220 to 750 bps with mean of 437.56 bps. Conclusions: PCR assay targeting K725 gene locus is a sensitive tool and discriminates mixed genotypes of G.lamblia. DFA and MZN are sensitive tools for detecting Cryptosporidium parvum in stool samples