Comparison evaluation of three methods (microscopic examination, direct fluorescent antibody assay, immunochromatographic method) in diagnosis of giardia intestinalis in stool specimens

Giardiosis caused by a flagellated protozoon G. intestinalis, is known as the most common protozoon disease all over the world, especially in developing countries. Prevalence rate is stated to be around 2-5% in industrial countries, 20-30% in developing countries. It becomes contagious especially in developing countries and among children, causing serious socio-economic loses. In order to prevent these loses, the first step is to determine the sick and disease carrier people and provide relevant cure by correct and fast diagnosis without doubt. In Turkey when recent studies are examined, different ratios between 0,8% and 54,8% are stated. In diagnosis of the parasite, many different methods are used, such as microscopic examination, various colouring techniques, Direct Florescent Antibody Assay (DFA), Enzyme Linked Immunosorbant Assay (ELISA), Immunochromatographic Method (IK) and Polymerase Chain Reaction (PCR). There is not enough study on these methods senstivity and specificity. The aim of this study is to make a comparison between direct microscopic examination and direct microscopic examination after concentration method and DFA and Immunocromatographic methods in finding out the parasite and the best suitable method for diagnosis. In this study 25 stool samples that G.intestinalis has been diagnosed through native-lugol and/or formol-ethil acetate concentration method and 25 non parasite diagnosed samples as control group has been examined. These samples have all been sent to our laboratory for parasite examination. After microscopic examination of stools, they have been kept at -20 ºC for future DFA and IK methods examination. The preserved stool samples have been studied with DFA (CeLLabs, Crypto/Giardia-Cel IF) and IK (RIDA QUICK, Cryptosporidium /Giardia Combi Dipstick) tests as per the manufacturing companies recommendations. In our study, by DFA method, parasites have been detected in all 25 stool samples that G.intestinalis has been diagnosed through native-lugol and/or formol-etil asetat concentration method. By IK method, particular bant for the parasite have been detected in 24 samples, whereas one has not been observed. No parasites have been determined in all 25 samples in the control group where G.intestinalis have not been diagnosed. As a result, in diagnosis of G.intestinalis, when microscopic examination is taken as reference, DFA's senstivity and specificity is noted as 100%, IK's senstivity is noted as 96% and specificity as 100%. In our study, it's been thought that IK method can be used in diagnosis laboratories and mass scanning due to its advantages in easy application, no experienced staff and laboratory infrastructure necessity and giving fast results. Besides, it's been observed that IK kit unit price of 12,80 TL is much cheaper than DFA kit unite price of 25,50 TL. It's been judged that DFA method can be evaluated in the laboratories with strong infrastructure with no experienced staff, but its cost is higher than the traditional methods. Keywords: DFA, Direct microscopic examination, Giardia intestinalis, IK.