Multilocus Genotyping of Giardial Assemblages associated with Diarrhea in Children and Adults in South India.

Shakti, Laishram (2011) Multilocus Genotyping of Giardial Assemblages associated with Diarrhea in Children and Adults in South India. Masters thesis, Christian Medical College, Vellore.


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INTRODUCTION : Giardiasis, caused by Giardia intestinalis in humans manifests as a wide clinical spectrum ranging from asymptomatic infections to acute or chronic diarrhea as well as functional bowel disease (Mandell, Bennett et al. 2005). It is prevalent in developed, developing and underdeveloped countries. In India, prevalence rates reported in patients with diarrhea range from 0.4 to 70%. Asymptomatic cyst passage has also been found to be as high as 50% . Apart from diarrhea, giardial infection in children can result in long term faltering of growth, stunting and decreased cognitive function. Keeping this in mind, this study aimed to characterize giardial isolates from south India to determine the predominant circulating assemblage using a MLG approach targeting the 3 most commonly used loci, tpi, gdh and β-giardin. This was carried out in children with and without diarrhea to detect any association of symptoms with a particular assemblage as well as adults with gastrointestinal symptoms. The usefulness of the 3 loci and any discordance between the loci was compared. Information on the circulating assemblages and association with symptoms can help plan future interventional measures to prevent giardiasis in this population. AIMS AND OBJECTIVES : Aim: To describe the assemblages of Giardia intestinalis in children and adults in South India using Multiple genetic loci. Objectives: 1. To identify the common giardial assemblages associated with diarrhea in children and adults Using multiple genetic loci, 2. To co-relate severity of diarrhea and clinical presentation with giardial assemblages, 3. To compare the 3 target genes used for detection of giardial assemblages, 4. To detect the presence of any zoonotic assemblages in humans. MATERIALS AND METHODS :The study subjects enrolled were children with diarrhea, children with no diarrhea and adults with gastrointestinal symptoms. The study was approved by the Institutional Review Board of Christian Medical College, Vellore. Informed consent was obtained from parents of children enrolled in the study. A waiver of consent was granted by the Institutional Review Board for the adult samples as they were taken from routine diagnostic work without patient identifiers. The inclusion criteria were - 1. Children under the age of 6 years presenting with diarrhea in the community, 2. Children without diarrhea under the age of 6 years in the community, 3. Adults (>18 years of age) with gastrointestinal symptoms attending the hospital for whom a stool routine examination for ova and cysts was requested, 4. Giardia cyst and/or trophozoites seen in stool microscopy Since this was a pilot study aimed at determining the common assemblages circulating in the community, an arbitrary sample size of 25 Giardia positive cases was included in each group. RESULTS : In order to determine the prevalent circulating giardial assemblages/genotypes in the region, stool samples from children with diarrhea, children with no diarrhea and adults with gastrointestinal symptoms that were microscopically positive for giardial cysts or trophozoites were included in this study. SUMMARY : Assemblage B was the predominant genotype in both adults and children (with and without diarrhea) in India with assemblage AII being the second most common. Tpi-PCR RFLP was the most sensitive among the 3 genotyping methods used. Co-infections with multiple assemblages and subgenotypes were seen more commonly in children. Assemblage A and B co-infections were seen exclusively and BIII and BIV more frequently in children. Some discordance of results was seen between the 3 methods used especially when sequencing was carried out warranting future more detailed studies. Though not statistically significant, more children with diarrhea had assemblage A infection either as single infection or as co-infections with assemblage B.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Multilocus Genotyping ; Giardial Assemblages ; Diarrhea Children ; Adults ; South India.
Subjects: MEDICAL > Microbiology
Depositing User: Subramani R
Date Deposited: 14 Aug 2017 01:28
Last Modified: 14 Aug 2017 01:28

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