Determining the Pattern of Gastrointestinal Parasitic Infections among Orang Asli at Kg. Serendah, Selangor, Malaysia using Molecular and Parasitological Methods

Abstract

Gastrointestinal parasite (GIP) infections have a global distribution and a major impact on the socioeconomic and public health of the bottom billion of the world’s poorest people. In Malaysia, the Orang Asli community are prone to these infections due to environmental and personal hygiene practices. Aside from the socioeconomic development plans, mass drug administration (MDA) with albendazole, a benzimidazole (BZ) group of anthelminthic (AH) drug are carried out periodically by the government to control GIP infection in this community. Albendazole (ABZ) is commonly used to treat GIP, mainly due to soil transmitted helminths (STHs). However, emergence of drug resistant among GIP has been a recent concern, as BZ resistance in GIP have been reported due to single nucleotide polymorphism (SNP) in β-tubulin gene. In this study, we investigated the prevalence of GIP and potential risk factors for infection among the Orang Asli community at Kg. Serendah in Malaysia. We studied the efficacy of single dose albendazole and explored the presence of single nucleotide polymorphism frequencies (SNPs) β-tubulin gene which confers resistance towards benzimidazole group of anthelminthic drugs. Stool samples were collected from 110 villagers. The stool samples were concentrated using formalin ethyl acetate concentration technique (FEACT) and floatation technique. The stool samples were stained with trichrome stain and acid fast stain to identify the parasite species by microscopy. DNA extraction was carried out using Stool Kit (Qiagen) and followed by conventional PCR assay to detect the parasites. All the participants in the survey were treated as follows: 400mg of albendazole for above 2 years old and 200 mg of albendazole for ≤ 2 years old. After deworming exercise, the villagers were examined at 1 and 6 months post treatment. PCR amplification and sequencing of β-tubulin gene from parasites at pretreatment and post treatment (1 & 6 months) were analyzed. Demographic socioeconomic and behavioural characteristics were treated as categorical variables and presented as frequencies and percentages. Pearson’s Chi- square (X2) test was used to test the association of GIP prevalence with demographic socioeconomic and behavioral factors. Odds ratio (OR) and 95% CI were computed. To identify risk factors associated with GIP infection variables that showed association in the univariate analysis were used in multivariate analysis. Data analysis was performed using SPSS version 18. Stool samples were collected from 110 villagers. The total samples obtained from male were 50 and female were 60. The prevalence for GIP found in this study was 67% and the parasites detected were Trichuris trichiura (50%), Ascaris lumbricoides (39%), Blastocystis hominis (10%), Cryptosporidium parvum (7.2%), Taenia spp (2.7%) and Microsporidia (2.7%). The prevalence was 68% and 66% in females and males respectively. Higher GIP prevalence was observed among children below 6 years compared to the adults. Univariate analysis showed the avaibility of latrine, the source of drinking water, boiling water before drinking and place of defecation were potential risk factors for GIP infection. Multivariate analysis showed that not using the toilet and drinking unboiled water was predictive of GIP infection in this study area. The cure rate after 1 month post treatment for A. lumbricoides was 87% and for T. trichiura was 46% after a single dose of albendazole. The cure rate after 6 months post treatment declined to 33% for A. lumbricoides but remained the same at 46% for T. trichiura. The poor cure rate for STH was not due to drug resistant as presence of SNP was not detected in β-tubulin gene sequenced. The conventional PCR assay developed in this work was efficient to detect STH but not protozoa. The overall prevalence of GIP in this study was 67% and mainly due to STH infection. Females had slightly higher prevalence compared to males. Moreover, children below 6 years of age had the highest GIP infection followed by adults. The overall cure rate was higher for Ascaris lumbricoides infection compared to Trichuris trichiura with a single dose albendazole after 1 month treatment. No SNPs were detected among all the STH sequenced before and after treatment. Summing up the result shows, resistant markers do not contribute to the high prevalence of STH among Orang Asli at Kg. Serendah.