Browsing by Author "P. Luksamijarulkul"

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    Detection and characterization of hepatitis A virus in water samples in Thailand
    (2006-06-01) L. Kittigul; A. Uthaisin; S. Ekchaloemkiet; F. Utrarachkij; P. Luksamijarulkul; Mahidol University
    Aims: Outbreaks of hepatitis A in Thailand have been reported continuely and associated with water supply. However, the genetic analysis of hepatitis A virus (HAV) in water is limited. This study described the application of virus concentration method and reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) to detect HAV RNA and analyse the genetic sequence of the virus in environmental water samples. Methods and Results: The HAV from water samples was concentrated by using a developed virus concentration method (adsorption-elution and subsequent speedVac reconcentration) and the viral RNA was detected by RT-nested PCR followed by sequencing of the amplified DNA products. Detection limit of HAV determined by the RT-nested PCR was 1.29 radioimmunofocus assay (RIFA) units ml-1. The DNA band appeared at 183 basepairs. No cross-reactivity was observed in the presence of other enteric viruses (poliovirus and rotavirus). A total of 180 water samples were collected, concentrated, and detected for HAV. The HAV was found in 6/40 (15%) of water samples collected from a swamp and 3/30 (10%) collected from a canal. Ten river samples and 100 tap water samples stored in containers for drinking and domestic uses were negative for HAV. In sequence analysis of the DNA products and alignment with the HAV sequence deposited in the GenBank, six water samples showed the nucleotide sequence associated with HAV. The 120 nucleotides in the N-terminal VP1 region obtained from two swamp samples showed 95 and 96.7% identity to HAV genotype IA. In nearly all water samples where HAV was present bacterial indicators (faecal coliforms and Escherichia coli) were found for faecal contamination. Conclusions: A coupled virus concentration method and RT-nested PCR was successfully applied to examine HAV in water samples collected from various sources. DNA sequencing of nested PCR products showed the genotype IA associated with HAV that is predominate in Thailand. Significance and Impact of the Study: This research is the first study of genetic sequence of HAV in water samples in Thailand. The presence of naturally occurring HAV might pose a potential health risk for people. © 2006 The Society for Applied Microbiology.
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    Hepatitis B sero-prevalence and risk factors among school-age children in a low socioeconomic community, Bangkok.
    (1995-01-01) P. Luksamijarulkul; P. Maneesri; L. Kittigul; Mahidol University
    A cross-sectional study of 165 school-age children who had no history of HBV vaccination was carried out in a low socioeconomic community of Din-Daeng, Bangkok. Blood specimens were collected for determination of HBV seromarkers (HBsAg, Anti-HBs and Anti-HBc) by EIA commercial kits. The results showed that the prevalence of HBV seromarkers was 24.85%, the HBsAg carrier rate was 3.64%, the anti-HBs positive rate was 15.15%, and the prevalence of only anti-HBc was 6.06%. To investigate factors associated with the positivity of HBV seromarkers, children were divided into two groups--the first group consisted of 41 children with HBV seromarkers and the second consisted of 124 children without HBV seromarkers. The study variables between the two groups were compared and analysed. The results revealed that factors associated with HBV positivity were (a) child factors: child's age, child's sex, ear piercing in female, sharing blade during haircutting, contact wound from other persons, using wares with other persons, searching things in garbage, and (b) family factors: older parent, low education in parent, low family income per month, low parent's knowledge and attitude about HBV infection and vaccination, (P < 0.05). After using stepwise regression analysis, the factor of ear piercing in female was only one significant variable.
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    Microbiological quality of drinking water and using water of a Chao Phya River community, Bangkok.
    (1994-12-01) P. Luksamijarulkul; V. Pumsuwan; S. Pungchitton; Mahidol University
    Safe water is essential for good health of humans. The contamination of water with infected fecal material is common in areas with poor standards of hygiene and sanitation. The determination of microbiological quality of water is essential. Simple routine testing of the bacteriological quality of drinking water is designed to detect the presence of coliform bacteria and virological assessment is to detect the presence of enteric viruses, especially hepatitis A virus (HAV). Therefore, this study attempted to determine the HAV and coliform bacteria contamination in drinking water and using water of a Chao Phya River community, Bangkok where crowded living conditions increase the risk of water-related diseases. 95 samples of drinking water and 75 samples of used water in containers were collected with sterile technique for determining HAV antigen by ELISA and coliform contamination by the Most Probable Number Technique (MPN). The results revealed that HAV and coliform contamination rates of drinking water were 25.26% and 64.21%, respectively. The rain water had the highest contamination (60.00% and 80.00%). Tap water was 23.73% for HAV (14/59 samples) and 64.41% for coliforms (38/59 samples) whereas running water had the least contamination (2.94% for HAV and 5.88% for coliforms). The contamination rates of used water were 10.69% for HAV and 68.67% for coliforms.