Dusit Sujirarat

Norovirus GII-4 2006b Variant Circulating in Patients With Acute Gastroenteritis in Thailand During a 2006-2007 Study

Noroviruses (NoVs) are recognized as a significant cause of acute gastroenteritis in children and adults. A 14‐month study, from January 2006 to February 2007, was undertaken in a hospital in Thailand to determine the prevalence and genetic characterization of NoVs in patients of all ages with acute gastroenteritis. Based on reverse transcription‐nested polymerase chain reaction (RT‐nested PCR), NoVs were detected in 122 of 273 (44.7%) collected stool samples. Of the 122 NoV‐positive samples, 28 (23%) belonged to GI, 79 (64.8%) belonged to GII, and 15 (12.2%) were mixed infections of GI and GII strains. Three NoV GI‐positive and 42 NoV GII‐positive samples were characterized successfully by DNA sequencing of the RT‐nested PCR products and phylogenetic analysis. For NoV GI, two genotypes were identified: GI‐2 (one sample) and GI‐6 (two samples). NoV GII could be classified further into five distinct genotypes: GII‐2 (1 sample), GII‐3 (3 samples), GII‐4 (14 samples), GII‐6 (3 samples), and GII‐17 (2 samples), and one unclassified genotype (19 samples). All NoV GII‐4 strains showed 88–98% nucleotide identity with NoV GII‐4 2006b variants reported worldwide. Among genotypes of NoV characterized, one co‐infected stool sample exhibited NoVs GI‐6 and GII‐4 2006b. This study suggests that there is an important role of NoVs as etiologic agents in patients with acute gastroenteritis. The predominant circulating genotype of NoV infections is GII‐4 2006b variant. J. Med. Virol. 82: 854–860, 2010.

An improved method for concentrating rotavirus from water samples

A modified adsorption-elution method for the concentration of seeded rotavirus from water samples was used to determine various factors which affected the virus recovery. An enzyme-linked immunosorbent assay was used to detect the rotavirus antigen after concentration. Of the various eluents compared, 0.05M glycine, pH 11.5 gave the highest rotavirus antigen recovery using negatively charged membrane filtration whereas 2.9% tryptose phosphate broth containing 6% glycine; pH 9.0 was found to give the greatest elution efficiency when a positively charged membrane was used. Reconcentration of water samples by a speedVac concentrator showed significantly higher rotavirus recovery than polyethylene glycol precipitation through both negatively and positively charged filters (p-value <0.001). In addition, speedVac concentration using negatively charged filtration resulted in greater rotavirus recovery than that using positively charged filtration (p-value = 0.004). Thirty eight environmental water samples were collected from river, domestic sewage, canals receiving raw sewage drains, and tap water collected in containers for domestic use, all from congested areas of Bangkok. In addition, several samples of commercial drinking water were analyzed. All samples were concentrated and examined for rotavirus antigen. Coliforms and fecal coliforms (0->1,800 MPN/100 ml) were observed but rotavirus was not detected in any sample. This study suggests that the speedVac reconcentration method gives the most efficient rotavirus recovery from water samples.

Determination of tumor necrosis factor-alpha levels in dengue virus infected patients by sensitive biotin-streptavidin enzyme-linked immunosorbent assay.

A modified sandwich enzyme-linked immunosorbent assay using biotin-streptavidin system (BS-ELISA) was developed to determine levels of tumor necrosis factor-alpha (TNF-alpha) in serum samples of children infected with dengue virus (n=99) and healthy controls (n=41). The minimum detectable concentration of TNF-alpha by the BS-ELISA was 3.3 pg/ml. The mean TNF-alpha level was highest in those patients with dengue shock syndrome (DSS) or dengue hemorrhagic fever (DHF) grade III (37.44+/-42.0 pg/ml). Lower levels were found in DHF grade I (28.44+/-42.7 pg/ml), DHF grade II (24. 21+/-25.4 pg/ml) and dengue fever (DF) (14.10+/-24.0 pg/ml). TNF-alpha in the sera of DF and DHF patients could be detected on days 2-6 after the onset of fever, the high level occurring on day 5. TNF-alpha was detected in 41.4% (24.01+/-35.2 pg/ml) of dengue virus infected patients and 7.3% (4.2+/-15.6 pg/ml) of control subjects. The sera of patients contained significantly higher levels of TNF-alpha than the sera of controls, P-value<0.001. DHF patients had significantly higher levels of TNF-alpha than DF patients (P-value=0.020) but no difference in the TNF-alpha levels from sera of DHF grades I-III patients was observed (P-value=0.295). The results indicate that the BS-ELISA is a very sensitive method for determining TNF-alpha in serum samples of DF and DHF patients. The TNF-alpha levels might be associated with dengue virus infection and related to disease severity of DHF.

Serum Cholinesterase Levels of Thai Chilli-Farm Workers Exposed to Chemical Pesticides: Prevalence Estimates and Associated Factors

Serum Cholinesterase Levels of Thai Chilli‐Farm Workers Exposed to Chemical Pesticides: Prevalence Estimates and Associated Factors: Prasit Kachaiyaphum, et al. Faculty of Public Health, Mahidol University, Thailand

Determining the burden of secondhand smoke exposure on the respiratory health of Thai children

BackgroundThe impact of secondhand smoke (SHS) on Southeast Asian children’s health has been assessed by a limited number of studies. The purpose of this study was to determine whether in Thailand, pre- and postnatal exposure to SHS is associated with acute lower respiratory conditions in young children.MethodsWe conducted a case control study of 462 children under age five admitted with acute lower respiratory illnesses, including asthma and pneumonia, at a major hospital in Bangkok. We selected 462 comparison controls from the well-child clinic at the hospital and matched them by sex and age. We used a structured questionnaire to collect information about exposure to SHS and other factors. We conducted bivariate and multivariate analyses to identify risk factors for acute lower respiratory conditions.ResultsThe number of cigarettes smoked at home per day by household members was significantly greater among cases. A greater number of household caregivers of cases held and carried children while smoking as compared to controls (26% versus 7%, p <0.05). Cases were more likely to have been exposed to SHS in the household (adjusted OR = 3.82, 95% CI = 2.47-5.9), and outside (adjusted OR = 2.99, 95% CI = 1.45-6.15). Parental lower educational level and low household income were also associated with respiratory illnesses in Thai children under five.ConclusionsThai children who are exposed to SHS are at nearly 4 times greater risk of developing acute lower respiratory conditions. Continued effort is needed in Thailand to eliminate children’s exposure to SHS, especially at home.

Glyphosate and Paraquat in Maternal and Fetal Serums in Thai Women

ABSTRACT Objectives: This longitudinal study measured the glyphosate and paraquat concentrations found in maternal and umbilical cord serum in 82 pregnant women who gave birth in three provinces of Thailand. Methods: Through questionnaires and biological samples collected at childbirth, factors such as personal characteristics, family members occupation, agricultural activities, and herbicide use in agricultural work were evaluated as predictors of glyphosate and paraquat levels in the pregnant women. Statistical analysis used univariate and binary multiple logistic regression, where the outcome was the probability of exposure to paraquat or glyphosate above the limit of detection associated with occupation and household factors. Results: The glyphosate concentrations in the pregnant women’s serum at childbirth (median: 17.5, range: 0.2–189.1 ng/mL) were significantly higher (P < .007) than those in the umbilical cord serum (median: 0.2, range: 0.2–94.9 ng/mL). However, the paraquat concentrations in the serum of the pregnant women at childbirth (83% ≤limit of detection [LOD], with maximum of 58.3 ng/mL) were similar to those in the umbilical cord serum (80% LOD in serum at childbirth were 11.9 times more likely to report work as an agriculturist (P < .001), 3.7 times more likely to live near agricultural areas (P = .006), and 5.9 times more likely to have a family member who worked in agriculture (P < .001). The only factors affecting paraquat exposures in pregnant women at childbirth were reporting the agricultural activity of digging in farm soil and working in the agricultural fields in the third trimester of pregnancy. Conclusions: These results show that pregnant women who work in agriculture or live in families that work in agriculture have higher exposures to the herbicides glyphosate and paraquat. The potential for long-term health impacts of these prenatal exposures to children should be evaluated, and greater regulation of the sale and use of herbicides should be considered in Thailand.

Factors influencing preventive behaviors for dengue infection among housewives in Colombo, Sri Lanka.

Dengue is an infectious disease prevalent in Sri Lanka. Some factors may influence preventive behaviors. This cross-sectional study aimed to determine the knowledge, attitude, and preventive behaviors associated with dengue and analyzed the factors influencing preventive behaviors among housewives in Colombo, Sri Lanka. The analytical study was designed, and data were collected using a structured questionnaire. The χ2 test and binary logistic regression were used to analyze data. The mean age of housewives was 39.41 years, 91% were married, 52% were Buddhist, and 46.5% had a family monthly income of 15 000 to 25 000 rupees. The knowledge of dengue preventive behaviors was 69.2%. The majority (91.5%) had a positive attitude toward dengue prevention. Only 39.3% used a mosquito net, and 89.3% had water storage container covers. Overall, 58.5% were knowledgeable about preventive measures. Age, religion, family income, education, knowledge, and attitude were associated with preventive behaviors. These findings are useful for dengue control in Colombo.

The Impact of Cigarette Plain Packaging on Health Warning Salience and Perceptions: Implications for Public Health Policy

The study employed a mixed methods design using focus group interviews with 6 student groups and self-administered questionnaires with 1239 students. The participants were nonsmoking, current smokers, and quit-smoking teenagers from secondary schools and colleges. Focus group revealed that although nonsmoking teenagers perceived fear appeals to warning messages, current smokers did not perceive fear appeals to health. Black and white backgrounds of the cigarette package were chosen as the best color for plain packaging. However, most participants suggested various pictorials and a bigger size of pictorial warnings for greater and more effective fear appeal. Odds ratio showed that males had 2.43 times the odds to perceive intention not to smoke. Teenagers who had never smoked and those who had quit smoking had 13.27 and 3.61 times the odds, respectively, to perceive intention not to smoke.

Respiratory effects among rubberwood furniture factory workers in Thailand.

ABSTRACT Respiratory symptoms and pulmonary function were examined among 89 rubberwood furniture factory workers. Acute and chronic irritant symptoms were assessed, lung function was measured both pre- and post-shift and personal inhalable dust exposure determined. The only symptoms with a significant increase among high dust level–exposed workers (>1 mg/m3) were those related to nasal irritation. High dust level–exposed workers had a significant cross-shift decrease in forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) compared with low dust level–exposed workers and increases in inhalable dust concentration levels (mg/m3) were significantly associated with decreases in the peak expiratory flow (PEF) across the work shift. For percent predicted pulmonary function levels, a significant decrement in PEF was found for high versus low rubberwood dust level–exposed workers, after controlling for confounders. These findings suggest the need for an occupational standard for rubberwood dust in Thailand.

Novel ellipsoid spatial analysis for determining malaria risk at the village level.

The distribution patterns of malaria incidence at a village level in Thailand were demonstrated with the use of a geographical information system (GIS), and provided the study of the malaria situation at a household level. Mosaic imageries from aerial photographs were used to create maps that contained X and Y coordinates. These digitized base maps were kept as computerized files. Standard Distance Ellipse (SDE) was used to measure the prevalence of dispersion around the mean center of malaria cases and points. Households in the SDE were at greater risk of malaria infection than those located outside the SDE. The spatial pattern of malaria incidence was investigated using spatial autocorrelation using Gearys ratio and Morans index. Five of seven villages had a clustered spatial distribution of malaria incidence, the vector point of which had a 2-3km range from the patients houses. Only one village had a significant clustered spatial distribution of malaria incidence (p<0.05). Control efforts should be focused on high-risk areas, especially those households with the heaviest caseloads. This approach would probably be more cost effective than the conventional malaria control methods. This SDE analytical technique would be a novel and useful epidemiological control method for use by public health administrators. The ellipsoidal areas required malaria control intervention.