Effects of the lockdown measure amid COVID-19 pandemic on outpatient department visits associated with air pollution reduction in Thailand.

We investigated the effects of COVID-19 lockdown on air quality and its consequences health and economic benefits in Thailand. The conditional Poisson regression model was applied to examine the association between air pollution and outpatient department (OPD) visits in each province and pooled the province-specific estimates using the random-effects meta-analysis to derive the national estimates. We then applied a random forest model with meteorological normalization approach to predict the concentration of air pollutants by means of business as usual during the lockdown period (April 3-May 3) in 2020 and further calculated the changes in the number of OPD visits and their consequent expenditure attributable to air pollution reduction using the obtained risk function performed earlier. The number of cardiovascular OPD visits attributed to PM10, PM2.5 and NO2 decreased by 4,414 (95% CI 982, 8,401), 4,040 (95% CI 326, 7,770), and 13,917 (95% CI 1,675, 27,278) cases, respectively, leading to reduced medical expenditure by 14,7180.21, 13,4708.31, and 46,4025.04 USD, respectively. The number of respiratory OPD visits attributed to PM10, PM2.5, NO2, and O3 reduction decreased by 2,298 (95% CI 1,223, 3,375), 2,056 (95% CI 740, 3,252), 3,326 (95% CI 542, 6,295), and 1,160 (95% CI 5,26, 1,804) cases, respectively, where the consequent medical expenditure was reduced by 76,618.48, 68,566.36, 11,0908.31, and 38,685.50 USD, respectively. Finding from this study showed that air quality during the lockdown period in Thailand was improved, contributing to the reduction of cardiovascular and respiratory OPD visits, and consequent medical service costs attributable to air pollution.

Reinfection by Opisthorchis Viverrini after Treatment with Praziquantel.

BACKGROUND: The prevalence of infection by the liver fluke, Opisthorchis viverrini (O. viverrini), has remained high in Northeast Thailand where it is a major risk factor for the eventual development of cholangiocarcinoma (CCA). The infection is acquired by the consumption of dishes containing unsafely prepared freshwater fish, a dietary tradition which has proved resistant to change. Since many people are aware that dosing with praziquantel (PZQ) is a successful treatment for an episode of the infection, there is a risk that, to avoid the long term consequences, they will engage in a cycle of infection, dosing and reinfection. OBJECTIVES: There is a dearth of studies of reinfection by O. viverrini, and the aims of this study were to assess re-infection rates in a typical province of Northeastern Thailand where O. viverrini infection is likely and to investigate factors associated with reinfection. MATERIALS AND METHODS: A total of infected 607 villagers were treated with PZQ, and those found to be no longer infected were followed up at six-monthly intervals over 12 months. RESULTS: At the end of this period data on 457 subjects were available for analysis using descriptive statistics and logistic regression, and 50 were found to have become reinfected, giving a cumulative reinfection rate of 10.9%. The results of a multiple logistic regression analysis showed that the only factor found to be associated with reinfection was past use of PZQ. CONCLUSIONS: Recommendations are made for future larger scale and better designed reinfection studies in the light of limitations of the current study. Further efforts are needed to discourage people from eating fish dishes likely to contain viable metacariae.

Infection with Opisthorchis viverrini and use of praziquantel among a working-age population in northeast Thailand.

Infection with Opisthorchis viverrini (OV) due to eating certain traditional freshwater fish dishes is the principal risk factor for cholangiocarcinoma in Northeast Thailand where the infection is endemic and the incidence of this form of primary liver cancer has been the highest in the world. This paper is the second report of a prospective research project to monitor the impacts of a national liver fluke control programme in a rural community of Northeast Thailand. A sample of 684 villagers aged 20-65 years completed an interview questionnaire and were tested for infection using the Kato thick smear technique. The questionnaire was designed for the exploration of associations between OV infection, previous treatment with praziquantel, and knowledge and beliefs about the drug. The data were analysed using descriptive statistics and multiple logistic regression. The overall prevalence of OV infection was 37.2% and was highest in the 20-35 year age group, in those with a university degree and in those employed in the government sector. As many as 91.8% reported eating fish dishes known to place them at risk of infection. In the multiple regression analysis, previous use of praziquantel and lack of knowledge about whether or not the drug has a protective effect against re-infection were the only factors related to OV infection (ORadj= 2.31, 95%CI =1.40-3.79 and ORadj= 1.95, 95%CI= 1.24-3.05). The findings were discussed in terms of the possibly unwise dependency on praziquantel as a primary element in a control programme.

Prevalence of OV infection in Yasothon Province, Northeast Thailand.

A liver fluke, Opisthorchis viverrrini (OV), is the major cause of the high incidence of cholangiocarcinoma in Thailand. The prevalence of OV infection remains high in various parts of the country, especially in Northeast Thailand and particularly in wetland rural areas where a large proportion of the community work in agriculture and continue the traditional practice of eating raw or undercooked cyprinoid fish products. The national control program seems to have had little impact in many of these areas, and it has been difficult to make precise assessments of the overall effectiveness of the program. This paper is the first report of prospective research project designed to monitor the impact of the national control program in rural communities located in a northeastern province and at high risk of OV infection. The participants in this initial survey were 1,569 villagers, aged 20-65 years, living in two subdistricts of Yasothon Province. Stool examinations showed that 38.68% were infected with OV. Males were slightly more likely to be infected than females, but the difference was not statistically significant. Infection was found to be positively associated with age in both males and females. The preliminary data indicate that the population selected for study is suitable for the purpose of the monitoring project.