Opisthorchis viverrini and Strongyloides stercoralis mono- and co-infections: Bayesian geostatistical analysis in an endemic area, Thailand

Epidemiology of Strongyloides stercoralis and Opisthorchis viverrini infections in northern and northeastern Thailand: Insights from urine-ELISA surveys

Strongyloides stercoralis and Opisthorchis viverrini are helminth parasites responsible for significantly neglected tropical diseases. This study aimed to evaluate the prevalence of these parasites and the risk factors for S. stercoralis and O. viverrini infections in northern and northeastern Thailand where relevant epidemiological data are scarce and outdated. A cross-sectional study was conducted in 2016 in six sub-districts across five provinces. Urine samples were analyzed to detect S. stercoralis and O. viverrini infection using urine enzyme-linked immunosorbent assays (urine-ELISA). Demographic data of participants were collected using a questionnaire. Environmental data, including land-surface temperature (LST), normalized difference vegetation index (NDVI), normalized difference water index (NDWI), and soil pH, were obtained from remote-sensing sources. Multiple logistic regression analysis identified risk factors associated with infection. Complete data were obtained for 2613 individuals. The overall prevalence was 39.15% (95% CI: 37.27-41.02) for S. stercoralis and 37.46% (95% CI: 35.61-39.32) for O. viverrini. Male sex was significantly associated with S. stercoralis (AOR, 1.53; 95% CI, 1.29-1.80, p < 0.001) and O. viverrini infections (AOR, 1.69; 95% CI, 1.43-2.00, p < 0.001). The prevalence of S. stercoralis infection increased with age. Spatially, the odds of S. stercoralis infection decreased with higher LST and soil pH, while O. viverrini infection was associated with higher soil pH and proximity to water bodies. Strongyloides stercoralis and O. viverrini are highly prevalent in these regions, highlighting the need for surveillance.

High-resolution mapping of age- and gender-specific risk of Clonorchis sinensis infection risk in Guangdong, China: a geostatistical modeling study

BACKGROUND

The latest national survey on the distribution of human parasites in China demonstrated that Guangdong was among the endemic provinces with the highest Clonorchis sinensis infection rates. High-resolution, age- and gender-specific risk maps of the temporal and spatial distributions are essential for the targeted control work.

METHODS

Disease data on the prevalence of C. sinensis infection from 1990 onwards, either age- and gender-specific or aggregated across age and gender, were collected through systematic review and four large-scale surveys in Guangdong Province. Environmental and socioeconomic variables were obtained from open-access databases and employed as potential predictors. A Bayesian geostatistical model was developed to estimate the C. sinensis infection risk at high spatial resolution.

RESULTS

The final dataset included 606 surveys at 463 unique locations for C. sinensis infection. Our findings suggested that following an initial increase and stabilization, the overall population-adjusted prevalence had declined to 2.2% (95% Bayesian credible interval: 1.7-3.0%) in the period of 2015 onwards. From 2015 onwards, moderate and high infection risks were found in the northern regions (e.g. Heyuan and Shaoguan cities) and the southern Pearl River Delta (e.g. Foshan, Zhongshan, Zhuhai and Jiangmen cities), respectively. Age- and gender-specific risk maps revealed that males had a higher infection risk than females, and the infection risk was higher in adults compared to children.

CONCLUSIONS

Our high-resolution risk maps of C. sinensis infection in Guangdong Province identified the spatial, temporal, age and gender heterogeneities, which can provide useful information assisting tailored control strategies.

Current prevalence and geographic distribution of helminth infections in the parasitic endemic areas of rural Northeastern Thailand

BACKGROUND

Helminth infection is a global health issue that not only causes acute helminthiasis but long-term infection may lead to complicated symptoms as well as severe complications. The World Health Organization cooperated with the Ministry of Public Health in many countries, particularly where high prevalence, spending a lot of resources for limiting the infection. In Thailand, the incidence of parasitic helminth infections was continuously declined in the last few decades according to several campaigns for parasitic elimination. However, the rural community in the northeast of Thailand where the highest prevalence of the country still needs to be monitored. This present study aims to report the current prevalence of parasitic helminth infections in Nakhon Ratchasima and Chaiyaphum provinces where sharing a huge area of the northeastern region of Thailand but only a few studies have been published.

METHODS

The stool specimens were collected from 11,196 volunteers and processed by modified Kato-Katz thick smear, PBS-ethyl acetate concentration techniques, and PCR. The epidemiological data were collected, analyzed, and used for generating of parasitic hotspots.

RESULTS

The results indicated that O. viverrini remains the major parasite in this area with a total prevalence of 5.05% followed by Taenia spp., Hookworms, T. trichiura, and Echinostoma spp., respectively. Mueang district of Chaiyaphum province has the highest prevalence especially O. viverrini with a prevalence of 7.15% that higher than the latest national surveillance. Interestingly, the prevalence of O. viverrini was hugely reported (more than 10%) in five subdistricts. The geographic localization of O. viverrini infections revealed that a lot of water reservoirs such as the lakes or branches of the river in the two-most prevalent subdistricts. Our finding indicated that gender and age were insignificantly different.

CONCLUSION

This finding suggested that the parasitic helminth infection in the rural areas of northeast of Thailand remains high and the housing location is a major contributing factor for the parasitic infection.

Association of Strongyloides stercoralis infection and type 2 diabetes mellitus in northeastern Thailand: Impact on diabetic complication-related renal biochemical parameters

BACKGROUND

Several studies have demonstrated that helminth infections provide a degree of protection against Type 2 diabetes mellitus (T2DM). However, the relationship between Strongyloides stercoralis infection and T2DM has scarcely been investigated and the protective effect of infection against development of diabetic complications is unclear. In this study, we aimed to investigate the relationship between S. stercoralis infection and T2DM in a rural area of Khon Kaen Province, Thailand. The impact of S. stercoralis infection on diabetic complication-related kidney function biochemical parameters and body-mass index (BMI) was also assessed.

METHODOLOGY

Using a cross-sectional study design, S. stercoralis infection and T2DM assessments were conducted between October 2020 and May 2021. Associations between S. stercoralis infection, T2DM, and socioeconomic factors were analyzed using multivariable logistic regression analyses. Diabetic complication-related biochemical parameters relating largely to kidney function (estimated glomerular filtration rate (eGFR), urine albumin-to-creatinine ratio (UACR), serum creatinine, uric acid, alanine transaminase (ALT), and low-density lipoprotein cholesterol (LDL-C)) and BMI of participants with and without T2DM were compared between groups with or without S. stercoralis infection.

RESULTS

One hundred and seven out of 704 individuals (15.20%) were positive for S. stercoralis, and 283 people were diagnosed with T2DM. Of those with T2DM, 11.31% (32/283) were infected with S. stercoralis and of those without T2DM, 17.82% (75/421) were infected with S. stercoralis. Multivariate analysis revealed that T2DM was inversely correlated with S. stercoralis infection (Adjusted OR  =  0.49; 95% CI: 0.30, 0.78; p  = 0.003), while male, increasing age, lower education level, and alcohol intake were positively associated with infection. Those infected with S. stercoralis had lower eGFR levels and higher ALT and UACR levels than those in the uninfected group.

CONCLUSION

This finding indicates that S. stercoralis infection was inversely associated with T2DM in northeastern Thailand, but participants infected with S. stercoralis had lower eGFR levels and higher ALT and UACR levels. Infection with S. stercoralis might lead to worse complication-related renal biochemical parameters.