From Perpetual Wetness to Soil Chemistry: Enumerating Environmental and Physicochemical Factors Favoring Oncomelania hupensis quadrasi Snail Presence in the Municipality of Gonzaga, Cagayan, Philippines.

Snail control to complement mass drug administration is being promoted by the World Health Organization for schistosomiasis control. Oncomelania hupensis quadrasi, the snail intermediate host of Schistosoma japonicum in the Philippines, has a very focal distribution; thus, scrutinizing baseline data and parameters affecting this distribution is very crucial. In this study in Gonzaga, Cagayan, Philippines, snail habitats were surveyed, and the various factors affecting the existence of the snails were determined. Malacological surveys and the mapping of sites of perpetual wetness in five endemic and five neighboring non-endemic barangays were conducted. Environmental and physicochemical factors were also examined. Maps of both snail and non-snail sites were generated. Of the fifty sites surveyed, O. h. quadrasi were found in twelve sites, and two sites yielded snails that were infected with S. japonicum cercariae. Factors such as silty loam soil, proximity to a snail site, water ammonia, and soil attributes (organic matter, iron, and pH) are all significantly associated with the presence of snails. In contrast, types of habitats, temperatures, and soil aggregation have no established association with the existence of snails. Mapping snail sites and determining factors favoring snail presence are vital to eliminating snails. These approaches will significantly maximize control impact and minimize wasted efforts and resources, especially in resource-limited schistosomiasis endemic areas.

The Global Prevalence of Schistosoma mansoni, S. japonicum, and S. haematobium in Pregnant Women: A Systematic Review and Meta-Analysis.

Schistosomiasis is a neglected tropical disease affecting 40 million women of childbearing age worldwide. Its global disease prevalence among pregnant women is still unknown. This meta-analysis determined the pooled prevalence of schistosomiasis among pregnant women globally. Additionally, this study also determined the pooled prevalence based on infection intensity based on eggs per gram. Observational studies on the prevalence of schistosomiasis among pregnant patients were obtained from Medline, Scopus, and CINAHL from January 2001 until August 2020. A review of titles and abstracts was done independently by six reviewers. The quality of the included studies was assessed using the Newcastle-Ottawa Scale for case-control, cohort, and cross-sectional studies. A total of 27 studies were included in the meta-analysis and meta-regression. The pooled prevalence of S. haematobium was 13.44 (CI: 8.90-19.80) per 100 observations, while the pooled prevalence of S. mansoni was 12.18 (CI: 4.47-29.12) per 100 observations. The prevalence of S. japonicum infection in one study was 53.54 (CI: 43.23-63.62) per 100 observations. Our results showed a prevailing health problem of schistosomiasis during pregnancy in various countries worldwide. This strengthens the need to conduct more schistosomiasis research, prevention, and control programs in pregnant women.

Circulating microRNAs as Biomarkers of Hepatic Fibrosis in Schistosomiasis Japonica Patients in the Philippines.

Host-derived microRNAs (miRNAs) play important regulatory roles in schistosomiasis-induced hepatic fibrosis. This study analyzed selected serum miRNAs among Filipino schistosomiasis japonica patients with ultrasound (US)-detectable hepatic fibrosis. A prospective cohort study design with convenience sampling was employed from 2017 to 2019. The study sites were eight endemic barangays in Leyte, Philippines. Eligible chronic schistosomiasis patients with varying severities of hepatic fibrosis were enrolled in the cohort and serially examined at 6, 12, and 24 months from baseline. Baseline serum miR-146a-5p, let-7a-5p, miR-150-5p, miR-122-5p, miR-93-5p, and miR200b-3p were measured using RT-qPCR. A total of 136 chronic schistosomiasis patients were included in this prospective cohort study. Approximately, 42.6% had no fibrosis, 22.8% had mild fibrosis, and 34.6% had severe fibrosis at baseline The serum levels of the antifibrotic miR-146a (p < 0.0001), miR-150 (p = 0.0058), and let-7a (p < 0.0001) were significantly lower in patients with hepatic fibrosis while the profibrotic miR-93 (p = 0.0024) was elevated. miR-146a-5p (AUC = 0.90, 95% CI [0.84, 0.96], p < 0.0001) has the most promising potential to differentiate patients with (n = 78) versus without (n = 58) hepatic fibrosis. The baseline level of serum miR-146-5p was significantly different in patients with progressive fibrosis (n = 17) compared to those who never developed fibrosis (n = 30, p < 0.01) or those who had fibrosis reversal (n = 20, p < 0.01) after 24 months. These findings demonstrate the potential utility of serum miRNAs, particularly of miR-146a, as a supplementary tool for assessing hepatic fibrosis in chronic schistosomiasis japonica patients.

Diagnostic Performance of Parasitological, Immunological, Molecular, and Ultrasonographic Tests in Diagnosing Intestinal Schistosomiasis in Fieldworkers From Endemic Municipalities in the Philippines.

Schistosomiasis remains to ha/ve a significant public health impact in the Philippines. The Kato-Katz (K-K) technique is the reference standard and most used technique for definitive diagnosis of intestinal schistosomiasis for control programs in endemic regions. However, this has a very low sensitivity when applied in areas of low endemicity and patients with light infection. Hence, this study determined the diagnostic performance of immunological, molecular, parasitological, and ultrasonographic tests in diagnosing intestinal schistosomiasis in endemic municipalities in the Philippines. We performed a community-based cross-sectional study to determine the positivity of schistosomiasis in Leyte, Philippines. The diagnostic performance of five different detection techniques: (1) three stool K-K with duplicate smears; (2) soluble egg antigen IgG ELISA; (3) urine point-of-care circulating cathodic antigen (POC-CCA) test; (4) detection of Schistosoma japonicum circulating DNA (SjcDNA) in serum and urine samples; (5) focused abdominal ultrasound (US), were also obtained in this study. Multiple stool examinations enhanced the sensitivity of K-K from 26.2% (95% CI [16.4, 38.8]) with single stool to 53.8% (95% CI [41.1, 66.1]) and 69.2% (95% CI [56.4, 80.0]) with two and three stools from consecutive days, respectively. Among the SjcDNA nucleic acid amplification test (NAAT)-based detection assays, loop-mediated isothermal amplification (LAMP) PCR using sera had the highest sensitivity at 92.3% (95% CI [82.2, 97.1]) with LAMP consistently identifying more positive cases in both serum and urine samples. This study showed that single stool K-K, which remains the only diagnostic test available in most endemic areas in the Philippines, had low sensitivity and failed to identify most patients with light infection. SjcDNA detection assay and POC-CCA urine test were more sensitive than stool microscopy in detecting schistosomiasis. On the other hand, US was less sensitive than the widely utilized K-K technique in diagnosing schistosomiasis. This study emphasizes the need to revisit the use of single stool K-K in the surveillance and case detection of schistosomiasis in endemic areas of the Philippines. The availability of advanced and more sensitive diagnostic tests will help better control, prevent, and eliminate schistosomiasis in the country.

Prevalence and spatial distribution of heterophyidiasis in Southern Philippines.

Heterophyidiasis is a fish-borne zoonotic disease that is considered to be an emerging public health problem in the Philippines. This study was carried out to determine the spatial distribution and risk factors of heterophyidiasis in five selected villages in New Corella, Davao del Norte in Southern Mindanao. Of the 1,101 individuals examined, 26 (2.36% overall prevalence rate, 95% CI 1.46-3.25) were positive for heterophyid eggs. Higher infection rate was observed in males (3.85%, 95% CI 2.27-5.43) than females (0.76%, 95% CI 0.02-1.5). Mapping of cases was done to show the spatial distribution of heterophyidiasis in New Corella. Multiple logistic regression analysis showed that gender, raw freshwater fish consumption, undercooked grilled fish consumption and proximity to rivers or creeks are the risk factors significantly associated with heterophyid infection. This study confirmed the presence of heterophyid infection in humans in the surveyed villages in New Corella in Southern Philippines.

Oncomelania hupensis quadrasi: Snail intermediate host of Schistosoma japonicum in the Philippines.

Oncomelania hupensis quadrasi is the snail intermediate host of Schistosoma japonicum in the Philippines. It was discovered by Dr. Marcos Tubangui in 1932 more than two decades after the discovery of the disease in the country in 1906. This review, the first for O. h. quadrasi, presents past and present works on the taxonomy, biology, ecology, control, possible paleogeographic origin of the snail intermediate host and future in research, control and surveillance of the snail. Extensive references are made of other subspecies of O. hupensis such as the subspecies in China for which majority of the advances has been accomplished. Contrasting views on whether the snail is to be considered an independent species of Oncomelania or as one of several subspecies of Oncomelania hupensis are presented. Snail control methods such as chemical methods using synthetic and botanical molluscicides, environmental manipulation and biological control are reviewed. Use of technologies such as Remote Sensing, Geographical Information System and landscape genetics is stressed for snail surveillance. Control and prevention efforts in the Philippines have consistently focused on mass drug administration which has proved inadequate in elimination of the disease. An integrated approach that includes snail control, environmental sanitation and health education has been proposed. Population movement such as migration for employment and economic opportunities and ecotourism and global climate change resulting in heavy rains and flooding challenge the gains of control and elimination efforts. Concern for possible migration of snails to non-endemic areas is expressed given the various changes both natural and mostly man-made favoring habitat expansion.

Modelling the impact of MAUP on environmental drivers for Schistosoma japonicum prevalence.

BACKGROUND: The modifiable areal unit problem (MAUP) arises when the support size of a spatial variable affects the relationship between prevalence and environmental risk factors. Its effect on schistosomiasis modelling studies could lead to unreliable parameter estimates. The present research aims to quantify MAUP effects on environmental drivers of Schistosoma japonicum infection by (i) bringing all covariates to the same spatial support, (ii) estimating individual-level regression parameters at 30 m, 90 m, 250 m, 500 m and 1 km spatial supports, and (iii) quantifying the differences between parameter estimates using five models. METHODS: We modelled the prevalence of Schistosoma japonicum using sub-provinces health outcome data and pixel-level environmental data. We estimated and compared regression coefficients from convolution models using Bayesian statistics. RESULTS: Increasing the spatial support to 500 m gradually increased the parameter estimates and their associated uncertainties. Abrupt changes in the parameter estimates occur at 1 km spatial support, resulting in loss of significance of almost all the covariates. No significant differences were found between the predicted values and their uncertainties from the five models. We provide suggestions to define an appropriate spatial data structure for modelling that gives more reliable parameter estimates and a clear relationship between risk factors and the disease. CONCLUSIONS: Inclusion of quantified MAUP effects was important in this study on schistosomiasis. This will support helminth control programmes by providing reliable parameter estimates at the same spatial support and suggesting the use of an adequate spatial data structure, to generate reliable maps that could guide efficient mass drug administration campaigns.

Current status of neglected tropical diseases (NTDs) in the Philippines.

In the Philippines, ten NTDs are prevalent, but only six namely LF, schistosomiasis, STH, food-borne trematodiases, rabies and leprosy are considered to be of public health importance. The 81 provinces in the country are endemic for at least one of these NTDs. Others may be endemic for two or even more of these diseases. Since 2000, after the Philippines accepted and implemented the WHO guidelines for NTDs prevention, control and elimination, significant progress has been achieved in reducing the magnitude of NTDs endemic in the country. Since 2009, out of 46 filariasis-endemic provinces, the number of provinces that has eliminated LF has progressively increased so that by 2015, 76% are already LF-free. By 2019, only four provinces remain endemic for LF. For schistosomiasis, as of 2012, report from the Department of Health (DOH) put the number of high endemic provinces at 10, moderately endemic at 6 and low to elimination levels at 12. For STH, results of the National Parasite Survey in the Philippines among school-aged children conducted in 2015 by the Research Institute for Tropical Medicine, the research arm of the Philippine DOH, however, showed that the overall cumulative prevalence was 28.4% with a prevalence range between 7.1% and 67.4%. The figures are way above the <20% prevalence standard set by the World Health Organization. Control and prevention efforts for FBTs just gained traction with the call of WHO for elimination of NTDs in 2015. There is an urgent need to update information by an intensive national baseline survey that can validate previous data as well as generate new information on the magnitude of the FBT problem in the Philippines. For leprosy, elimination activities have been intensified in high prevalence areas and from 2009 to 2013, case detection and prevalence were sustained at <1.0 per 10,000 population. Rabies elimination activities have been effective that by 2011, only five regions out of 16 remained with the highest number of rabies cases. In a period of seven years from 2010 to 2017, the number of rabies-free provinces and municipalities increased from 3 to 49. Problems continue to hound the NTD programmes in the Philippines as priorities shift to more urgent health problems in a country that is weighed down not only by the triple burden of disease but serious health consequences of emergencies and disasters and the fast-growing population itself. Paradigm shifts are suggested to replace the traditional and conventional perspectives of control. These include change from disease approach to intervention approach to allow for integration of strategies targeting several NTDs and multisectoral, multidisciplinary approach requiring strong, viable and sustainable partnerships involving various agencies of the government, public and private sector, pharmaceuticals, academe, researchers, local government units and the endemic communities themselves.

Detection of Schistosoma japonicum and Oncomelania hupensis quadrasi environmental DNA and its potential utility to schistosomiasis japonica surveillance in the Philippines.

In recent years, the prevalence and infection intensity of Schistosoma japonicum in endemic areas of the Philippines have significantly decreased due to yearly population-based treatment strategies, yet transmission rates remain high and uninterrupted. An important indicator of active disease transmission is the presence of Schistosoma japonicum and its snail intermediate host Oncomelania hupensis quadrasi in freshwater habitats. In this study, we sought to apply a species-specific real-time PCR (qPCR) assay for the detection of S. japonicum and O. hupensis quadrasi in freshwater samples using environmental DNA approach that can complement the commonly utilized malacological survey in determining potential transmission foci in order to have a more effective snail surveillance strategy for schistosomiasis japonica in endemic areas. The newly developed assay was specific to S. japonicum and O. hupensis quadrasi with no amplification detected against non-target trematode Fasciola spp. and snails such as Lymnaea spp., Pomacea canaliculata, and Melanoides spp. that typically co-exist in the same environment. The assay effectiveness was determined using 19 environmental water samples collected from Northern Samar (N = 5 sites), Leyte (N = 11 sites) and Compostela Valley (N = 3 sites) and compared to malacological survey for determining O. hupensis quadrasi snail colonies and snail crushing to visualize S. japonicum cercariae. TaqMan qPCR targeting a short fragment of the cytochrome c oxidase subunit 1 (cox1) gene was positive for S. japonicum in 9 sites, for O. hupensis quadrasi in 9 sites, and for both S. japonicum and O. hupensis quadrasi in 5 sampling sites. Moreover, it was able to detect O. hupensis quadrasi in 3 out of 12 sites found negative and 6 out of 7 sites found positive through malacological survey, and in 4 of the 5 snail sites positive for snails with cercariae. Overall, this method can complement malacological surveys for monitoring of schistosomes in endemic areas of the Philippines, especially those with high risk of human infection.