RESUMEN
Physiographic and hydrologic complexities play major role in determining the habitat suitability for river dolphins. However, dams and other water development structures alter hydrologic regimes that degrade habitat conditions. For the three extant species of obligate freshwater dolphins, namely: Amazon dolphin (Inia geoffrensis), Ganges dolphin (Platanista gangetica), and Indus dolphin (Platanista minor), the threat is high as dams and water-based infrastructure dotted throughout their distribution range impact dolphin populations by restricting their movement. But there is also evidence of localized increase in dolphin population in certain segments of habitats affected by such hydrologic alterations. Hence, the impacts of hydrologic alterations on dolphin distribution are not as binary as it seems. We aimed to ascertain the role of hydrologic and physiographic complexities in determining the distribution of the dolphins in their geographic ranges using density plot analysis and also to understand how hydrologic alterations in the rivers affect their distribution using a combination of density plot analysis and review of literature. The influence of some of the study variables such as distance to confluence and sinuosity was similar across species-for instance, all three dolphin species preferred slightly sinuous river segments and habitats near confluences. However, varying influences across species were observed for some other variables such as river order and river discharge. We assessed 147 cases of impacts of hydrological alterations on dolphin distribution by categorizing the reported impacts in nine broad types out of which habitat fragmentation accounted for the majority of the impacts (35%) followed by habitat reduction (24%). These endangered species of freshwater megafauna will experience further intensified pressures as more large-scale hydrologic modifications such as damming and diversion of rivers are underway. In this context, basin-scale water-based infrastructural development planning should take into consideration the salient ecological requirements of these species to ensure their long-term survival.
RESUMEN
INTRODUCTION: Intestinal parasitic infections are most common and prevalent among children and accounts for great morbidity and mortality. OBJECTIVE: This research is aimed at studying the prevalence and related risk factors of parasitic infections among private school-going pupils of Dharan Submetropolitan City. METHODS AND MATERIALS: This was a cross-sectional laboratory-based study conducted from 13 November 2018 to 26 February 2019 among 400 private school pupils. The stool samples were collected and microscopically examined for parasites using the formalin ethyl acetate sedimentation technique. Data Analysis. Statistical analysis was performed by using SPSS version 16.0. Pearson's Chi-square test was used to establish association between dependent and independent variables. The association was also determined using crude and adjusted odds ratio, and the test considered a P value < 0.05 as statistically significant with 95% confidence interval. RESULT: In this study, 46 (11.5%) children were positive for intestinal parasites. In this study, 3 protozoans (Entamoeba histolytica = 3 (0.75%)) and 43 helminths (Ascaris lumbricoides = 22 (5.5%); Enterobiusvermicularis = 6 (1.5%); Ancylostoma duodenale = 2 (0.5%); and Trichuris trichiura = 13 (3.25%)) were isolated and identified. Statistically, significant difference in the parasitic prevalence with respect to age and gender was not seen (P > 0.05). However, the prevalence of parasitic infection was strongly associated with the ethnicity of the pupils (P = 0.001). The strong associated risk factors of intestinal parasitic infections were nail-biting habit, source of drinking water, biannual deworming, thumb-sucking, hand sanitation before having food and after toilet, knowledge of parents on parasitosis, health and sanitation, keeping cat/dog as pet, and wearing protective shoes during play (P = 0.001). Bowel syndromes like abdominal cramp and constipation also had a strong statistical association (P = 0.001) with the prevalence of parasitic infection. According to binary and multivariate logistic regression analyses, the parents without awareness, pupils with a nail-biting habit, pupils not wearing shoes during play, lack of deworming, drinking direct tap water, and pupils with poor hand sanitation were more likely to be infested with intestinal parasitic infections. CONCLUSION: This study concludes that intestinal parasites are still prevalent among private school-going pupils of Dharan Submetropolitan City. The poor sanitation and sanitary habits like biting nails, consumption of untreated drinking water, and failure to practice proper hand washing were studied as contributors to the acquisition of intestinal parasitic infections. Therefore, integration of control measures such as provision of clean and safe drinking water, improved sanitation and hygiene, with biannual administration of drugs are necessary for effective eradication of parasitic infections.
