Doctor of Biomedical and Veterinary Medical Sciences-Pathobiological Sciences (PVMPB)
Soil-transmitted helminth (STH) infections impact billions of people worldwide. The traditional STH control approach is a morbidity control strategy implementing mass drug administration (MDA) programs targeting school-aged children (SAC). In Brazil, this control strategy has decreased STH prevalence to less than 20% in most of the country and providing an opportunity to transition from the morbidity control program and towards a surveillance and response system geared towards STH elimination. Surveillance and response systems geared towards elimination require the implementation higher accuracy diagnostics to detect infection in low-transmission communities, surveillance of entire households, high-resolution modeling at the household-habitat scale, and targeted treatment approaches tailored to specific communities. This study proposed to create a STH elimination surveillance and response system for the city of Feira de Santana, Brazil. Three communities were evaluated using three diagnostic techniques, entire households were sampled, and high resolution (30 m2) and very high-resolution (VHR) (m2) satellite products were utilized to produce STH ecological niche models (ENMs). In a separate study, a zoonotic Ascaris case in the southern United States was examined. The comparison of the mini-FLOTAC, quantitative PCR (qPCR) and the Ministry of Health Kato-Katz thick smear diagnostic tests revealed that the qPCR diagnostic quantified a significantly greater number of hookworm eggs in stool samples than either the Kato-Katz or the NaCl mini-FLOTAC. Sampling revealed the need to test whole families, as the mean age of STH (29.03), hookworm (29.0), Ascaris lumbricoides (22.29), and Trichuris trichiura (19.2) infections demonstrated. The production of ENMs using the VHR satellites GeoEye-1 (GE1) and WorldView-2 (WV2), and the high-resolution satellite Landsat 8, demonstrated that GE1 provided either superior or comparable model performed compared to WV2, and provided the resolution needed to effectively model STH niches at the household and its surrounding habitat. The differing STH prevalence and environmental risk factors between the 3 communities demonstrated the need to evaluate communities individually and craft targeted interventions. Genetic analysis in the case study determined that the cause of infection was zoonotic Ascaris suum. This study outlined steps towards implementing an STH elimination surveillance and response system for Fiera de Santana, Brazil.
Avery, Ryan Harry, "The Use of Geospatial Modeling and Novel Diagnostics to Detect and Map Risk Factors of Soil-Transmitted Helminths in Feira de Santana, Brazil" (2019). LSU Doctoral Dissertations. 4953.
Malone Jr., John