PROJECT 1: Identifying Reservoirs of Plasmodium Infections in Odisha, India

PROJECT 1 SUMMARY Maintenance of Plasmodium cases in Odisha, India, continues despite active efforts by the state malaria control program targeting high endemicity foci with mass screening and treatment (MSAT), intensified vector control measures (LLINs, IRS), and community education. An improved understanding of what is driving the maintenance of Plasmodium reservoirs in Odisha despite these efforts is the broad goal of Project 1, and the knowledge generated from three aims will be used to design new tools required to further the state's progress toward elimination. A four-year community-based cohort in three Odisha districts of differing endemicity will enable Aim 1 to be realized. In each district, 1000 individuals will be selected across 5 villages/hamlets and will be followed for the duration of the study (15 villages total; 3,000 subjects total). Visits and sample collections will be carried out at baseline and then every 6 months, including before and after rainy seasons. Infections will be determined by microscopy, RDT, and PCR, and changes in clinical status will be monitored over time. To obtain a true estimate of the impact of false negative RDTs leading to malaria detection and treatment failure, the cohort surveillance will be augmented with passive surveillance enrolling patients with febrile illnesses presenting for care at the three district healthcare centers. Using samples and survey data collected from the same cohort, Aim 2 will evaluate the frequency of false negative and erroneous species identification at the three sites by (i) comparing results between different diagnosis methods (microscopy vs. RDT vs. PCR) in our cohort, (ii) identifying Pfhrp2 and Pfhrp3 gene deletions in P. falciparum infections and their prevalence over time, and (iii) investigating whether other Plasmodium species are rising into the niche vacated by P. falciparum. Lastly, Aim 3 will focus on evaluating Anopheles species composition and density in households and adjacent cattle sheds of a subset of participants, and monitor changes in insecticide susceptibility over time. Understanding where, why, and how reservoirs of infection remain in Odisha is the key focus of Project 1, and the data generated through the three subprojects will support the design of new control and intervention approaches to advance the state's goal of elimination before 2030.