Descriptive, Hospital-Based, 10-Year Study of Malaria Transmission in Goa, a Southwest Indian State in the Malaria Elimination Phase

Abstract

ABSTRACT. The South Asia International Center of Excellence for Malaria Research, an NIH-funded collaborative program, investigated the epidemiology of malaria in the Indian state of Goa through health facility–based data collected from the Goa Medical College and Hospital (GMC), the state’s largest tertiary healthcare facility, between 2012 and 2021. Our study investigated region-specific spatial and temporal patterns of malaria transmission in Goa and the factors driving such patterns. Over the past decade, the number of malaria cases, inpatients, and deaths at the GMC decreased significantly after a peak in 2014–2015. However, the proportion of severe malaria cases increased over the study period. Also, a trend of decreasing average parasitemia and increasing average gametocyte density suggests a shift toward submicroscopic infections and an increase in transmission commitment characteristic of low-transmission regions. Although transmission occurred throughout the year, 75% of the cases occurred between June and December, overlapping with the monsoon (June–October), which featured rainfall above yearly average, minimal diurnal temperature variation, and high relative humidity. Sociodemographic factors also had a significant association with malaria cases, with cases being more frequent in the 15–50-year-old age group, men, construction workers, and people living in urban areas within the GMC catchment region. Our environmental model of malaria transmission projects almost negligible transmission at the beginning of 2025 (annual parasitic index: 0.0095, 95% CI: 0.0075–0.0114) if the current control measures continue undisrupted.