Epidemiological and clinical characterization of dengue virus serotypes during 2017-2019 in southern Kerala, India.

BACKGROUND: In the context of the largest dengue outbreak in the state of Kerala, India in 2017, along with global evidence of changing epidemiology of dengue virus and its distribution, this study was planned to understand the epidemiological pattern of dengue infection and contemplate the clinical presentations of different serotypes. METHODS: This cross-sectional study was conducted in the Thiruvananthapuram and Kollam districts of Kerala, India, spanning 3 y from 2017 to 2019. We recruited adult patients based on the World Health Organization case definition of probable dengue fever to study their virological, spatial and clinical characteristics. RESULTS: Dengue infection was identified in 113 (33.9%) of the 333 probable dengue patients recruited. Dengue virus 1 (DENV1), along with its combinations (59.09%), was the predominant serotype during 2017, followed by DENV2. There was a marked increase in the proportion of DENV4 cases (34.56%) and concurrent infections (26%) in 2019. DENV3 infections were more likely to present with warning signs (adjusted relative risk 6.14 [95% confidence interval 1.3 to 29.4]) and a significantly lower platelet count (p=0.02). CONCLUSIONS: The results highlight the hyperendemicity of dengue infection in the state and the changing pattern of dengue virus predominance along with redominance. The rise in DENV4 and concurrent infections put forth the possibility of a more severe future outbreak.

Contamination of Household Open Wells in an Urban Area of Trivandrum, Kerala State, India: A Spatial Analysis of Health Risk Using Geographic Information System.

OBJECTIVE: To assess the sanitary condition and water quality of household wells and to depict it spatially using Geographic Information System (GIS) in an urban area of Trivandrum, Kerala state, India. STUDY DESIGN: A community-based cross-sectional census-type study. METHODS: Study was conducted in an urban area of Trivandrum. All households (n = 449) residing in a 1.05 km2 area were enrolled in the study. Structured questionnaire and Differential Global Positioning System (DGPS) device were used for data collection. Water samples taken were analyzed in an accredited laboratory. RESULTS: Most of the wells were in an intermediate-high contamination risk state, with more than 77% of wells having a septic tank within 7.5 m radius. Coliform contamination was prevalent in 73% of wells, and the groundwater was predominantly acidic with a mean of 5.4, rendering it unfit for drinking. The well chlorination and cleaning practices were inadequate, which were significantly associated with coliform contamination apart from a closely located septic tank. However, water purification practices like boiling were practiced widely in the area. CONCLUSION: Despite the presence of wells with high risk of contamination and inadequate chlorination practices, the apparent rarity of Water-borne diseases in the area may be attributed to the widespread boiling and water purification practices at the consumption level by the households. GIS technology proves useful in picking environmental determinants like polluting sources near the well and to plan control activities.