Temporal trend of microsporidial keratoconjunctivitis and correlation with environmental and air pollution factors in India

PURPOSE: The aim of this study was to describe the correlation between the temporal pattern of presentation of acute microsporidial keratoconjunctivitis (MKC) with meteorological parameters such as environmental temperature, rainfall, humidity, windspeed, and air pollution. METHODS: This cross-sectional hospital-based study included 182,789 patients presenting between January 2016 and December 2019 hailing from the district of Hyderabad. Patients with a clinical diagnosis of MKC in at least one eye with an acute onset (≤1 week) of presentation were included as cases. Correlation analysis was performed with the local environmental temperature, rainfall, humidity, and windspeed (Telangana State Development and Planning Society) and air pollution (Central Pollution Control Board, Government of India). RESULTS: Overall, 84 (0.05%) patients were diagnosed with acute onset MKC from the district of Hyderabad. The mean monthly prevalence in this cohort was 0.05% with peak prevalence in the months of July (0.08%), August (0.09%), September (0.12%), and October (0.08%). The environmental parameters of rainfall (r(2) = 0.87/P = < 0.0001), humidity (r(2) = 0.78/P = 0.0001), windspeed (r(2) = 0.38/P = 0.0321) were significantly positively correlated and the air pollution parameters such as ground level ozone (r(2) = 0.89/P = < 0.0001), particulate matter PM(10) (r(2) = 0.65/P = 0.0013), PM(2.5) (r(2) = 0.50/P = 0.0095), nitrogen dioxide (r(2) = 0.53/P = 0.0071), and carbon monoxide (r(2) = 0.69/P = 0.0008) were significantly negatively correlated with the temporal pattern of MKC in the population. CONCLUSION: Parasitic infections like MKC show a distinct temporal trend peaking during the monsoon season in the population. An increase in humidity, wind speed, and especially rainfall contributes to a higher prevalence of MKC cases during the year. An increase in ground-level ozone seems to be protective against infection.