A recent study conducted in Vellore, Tamil Nadu, explores the relationship between meteorological factors and scrub typhus cases. Scrub typhus is an infectious disease caused by Orientia tsutsugamushi bacteria, transmitted through infected mites. The study investigates the influence of temperature, rainfall, and humidity on the prevalence of scrub typhus.
Methodology:
Researchers analyzed 15 years of scrub typhus data from a tertiary care hospital in Vellore. The study involved 11,001 individuals, with 2,784 testing positive, resulting in an overall positivity rate of 25.3%.
Meteorological Factors:
- Monthly scrub typhus cases increased by 7.6% for every 1% rise in mean relative humidity.
- Monthly cases decreased by 18.8% for every 1°C increase in temperature.
- The maximum number of cases occurred at a mean temperature of 26.8°C, indicating a preference for lower temperatures.
Seasonal Patterns:
- Scrub typhus cases peaked from August to February, with the highest numbers in October and November.
- The disease is generally more prevalent in cooler months, aligning with findings in other regions like China, Laos, and Taiwan.
Impact of Rainfall:
- Every millimeter increase in rainfall led to a 0.5 to 0.7% rise in monthly scrub typhus cases.
Demographic Trends:
- The disease is more prevalent in people in their third decade of life (older than 60 years) with a prevalence rate of 21.1%.
- Socioeconomic factors play a role, with farmers, daily wage laborers, and housewives being more susceptible.
Preventive Measures:
- The study suggests that healthcare professionals should be prepared for early diagnosis and treatment during the rainy season and cooler months with increased humidity.
Conclusion:
Understanding the impact of meteorological factors on scrub typhus prevalence can aid in developing strategies for early detection and prevention, especially during specific seasons and in vulnerable demographic groups.