The weather varies significantly; hence, the study determined how changing monsoon patterns have altered the prevalence in Pune, a hotspot for the disease in India.
Extreme weather events aside, warming due to climate change is likely to increase dengue incidence at the global level, with India being the source of one-third of the yearly 100 to 400 million infections, according to a new study by Indian scientists.
Dengue, one of the world’s most widespread and fastest-growing vector-borne diseases, is heavily driven by shifts in meteorological conditions. The new study—published in the peer-reviewed scientific journal Scientific Reports—assessed how changing monsoon patterns have modified the prevalence of the disease in Pune, a known dengue hotspot in India.
The team led by researchers from the Indian Institute of Tropical Meteorology (IITM), Pune, showed that heavy rains above 150 mm in a week reduce dengue prevalence by flushing out mosquito eggs and larvae. However, moderate rains spread over the monsoon increase dengue mortality, indicating the links between the disease and changing monsoon variability due to warming.
The research team’s findings suggest that not so much the sheer volume of rain but how it falls has a significant bearing on dengue transmission in Pune.
The years with higher dengue mortality rates in Pune witnessed temperatures ranging from 27 degrees Celsius to 35 degrees Celsius, evenly distributed rains, and relative humidity levels between 60 percent and 78 percent during the southwest monsoon season, which runs from June to September.
The infections are low from December to May but begin to rise after the onset of the summer monsoon in June and peak in November. The analysis further showed that Pune recorded the highest number of dengue mortalities in 2014 during the study period (2004 to 2015), with 81 deaths in total.
