The temperature records broken over the years due to climate change have left city residents in discomfort, but a study has found that hot weather could also make you fall sick. Researchers found that the incubation period of two parasites, Plasmodium falciparum and Plasmodium vivax, that cause malaria through female Anopheles mosquitoes, has decreased in environments with presence of asbestos and concrete-roofed structures where temperatures increased over a period.This may transmit the disease to human beings faster.
In asbestos-roofed structures, the incubation period dropped from 7.01 days to 6.35 days when the average indoor daily temperature range (DTR) increased from 4.3°C in 2012-13 to 12.62°C in 2021-22 and outdoor DTR from 5.02°C to 8.76°C. These structures also recorded the highest indoor and outdoor average temperatures of 34.92°C ± 1.79 and 32.91°C ± 1.90 during summer compared to concrete and thatched-roof structures. In concrete structures too, the incubation period decreased from 7.10 days to 6.96 days as the average indoor DTR increased from 1.93°C to 2.95°C during the 10-year period, while there was no change in outdoor DTR.
“During the pre-monsoon season, both indoor and outdoor extrinsic incubation periods showed a decrease in 2021-22, indicating that parasite development now occurred much faster than in 2012-13. There is ample evidence from previous studies that even a small change in extrinsic incubation period for minimal days can have a drastic impact on the transmission risk. With increased temperature and the resultant decrease in extrinsic incubation period, it is obvious that transmission of the disease might quickly get faster,” said Alex Eapen, corresponding author of the study titled ‘Impact of climate change on temperature variations and extrinsic incubation period of malaria parasites in Chennai, India: implications for its disease transmission potential’.
The transmission of malaria starts when an infected female Anopheles mosquito bites a person. The sporozoites are injected into the host’s bloodstream. After getting bitten, it may take two to four weeks for symptoms to appear.
The study was conducted bdfy researchers in ICMR institutes National Institute of Malaria Research in Chennai and New Delhi, National Institute of Immunohaematology, Chandrapur, Maharashtra and Academy of Scientific and Innovative Research (AcSIR), Ghaziabad. Researchers analysed the incubation period for every season. The study, done in Besant Nagar, involved researchers collecting larval and adult samples of mosquitoes and studying mosquito density. While adults that grew from the larva were Anopheles stephensi, in the adult collection only one was Anopheles stephensi along with other species such as Culex quinquefasciatus, Stegomyia aegypti, Culex gelidus and Culex tritaeiorhynchus, which spread filaria, dengue and chikungunya.
