Impact of El Nino-Southern Oscillation and Indian Ocean Dipole on malaria transmission over India in changing climate

An effort is made to understand the role of El Nino-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) events on the malaria transmission intensity over India during the period 1951-2020 (70 years) with the help of a realistically simulated dynamical malaria model. The results suggest that the La Nina years pose a greater threat of malaria disease, especially in the densely populated Indian states. During El Nino years, the malaria transmission intensity and distribution over India greatly reduce, except in the regions such as Orissa, Chhattisgarh, Jharkhand, Western Ghats, parts of Madhya Pradesh, and Andhra Pradesh. It is found that in the positive IOD years, the malaria transmission intensity increases (decreases) over the entire central Indian region and along coastal regions of Tamil Nadu and Kerala (southern peninsular states of India and northeast India). An almost opposite behavior is seen during the negative IOD years. The malaria transmission variability over India is becoming increasingly heterogeneous in recent decades during the El Nino and La Nina years as a result of global warming. The period of 1986-2020 witnessed a substantial decrease (increase) in the malaria transmission intensity during the positive (negative) IOD years, except for a few regions of India. The implications of the results presented in the paper linking the ENSO and IOD signals with the intensity and distribution of malaria over India in a warming world are enormous, especially for the densely populated Indian states.

Automated summary

This study investigates the impact of El Nino-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) events on malaria transmission intensity in India. The results show that La Nina years pose a greater threat of malaria, particularly in densely populated Indian states. During El Nino years, malaria transmission intensity greatly reduces in most parts of India, except for specific regions. Positive IOD years lead to an increase in malaria transmission intensity over central India and coastal regions, while negative IOD years show the opposite effect. The study highlights the significant implications of ENSO and IOD on malaria intensity and distribution in a warming world, especially for densely populated Indian states.