Floods, droughts compound diseases in India

Monsoon fury was in full display this year with record floods over Kerala as well as widespread floods from Gujarat to the North-East. The season also produced a wide swathe of drought that covered much of peninsular India with a smattering of districts from Gujarat to the eastern regions and the North-East. Considering that even a normal monsoon season consists active and break periods, India is a unique place with floods and droughts juxtaposed in space and time.

Both floods and droughts degrade water quality and exacerbate health and hygiene issues not only from water-borne diseases but also from vector- and air-borne and zoonotic diseases. Confounding the floods and droughts, India’s mean temperatures are also generally optimal for maximum disease prevalence.

Air pollution in India is getting the much deserved attention recently, especially in terms of the unacceptably high number of premature deaths, not to mention the Disability-Adjusted Life Years (DALY). DALY provides an estimate of disease burden in terms of years lost due to the disability caused by or premature mortality because of the disease. Air pollution is typically associated with chronic diseases such Chronic Obstructive Pulmonary Disease, asthma, and according to some new evidence, also diabetes.

What has not been getting as much attention is the disease morbidity due to floods and droughts.

India remains a hotspot for cholera, typhoid, malaria, filariasis, leptospirosis, schistosomiasis, Japanese encephalitis, etc., on the one hand, and for dengue, malaria, Chikungunya, and also incidences of swine flu and Zika.

Changes in monsoon

It is also evident now that all changes in monsoon occur as variations of these wet and dry spells. From ice ages to El Niño and La Niña, monsoon variability is manifest as alterations in the intensity and frequency of the active/break periods. Global warming is also beginning to make the wet periods more intense and break periods more frequent.

Responses of the whole host of diseases to this inherent character of monsoon distribution remains to be understood thoroughly if India wants to reduce the disease burden. All the major species of mosquitoes that are endemic to India have life cycles from eggs to adulthood of only 6-10 days. This means that the active/break periods may be leading to some unique human ecology, i.e., interactions between humans and their surroundings, which include the natural and social environments as well built infrastructure.

For example, Aedes albopictus , a species of mosquito that is commonly known as the tiger mosquito is also known as the forest mosquito because it is much less adapted to urban environments. It is also not as fond of human blood as the more common Aedes aegypti . However, now it is found to be breeding in human structures like drums, potted plants, etc., in the urban setting.

Another factor that could be important but not understood well is the dependence of the proximity of disease vectors like rodents to humans during wet and dry periods. Availability of food for them is bound to be affected by dry periods. Urban settings have also become breeding grounds for rodents, which create a deadly mix with mosquitoes during floods and droughts.

India has seen a burgeoning of domestic air travel, which is expected to continue in the coming years. Total number of vehicles has gone up from just about five million in 1981 to more than 230 million by 2016. The movement of people by planes, trains and automobiles is a massive disease vector itself. A prime example of increased travel on diseases is that a new strain of Chikungunya of African origin has been introduced into India over the last decade. Data gathering on diseases, air and water quality and the relevant vectors and the human ecology of diseases deserve much more attention in India. .

New fields of studies like Social Computing or Computational Social Science, which bring computational methods to social behaviour, can now track spreading of diseases by combining meteorological connectivities (for example, winds blowing from one region to another and carrying viruses/bacteria), and physical connectivities (people movements) and social behaviour (from shaking hands to sharing facilities, schools, office spaces, etc.).

India’s advances in weather and climate predictions, public health, biotechnology and medical research can be brought together to advance preventive care and environmental predictions for human health. This is a national imperative to avoid disease burden and DALYs in a warming world from becoming an impediment to India’s goals on economic growth.

The writer is a professor of Atmospheric and Oceanic Science and Earth System Science at the University of Maryland.

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