Are you feeling hot, dry, or feeling unwell?How Earth Changes Cause Disease

BANGKOK, Thailand — Humans have made the Earth warmer, more polluted, and less habitable for many species. These changes are causing the spread of infectious diseases.

A warmer, wetter climate may expand the range of vector species such as mosquitoes, while habitat loss may bring disease vectors into closer contact with humans.

New research reveals how complex our impacts on climate and the planet are, accelerating some diseases and changing transmission patterns of others.

Biodiversity loss appears to play a major role in the rise in infectious diseases, according to a study published this week in Nature.

The study will examine how biodiversity loss, climate change, chemical pollution, habitat loss or change, and species introduction affect infectious diseases in humans, animals, and plants. We analyzed approximately 3,000 datasets from the study.

They found that biodiversity loss was by far the biggest factor, followed by climate change and the introduction of new species.

Parasites target species that are more abundant and offer more potential hosts, explains lead author Jason Lohr, a professor of biological sciences at the University of Notre Dame.

And species with large populations are likely “investing in growth, reproduction and dispersal at the expense of defenses against parasites,” he told AFP.

But more resistant and rare species are more vulnerable to biodiversity loss, leaving us with “more abundant and suitable hosts for the parasite.”

Warmer weather brought about by climate change not only creates new habitat for disease-carrying animals, but also lengthens the breeding season.

“More generations of parasites and vectors can lead to more diseases,” Lohr said.

variable speed transmission

However, not all human adaptations to the planet increase infectious diseases.

Habitat loss or change is associated with reductions in infectious diseases, primarily due to improvements in sanitation, such as water and sanitation systems, associated with urbanization.

The impact of climate change on disease is also uneven across the world.

In tropical climates, dengue fever is exploding due to warmer and humid weather.

However, Africa's dry conditions may cause the area affected by malaria to shrink in the coming decades.

The study, published this week in the journal Science, modeled the interaction between climate change, hydrological processes such as rainfall and evaporation, and the rate at which water sinks to the ground.

It predicts a greater reduction in areas suitable for disease transmission than predictions based on rainfall alone, starting in 2025.

They also found that the malaria season in some parts of Africa could be four months shorter than previously estimated.

The study's findings aren't necessarily good news, warns lead author Mark Smith, associate professor of water research at the University of Leeds.

“The location of suitable areas for malaria will change,” he told AFP, adding that Ethiopia's highlands are likely to be newly affected.

People in these areas may be more vulnerable because they are not infected.

Additionally, populations are projected to grow rapidly in areas where malaria remains or becomes more transmissible, which may increase the overall incidence of malaria.

Prediction and preparation

Mr Smith warned that conditions that are too tough for malaria may also be too tough for us.

“Changes in the availability of drinking water and agricultural water could indeed be very significant.”

The link between climate and infectious diseases means that climate modeling can help predict outbreaks.

Regional temperature and precipitation forecasts are already used to predict dengue increases, but they have short lead times and can be unreliable.

One alternative could be the Indian Ocean Basin-Wide Index (IOBW), which measures the regional average of sea surface temperature anomalies in the Indian Ocean.

The study, also published this week in Science, looked at dengue fever data from 46 countries over 30 years and found a close correlation between variations in IOBW and outbreaks in the Northern and Southern Hemispheres.

As this study is retrospective, the predictive power of IOBW has not yet been tested.

But monitoring it could help authorities better prepare for disease outbreaks, which are a major public health concern.

But at the end of the day, Lohr said, addressing rising infections means addressing climate change.

Research “suggests that disease increases in response to climate change will be consistent and widespread, further highlighting the need to reduce greenhouse gas emissions,” he said. .