Researchers issue warning amid unpredictable spread of dangerous disease: 'We see so much variation'

Rising temperatures and shifting weather patterns are already changing how diseases move around the world. But according to a new global analysis, the way animal-to-human illnesses respond to these changes is much more unpredictable than expected. Some diseases spread more easily in warmer conditions. Others show mixed or opposite responses depending on location and timing. 

What's happening?

A study published in Proceedings of the National Academy of Sciences analyzed 218 studies from 65 countries. It tracked how temperature, rainfall, and humidity have affected 53 different illnesses that spread from animals to humans. The researchers found that most of the diseases showed some sensitivity to changing conditions, but the direction and strength of the effects varied widely. 

Temperature, the study said, was the most consistent factor, especially for illnesses spread by mosquitoes and ticks. In many cases, warmer conditions were linked to higher disease risk. 

Rainfall and humidity, however, produced mixed results. These factors increased or lowered risk, depending on the disease and region. 

"We see so much variation, even within the same disease, so we need much more nuance in how we summarize the future health impacts of climate change," said lead researcher Artur Trebski in a Natural History Museum press release. 

Why are warmer conditions a concern?

Hotter conditions are already allowing insects like mosquitoes to survive in new places and stay active for longer periods through the year. NASA reported that heat waves are becoming more frequent, severe, and long-lasting, which can create favorable conditions for disease-carrying insects. 

Because of the changes in environmental conditions, illnesses like dengue, malaria, and leptospirosis have increased. This is due in part to how rodents and mosquitoes have been able to spread the diseases for longer periods of time. 

The study warned that while warming trends increase risk for diseases, the effects are not the same everywhere. That makes it harder for hospitals, health agencies, and communities to plan for outbreaks. 

What's being done about protection?

The study's researchers believe there needs to be more detailed research models that can account for how different species respond to heat, rain, and humidity. 

While the effects of rising global temperatures on diseases are unpredictable, early detection programs and community education have helped slow outbreaks in some regions. 

It's also important to focus on practical prevention. Public health agencies recommend using insect repellent, wearing protective clothing, and reducing standing water around homes to limit mosquito breeding. 

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