The "Deadly Dozen" Diseases Worsened by Climate Change (Part 2)

Publish date:
Updated on

Yesterday, I opened this series with an overview of how certain pathogens pose increased threats to human and animal health as our climate warms.


This is an extremely important story, so let’s spend some time examining the specifics. Today, we’ll cover three of the “dirty dozen” diseases: avian flu, babesiosis and cholera. Tomorrow, we’ll examine ebola, intestinal and external parasites, and Lyme disease.

Avian Influenza

Like human influenza, avian influenza (“bird flu”) viruses occur naturally in wild birds, although often with no dire consequences.

The virus is shed by infected birds via secretions and feces. Poultry may contract the virus from other domestic or wild birds.

A highly pathogenic strain of the disease—H5N1—is currently a major concern for the world’s governments and health organizations, specifically because it has proved deadly to domestic and wild birds, as well as humans. It has the potential to evolve into a strain that can spread from human to human.

Current data indicate the movement of H5N1 from region to region is largely driven by the poultry trade, but climate changes like severe winter storms and droughts can disrupt wild birds’ normal movements and bring both wild and domestic bird populations into greater contact at water sources.


Babesia are tick-borne diseases that affect domestic animals and wildlife, and babesiosis is an emerging disease in humans.

In some instances, babesia may not cause severe problems by themselves; however, when infections are severe because of large tick populations, the host becomes more susceptible to other infectious diseases. This has been seen in East African lions (above) affected by canine distemper.

In Europe and North America, the disease is becoming more common in humans, also linked with tick distributions. Diseases like babesiosis, which were previously thought to have limited impact, must be monitored closely in a changing climate. Scientists need to assess how environmental conditions may tip the scale and cause more significant impacts on ecosystems, animals and people.


Cholera is a waterborne diarrheal disease that affects people primarily in the developing world. It is caused by a bacterium that survives in small organisms in contaminated water sources. It may also be present in raw shellfish like oysters.

Once contracted, cholera quickly becomes deadly. It is highly temperature dependent: Increases in water temperature are directly correlated with disease occurrence. Rising global temperatures caused by climate change are expected to increase the incidence of this disease.

Tune in tomorrow for Part 3 of this article.

Editor’s Note: publishes environmental news so organic consumers have access to the latest information on climate change and other threats. You can view similar posts by visiting the Environment Section of our blog.

Photo by Julie Larsen Maher. © Wildlife Conservation Society.

Related Stories