Climate Change Increases Zoonotic Disease

How Climate Change Increases Zoonotic Disease

Climate change is one of the most significant issues of our time and it brings unforeseen consequences. One such consequence is an increase of zoonotic diseases, which are illnesses transmitted from animals or insects to humans.

These illnesses include COVID-19, mpox, Lyme disease, and highly pathogenic avian influenza. While some of these illnesses are strictly spread from animals to humans, others have the potential to spread human-to-human for more sustained transmission.

Zoonotic diseases are very common, both in the United States and around the world. It is estimated that more than 60% of known infectious diseases in people can be spread from animals, and 75% of new or emerging infectious diseases in people come from animals ¹.

Climate Change and Ecosystem Disruption

Changing temperatures and more frequent extreme weather events are disrupting local habitats, forcing wildlife to either adapt or migrate. As animals like bats, rodents, and insects move into new regions, they come into closer contact with people. Climate change has fueled population growth for some insects, allowing them to thrive in environments that were once too cold for survival. This increases the risk of zoonotic disease outbreaks as invasive species spread into new areas.

For example, ticks, which spread Lyme disease, have expanded their range across Pennsylvania. In some regions of the United States, a bite from the lone star tick may cause Alpha-gal Syndrome (AGS). AGS can make people allergic to certain types of meat. Because of changing movement patterns, the lone star tick is now more common in Pennsylvania than it used to be. Ticks carry other diseases, too, like anaplasmosis, ehrlichiosis, babesiosis, and Powassan virus.

Other species of insects, like mosquitos, can transmit diseases, too. While Pennsylvania reports yearly cases of West Nile Virus, mosquitos are also capable of transmitting infections such as Eastern Equine encephalitis (EEE), dengue, and malaria.

Dengue and malaria infections in the United States are usually acquired during travel to other countries, but in recent years there were cases of malaria acquired locally in Texas, Florida, and Maryland, which may indicate that the type of mosquito responsible for transmitting malaria is adapting to different environments.

Locally acquired cases of dengue were reported, too. Warmer temperatures and mild winters cause more mosquitos – and more mosquitos means it is more likely to get bitten! While malaria and dengue may not be a concern in Pennsylvania, other mosquito born diseases like West Nile or EEE can be transmitted here.

Wildlife

Natural disasters push animals and humans into closer proximity, in turn increasing the risk of zoonotic disease transmission. Flooding and heavy rainfall creates ideal conditions for diseases like leptospirosis. This bacterial infection spreads through water contaminated by animal urine. Stagnant and slow-moving water is more likely to be contaminated. Pets can also be infected.

Climate change influences the ecosystems that support deer, too, which are the primary carriers of Chronic Wasting Disease (CWD). While CWD has not been shown to cause harm in humans, it is still being studied for its potentially serious implications on human health, especially in people who touch or consume deer meat.

The Pennsylvania Game Commission recently expanded their management regions to better control the disease’s spread in areas experiencing new infection rates, like Dauphin and Indiana counties. Deer also serve as a primary host for adult ticks, so a high deer population can increase the number of ticks in the area.

Agricultural and Livestock Changes

Farming practices are becoming more concentrated, with animals often kept in close quarters. These crowded conditions increase the risk of zoonotic diseases because they provide more opportunities for pathogens to spread between animals and humans.

Highly pathogenic avian influenza (HPAI), commonly known as bird flu, is another zoonotic disease exacerbated by close animal quarters. This virus spreads rapidly among poultry and can occasionally infect humans who come into contact with infected birds or contaminated environments.

Pennsylvania’s mix of commercial farming and backyard poultry flocks increases the risk of HPAI outbreaks. The virus poses a significant threat to both animal health and public health, as mutations in the virus could lead to greater transmissibility among humans.

Keeping backyard animals like chickens can contribute to the spread of other zoonotic diseases (especially salmonella). While many people think of salmonella as a foodborne illness, most often transmitted by consuming undercooked meat, it can also be transmitted by handling chickens or eggs. Proper handwashing can help reduce this risk.

The Future of Zoonotic Disease

Pennsylvania is addressing zoonotic diseases through a combination of public health initiatives, research, and surveillance. A notable advancement in this fight includes HNL Lab Medicine’s development of a new test with DiaSorin Molecular to help diagnose and treat tick-borne illnesses like anaplasmosis, babesiosis, and ehrlichiosis.

The University of Pennsylvania’s Institute for Infectious and Zoonotic Diseases is also focused on detecting and preventing diseases that spread between animals and humans, such as Lyme disease, West Nile virus, and rabies.

These diseases are also monitored by the Department of Health. Being aware of how zoonotic diseases might harm your health is only the first step of controlling the spread of these diseases. Take action through simple preventative measures like eliminating standing water or using mulch as a tick barrier.

If you experience any symptoms of a zoonotic disease, visit your healthcare provider right away. HNL Lab Medicine has convenient options to complete your lab work, including the ability to order a Lyme disease panel on HNL Lab Tests Direct, and you can bring your doctor’s lab order to any of our convenient Patient Service Center locations. By taking small steps to safeguard the environment and our health, we can lessen the spread of zoonotic disease.

REFERENCE
¹ Centers for Disease Control and Prevention. (2024, February 29). About zoonotic diseases. U.S. Department of Health and Human Services. https://www.cdc.gov/one-health/about/about-zoonotic-diseases.html.