Is climate change affecting parasite prevalence?

The warming environment has already caused changes in Arctic ice. What does it mean for parasites? | Shutterstock.com

Talk about climate change has been ever-increasing over the last few years, and there's evidence of the consequences that it'll have on the weather and other natural phenomenon. But what about prevalence for disease-carrying parasites that affect pets and people? Fetch dvm360 speaker Richard Gerhold, DVM, MS, PhD, runs through a few parasites that could already be affected by these changes.

Dirofilaria immitis (heartworm)

A warming environment can lead to an increase in larval stage development in mosquitoes, potentially influencing the expansion of heartworm disease incidence. Other factors include an increase in mosquito populations in cooler months and certain mosquito species that are able to inhabit northern or higher-altitude regions that weren't previously occupied by vector-carrying species, Dr. Gerhold says. Another factor that's contributing to the spread of heartworm disease is urbanization. More areas of standing water, such as flower pots, old tires and buckets, provide space for mosquitoes to breed. Similar trends of increasing infection are expected for humans, domestic and wild animals, which has already been observed in certain northern states in the United States, Dr. Gerhold notes.

Toxoplasmosis

In the environment, sporulation of Toxoplasma gondii occurs between one to five days, and under favorable conditions sporocysts can survive about 18 months in fresh or salt water, Dr. Gerhold says. Sporulation can happen faster in warmer environments, leading to a more rapid production of oocysts in the environment.

Coccidia

Like Toxoplasma gondii, sporulation with coccidia happens in one to five days, and under favorable conditions, oocysts can survive for about 18 months. This sporulation can happen faster in warmer climates, leading to more oocysts in the environment. Higher oocyst production and ingestion leads to greater pathology because of parasite replication within the host cells, Dr. Gerhold says.

Ancylostoma species (hookworm)

The increase in air and soil temperatures will likely lead to increased numbers of infective L3 larva in the environment, Dr. Gerhold says. This has been seen with a higher incidence of human cutaneous larval migrans due to both canine and feline hookworm species during abnormally warm periods in various regions.

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