Influence of climate change on ectoparasites

Climate change is by definition, a change in the planets climate caused by human activities starting in the late 20th century. Activities such as the burning of fossil fuels, deforestation and urbanisation have all led to a difference in regional climates (usually we’re referring to temperature), which effects the animals inhabiting that space.

This change to the climate in turn effects ectoparasites that feed on our dogs and cats, such as ticks and fleas (Ostfeld and Brunner, 2015). The life cycle of these parasites is strongly connected to weather and temperature, as are the very habitats in which they live, and animals they feed upon (Dantas-Torres, F., 2015). This has led to studies looking at whether climate change is affecting the risk of diseases these parasites transmit becoming more prevalent (Léger et al., 2013).

Deforestation is the process whereby humans are cutting down important forested areas to either obtain wood, or to clear land for farming etc. This has a few effects on ticks. Ticks are dependent on a host species (birds, deer and other small animals), this host species in turn is dependent on vegetation to eat and hide from predators! In essence, a lack of habitat means that ticks are likely unable to find hosts to move on which will then effect their ability to transfer over to our pets (Jore et al., 2014)! This in theory should then reduce ticks abilities to transmit diseases to humans and pets, so why then are we still seeing diseases such as Lymes becoming increasingly more common (Gasmi et al., 2017)?

We know already that some species of tick have massively increased the range of areas that they are able to live in over the last 30 years (Jaenson et al., 2012). It’s believed that this is because climate change has led to milder winters and extended growing seasons. This means that ticks which can only survive in a certain range of warmer temperatures have more time to propagate, find hosts and even transfer disease (Korotkov et al, 2015).

Interestingly, another study has found that ticks demonstrate a preference for a human host (verses dogs) at hotter temperatures tested. This same study also found that ticks were far less likely to choose either host in temperatures that exceeded 38 degrees (Backus et al.,2021). This means that we need to be extra careful now to check ourselves over, as well as our dogs after walking in areas where ticks might be present!

So, why does this information matter? Predicting how ticks respond to changing temperatures across the globe can help inform us on how to best protect our dogs from these parasites. Whilst we are advised to protect our dogs from ticks all year round, many people still only use preventative measure during what they assume to be the main problematic season. We need to use this new science to help inform peoples choices and ensure that our pet dogs are protected from ticks and the diseases that they carry all year round, even in this changing climate.

About The Author:

Annie-Mae Levy

Dog Behaviourist & Trainer

Canine Nutritionist

[email protected]

Give her a follow –

Instagram: @annietrainsdogs

Facebook: @anniesdogs

Forum on Microbial Threats; Board on Global Health; Health and Medicine Division; National
Academies of Sciences Engineering, and Medicine. Global Health Impacts of Vector-Borne
Diseases: Workshop Summary. Washington, DC: The National Academies Press, 2016.
Ostfeld RS, Brunner JL. Climate change and Ixodes tick-borne diseases of humans. Philos Trans R
Soc Lond B Biol Sci 2015; 370 pii
Gasmi S, Ogden NH, Lindsay LR, Burns S, Fleming S, Badcock J, Hanan S, Gaulin C, Leblanc MA,
Russell C, Nelder M, Hobbs L, Graham-Derham S, Lachance L, Scott AN, Galanis E, Koffi
JK. Surveillance for Lyme disease in Canada: 2009-2015. Can Commun Dis Rep 2017.
Oct;43(10):194–9. 10.14745/ccdr.v43i10a01
Papa A, Chaligiannis I, Xanthopoulou K, Papaioakim M, Papanastasiou S, Sotiraki S., 2010. Ticks
parasitizing humans in Greece. Vector-borne Zoonotic Dis 11: 539–542.
Backus, L.H., Pérez, A.M.L. and Foley, J.E., 2021. Effect of Temperature on Host Preference in Two
Lineages of the Brown Dog Tick, Rhipicephalus sanguineus. The American Journal of Tropical
Medicine and Hygiene, 104(6), p.2305.
Korotkov, Y., Kozlova, T. and Kozlovskaya, L., 2015. Observations on changes in abundance of
questing I xodes ricinus, castor bean tick, over a 35‐year period in the eastern part of its range (R
ussia, T ula region). Medical and veterinary entomology, 29(2), pp.129-136.
Jaenson, T.G., Hjertqvist, M., Bergström, T. and Lundkvist, Å., 2012. Why is tick-borne encephalitis
increasing? A review of the key factors causing the increasing incidence of human TBE in
Sweden. Parasites & vectors, 5(1), pp.1-13.
Jore, S., Vanwambeke, S.O., Viljugrein, H., Isaksen, K., Kristoffersen, A.B., Woldehiwet, Z., Johansen,
B., Brun, E., Brun-Hansen, H., Westermann, S. and Larsen, I.L., 2014. Climate and environmental
change drives Ixodes ricinus geographical expansion at the northern range margin. Parasites &
vectors, 7(1), pp.1-14.
Léger, E., Vourc’h, G., Vial, L., Chevillon, C. and McCoy, K.D., 2013. Changing distributions of ticks:
causes and consequences. Experimental and Applied Acarology, 59(1), pp.219-244.
Dantas-Torres, F., 2015. Climate change, biodiversity, ticks and tick-borne diseases: The butterfly
effect. International Journal for Parasitology: parasites and wildlife, 4(3), pp.452-461.