Blood-sucking arthropods, such as mosquitoes, insects and ticks, are increasingly sharing their environment with humans due to climate – with chronic results. Part two of a series on the relationship between climate change and disease.
Every organism on earth is affected by the consequences of climate change. But for those who rely on proximity to humans to spread disease, there may never have been a better time to live. To fend them off, humans will need to improve global data sharing.
The Covid-19 pandemic has brought to the fore the consequences that zoonotic diseases can have on our global society – loss of life, long-term health complications, supply chain disruptions, school disruptions and loss of societal connectivity. . Zoonoses, or rather diseases transmitted from animals to humans, are responsible for nearly 60% of emerging infectious diseases worldwide.
Read Part One: Preserving Local as Chinese United Goes Global
In the United States, zoonotic diseases caused by blood-sucking arthropods, such as mosquitoes and other insects, pose the most serious threat to public health. Ticks in particular are increasingly overlapping with humans and other wildlife due to climatic redistribution, with 95% of vector-borne zoonotic diseases reported in the United States being linked to ticks.
Ten new tick-borne diseases that pose a risk to humans have been identified since 1984 alone. They are technically difficult to diagnose, especially in resource-strapped areas, and can cause serious chronic health problems that require costly long-term care if undetected.
Climate change and urban expansion increase the risk of zoonotic diseases in human populations. Animals move where they live to find suitable food and habitats in a phenomenon known as climatic redistribution. As a result, we are now sharing more and more space with new animal neighbors. Likewise, animals also interact with each other in ways that are not native to their ecosystems. This creates even more opportunities for zoonotic diseases to find new pathways into human populations.
SARS-CoV-2, the virus that causes Covid-19 disease, likely evolved in bats before being transferred to humans. Ebola, another zoonotic disease outbreak of the past decade, first evolved in an unknown animal, though likely bats or primates, before infecting humans.
Our individual and societal risk of tick-borne zoonotic diseases is only increasing as humans continue to use land in new ways, such as in urban and rural development and outdoor recreation. This shrinks the barrier between urban and wild spaces and puts ticks and humans in greater contact. As temperatures warm in the United States, tick habitats have also expanded north and south into cooler climates. The altered seasonal weather conditions allowed them to be more active throughout the year, rather than primarily during the hotter summer months.
Climate change has also altered the timing and land use of migratory mammal species like deer, foxes and elk. With ticks residing in new habitats and becoming increasingly active, they can use these species as food and transport to continue their expansion and potentially introduce diseases to new areas along the way. Ultimately, this dynamic exchange between tick and animal distributions and the availability of more suitable tick habitats increases the risk and prevalence of tick-borne diseases in humans, livestock, and wildlife.
For example, from 2016 to 2017, there was a 46% increase in cases of spotted fever rickettsiosis in the United States and a 250-300% increase in the prevalence of Lyme disease in northern states. -east and north-central.
There are several potential policy options to address these risks, but the focus should be on implementing robust global monitoring, reporting and research systems. While surveillance, tracking and prevention of tick-borne diseases pose serious challenges, leveraging knowledge from zoonotic disease research around the world shows how we can better adapt and increase resilience.
There are three main options for tackling tick-borne diseases: Improve international surveillance and communication through intergovernmental agencies such as the World Health Organization and the United Nations; increase and integrate tick monitoring into pre-existing local wildlife agencies; and promote community resilience against tick-borne diseases with public health education campaigns. While there are various pros and cons to each of these policy options, one stands out in terms of its overall effect.
Although unlikely to fully mitigate the risks of tick-borne zoonotic diseases, improving international surveillance and response efforts to manage this risk can be improved. The most effective, feasible and likely of these strategies that can have an immediate impact is to tap into existing programs offered by various international organizations, including the United Nations Environment Programme.
As in other areas of scientific advancement, increasing the amount and availability of data in this area will increase the effectiveness of existing programs and provide new opportunities for collaboration. This requires increased buy-in from governmental and non-governmental organizations, both financially and scientifically.
The involvement of public health officials is essential before and during epidemics. Wildlife and agriculture managers, community leaders and public health officials also play an important role in managing and responding to zoonotic disease risks for all animal species, not just ticks.
Without wildlife and agriculture officials working and monitoring the presence of ticks in animal populations and their health, outbreaks may go undetected. They can also help educate the public on how to avoid tick-borne diseases,
It is important to recognize the nuances and high risks that climate change and our land use behavior create. Ticks are not the only piece of this puzzle. Animals change habitats, interact with unfamiliar animals and humans in new ways. All of these factors combine to create new potential for zoonotic disease transmission. A global problem that will require a global response.
This article is based on Philson et al. 2021
Conner S. Philson holds a Ph.D. Candidate in ecology and evolutionary biology at UCLA and graduate researcher at Rocky Mountain Biological Laboratory.
William M. Ota holds a Ph.D. Candidate in Evolution, Ecology and Organismal Biology at the University of California Riverside.
Dr. Lyndsey Gray, PhD MPSH is an infectious disease epidemiologist, microbiologist, and global health expert who currently serves as the Chair of Science Diplomacy at the National Science Policy Network.
Lindsey Pedroncelli holds a Ph.D. Candidate in microbiology and plant pathology at the University of California Riverside.
The authors declare no conflict of interest.