Welcome to the second installment of the Native Plants for Healthy People and a Healthy Planet series. The previous blog post covered the benefits of biodiverse native plants on chronic health. In particular, native plants are beneficial for our immune systems, as well as respiratory and cardiovascular health. I also mentioned that native landscapes are vital for disease control; this edition will dive deeper into the topic of disease control by covering biodiversity’s effect on infectious diseases and how native plants can help stave them off.
By: Helene Wierzbicki
While infectious disease numbers have declined over the past few decades, they still account for a large number of deaths globally each year. The World Health Organization (WHO) estimates that infectious diseases cause over one billion infections annually, with millions of deaths globally (2015). Any individual disease can cost billions of dollars in healthcare costs. In 2019, infectious diseases accounted for 26.35% of the global burden of disease, a metric that measures both the number of deaths and number of disabilities caused by chronic and infectious diseases (Roser et al. 2021). Importantly, the potential for the spread of disease has increased over the years. In a growing world of urbanization and global connectivity, viruses and pathogens spread easily across countries (Joi, 2020) The risk of spread is further exacerbated by human activities contributing to the loss of biodiversity. Deforestation, land-use change, dams, and irrigation disrupt the natural order of disease prevention and create reservoirs of communicable disease (WHO, 2015). Humans are coming into closer contact with animals as we encroach on their habitats, increasing the risk of animal-to-human transmissions (Joi, 2020). Warming climates create favorable conditions for the spread of tuberculosis and malaria (Bishen, 2023). We can see that creating a world with fewer and fewer natural habitats is putting the entire human population at risk.
Source: Hajek, Olaf. The New York Times. 2012.
Native plant biodiversity protects communities from infectious diseases. Infectious diseases are illnesses caused by agents such as bacteria, viruses, or parasites, that enter the body, multiply, and can cause an infection. Often infectious diseases originate from microbes and other disease agents found in wildlife (WHO, 2015). A species that hosts a disease-causing agent can transmit it to others. Non-reservoir species typically do not pass on disease as efficiently as the reservoir. When species biodiversity is high, the infectious agent becomes diluted among all organisms and limits the overall spread of the disease (Kulkarni, 2022). A prime example of this dilution effect can be seen in the spread of Lyme disease over the past few decades. White-footed mice are highly efficient at transmitting the bacteria that causes Lyme disease (Borrelia burgdorferi) to its primary vector, the black-legged tick. The presence of a diverse array of native plants supports a wider range of wildlife species, which reduces the likelihood of ticks feeding on infected hosts. (Ferro, 2013). Furthermore, diverse forests have been found to support more species that are poor reservoirs of Lyme disease, such as squirrels and birds, which diverted ticks from feeding on white-footed mice (Ostfeld and Keesing, 2000). As a result, fewer ticks become carriers of the Lyme disease bacterium and fewer people become infected with Lyme disease. By including a rich array of native plants into our landscapes, we can nurture native wildlife and protect ourselves from the spread of disease.
Source: Kalkurni, Sanjana. September 2022. Biodiversity loss can increase the spread of zoonotic diseases.Science in the News.
In addition to providing biodiverse habitats that reduce the density of disease agents and hosts, native plants and natural landscapes contribute to microclimates– including temperature, humidity, wind reduction, lighting, and even rainfall patterns. Malaria cases give us a good illustration of these elements at play. Terrain restoration projects affect local mosquito populations by regulating water flow and quality. Native grasses enhance soil stability, reducing stagnant water pools where many mosquito vectors commonly breed (Hess and Bay, 2010). Additionally, native trees and undergrowth can lower surface and air temperatures through shading and transpiration, which in turn can influence the survival and reproduction rates of pathogens and vectors (Olson et al. 2010). Conversely, deforested areas give way to what is known as “frontier malaria,” characterized by its highly modified transmission rate (Laporta et al. 2013).
Lower-income and minority communities are more susceptible to disease and will benefit the most from habitat restoration. Research shows that diseases caused by microbes often spread more rapidly in densely populated and economically disadvantaged areas, where conditions such as limited access to healthcare and crowded living conditions enhance the risk and impact of these diseases (Sahasranaman and Jensen, 2020). Aspects of poverty are exacerbated when sick people have to take time off of work, find childcare, or accrue healthcare costs. Low-income communities also have less access to green spaces. Specifically, restoring native plant habitats within urban environments could play a critical role in reducing the prevalence of microbial diseases. Native plants can alter the local ecology, potentially disrupting the life cycles of disease vectors such as mosquitoes and ticks, which thrive in degraded landscapes lacking biodiversity (Jones and Ostfeld, 2021). Improving access to native plant habitats not only addresses the immediate vulnerabilities of low-income and minority communities to infectious microbes but also contributes to their long-term resilience and sustainability, bolstering their defenses against future outbreaks.
When it comes to preventing the spread of disease, we need an attitude of “the more, the merrier.” More intact native plant habitats represent a vital public health strategy. As we’ve discussed before, native plants are best suited for maintaining ecological balance and stability while also building long-term ecological resilience. I hope this post helps illustrate how important native landscapes are fundamental assets in our collective health and well-being. Thank you very much for reading, and I hope your gardens flourish!
About the Series
Native Plants for Healthy People and a Healthy Planet series will explore the importance of strengthening biodiversity resilience by protecting and restoring native plants and natural landscapes. My goal in writing this blog series is to channel biodiversity through a healthcare lens and examine its relationship with human chronic, acute, and mental health. If more people understand how entwined biodiversity is with human health, perhaps policy-makers will take biodiversity resilience more seriously. Native landscapes are vital for improving health outcomes within communities. This series is made possible though the ANHE Environmental Health Nurse Fellowship Program.
The Alliance of Nurses for Healthy Environments (ANHE) is dedicated to connecting nursing and environmental health. They focus on educating nurses, advancing research, and influencing policies to promote healthier people and environments. ANHE recognizes the crucial role nurses play in addressing environmental health issues within communities and at policy levels, aiming to equip them with the necessary knowledge and leadership skills for this challenge.
About the Author
Helene Wierzbicki is a community-psychiatric nurse from Portland, OR. She works with the Washington County ACT team through the nonprofit LifeWorks NW. Helene is a fellow with the 2024 cohort of Allied Nurses for Healthy Environments (AHNE). For her AHNE project, Helene is contributing to Wild Ones through a blog series titled “Native Plants: Healthy Planet & Healthy People
References
Bishen, S. (2023). Climate change is adding to a growing infectious disease burden – we need coordinated action now. World Economic Forum. https://www.weforum.org/agenda/2023/01/climate-change-is-adding-to-a-growing-infectious-disease-burden-our-healthcare-systems-need-coordinated-action-now/
Ferro, J. (2013). Biodiversity impacts Lyme Disease. Carey Institute of Ecosystem Studies. https://www.caryinstitute.org/news-insights/media-coverage/biodiversity-impacts-lyme-disease
Hess, A. D., & Bay, E. W. (2010). Impact of native plant restoration on vectors of West Nile virus. American Journal of Public Health, 100(6), 1129-1136.
Joi, P. (2020). 5 reasons why pandemics like COVID-19 are becoming more likely. Gavi, the Vaccine Alliance. https://www.gavi.org/vaccineswork/5-reasons-why-pandemics-like-covid-19-are-becoming-more-likely
Jones, C. G., & Ostfeld, R. S. (2021). Native plants and ecosystem services: Reducing disease vector populations in degraded landscapes. Ecological Applications, 31(4), e02210. https://doi.org/10.1002/eap.2210
Kalkurni, S. (2022). Biodiversity loss can increase the spread of zoonotic diseases. Science in the News. https://sitn.hms.harvard.edu/flash/2022/biodiversity-loss-can-increase-the-spread-of-zoonotic-diseases/
Laporta GZ, Lopez de Prado PI, Kraenkel RA, Coutinho RM, Sallum MA. Biodiversity can help prevent malaria outbreaks in tropical forests. PLoS Negl Trop Dis. 2013;7(3):e2139. doi: 10.1371/journal.pntd.0002139. Epub 2013 Mar 21
Olson, S. H., Gangnon, R., Silveira, G. A., & Patz, J. A. (2010). Deforestation and malaria in Mâncio Lima County, Brazil. Emerging Infectious Diseases, 16(7), 1108-1115.
Ostfeld, R.S., & Keesing, F. (2000). “Biodiversity and disease risk: the case of Lyme disease.” Conservation Biology, 14(3), 722-728.
Roser, M., Ritchie, H., & Spooner, F. (2021). Burden of Disease. Our World in Data. https://ourworldindata.org/burden-of-disease
Sahasranaman, A., & Jensen, H. J. (2020). Disease spread in small-size populations: Disease dynamics in small populations often results in more rapid spread in densely populated and economically disadvantaged areas. Epidemiology and Infection, 148, e122. https://doi.org/10.1017/S0950268820001404
World Health Organization. (2015). Biodiversity and Health. https://www.who.int/news-room/fact-sheets/detail/biodiversity-and-health
World Health Organization. (2015). Connecting Global Priorities: Biodiversity and Human Health. https://www.cbd.int/health/SOK-biodiversity-en.pdf