top of page

On the Importance of Conserving Parasite Species

We explore the essentiality of parasites and the argument that they are fundamental ecosystem components deserving of conservation.

Parasite photo

Parasite conservation? Hear us out


Parasitism defines a relationship between two organisms in which one benefits at the expense of the other. Such organisms have been around for millions of years, and this relationship has been observed in every ecosystem, from the sea to the Sahara. Given the nature of a parasitic relationship, infection usually leads to disease or death of the host organism. Parasitic infections, though observed all over the world, are generally most present in developing countries, with a prevalence rate of 30-60%. The potential harm to health due to infection has resulted in a widespread negative perception surrounding parasite species, so much so, that the word ‘parasite’ is often used in a derogatory manner. 


However, parasites are a hugely diverse group of organisms. According to some scientists, around half of all living organisms can be classified as parasitic, although the exact number of parasites in existence is still yet to be determined. Whilst some parasites do cause debilitating diseases with huge economic, mortal, and sociological costs, most parasites play vital roles in the ecosystems they inhabit. This article will explore some of the beneficial roles of parasites, adding fuel to the argument that they are fundamental ecosystem components deserving of conservation, just as any other organism.  



Parasite-derived ecosystem benefits


Parasitic species can provide invaluable information on the state of an ecosystem. Studies have found that some parasites can be used as biological indicators of habitat degeneration, or fragmentation, as well as changes in climate change. In marine environments threatened by ocean acidification, parasitic abundance has been shown to be associated with increased levels of carbon dioxide. Some parasitic species are able to accumulate pollutants from hosts. For example, some helminth (parasitic worm) species can bio-accumulate metals such as zinc and cadmium. Studies have found that in saltmarsh ecosystems, parasites are responsible for concentrating over 50% of the heavy-metal pollutants in the system.



Parasites as therapeutics


Despite their connotation with disease, and death, parasites might have application as therapeutic organisms for treating autoimmune problems. Scientists have been increasingly exploring a theory known as the “health hypothesis”. This theory suggests that decreased parasite/pathogen exposure (usually resulting from urbanisation), is responsible for an increase in the frequency of allergies and other diseases (e.g., type 1 diabetes, multiple sclerosis). As such, some scientists have begun exploring this by intentionally infecting mouse models with hookworms, and it has been found that infection stimulates an immune response that can help protect tissue from autoimmune problems. In humans, therapies have been used involving whipworm infections, to downregulate the patient’s immune response and achieve remission in Crohn’s disease.


Parasitic influence on the host communities


Perhaps most important of all is the effect that parasite species have on both individuals and host communities. After infection, the parasite will begin to remove resources from the host body which would otherwise be used for growth, reproduction, and development. Hosts will attempt to compensate for the negative effects by altering other traits not directly associated with the parasite (e.g., dispersal patterns or developmental rate). By altering the host traits, parasites can cause variation in host growth, survival or reproductive rate, thus altering the structure of the whole host community.



Final thoughts


Whilst some researchers are starting to take note of parasite importance, in many cases their negative reputation precedes them, discouraging potential sponsors, academics, and even the public from taking an interest in parasitic research. Though there has been some movement to conserve parasites on a global scale, this is still a long way off and would require a drastic change in public opinion. This change will not come about easily – parasites and the illnesses they bring are still responsible for millions of deaths worldwide every year. There is also the added issue of climate change; as the Earth’s temperature rises and species struggle to adapt to changing conditions, many are going extinct before science can catch up. Given their reputation, parasitic species are at even greater threat of extinction as they do not attract or inspire the same attention or funding as other more charismatic species. As a result, parasite species are mainly absent from threatened species lists and are not protected by legislation. 


Parasites have always existed, co-evolving alongside species. Even the earliest writings describe parasites and the infections they caused. However, as the world continues to warm, and many parasitic species continue to be ignored, scientists worry about how this could impact our world, and the species that inhabit it. Perhaps not all parasitic species deserve conservation attention, however it is important to recognise and understand their roles in nature. Parasites are weaved into the fabric of our world, and without them, life would certainly look very different.

author profile picture

Author

Olivia Kolasinski, freelance contributor

bottom of page