I think, we are all aware of the upcoming dangers of climate change more or less, yet perhaps, we might not anticipate these ones arriving slowly: Allergies and autoimmune diseases, increase in vector diseases, weakness in immune systems in general.

Although there is still a need for solid proof to declare a link between climate change and immune system issues, some researches indicate that it might not be a figment.

According to a Rutgers researcher, Xue Ming who published a paper in the International Journal of Environmental Research and Public Change, climate change and biodiversity problems increases the amount of susceptibility we hold to allergies and autoimmune diseases.  It affects the micro-biome of human body which is the beneficial microbial organisms inside of a human body – for homeostasis and other mechanisms.  

But how is it possible?

When we connect the dots, it is not farfetched at all. As a result of increasing concentration and distribution of air pollutants and, unexpectedly, the pollens. Another proof for this subject have come from American Academy of Allergy Asthma & Immunology as climate change has both increased  the intensity of the pollen season as well as prolonged its duration.

The main reason lays behind excessive pollen production is the high amounts of CO₂ concentrations since it increases the plant reproduction, particularly of plants which thrive at these high levels.

For instance, it has been observed that ragweed pollen have increased in years and its level is expected to increase by four times in the next 30 years. With the capacity to hold water and allergenic grain particles together and then releasing it with a thunderstorm, the frequency of irregular precipitation also seems to affect pollen distribution.

Also a growing and linking evidence between asthma, allergenic reactions and the increasing amount of pollutants in the air can be fund due to industrialization.

Regarding to ecosystem change, as a species extinct, another one emerges. For example when oak trees where excessively have been cut for architectural purposes, another species have emerged in the specific area, which corresponds a new pollen type – requires new allergenic system perhaps we have not developed yet.

In addition to these, the loss biodiversity might cause a radical change in the micro-biome systems of organisms which leads to a senility for immunological diseases such as food allergies. Several researches indicates the altered characteristic in peanut composition causes more difficult for body immune system to adapt it which later results in peanut allergy CITATION Pat20 l 1055 (Verbanas, 2020).

Within the atmospheric aspect of the impacts and their sinks on Earth, increase in atmospheric carbon dioxide concentration causes marine environment to undergo physical changes. Under the CO₂ scenario run by IPCC IS92a, ocean pH is expected to drop by 0.2-0.4 units by the year 2100. With this increase in pH, the temperature balance mechanism will be disrupted and the surface water temperature will increase from 19.7 ^oC to 22.7 ^oC by the end of this century.

The ability to adjust our systems is crucial for survival, it is also the same for other creatures such as marine organisms. The organisms which are not able to adjust and adapt will face serious threats. For instance, bivalves are unable to thermo-regulate and regarded as poor regulators of haemolymph acid base balance. Haemolymph system is similar to blood circulation system of human body, since bivalves do not have blood, they have another liquid to regulate their circulation system. This circulation system bivalves hold has a tendency to be affected under hypercapnic conditions- which are such conditions defined as elevation of carbon-dioxide tension in arterial.

In human body, this condition usually evaluated when someone suffers from dyspnea or altered sensorium. In the scope of bivalves, it pushes immune system to failure implicitly since the circulation system is a significant part of the bivalve immune system. The circulating cells called haemocytes representative of the major cellular component of immune system of these animals. They are in charge of multiple duties for immune defense such as phagocytosis and encapsulation of foreign or diseased cells and release of cytotoxic substances.

It is widely known that atmospheric changes have an impact on water bodies on earth, however the after effect as a bad impact on immune systems have less proof to be confirmed. The various immunological parameter are the decrease in number of haemocyte numbers, phagocytosis and oxidative burst response.

As immune response decreases, a risk of outburst of diseases in shellfish culture increases. Therefore any direct correlation between decrease in immune response system and the frequency of shellfish diseases could be possible.

Global climate change also has increased the pathogen development and survival, strength disease transmission and heightened the host susceptibility in the last years. Increment in development of diseases can eventually lead to extinction of species.

With higher temperatures some parasites have much change to reproduce successively and stay alive for long time. Higher temperatures in water result in lower oxygen levels which then leads increase in stress levels –triggers the susceptibility to any disease.

To demonstrate as an evidence, according to the paper have been published by Clara L. Mackenzie, Sharon A. Lynch , Sarah C. Culloty and Shelagh K. Malham, a few experiments about bivalve species have been conducted. They applied the IPCC scenario values to the medium of species such as mussels and then measured their immunological response, phagocytosis ability and then their disease status CITATION Cla14 l 1055 (Clara L. Mackenzie1, 2014).

According to the experiment conducted on M.edulis, there are confirmations about the parallel implications for immune and disease. The results also show that there might be a higher impact caused by temperature more than pH change. As it can be observed in Figure 1, since haemocyte (the immune effector cells) count is lower when warming and acidified mediums are compared, it might be concluded as warming, damages the response of immune system more.  

As it is also indicated in the below graph, the parasite prevalence in the subject M. edulis is not enough to conclude a remarkable parasite production prevailed in the diverse scenario mediums however the observed values shall not be neglected either.

 

As a conclusion, they stated that immune system of marine bivalves such as the subject M.edulis may have reduced capacity to cope with climate-induced stress factors such as ocean warming and acidification while having to deal with changes in parasite loads and pathogenic incidences.

On the other hand these changes can also affect the parasites and toxic microorganisms and weaken the thermal barrier our body has by making them resistant to our body temperature. Scientific American states as we have 37 ^oC body temperature, without global warming, most of the microorganism are not able to infect us since they are not resistant to this temperature. However, as temperature raises, the adaptation mechanism of these microorganisms starts to function too. As a result, they will begin to survive although the temperature is 37 ^oC in our body.

In a study published in Science in 2017, it is stated that animals migrate towards cooler climates from the warmer ones, for land species estimated pace is 17 km/ decade, for marine environment it is 72 km/decade. Such reshuffling and settling of animals will enable cohabitation of organisms who are the host of unique diseases and the ones who normally have never been a host of these diseases, therefore have not developed an immune response before. It will also create new transmission pathways among ecosystems.

 

To continue with other studies, Tokyo Mouse study is an experiment conducted to measure the effect and scale of heat wave impact on immune response systems. In the study two mouse which were in different temperatures were compared. They were both infected with the flu. However direct effect was not observable although the high temperature caused loss of appetite which then led to nutritional deficit & weakness of immune system. The researches in this study have concluded that extreme nutritional deficit which follows heat waves might cause energy stock inadequacy and in return lack of immune response CITATION Cli19 l 1055 (Climate change can affect immune system: Study, 2019)

 

Foxman, also a scientist who acknowledged the Tokyo Mouse study, states that directly concluding as global warming makes humans much more directly susceptible to viral infections would be a leap conclusion. Apart from this, she adds acknowledging the changes in climate could alter the way animals host or the number of host animals, their route and human exposure response mechanisms is a possible outcome CITATION Sar20 l 1055 (Goudarzi, 2020).

A group of researches in Lund University/Sweden, have stated some birds might be exposed to diseases they are not equipped to handle and the evolution necessary for the defense might progress slower than climate change. There is a high risk of animals not being able to keep up with the changes due to climate change which mediately expose them to pathogens they are not built to fight.

Rapid changes increase risk that these tailor-made immune systems might face and be insufficient, and not only in birds, Emily O’Connor states, one of the researchers behind the study CITATION Imm20 l 1055 (Immune System Unprepared for Climate Change, 2020).

You might realize while in these studies  , the mentioned stress factor is usually heat stress since the expected change in the environment due to climate change is often starts with heat fluctuation stress. Then, this heat, triggers other mechanisms which might cause different damages on earth.

The holy triad of disease causality were used in one of the articles I had a chance to read. In this scope, the factor is environmental stress (heat stress) and the sample is a molluscan (abalone) host. Most of the studies are sampling marine environment to understand effect on marine- also molluscan and other organisms I have aforementioned are usually commercial organisms for the fisheries. Thus, they also have a financial status that makes them double important CITATION Vin12 l 1055 (Vinh T. Dang, 2012).

In addition to effects of heat stress , viral abundance has been observed to increase with water temperature increase in different oceanic mediums, only few degrees of surface water temperature have been associated with doubling of viral abundance. Increase in temperature also leads to higher host metabolism which has been linked to higher rates of virus production.

Although these studies exist, immunity and immunology as a branch of science depends on a complex interactions among multiple factors in systems, all of which can be impacted by environmental stressors comparison and with previous studies, it is implied that different immune responses to elevated temperature can occur in different species, further complicating the ability to predict patterns of disease susceptibility.

All in all, it is apparent that climate change-disease interactions are complex and hence, an interdisciplinary perspective should be taken to comprehend more to reach solid proofs via further investigation rather than neglecting it as labeling ‘unlikely’.

 

My references are linked down below. I am also adding some further readings as well in case you are interested in. ( I have mentioned some of the references in the article as well, if you are specifically interested in an article or source I have used, you can also find it that way.)

 

Thank you for reading!!

References

BIBLIOGRAPHYClimate change can affect immune system: Study. (2019, February 5). Retrieved from Business Standard: https://www.business-standard.com/article/news-ani/climate-change-can-affect-immune-system-study-119020500291_1.html

Drew Harvell, S. A. (2009). Climate Change and Wildlife Diseases: When Does the Host Matter the Most? Ecology, 912-920.

Goudarzi, S. (2020, April 29). How a Warming Climate Could Affect the Spread of Diseases Similar to COVID-19. Retrieved from Scientific American: https://www.scientificamerican.com/article/how-a-warming-climate-could-affect-the-spread-of-diseases-similar-to-covid-19/

Immune System Unprepared for Climate Change. (2020, February 6). Retrieved from Immuniology & Microbiology: https://www.technologynetworks.com/immunology/news/immune-system-unprepared-for-climate-change-330387

Verbanas, P. (2020, August 5). How Climate Change Affects Allergies, Immune Response and Autism . Retrieved from Rutgers Today: https://www.rutgers.edu/news/how-climate-change-affects-allergies-immune-response-and-autism

Vinh T. Dang, P. S. (2012). Influence of elevated temperatures on the immune response of abalone Haliotis rubra. Fish & Shellfish Immunology, 732-740.

 

Further Readings

G. Husmann, E. P. (2010). Immune response of the Antarctic bivalve Laternula elliptica to physical stress and microbial exposure. Journal of Experimental Marine Biology and Ecology, 83-90.

Andrew N. Gherlenda, A. M. (2015). Climate change, nutrition and immunity: effects of elevated CO2 and temperature on the immune function of an insect herbivore. Journal of Insect Physiology, 1-22.

C. J. Brothers, J. H. (2016). Sea urchins in a high-CO2 world: the influence of acclimation on the immune response to ocean warming and acidification. The Royal Society Publishing, 1-10.

Mariangela Caroprese, M. G. (2017). Climate Change Impact on Immune Response in Sheep. Department of the Sciences of Agriculture, Food and Environment, 95-116.