Climate Change and Health, Part 3: Infectious Disease

~Written by Joann Varickanickal (Contact: joann.varickanickal@gmail.com)

This is my final post of a three part series on climate change and health. The first post looked at how climate change will influence the onset and severity of droughts in some areas. The second post examined how some regions are predicted to see an increase in droughts, which would decrease food supply; thus, increasing nutrient deficiencies in those areas. This post will briefly discuss the influence of climate change on waterborne diseases.

Change in climate, including the increases in temperature and changes in rainfall patterns may lead to an increase in waterborne diseases, where insect vectors contaminate the water (Shuman, 2010). Often, higher temperatures are needed for some insects to complete their life cycle. This is the case for mosquitoes, as they live in warm, aquatic habitats (Shuman, 2010). With an increase in temperature and more flooding, there will be an increase in mosquitoes (Shuman, 2010). Thus, there may be an increase in the transfer of dengue and malaria (Ramasamy & Surendran, 2011). These warm, aquatic habitats will also be ideal for snails, which transfer schistomiasis (Ramasamy & Surendran, 2011). Furthermore, with a rise in sea levels, there is likely to be an increase in saline levels (Ramasamy & Surendran, 2011). Certain types of mosquitoes and snails have a high tolerance for salt water and are thus able to breed in water with high salt concentrations (Ramasamy & Surendran, 2011).

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Taken from: Watts N, Adger W N, Agnolucci P, Blackstock J, Byass, P, Cai W, Costello A (2015). Health and climate change: policy responses to protect public health. The Lancet, 6736(15)

The relationship between climate change and health is complex because there are many different contributing factors and there is limited scientific evidence for many regions, several of which are under-resourced (New York Times, 2015). Furthermore, areas of high-resource have not been impacted in the same way, due to advantages as simple as air conditioning (New York Times, 2015). Thus, more scientific evidence is needed, to determine more ways in which climate change could possibly influence the health of a population. More recognition also needs to be given to this issue so that contingency plans can be made for possible outbreaks of diseases that were discussed in this blog post.

References:

Shuman, E. K. (2010). Global Climate Change and Infectious Diseases. The New England Journal of Medicine , 362 (12), 1061-1063.

Ramasamy, R., & Surendran, S. (2011). Possible impact of rising sea levels on vector-borne infectious diseases. BMC Infectious Diseases , 11 (18).

Tavernise, S. (2015, July 13). Unraveling the Relationship Between Climate Change and Health. Retrieved September 10, 2015, from http://www.nytimes.com/2015/07/14/health/unraveling-the-relationship-between-climate-change-and-health.html?_r=0

Climate Change and Health, Part 2: Droughts, Food Insecurity and Culture

~Written by Joann Varickanickal (Contact: joann.varickanickal@gmail.com)

In my last blog post, I highlighted how climate change has impacted the frequency, severity and onset of floods, thus, have various impacts on the health and well-being of flood victims. In this blog, I will be discussing how food security will be impacted by climate change.

Overall, an increase in temperature would lead to a decrease in nutrient acquisition in crops and could disturb general nutrient cycling (St.Clair & Lynch, 2010). This would also cause an increase in the decomposition of soil organic matter, thus, reducing the fertility of soil and possibly impacting crop nutrition (St.Clair & Lynch, 2010).

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"Representation of the 11 Signs of Climate Change." Source: A Students Guide to Global Climate Change, Environmental Protection Agency (EPA)

Borana, Ethiopia is one region where droughts have been severe (Megersa et al., 2013). In this area, cattle ownership not only provides milk, an important part of the diet, but also indicates attaining the socio-cultural status set by the community. With an increase in temperatures, rangelands in this area have dried up. As there is less land for grazing, there has been a great loss in the number of cattle, and a reduction of milk produced by surviving cattle. This has led to negative health consequences as stunting has become more prevalent among children (Megersa et al., 2013). There has also been an increase in physical ailments among adults (Megersa et al., 2013). With this, 77 percent of households have claimed to be food insecure for over five months per year (Megersa et al., 2013).

As revealed in the above example, issues of food security can be closely associated with cultural norms, as diet is often influenced by the local tradition. Thus, when there is a decrease in what is considered to be a staple-food in the region, a diversification in diet can help alleviate food insecurity (Megersa, Markemann, Angassa, & Valle Zárate, 2013). However, adapting to dietary changes can be a difficult process, especially when diets are so deeply rooted in traditions (St.Clair & Lynch, 2010). Cultural norms also influence how vulnerable populations are impacted by food insecurity. For example, issues of food insecurity related to climate often leads to more issues for women and children because they are already lower on the “food hierarchy” (Watts et al., 2015).

The recent article on climate change and health published by the Lancet discussed many potential options for adaption (Watts et al., 2015). For example, efforts should be made to improve ecosystem management (Watts et al., 2015). Investments should also be made in agricultural research in order to increase food security for the long-term (Watts et al., 2015). Furthermore, early warning systems and food reserves also need to increase in order to potentially avoid issues of nutritional deficiencies (Watts et al., 2015).

As often, this issue is complicated, and there are several questions that can be asked. For example, how can policies be formed to alleviate the impacts on the most vulnerable populations? Furthermore, should those in high-resourced countries be concerned about how those in low-resource regions could be impacted by an increase in droughts? Or even how those living in developed countries could also be impacted by these droughts? 
Or is the problem maybe too far from home to be a concern in the first place?


References:
Megersa, B., Markemann, A., Angassa, A., & Valle Zárate, A. (2013). The role of livestock diversification in ensuring household food security under a changing climate in Borana, Ethiopia. Food Security, 6(1), 15–28. doi:10.1007/s12571-013-0314-4

St.Clair, S. B., & Lynch, J. P. (2010). The opening of Pandora’s Box: climate change impacts on soil fertility and crop nutrition in developing countries. Plant and Soil, 335(1-2), 101–115. doi:10.1007/s11104-010-0328-z

Watts, N., Adger, W. N., Agnolucci, P., Blackstock, J., Byass, P., Cai, W., … Costello, A. (2015). Health and climate change: policy responses to protect public health. The Lancet, 6736(15). doi:10.1016/S0140-6736(15)60854-6

Climate Change and Health, Part 1: Floods

~Written by Joann Varickanickal (Contact: joann.varickanickal@gmail.com)

The Lancet recently published an article on climate change and health, extensively examining the types of health risks related to climate change as well as recommendations for policy changes, in order to address these risks (Watts et al., 2015). This article re-emphasized how complex this issue is because there are several contributing factors, and elements that can be potentially impacted (Figure 1).  As there are so many aspects of this topic, for my next few blog posts I will focus on briefly highlighting some of the health risks associated with climate change. This post will focus on natural disasters, specifically looking at floods.

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Figure 1: Relationship between health, climate change and greenhouse gas emission (Watts et al., 2015)

Since 1900, floods have left more than 88 million people homeless, $595 billion in damages, and the deaths of nearly 7 million people (Khedun & Singh, 2013). Overall, climate change will have a direct impact on human health through natural disasters, such as flooding. South Asia is especially at risk as there is already regular flooding. A change in climate can affect the onset of monsoons. For example, in Kerala, a state in southern India, the monsoon season generally begins on June 1st and ends in early September, with a standard deviation of about seven days (Mirza, 2011). However, in the last 50 years this has more than doubled with the earliest onset on May 14th, and the latest date of onset on June 18th (Mirza, 2011). While this may not seem significant, it can influence the level of preparedness in communities that are at risk. Furthermore, the frequency and intensity of rainfalls will also increase. According to climate models, monsoon intensity increases during the summer, as the air over land is warmer than air over the oceans (Mirza, 2011). Floods, that result from the monsoon weather, not only increase the risk of drowning, but also affect the quality of water, thus increasing the exposure to waterborne diseases such as dysentery and diarrhea (Mirza, 2011).

Mental health issues, such as anxiety and depression, can also develop after losing property or facing a financial crisis after a flood (Khedun & Singh, 2013). Furthermore, the impacts of climate change, such as increased flooding, disproportionately influence certain populations such as marginalized communities, women, children, and the elderly (Watts et al., 2015). Thus, they suffer most of the negative health consequences associated with flooding and other disasters related to climate change (Watts et al., 2015). This highlights the complexity of the issue in terms of trying to address how to help those who are most impacted by floods.

There are several mitigation efforts that can be taken in order to reduce the impact of floods. For example, urban planners and engineers can work to ensure that forested areas are preserved and development occurs in areas where soil and vegetation conditions work best to reduce the risk of flooding. Many non-structural methods can also be implemented. For example, in some areas it may be beneficial to create zoning laws that would prohibit development in areas that are prone to flooding (Watts et al., 2015). Government officials and private officials can also work together to improve early warning systems and develop better policies for flood-insurance and emergency preparedness (Watts et al., 2015). Taking these steps can help to ensure that health issues associated with floods will not be exacerbated.

References:

Khedun, C. P., & Singh, V. P. (2013). Climate Change, Water, and Health: A Review of Regional Challenges. Water Quality, Exposure and Health, 6(1-2), 7–17. doi:10.1007/s12403-013-0107-1

Mirza, M. M. Q. (2011). Climate change, flooding in South Asia and implications. Regional Environmental Change, 11(SUPPL. 1), 95–107. doi:10.1007/s10113-010-0184-7

Watts, N., Adger, W. N., Agnolucci, P., Blackstock, J., Byass, P., Cai, W., … Costello, A. (2015). Health and climate change: policy responses to protect public health. The Lancet, 6736(15). doi:10.1016/S0140-6736(15)60854-6

Infectious Diseases Come from Animals? - Zoonotic Transmission

~Written by Theresa Majeski (Contact: theresa.majeski@gmail.com)

For those people who have been following the Ebola outbreak relatively closely or who have been doing their own research into Ebola, you may have heard that scientists think Ebola is introduced into the human population through fruit bats and/or the butchering of bush meat. 

This concept of infectious diseases passing between animals and humans is not new and is called zoonotic transmission. Now Ebola is a virus, but other disease causing agents such as bacteria, parasites and fungi can also be spread between animals and humans. While you may not have heard of zoonotic transmission before, I bet you’ve heard of some zoonotic diseases. Examples include anthrax, Lyme disease, Avian influenza, plague, malaria, dengue, West Nile virus infection, and rabies. The WHO says there are over 200 zoonotic diseases known to us thus far. I also bet you didn’t know that about 75% of recently emerging infectious diseases affecting humans are of animal origin and approximately 60% of all human pathogens are zoonotic. (I just learned these facts as well and am sufficiently surprised the numbers are that high). 

So how in the world does someone get a zoonotic disease? Well, for instance, anything transmitted by mosquitos or ticks are zoonotic diseases, so take proper precautions to prevent being bitten by all ticks and mosquitos. You can also come into contact with zoonotic diseases through petting zoos, pet stores, nature parks, farms, etc. Our beloved pets can also transmit diseases like salmonella, hookworm, and roundworm. The moral of the story is to make sure you’re washing your hands after handling animals and to be careful about petting every fluffy creature you come across. 

Now I would be missing a big part of the picture if I didn’t investigate some of the human-induced reasons why more and more of the population is in danger of being directly impacted by these “remote” zoonotic diseases. Zoonotic diseases transmitted by mosquitos for example, generally only impact people living in areas where those mosquito species are found. Climate change is allowing for some of these mosquitos to expand their territory, thereby bringing zoonotic diseases to new areas of the world. For example, two mosquito species known to carry malaria are now found at the US-Mexican border. Additionally, our expanding population and changes in how humans are migrating are causing interactions with species we’ve never encountered before through practices such as forest clear-cutting and wetland draining. 

I have no easy solutions to these problems as they stem from much larger human population growth issues. But the good news is that we, as humans, have noticed that zoonotic diseases are a growing issue and have stepped up efforts to stay on top of things. The European Union has passed legislation requiring member states to increase their monitoring of zoonotic diseases and has specific guidelines on how to do that. Self-proclaimed “Virus Hunter” Nathan Wolfe did a TED Talk on how his team and he are working on the frontlines of novel virus detection by using innovative ways to collect specimens, detect, and track previously unknown viruses in humans. (I highly recommend watching the talk even if you’re not really interested in emerging infectious diseases as it provides a practical look into the challenges of doing fieldwork in remote areas where these diseases are coming from.)

The important thing to take away from all this information is that zoonotic diseases are almost unavoidable as we humans are interacting with our world, and that world includes all sorts of known and unknown pathogens. By prioritizing innovative ways for early detection we can hopefully learn about potential diseases and create possible remedies before they become global pandemics