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Malaria in the Arctic - The diseases of climate change - (3/1/2018)

By Dr. Ron Gasbarro

The year is 2118. The popular vacation destinations are visiting what was once New York City and Cape Cod. Because the oceans are so polluted due to the contaminants that were released within the polar caps when they melted, it was impossible to visit these once vital locations directly. But technology saved the day with virtual reality cameras that allowed one to believe that they were dancing down Fifth Avenue or eating lobster in P-Town.  The year was 2068 – just 50 years earlier – when the last person left Manhattan. Now the city was inundated from the bottom of the 14th St. subway station to the 210th floor of the King Trump building. Climate change finally eroded what was once the East Coast of the United States, as well as other coastal cities around the world. The glaciers melted and people migrated to the west. The loss of human life was great as climate change took control. Atlantic hurricanes with winds over 300 miles destroyed much of the eastern US. Between those incredible tropical storms, hundreds of F5 tornadoes, and other superstorms some cities were completely destroyed: Oklahoma City, New Orleans, Buffalo, Toledo, Miami – all gone. So were all the lobsters and most other ocean life.  Do you think climate change is a political hoax? Read on.  

Evidence of climate change 
Global temperature rise – Earth’s average surface temperature has risen about 2.0° F (1.1° C) since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere. Most of the warming has occurred in the past 35 years, with 16 of the 17 warmest years on record occurring since 2001. The warmest year on record as 2016, while 2017 was the third warmest year, according to the National Oceanic and Atmospheric Administration (NOAA.gov).

Warming oceans
– The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of 0.302° F since 1969 [Levitus, 2009]. 

Shrinking ice sheets
– The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery and Climate Experiment show Greenland lost 150 to 250 cubic kilometers (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometers (36 cubic miles) of ice between 2002 and 2005.

Glacial retreat
- Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa [National Snow and Ice Data Center, 2017]. 

Decreased snow cover
- Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier. [National Snow and Ice Data Center, 2017]

Sea level rise – Global sea level rose about 8 inches in the last century. The rate in the last two decades, however, is nearly double that of the last century [Church, 2006]. 

Declining Arctic sea ice
– Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades [Kwok, 2009]. 

Extreme events – Since 1950, the number of record high-temperature events in the US has been increasing, while the number of record low-temperature events has been decreasing. The US has also witnessed increasing numbers of intense rainfall events [Kunkel, 2013]. 

Ocean acidification – Since the beginning of the Industrial Revolution (ca 1760), the acidity of surface ocean waters has increased by about 30%, according to NOAA. This increase is the result of humans emitting more carbon dioxide into the atmosphere and, thus, more being absorbed into the oceans. The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by about 2 billion tons per year [Sabine, 2004]. 

Mercury
A 2018 report in the journal Geophysical Research Letters states that as the permafrost in the Arctic thaws due to global warming, mercury, which is a neurotoxin that can cause brain and nerve damage, will be released into the oceans and will threaten our food supply [Schuster, 2018]. There are an estimated 32 million gallons of mercury embedded in the permafrost. 

Permafrost, the Arctic’s frozen soil, acts as a massive ice trap that keeps carbon in the ground and out of the atmosphere — where, if released as carbon dioxide, the greenhouse gas would drive global warming. But as humans heat up the climate, they risk thawing that permafrost and releasing that carbon, with microbial organisms becoming more active and breaking down the ancient plant life that had previously been preserved in the frozen earth. Mercury, a naturally occurring element, binds with living matter across the planet — but the Arctic is special. Normally, as plants die and decay, they decompose and mercury is released back into the atmosphere. But in the Arctic, plants often do not fully decompose. Instead, their roots are frozen and then become buried by layers of soil. This traps mercury within the plants, where it can be unleashed as permafrost thaws.

How climate change will influence infectious disease

Expect climate change to affect the geographic and seasonal patterns of vector-borne diseases (that is, diseases caused by pathogens transmitted by mosquitoes, ticks, fleas, or other arthropods) in the US. Diseases that are well known to be climate-sensitive, such as malaria, West Nile virus, cholera, and Lyme disease, are expected to worsen as climate change results in higher temperatures and more extreme weather events.

West Nile Virus 
West Nile virus (WNV) was first detected in the US in 1999 and is now the most common cause of mosquito-borne disease in the US in most years. While many infected people are asymptomatic, some can experience symptoms such as headache, body aches, joint pains, vomiting, diarrhea, and rash, as well as more severe damage to the central nervous system, causing encephalitis, meningitis, and occasionally death [CDC, 2016]. From 1999 to 2014, 41,762 cases of WNV disease were reported to the Centers for Disease Control and Prevention (CDC). Nearly half of the reported cases of people infected with WNY were neuroinvasive—that is, affecting the brain or causing neurologic dysfunction [CDC, 2016]. Mosquitoes acquire the virus by biting infected birds, which are the main hosts of the virus. People are then infected when they are bitten by these virus-carrying mosquitoes. 

Climate change may raise the risk of human exposure to WNV. Studies show that warmer temperatures associated with climate change can speed up mosquito development, biting rates, and the incubation of the disease within a mosquito [Beard, 2016]. The effects of climate change on birds may also contribute to changes in long-range virus movement, as the timing of migration and breeding patterns are driven by climate. Mild winters and drought have been associated with WNV disease outbreaks [Hahn, 2015], while rainfall can also play a role by creating breeding sites for mosquitoes [Beard, 2016]. Vaccine – No. 

Lyme disease
Lyme disease is a bacterial illness that can cause fever, fatigue, joint pain, and skin rash, as well as more serious joint and nervous system complications. Lyme disease is the most common vector-borne disease – that is, a disease transmitted by mosquitoes, ticks, or fleas – in the US. In recent years, approximately 20,000–30,000 confirmed cases of Lyme disease per year have been reported to the CDC [CDC, 2015].

Lyme disease is transmitted through the bite of certain species of infected ticks (commonly referred to as deer ticks) that carry the bacteria that cause Lyme disease [CDC, 2015]. These ticks live not only on deer, but also on rodents, birds, and other host animals. Deer do not harbor the bacteria that cause Lyme disease, but certain other hosts such as white-footed mice do, and ticks pick up the bacteria by feeding on these infected hosts.

Climate is just one of many important factors that influence the transmission, distribution, and incidence of Lyme disease; however, studies provide evidence that climate change has contributed to the expanded range of ticks [Beard, 2016], increasing the potential risk of Lyme disease, such as in areas of Canada where the ticks were previously unable to survive. The life cycle and prevalence of deer ticks are strongly influenced by temperature [Beard, 2016]. For example, deer ticks are most active when temperatures are above 45°F, and they thrive in areas with at least 85% humidity. Thus, warming temperatures associated with climate change are projected to increase the range of suitable tick habitat and, therefore, are one of the multiple factors driving the observed spread of Lyme disease [Beard, 2016]. Because tick activity depends on temperatures being above a certain minimum, shorter winters could also extend the period when ticks are active each year, increasing the time that humans could be exposed to Lyme disease. 

Malaria
Climate change will allow malaria to spread into new areas, according to the National Center for Atmospheric Research. Malaria is caused by a parasite called Plasmodium falciparum and is transmitted by Anopheles mosquitoes. When an Anopheles mosquito bites a person infected with the malaria parasite, the mosquito becomes a carrier of the disease. When that mosquito bites another person, that person becomes infected with the parasite too. Malaria causes the infected person to develop a fever and flu-like symptoms. While most infected individuals recover from malaria, it can cause death, especially in children. Each year there are between 350 million and 500 million cases of malaria worldwide. Over one million of those people die from the disease. Most of the people who die from malaria are children in Sub-Saharan Africa.

The geographic distribution of malaria depends on climate. Regions where the climate is ideal for the mosquitoes that transmit malaria parasites are more prone to the disease. Anopheles mosquitoes thrive in regions with warm temperatures, humid conditions, and high rainfall. Thus, tropical and subtropical areas are ideal. Warm temperatures are also required for malaria parasites to complete their growth cycle within the mosquitoes. At temperatures below 20°C (68°F) the parasite P. falciparum cannot complete its growth cycle in the mosquitoes so it cannot be transmitted. However, there is another strain of malaria parasite called Plasmodium vivax which can complete its life cycle at lower temperatures.

The geographic distribution of malaria and the number of infected people are expected to change as climate change continues. Malaria may expand into new regions. In some areas, there will be less malaria because of climate change. For example, in Sub-Saharan Africa, where climate change is expected to decrease rainfall, the number of mosquitoes may decrease and so malaria transmission rates would decline.  

Cholera 
Cholera is an infection of the small intestine by some strains of the bacterium Vibrio cholera. Symptoms may range from none to mild, to severe [CDC, 2017]. The classic symptom is large amounts of watery diarrhea that lasts a few days [WHO, 2010]. Vomiting and muscle cramps may also occur [CDC, 2017]. Diarrhea can be so severe that it leads to severe dehydration and electrolyte imbalance within hours[WHO, 2010]. Cholera affects an estimated 3–5 million people worldwide and causes 28,800–130,000 deaths a year [WHO, 2010]. Although it is classified as a pandemic as of 2010, it is rare in the developed world [WHO, 2010]. Children are mostly affected [WHO, 2010]. Cholera occurs as both outbreaks and chronically in certain areas [WHO, 2010]. Areas with an ongoing risk of disease include Africa and Southeast Asia. The risk of death among those affected is usually less than 5% but may be as high as 50%. Modern sanitation has eliminated cholera in most developed countries, but regions of the world with poor water sanitation and crowded living conditions are still largely vulnerable, including many parts of Haiti, Pakistan, and coastal Africa.

Researchers have found that both unusually high air temperatures and periods of excessive rainfall create environmental conditions that favor bacterial growth [Colwell, 2014]. In dry conditions, river levels decrease, and bacteria accumulate in dangerously high concentrations. During excessive rainfall, flooding can spread bacteria to regions that have not previously been infected, resulting in fast-spreading epidemics. Given that both extreme heat and more intense storms are expected to increase due to climate change, researchers anticipate that cholera outbreaks could become more frequent in the future [Colwell, 2014]. Even in the past decade, regions of Africa have seen a re-emergence of the disease due to extreme weather, the team reported.

How climate change will influence cancer
Treatments for cancer are improving and saving the lives of many people. In 2005, the death rate from lung cancer was 95% [ACS, 2005]. In 2018, the death rate from lung cancer will be 66% [ACS, 2018]. However, climate change may result in many more new cases than we have now. That increase could cripple the world’s health care systems. According to the National Institutes of Health, increased exposure to toxic and carcinogenic chemicals can impact cancer rates. Such substances could be released into the environment following heavy rainfalls or flooding as well as by increased volatilization of chemicals under conditions of increased temperature. Depletion of the ozone layer in the stratosphere leads to an increase in ultraviolet (UV) exposure and temperature, increasing the risk of skin cancer and cataracts. A decline in air quality and rise in concentrations of certain air pollutants increases the risk of lung cancer.
 
Many epidemiological studies have implicated solar radiation (UVR) as a cause of skin cancer in fair-skinned humans [IARC, 1992]. Assessments by the United Nations Environment Program project increases in skin cancer incidence and sunburn severity due to stratospheric ozone depletion for at least the first half of the 21st century [UN, 1998]. 

The groups most vulnerable to skin cancer are white Caucasians, especially those of Celtic descent living in areas of high ambient UVR. Further, culturally-based behavioral changes have led to much higher UV exposure, through sun-bathing and skin-tanning. Scientists expect the combined effect of recent stratospheric ozone depletion and its continuation over the next 1 to 2 decades to be an increase in skin cancer incidence in fair-skinned populations living at mid to high latitudes [Madronich, 1993]. The modeling of future ozone levels and UVR exposures study has estimated that a ‘European’ population living at around 45 degrees North will experience, by 2050, an approximate 5% excess of total skin cancer incidence. The equivalent estimation for the US population is for a 10% increase in skin cancer incidence by around 2050.

How climate change will influence cardiovascular disease 
According to the National Institute of Environmental Health Sciences, cardiovascular disease is the leading cause of death in the United States. Stroke is the third leading cause. Cardiovascular diseases, such as hypertension, coronary artery disease, heart attack, and stroke, affect an estimated 80 million Americans. Extreme cold and extreme heat directly affect the incidence of hospital admissions for chest pain, stroke, cardiac dysrhythmia (irregular heartbeat), and other cardiovascular diseases. The elderly and isolated individuals are at the greatest risk for cardiovascular disease and stroke when triggered by temperature extremes.
Extreme cold and extreme heat increase hospital admissions for heart-related disorders and disease, such as dysrhythmias and stroke
Increased ozone formation due to higher temperatures harms pulmonary gas exchange and causes stress on the heart. Increased ozone concentrations are associated with heart attacks
Increased particulate matter due to droughts and other conditions is associated with systematic inflammation, compromised heart function, deep venous thrombosis, pulmonary embolism, and blood vessel dysfunction
Stress and anxiety as a result of extreme weather events are associated with heart attacks, sudden cardiac death, and stress-related cardiomyopathy (heart disease)
Cardiovascular manifestations caused by certain vector-borne and zoonotic diseases (diseases carried by animals), such as Lyme disease.

How climate change will influence respiratory diseases

A 2011 study of North American pollen seasons found that some cities had significant increases of 11-27 days, compared with 15 years before [Ziska, 2011]. If warming trends accompany long-term climate change, greater exposure times to seasonal allergens may occur with subsequent effects on public health.

A 2018 study published in the New England Journal of Medicine revealed the respiratory dangers of increasing wildfires, noting the carbon dioxide, particulate matter, trace minerals, and thousands of other compounds that are unleashed [Balmes, 2018]. 

A 2017 review noted the impacts of the consequences of climate change, from increased allergies due to heavy precipitation events, asthma prompted by intense tropical cyclones, and allergic conditions caused by extremely high sea levels [Lake, 2017].

How to weather climate change
Mind your health - As the climate changes, there will be diseases that were once seen only in the tropics. Get vaccines for as many of these diseases as possible. A hotter climate will be more taxing on the heart and lungs. Make sure you take your medications as directed so you can keep cardiac and respiratory problems at bay. Wetter conditions mean that mosquito-borne and fungal-borne diseases will be more prevalent.   

Prepare for societal changes – There may be conflicts that involve food and water shortages. Growing one’s own food may help in this regard. On the other hand, industries that can help urban areas adapt to climate change will become quite lucrative. 

You may have to move – As sea levels rise, you may be forced to move farther inland. And that clear view of the ocean may be blocked by seawalls and dikes that will need to be built to preserve coastal areas. 

Control water usage – Water may not be free in the future. Longer droughts and underground water supplies will be stressed. Get used to brown lawns, taking showers with buddies and take care of your gardens with wastewater. 

Keep your cool – Urban life is already unbearable in some cities. Scorching city nights will lead the way for social disorder, ill health, and overall bad moods. As water and power shortages become more frequent, migrations out of blistering cities to the cooler rural areas will tremendous.

On the bright side (?) – You may not experience the profound effects of climate change in your lifetime. Unfortunately, your grandchildren will have to adapt or die.    
  
Ron Gasbarro, PharmD, is a registered pharmacist, medical writer, and principal at Rx-Press.com. Read more at www.rx-press.com 

References
American Cancer Society. Cancer Facts and Figures 2005. Atlanta: American Cancer Society; 2005. 

American Cancer Society. Cancer Facts and Figures 2018. Atlanta: American Cancer Society; 2018.

Balmes JR. Where there’s wildfire, there’s smoke. N Engl J Med 2018; 378:881-3.

Beard CB, Eisen RJ, Barker CM, et al. The impacts of climate change on human health in the United States: A scientific assessment. Chapter 5: Vector-borne diseases.  US. Global Change Research Program; 2016. https://health2016.globalchange.gov.

Centers for Disease Control and Prevention (CDC). Cholera – Vibrio cholerae infection. Information for Public Health & Medical Professionals; 2017. Available at: https://www.cdc.gov/cholera/healthprofessionals.html .

Centers for Disease Control and Prevention (CDC). Lyme disease data and statistics; 2015. Available at: www.cdc.gov/lyme/stats/index.html. 

Centers for Disease Control and Prevention (CDC). West Nile virus symptoms and  treatment; 2016. Available at: www.cdc.gov/westnile/symptoms/index.html. 

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Derksen C, Brown R. Spring snow cover extent reductions in the 2008-2012 period exceeding climate model projections. Geophys Res Lett. 2012;39:L19504.

Environmental Protection Agency (EPA). Climate Change Indicators: West Nile Virus; 2016. Available at:  https://www.epa.gov/climate-indicators/climate-change-indicators-west-nile-virus 

Hahn MB, Monaghan AJ, Hayden MH, et al. Meteorological conditions associated with increased incidence of West Nile virus disease in the United States, 2004–2012. Am. J. Trop. Med. Hyg. 2015;92:1013–22.

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Levitus S, Antonov JI, Boyer TP, Locarnini RA, Garcia HE, Mishonov AV. Global ocean heat content 1955–2008 in light of recently revealed instrumentation problems. Geophys Res Lett. 2009;36: L07608.

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