Global Warming and the Spread of Disease

Global warming will affect our planet in unpredictable ways. With temperature increases of 1.4 to 5.8°C expected by the end of the century, the full impact is still unknown. We have been warned about rising floodwater from melting glaciers and Arctic ice sheets, as well as increased rainfall, but that is only the beginning. The result of these extreme weather changes could lead to other problems, some of them catastrophic in nature. As waters rise, huge numbers of people could be displaced to areas further inland, causing overcrowded conditions that facilitate the spread of infectious disease. Water and insect-borne viral infections alone could have a tremendous impact on human health.

A warmer earth will mean increased rainfall, and more breeding spots for insects. Due to the increasingly soggy environment, bloodsucking insects, especially disease-carrying mosquitoes, will be of particular concern. Diseases like malaria could become a major health concern, and viruses that are now primarily restricted to tropical areas could spread to the general population.

One such virus is Dengue Fever, a member of the arbovirus family. Its symptoms include fever, pain, rash, and sometimes hemorrhaging. Dengue Fever can be especially serious in children. Yellow fever is also a mosquito-borne virus, with symptoms that include weakness, fever, and pain. Serious cases can involve the kidney, liver, and heart. In the case of West Nile Virus infection, humans and horses are the common hosts. In humans West Nile Virus may have no symptoms, or only mild symptoms that may consist of fever, headaches, nausea, vomiting, and body aches. More serious cases can result in convulsions, vision loss, and paralysis. Climate change may also increase the incidence of the tick-borne encephalitis virus, with symptoms that include headaches, muscle aches, and fever, and in its secondary phase can affect the central nervous system. Mosquito control and an adequate vaccine supply will be crucial in controlling the spread of these viruses.

The risk of water-borne disease could intensify as well. The number of cases of viral gastroenteritis, caused by rotavirus and norovirus, with symptoms of diarrhea, nausea, and vomiting, could increase significantly. Hepatitis A is spread in contaminated food and water, and can cause liver infection. Hepatitis E, a water-borne virus, is also a liver disease that can be fatal in pregnant women. Protection of the water supply against these pathogens would become a high priority.

The above-mentioned illnesses represent only a partial listing of potential health hazards that could arise as a result of global warming. With so much uncertainty, it is difficult to predict how changes in the way infectious disease is transmitted will affect human health. History has demonstrated how the movement of large numbers of human beings can facilitate an outbreak. One example is the Spanish flu pandemic of 1918 that killed millions of previously healthy people. It is believed that massive troop movements, as well as increased travel due to the advent of modern transportation systems, accelerated the spread of infection.

Preparation for the consequences of climate change will be crucial, if we are to head off a global pandemic of perhaps epic proportions. Prevention of insect and water-borne infections facilitated by increased contact between humans will require diligence and study on the part of experts in the areas of epidemiology and climate change. Protection of water and food supplies to avoid contamination and increased vaccine production will be of tremendous importance.

Who knows? We may still have some time. The problem is that no one, not even the experts, knows for sure how much time is left before the greenhouse effect becomes an irreversible certainty. Drastic cutbacks in the burning of fossil fuels may still bring about a halt in global warming. However, oil and coal are still our prime sources of energy, and consumption in the United States appears to be as voracious as ever. With no clear plan for significant reductions, it seems inevitable that the dire warnings will become reality. The warm up is coming, time to get ready.

References

1) Schvoerer, E., Massue, J.P., Gut, J.P., Stoll-Keller, F.

Climate Change: Impact on Viral Diseases

The Open Epidemiology Journal

2) http://www.medicinenet.com/dengue_fever/article.htm

3) http://www.cdc.gov/ncidod/dvbid/YellowFever/index.html

4) http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/TBE.htm

5) http://www.cdc.gov/ncidod/dvbid/westnile/wnv_factsheet.htm