Global Warming and Infectious Diseases

1. Global Warming and Infectious Diseases • Joseph witzke • Climatology • November 2010

2. So What? • Diseases Kill people and animals • There may be a correlation between global warming and spread of infectious diseases • So if you believe that the earth is going to continue to warm at an alarming rate you better get your vaccinations because the diseases may get you before the heat does! • But warming may not be the only factor...

3. Some Questions • Will a rise in global temperatures increase the intensity and frequency of infectious diseases? • Does the geographic range of these diseases simply increase? • Or will there just be a shift in the Regions of these diseases? • What are other factors contributing to the spread of these diseases?

4. Range of Diseases • Many are Restricted to or more prevalent in tropical and subtropical zones • More prevalent at lower latitudes, lower altitudes and warmer temperatures • Warmer conditions promote vectors for disease spread

5. Range Shifting Vs. Expanding • In theory parasites should already be in their optimum ranges • If temperatures increase, warming new areas, then the parasites should be able to move to new territories • But the temperature could also become too hot in some areas • The ranges would shift instead of expanding • Historical ranges included much of Europe and North America where today malaria is practically absent due to human intervention

6. The Other Factors “Techniques to eradicate malaria have been available for decades. It is a disease of poverty, not a disease of climate change.” -Plimer • Precipitation • Humidity • Ecological • Sociological • Economic • Evolutionary

7. Mosquitoes • Diseases carried by mosquitoes are of most concern • Transfer diseases amongst humans and animals • Are very sensitive to the climate they inhabit • Go to the cold to get away!!

8. So Why the Mosquito? • Mosquitoes thrive in the heat, Bitting more frequently and reproducing faster • Still water caused by floods and droughts are an excellent breeding ground for mosquitoes • Winter freezing kills eggs, larvae and adults • Cold limits mosquitoes to seasons or areas where temperatures stay above certain minimums • Warmer temperatures may enable them to transfer more diseases for a longer period of time

9. Eww c’mon More Mosquitoes? • They carry malaria, dengue fever, yellow fever and encephalitis • Pathogens inside the mosquito mature faster in the heat, increasing the chance of the disease being spread since mosquitoes live only several weeks. • Sustained outbreaks of malaria only where temperatures routinely exceed 60 degrees F • Yellow and Dengue fever only where temperatures rarely fall below 50 degrees F

10. What Diseases? • Malaria • Encephalitis • West Nile Virus • Dengue fever • Snail Fever • Yellow Fever • and other insect, rodent and water carried diseases

11. Malaria 3.3 billion people, half of the world’s population, are at risk of malaria!

12. It’s the Heat! NO IT’S THE MALARIA! • The most popular disease mentioned when it comes to the global warming debate • 250 million cases every year, nearly 1 million deaths every year • An average of 1500 cases in the United States reported every year • Between 1957 and 2009, in the United States, 63 outbreaks of locally transmitted mosquito-borne malaria have occurred • 5th leading cause of death from infectious diseases worldwide (after respiratory infections, HIV/AIDS, diarrheal diseases, and tuberculosis).

13. Poor Countries are most Vulnerable • In Africa: • 89% of the malaria deaths worldwide occur here • One in five childhood deaths are due to malaria • An African child may average between 1 and 6 episodes of malaria fever each year • 10,000 pregnant women die • 200,000 infant deaths • Every 30 seconds a child dies from the disease

14. What Exactly? • Malaria or a disease resembling malaria has been noted for more than 4,000 years. From the Italian for "bad air," mal'aria has probably influenced to a great extent human populations and human history. • The symptoms of malaria were described in ancient Chinese medical writings as far back as 2700 BC • Malaria is a mosquito-borne disease caused by a parasite. People with malaria often experience fever, chills, and flu-like illness. Left untreated, they may develop severe complications and die. • Curable disease if diagnosed, treated promptly and correctly

15. Prevent Malaria! • New antimalarials replacing drugs such as chloroquine that the parasite has become resistant to • Control the mosquitoes DUH! • Use insect nets, spray insecticides, manage breeding habitats • Malaria is basically eliminated once the per capita income reaches $3100

16. Blue is decreasing, red is increasing

17. Dengue Fever • Mosquito-borne infection found in tropical and sub-tropical regions around the world, predominantly in urban and semi-urban areas. • Dengue hemorrhagic fever (DHF) is a potentially lethal complication • The incidence of dengue has grown dramatically around the world in recent decades. Some 2.5 billion people – two fifths of the world's population – are now at risk from dengue. WHO currently estimates there may be 50 million dengue infections worldwide every year. • Medical care treating DHF can decrease mortality rates from more than 20% to less than 1%

18. Not quite as widespread as malaria

19. West Nile Virus • So far in 2010 there has been 39 deaths due to WNV in the united states • First arrived in North America in 1999 • Warmer temperatures, elevated humidity, and heavy precipitation increased the relative rate of human WNV infection in the United States independent of season and each others’ effects (Soverow et al. 2009).

20. Tick-borne Encephalitis • Viral infectious disease involving the central nervous system that manifests as inflammation of the brain, the membrane surrounding the brain and the spinal cord. • Ticks are the vector and rodents are their host • TBE is not dependent on temperature, but over the last 30 years an impact of climate warming on the vertical disease distribution in Central Europe is evident. • Only several thousand cases are reported annually

21. Maybe I don’t want to go for that hike after all...

22. Killing Corals • Most coral diseases occur at higher sea water temperatures • Coral Bleaching • Black and White Band Diseases • Coral Plague • Aspergillosis • 1997–1998, the world's largest bleaching event ever killed 16% of the world's reefs

23. And Annihilating Amphibians • An estimated 67% of the 110 or species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. • Warmer climates are more optimum for growth of this pathogen

24. Discussion • Global warming can be a factor in increasing distribution and incidence of infectious diseases • Ranges of these diseases are more likely to shift than expand • Warmer weather is mostly a more suitable environment for many parasites and the vectors • Non climatic factors are more likely to determine the extent the infectious diseases spread • Many of the incidences in the United States are due to traveling • Questions?

25. Literature Cited • Epstein, Paul R. 2000. Is global warming harmful to health? Scientific American 283: 50-57. • Gething, Peter W., Smith, David L., Patil, Anand P., Tatem, Andrew J., Snow, Robert W., Hay, Simon I. 2010. Climate change and the global malaria recession. Nature 465: 342-345. • Ostfeld, Richard s. 2009. Climate change and the distribution and intensity of infectious diseases. ecology 90: 903-905. • Pascual, Mercedes and Menno J. Bouma. 2009. Do rising temperatures matter? Ecology 90: 906-912. • Malaria. 2010. Centers for Disease Control and Prevention. November 2010 <http://www.cdc.gov/malaria/>

26. J. Alan Pounds, Martin R. Bustamante, Luis A. Coloma, Jamie A. Consuegra, Michael P. L. Fogden, Pru N. Foster, Enrique La Marca, Karen L. Masters, Andres Merino-Viteri, Robert Puschendorf, Santiago R. Ron, G. Arturo Sanchez-Azofeifa, Christopher J. Still & Bruce E. Young. 2006. Widespread amphibian extinctions from epidemic disease driven by global warming. Nature 439: 161-167. • Jonathan E. Soverow, Gregory A. Wellenius, David N. Fisman, and Murray A. Mittleman. 2009. Infectious Disease in a Warming World: How Weather Influenced West Nile Virus in the United States (2001–2005). Environmental Health Perspectives 117: 1049-1052. • Malaria. 2010. World Health Organization. November 2010 <http://www.who.int/topics/malaria/en/>. • Rosenberg, Eugene and Yael Ben-Haim. 2002.Microbial diseases of corals and global warming. Environmental Microbiology 4: 318–326

27. Environmental Health Perspectives; John Bruno. "Global warming takes a toll on coral reefs". 2009. Encyclopedia of Earth. Encyclopedia of Earth. November 2010 <http://www.eoearth.org/article/Global_warming_takes_a_toll_on_coral_reefs?topic=49513> • Chavarria, Gabriela, Kim Knowlton, and Dylan Atchley. 2010. The human-climate-wildlife nexus. Bulletin of the Atomic Scientists 66: 48-56 • Plimer, Ian. Heaven and Earth: global warming the missing science. Lanham: Taylor Trade, 2009. • Zemana, Petr and CestmirBeneš. 2004. A tick-borne encephalitis ceiling in Central Europe has moved upwards during the last 30 years: Possible impact of global warming? International Journal of Medical Microbiology Supplements 293: 48-54. • Lafferty Kevin D. 2009. The ecology of climate change and infectious diseases. Ecology 90: 888–900.