The physician author of an article appearing in the August 2000 issue of Scientific American is worried. He is worried that effective, corrective measures to global climate changes will not be instituted soon enough to ward off coming problems. He is worried that multiple factors are destabilizing global climate systems and could cause the planet to jump out of its current state and that at any time; the world could suddenly become much hotter. His main worry is that this sudden, catastrophic change is the ultimate health risk.
The youngest of children can parrot the worst of the outcomes of global warming: the oceans will warm, glaciers will melt causing sea levels will rise, farming zones will shift, droughts and floods will become the norm, etc. Yet, according to scientists, it is the less familiar effects that may turn out to be the most detrimental to humankind.
Current computer models indicate that many diseases will surge as the earth's atmosphere turns up the heat. Unfortunately, some of the computer-aided predictions have already started to hold true. Diseases relayed by mosquitoes, such as malaria, dengue fever, yellow fever and several kinds of encephalitis, have already reached higher elevations and moved into geographic areas where, until now, they had been rare or nonexistent. If current global warming trends continue, the zone of potential malaria transmission will move from an area containing 45 percent of the world's population to an area containing about 60 percent. This is bad news for future patients, since there is no available vaccine against the malaria parasite, which grows more resistant to standard drugs by the minute. Malaria currently kills 3,000 people every day. That number is expected to rise.
Dengue fever, a severe flu-like viral illness that can kill by causing severe internal bleeding, has found its way into the Americas over the past decade. It has also reached as far down as Buenos Aires and into northern Australia. There is no vaccine or drug treatment yet available.
Other diseases, such as West Nile encephalitis, hantavirus pulmonary syndrome and cholera are on the rise and expanding their areas of geographic reach. Though not all of the outbreaks can be traced directly to global warming, it appears that warming temperatures are at least partially responsible for helping the diseases spread. Other conditions, such as world travel by unsuspecting hosts play a contributing a role.
The toll taken by current and future outbreaks will depend primarily on the steps taken now to prepare for the dangers. Global surveillance systems to spot emergence or resurgence of infectious diseases are in need of expansion; better climatological observation, so health professionals are aware of when conditions are ripe for infectious outbreaks, could be very helpful; an attack on the causes of global warming itself; and stepped up vaccine programs (already underway in the case of malaria) could all help control the problems before they reach epic proportions.
The topic of global warming is a hot one (pun intended) for the media. Press releases from the International Conference on Emerging Infectious Diseases, which is underway this week (July 16-19) in Atlanta, Georgia are sure to thrust the topic and its sequelae into the popular press all month.