The following article was adapted from an article originally written by Dr. Lund in the fall of 2002 for ReMARCs, a newsletter for MARC’s employees.
The West Nile Virus, The Mosquito, Global Warming & 9/11
Vector-bourne Diseases
Dr. R. W. Lund
“West Nile toll for Illinois at 18"#8221; banners an article in the September 17 edition of the Atlanta Journal-Constitution in which the Centers for Disease Control and Prevention (CDC) report that of the 66 deaths nationally due to the West Nile Virus the state of “MARC North” has been the most afflicted. This topic was not used as a “filler” in the Atlanta newspaper; we found on September 14, “West Nile virus outbreak not terrorism, experts say” and on the front page on September 13, “W. Nile blood worries deepen.” The latter article details concerns over apparent transmission of West Nile Virus (WNV) through blood transfusion and organ donation. Not only the lay press but also the medical literature, from prominent scientific periodicals to “throw-away journals” has been inundated lately with articles about the WNV. Appearance of new diseases is not unusual. Since 1975, the World Health Organization (WHO) has reported the recognition of over 30 diseases new to medicine including HIV, Ebola virus, Lyme disease, Legionnaires’ disease (how many remember the Legionnaires’ convention in Philadelphia in 1976?), toxic Escherichia coli (of local Atlanta Whitewater fame), and a new hantavirus in the Southwestern United States. In addition, there has been a resurgence of recognized diseases such as malaria and cholera and development of significant antibiotic resistance in some important bacteria. All of the above have received extensive coverage in both the media and scientific literature. Certain aspects of the arrival on the scene of the West Nile Virus as the current “infectious illness du jour” are different from the appearance of those noted above, however, and very much reflect the times in which we live. Affliction with vector-borne disease is as old as the history of man, who has shared this planet with insects long before he was able to consciously express it (except by slapping and scratching). Development of agrarian society was associated not only with altering the environment in ways favoring propagation of insects, such as mosquitoes, (e.g., deforestation) but also with the concentration of populations of people close together, conditions that favored development of vector-borne disease. A vector is a carrier (usually an insect) that becomes infected when it ingests an infectious agent such as a virus while feeding on the blood of an infected animal (host). It then transfers the infective agent to another host through its saliva while in the process of biting. A classic example is malaria (two possible word origins are Italian: mala aria, “bad air,” or early English settlers in Africa who noted that low lying areas (“mal arias”) were associated with development of febrile illness). The mosquito is the vector that transmits the malaria organism between hosts and it is the vector for the West Nile Virus as well. Other “famous” vectors include the flea (bubonic plague) and the tick (Rocky Mountain spotted fever and Lyme disease). Of the involved hosts, one may be an animal (the rat in plague) or the host may be exclusively human (as in malaria). Incidence of vector-borne disease increases during seasons of the year when the vector is most prominent; frequently this is the fall. “Autumnal fever” has been noted as far back as 800 BC where Homer in his Iliad notes, as Achilles prepares to fight Hector:
And old King Priam was first to see him coming, surging over the plain, blazing like the star that rears at harvest, flaming up in its brilliance—far outshining the countless stars in the night sky, that star they call Orion’s Dog—brightest of all but a fatal sign emblazoned on the heavens, it brings such killing fever down on wretched men.
Scholars feel that the autumnal fever noted in the Iliad was most likely due to malaria. Movement of large numbers of people is often responsible for exposing new populations to infectious illness as evidenced by the epidemics associated with the crusades. In addition to concentration and movement of populations, infectious illnesses that are vector borne are also very sensitive to environmental changes that affect reproduction and viability of the vector (most frequently the mosquito). The reason that many vector-borne illnesses tend to be predominantly equatorial in distribution is that yearly winter freezing produces some control on vector populations in more temperate latitudes. This is why the (then) Communicable Disease Center (the forerunner of the U.S. Centers for Disease Control and Prevention—the CDC), established by the United States Congress in 1946, was located in subtropical Atlanta, Georgia. The only federal government agency not based in Washington, D.C. was located in the South because its principal mission originally was to eradicate malaria from the entire country and the southern states, at that time, were the main region still affected by the disease. The principal vector for the WNV, the Culex pipiens mosquito, is primarily a city-dwelling mosquito whose breeding is favored by mild winters and dry summers (sound familiar Atlantans?). Such conditions also are detrimental to the usual mosquito predators such as amphibians and dragonflies, resulting in greater mosquito survival. It is also felt that in drought conditions water available for birds (a major host for the WNV) diminishes, resulting in greater concentration of birds at dwindling watering sites, fostering propagation of the virus in its avian reservoir. The virus itself experiences accelerated maturation in hot climates.
West Nile Disease (WND)
Actually, the West Nile Virus is not really a “new disease” but rather is new only to North America, having been recognized for decades as infecting wild or domestic animals in Africa, the Middle East, Europe and Asia. Horses, in addition to wild birds, are well-recognized reservoirs for the disease. Since first noted to be a potential human pathogen in 1937, when it was isolated from an infected woman in the West Nile district of Uganda, it had been associated with occasional outbreaks in man until the mid 1990‘s, after which the frequency and severity began to increase. The West Nile Virus joins dengue fever, yellow fever, malaria, and plague as important vector-borne diseases imported to North America from an outside geographic region. The first appearance of the virus in North America was noted in New York in 1999. The virus probably traveled to the New World in an infected bird or mosquito (cases of so-called “aircraft malaria”—development of malaria in workers bitten by mosquitoes while servicing aircraft coming from endemic overseas regions—are not uncommon in this mobile age). Efforts to contain the virus, mainly through control of its mosquito vector, were unsuccessful and from the initial toehold in New York in 1999 the virus has now spread so that it has been found, still mainly in animal hosts, in most of the regions where the mosquito is noted to exist as a disease vector. The extent of its spread in three years indicates that it will be a permanent viral pathogen in North America. It is interesting to note that its current distribution (again, mainly in animal hosts) in the United States approximates that of malaria (also transmitted by the mosquito) in the late 1800‘s prior to efforts of malarial control. See below:
 |
Distribution of Malaria in the United States and Canada in 1882 |
 |
Extent of West Nile Virus in the United States: The red-shaded areas represent states where the infection was initially identified and the chocolate brown-colored states show areas of detection in animal hosts as of August 2002. The cross hatching indicates states having cases of confirmed human infection. |
The above geographical distribution of West Nile Virus may well be more readily maintained for the animal reservoir than for humans; it is likely that recordings of human infections will soon involve all of the states. The reason for this is that not only are our people very mobile but West Nile Virus has now been transmitted, as noted above, through blood transfusion and organ donation with the involved states (Mississippi, Louisiana, North Dakota, Georgia, and Florida) being geographically disparate.
Cases of human infection with West Nile Virus tend to occur most often in the fall but have been identified from mid July to early December. Statistically, only about one in five develops significant symptoms and only one of two symptomatic individuals will seek medical help (that is only about ten percent of all those infected feel bad enough to seek medical attention). Typical symptoms are similar to other viral (flu-like) illnesses but more severe cases tend to demonstrate disproportionate muscle aching and weakness and neurological symptoms of headache and stiff neck suggesting development of encephalitis (inflammation of the brain) and/or meningitis (inflammation of the meningeal lining of the brain and spinal cord). Although neurological involvement is the most serious expression of the disease and may be fatal, it is relatively rare with only about one in every 150 infections developing meningitis or encephalitis.
The risk of death increases for infected individuals above age 50 who develop either meningitis or encephalitis and is especially high in those above age 70. Long-term follow up remains to be assessed, but at one year from initial infection in those who were symptomatic (that is in 20% of all those infected), about one half continued to have some persistent symptoms.
As with many viral illnesses, there is no effective treatment other than supportive care. There is no current preventive vaccine available (although efforts to develop a vaccine are underway). Prevention efforts currently must be directed at controlling the transmitting vector, the mosquito. This should be pursued through broad control measures fostered by governmental public health agencies to drain water from mosquito breeding sites and eliminate standing water. Pesticide spraying to control adult mosquito populations is appropriate. In addition, individuals should take steps to control their exposure. Small areas of standing water on private property (such as children’s wading pools, etc.) should be drained. DEET is the most widely used mosquito repellent and can be applied to skin as well as clothing, tents, bedrolls, etc. Formulations containing higher than 50% concentration of DEET demonstrate little enhancement of effectiveness over those having from 10% to 50% concentration and are not recommended for use. Pediatricians recommend that no more than 10% concentrations of DEET be used on children and that no DEET at all be used on infants younger than two months of age. Permethrin is another repellent that can be applied to clothing, tent walls, etc., but application to the skin is not recommended by the Environmental Protection Agency (EPA). Other basic measures such as wearing long sleeves and long pants, using mosquito netting and other appropriate barriers are all potentially helpful.
It must be remembered that the likelihood of contracting WNV is quite low and that only one in five of those infected will even become significantly symptomatic. The severe cases associated with central nervous system infection and possible death occur predominantly in those over 50 years of age, especially in debilitated elderly. We have known for decades of other viral agents, such as St. Louis encephalitis, that may produce a similar illness. Infection with one of these other agents also may be fatal but it is relatively uncommon and progressively more severe epidemics over time have not been observed.
“WNV was the largest outbreak of encephalitis in the US in modern times,” per the Atlanta Journal Constitution (AJC), Nov. 21, 2002, which went on to note that the potential for transmission remains high, especially in South Georgia where a warmer winter may enable year round transmission of the virus (according to Stacy Kramer, state epidemiologist). It is noted that recent onset of the WNV has absolutely rejuvenated mosquito control efforts and the (mosquito control) industry in Georgia. Some evidence has been gathered suggesting that spread of the virus in natural reservoirs has been somewhat greater than expected. For example, it has been reported (unpublished data) that 125 out of 125 randomly selected ducks killed during this fall’s duck hunting in Manitoba, Canada tested positive for the virus—a disturbing indicator of prevalence (although the 100 percent positive test result is probably unlikely even if only the specimen handling and technical testing limitations are considered per Dr. Margo Brinton, a prominent Atlanta virologist). However, there can be no question that a large percentage of these ducks tested positive for WNV. Different animal species are becoming infected with the virus including a recent report of infected alligators in Florida.
Bioterrorism
The medical literature now confirms that, in addition to the findings that we noted above, West Nile viral infection can also present with an involvement of the spinal cord similar to that produced by the poliovirus with a resultant poliomyelitis-like illness. Prior to this realization, one patient presenting with the poliomyelitis-like syndrome from WNV provoked anxiety reflective of the times in which we live. “Emory patient caused temporary bioterror fear . . . An Emory University patient who was among the first to be diagnosed with West Nile paralysis had such unusual symptoms that her doctors feared she might be the victim of a biological attack,” (AJC, Tuesday, Sept. 24, 02). This newspaper article is reflective of the undercurrent anxiety and suspicion that has been present for the last 14 months in this country, especially since the threat of a biological agent (anthrax-laced letters) was linked in time with 9/11. The West Nile Virus has appeared in roughly the same time frame and has been accused on more than one occasion of being an agent of bioterror (bioterrorism is defined as the deliberate release of a harmful biologic agent to intimidate civilians and their government). Even before 9/11 concerns that the WNV might be an agent of bioterror had been raised. At the time of its initial appearance in North America in 1999 suspicion that the appearance of this virus, previously unknown to North America, may represent an expression of bioterrorism prompted an investigation by the CIA. It has been rumored for some years that Saddam Hussein employs a virus as part of his bioweapons arsenal.
Most recently in September of this year senator Patrick Leahy (D-VT) posed the question, “Is it coincidence that we’re seeing such an increase in West Nile virus, or is that something that is being tested as a biological weapon against us?” Incidentally, Senator Leahy was the target of an anthrax-laden letter in the fall of ’01. It is highly unlikely that WNV represents an expression of bioterror since other biological agents, such as anthrax, smallpox and plague, are so much more lethal. However, the possibility of bioterror raised by the entrance of WNV into North America has prompted discussion in the scientific literature concerning public health, the media and exactly what is best to publicly disclose in the event of bioterrorism (as well as an ongoing battle concerned with whether traditional state and local public health agencies, or a federal agency, should be responsible for surveillance and protection from bioterrorism). “The media frenzy that accompanied (the appearance of WNV in 1999) was without precedent. Under an intense media spotlight, public health officials scrambled to find ways to explain how it got here . . . including some passing speculation about whether the virus was the result of an intentional bioterrorist act,” (Journal of Urban Health: Bulletin of the New York Academy of Medicine, Vol. 79, No. 1, March 2002). Remember that earlier in this article it was noted that since 1975, 30 new diseases have been recognized by the World Health Organization, among them the infectious diseases of HIV, Ebola virus, Lyme disease, Legionnaires’ disease, toxic Escherichia coli, and a new hantavirus. Think of the media mania if any of these had first appeared after 9/11. In 1996, novelist Tom Clancy published Executive Orders, which depicts an attack on the United States by terrorists using the Ebola virus. There followed in 1997 a novel by Richard Preston called The Cobra Event in which a classic “mad scientist” sets out to thin the world’s population with a death dealing man-made virus (think of subsequent public reception if the author had chosen anthrax as the biological agent instead of a virus). It is said that then president Clinton became concerned and involved in the issue of bioterrorism after reading The Cobra Event. Subsequently, we have experienced the terrible events of September 11 and anthrax-laced mail (suspected to be perpetrated by a scientist with an “ax to grind”). Since these events and the possibilities (described for public consumption heretofore only in novels) for bioterrorism, the reality of public perception of a “new disease” such as the West Nile Virus has been radically altered.
Global Warming
It is felt that very possibly the WNV would never have significantly propagated in North America if it weren’t for the abnormally warm Northeastern winter of 1999–2000. Normal colder temperatures would very possibly have resulted in elimination of the mosquito vector. That the expected colder temperatures did not occur is representative of a worldwide climatic trend that is altering the pattern of vector born disease (one among many effects)—this is the trend towards Global Warming. Man has contemplated nature and its relationship with his fate for centuries. Originally, he at times blamed his misfortunes on alterations in the natural world (“the sun, the moon, and the stars”) as the Earl of Gloster implies in the first act of King Lear. Edmund’s reply to his father scoffs at this “foppery.”
Earl of Gloster: “These late eclipses in the sun and moon portend no good to us: though the wisdom of nature can reason it thus and thus, yet nature finds itself scourg’d by the sequent effects. Love cools, friendship falls off, brothers divide . . . "”
Edmund (son of Gloster) replies: “This is the excellent foppery of the world, that, when we are sick in fortune, (often the surfeit of our own behaviour), we make guilty of our disasters the sun, the moon, and the stars; as if we were villains by necessity, fools by heavenly compulsion, knaves etc, by an enforc’d obedience of planetary influence . . . "”
When Shakespeare wrote these lines, around the year 1604, the earth was experiencing what has been called the “Mini Ice Age”—the planet experienced abnormally low temperatures for about 150 to 200 years. Scientists have found that glaciers are very responsive to the earth’s climatic changes. A glacier is a large mass of ice and snow that forms in areas where the rate of snowfall constantly exceeds the rate at which the snow melts, such as towards the earth’s polar regions, usually at higher elevations where it is colder. After formation, the glacier moves slowly down a mountain slope or valley until it melts or breaks away (marginal ablation). During climate cooling the rate of ablation at the margin of the glacier diminishes and, conversely, during climate warming, increased marginal ablation occurs, forcing a glacier margin to retreat. The mass of rocks, gravel, sand, etc. that is carried or deposited by a glacier is called a moraine. Various techniques, including measurement of moraines, as well as radiocarbon dating of plant and animal material, enable scientists to reconstruct glacier expansion and contraction that has occurred during prior centuries and estimate the climatic conditions present many hundreds of years back in time. This has enabled an estimation of the earth’s temperatures long into the past and long before the thermometer was developed. The number of retreat moraines is a measure of the overall rate of retreat of a glacier (which occurs with warmer temperatures).
The following chart depicts the number of retreat moraines (the vertical brown bars) over the last several hundred years that have been found in the Kenai Mountains and other areas in the Gulf of Alaska, along with associated estimated temperature variation (degrees centigrade appears on the left). High temperature variations are shown as the red areas above the temperature base line and Low temperature variations as the light blue areas below the baseline. Progressive abnormal increases in environmental temperatures are apparent since the early 1900‘s.
Examination of the above graph suggests that global warming, as evidenced by glacial retreat moraines, was present long before significant fossil fuel consumption (on whose doorstep the fault of global warming is usually laid) began. However there can be little doubt that global warming accelerated when, in the mid-Nineteenth Century, the Industrial Revolution wedded economic progress to the burning of coal. “Across central Europe the great coalfields lie like a glittering black belt, waiting to flame into power. This priceless lode, without which the industrial revolution would have been impossible, starts in Wales and ends in Poland” (William Manchester: Arms of Krupp). One of the richest veins of coal lay in northwestern Germany’s Ruhr valley . . . “The entire Ruhr was changing as men explored coke’s marvelous uses . . . Each year the sky overhead grew grayer; each year the smelters used more coke . . . The factory air was filthy . . . ” (Manchester, ibid). The Industrial Revolution was also surging in England around 1850 when these descriptive lines were written . . . “ of tall chimneys, out of which interminable serpents of smoke trailed themselves forever and ever, and never got uncoiled . . . where the piston of the steam-engine worked monotonously up and down like the head of an elephant in a state of melancholy madness . . . ” (Charles Dickens: Hard Times).
Here in the New World we were not initially quite so prolific in our consumption of fossil fuels, but one man helped us make up for lost time (and, ultimately, “then some”); his name was Henry Ford. Ford accomplished two things that subsequently contributed to global warming. The first was that, upon realizing that boiler-requiring steam engines could never be made light enough to power vehicles such as tractors, he turned to the gasoline-burning internal combustion engine for this purpose and the “horseless carriage” was born. In 1903 the Ford Motor Company sold 1,708 two-cylinder, eight horsepower automobiles. Henry Ford threw America’s Industrial Revolution into high gear when, in 1914, he instituted the second of his contributions to global warming, the assembly line. His famous quote: “Every man should make enough money to own a home, a piece of land and a car,” should have the word car underlined. The United States is truly the land of the automobile and everyone at MARC is well aware of the automobile’s grip on our lives and its contribution to global warming. Most of us begin and end our workdays sitting in traffic, each doing his little part to warm the planet. Ford’s Highland Park plant with the world’s first automatic conveyor belt could churn out a car every 93 minutes by the end of 1914. Actually, the principal greenhouse gas is water vapor, but CO2 receives most of the public attention since it is the product of combustion of the two fossil fuels that we have mentioned above (coal and petroleum products). The third contributing fossil fuel, natural gas, whose combustion also produces CO2, has arrived somewhat later (and less dramatically) on the stage. Since the photosynthetic process of plants removes CO2 from the atmosphere it should be noted that deforestation since the middle of the Nineteenth Century has contributed to about one fifth of the excess accumulated greenhouse CO2.
Mt. Kilimanjaro
Ernest Hemingway described Africa’s famous snow-capped Mount Kilimanjaro to be “wide as the world, great, high, and unbelievably white in the sun.“The Snows of Kilimanjaro,” his famous short story, published in 1927, ended with the dying protagonist, Harry, hallucinating that he had crashed in a small airplane into the snowy summit at the moment of his actual death. A century later this story would probably have had a very different ending. It is now predicted that the glaciers and snowfields topping Kilimanjaro, which have shrunk by 80 percent in the last century, will be gone within two decades. In spite of such evidence of equatorial global warming, the warming process is not uniform, occurring more rapidly towards the earth’s polar regions than along the equator. The Arctic ice cap has diminished 43 percent in thickness in the last 40 years and the northern landmass that earlier existed as permafrost now experiences disruption of roads and buildings as the permafrost melts. The glaciers in Glacier National Park are receding so rapidly that they are predicted to have disappeared within two decades, converting the park’s name into rueful irony. Other more direct adverse effects occur such as when a 500 foot high piece of glacier crashed down a mountainside in Russia this fall burying a village in ice and leaving at least 100 dead (AJC, Sep 22, 2002).
Science has predicted for some time that global warming would bring with it extreme weather events including more droughts, floods and wildfires. “Major floods have hit Europe, Nepal, India, and China, and the international insurance industry is in dismay because flood levels historically expected to occur once every 500 years are coming far more often” (AJC, Sept. 19, 2002). Our own company has not been exempt from the effects of global warming with its associated extreme weather events.
Here is a graphic depiction of “Great natural catastrophes with trends” taken from Munich Re’s Annual Review: Natural Catastrophes 2001.
The contribution due to climatically sensitive windstorms and flooding, graphically expressed above, definitely shows an increase over the last 50 years (it should be noted that “Great Natural Catastrophes” were deemed to be those where “the ability of the region to help itself is distinctly overtaxed . . . " making this not an absolute catastrophe assessment). This past summer Germany experienced record flooding along the Elbe River causing damage into the billions of dollars—and provoking a series of articles in German newspapers concerned with the ills of the greenhouse effect and global warming (many including critical comments of energy use patterns in the United States). The political power structure in Germany was even possibly effected by this flooding as it has been suggested that the recent extremely closely contested German national elections were decided because the (environmentally concerned and liberal) Green Party picked up several more percentage points of the vote than had been expected, possibly, in part, because of voter response to the destruction of the flooding. This enabled the liberal, Gerhard Schroeder led, government to remain in power. If the more conservative CDU/CSU union (which supports our policy in Iraq) had won the international scene over the last several months probably would have been quite different.
Global Warming and the Spread of WNV
Global warming occurs preferentially not only at the poles but also twice as fast during the winter months and during nighttime, which is probably significant since diurnal rhythms are integral to many basic biological processes whose interrelationship is being adversely effected. One example concerns the relationship between butterflies and the time when flowers bloom. Spring flowers are blooming earlier than ever putting their maturation out of sync with the life cycle of butterflies. The butterflies are not emerging when fruit plants and nectars they feed on are available. Insect pollination patterns may be significantly affected, which could have adverse effects on the plant life dependent upon them for this function.
How is all this related to the West Nile Virus? Simple, “The conditions underlying the outbreak of West Nile virus can be traced to global environmental change. While the precise means of introduction are not known, we have good evidence that the conditions that amplify the life cycle of the disease are mild winters coupled with prolonged droughts and heat waves—the long-term extreme weather phenomena associated with climate change . . . In the spring and summer of 1999, all of these factors were present in the northeastern and mid-Atlantic states . . . extreme weather contributed to the launching of West Nile virus in this hemisphere in 1999” (Epstein, “West Nile Virus and the Climate,” Journal of Urban Health: Bulletin of the New York Academy of Medicine, Vol. 78, No. 2, June 2001).
Vector-borne diseases (see Part I for a definition of “vector-borne disease”), especially those due to mosquito vectors (as is the case with the WNV), are particularly sensitive to meteorological conditions. Within their survivable range, warmer temperatures increase mosquitoes’ reproduction and biting activity and the rate at which pathogens mature within them. Warm nights and warm winters favor insect survival. Fossils from the end of the last Ice age demonstrate that rapid, poleward shifts of insects accompanied warming . . . ” (Epstein: “Climate change and emerging infectious diseases,” Microbes and Infection 3, 2001, 747–754). As the climate warms, many vectors—not just mosquitoes that transmit malaria and various viruses including WNV—are likely to expand their ranges and new vector species may be introduced from the tropics. This effect is already being seen in northern Europe with tick borne diseases such as Lyme disease and tick-borne encephalitis occurring at higher than usual latitudes. Evidence for alteration of vector range is also being observed in the United States. Rocky Mountain spotted fever may actually decline in the southern USA owing to tick intolerance of high temperatures and diminished humidity. Lyme disease and encephalitis will increasingly become public health threats in the USA, as suitable conditions for transmission increase.
Epstein (ibid) notes . . . “Changes in greenhouse gas concentrations, ozone levels . . . ocean temperatures, land use and land cover challenge the stability of our epoch (the Holocene) . . . The impacts of climatic volatility are a particularly potent combination creating conditions conducive to disease emergence and spread. Given the rate of changes in local and global conditions, we may expect more synergies and new surprises.”
Timeline of Global Warming:
The lines from King Lear quoted above are metaphorical and concerned with the “unnaturalness of human relationships” in that play, but Gloster’s lines contained inadvertent prescient significance: we are indeed “sick in (the) fortune” of our environment; we have surfeited ourselves on this planet and by our own hand created “disasters of the sun, the moon, and the stars,” which indeed “portend no good to us . . . ”
Ozone Depletion
The earth has proven to be a resilient home and, before we become too distressed over the trends outlined above, it is helpful to cite a current example of man-generated detrimental environmental alteration that subsequently is being corrected, namely the problem of ozone depletion (with associated problems such as increased incidence of human skin cancers. The use of chlorofluorocarbons (CFCs) was found to be responsible for depletion of the UV-absorbing ozone layer and, in the Montreal Protocol of 1987, agreement was reached on the phasing out of CFCs and related compounds. Now in the AJC on Sept. 19, ’02 we read: “Study predicts hole in ozone will close . . . Chlorine-based chemical levels in the atmosphere are falling, and the hole in the ozone layer over Antarctic should close within 50 years . . . ” Epstein (ibid) notes: “Human and ecological systems can heal after time-limited assaults, and the climate system can also be restabilized, but only if the tempo of destabilizing factors is reduced. The Intergovernmental Panel on Climate Change calculates that stabilizing atmospheric concentrations of greenhouse gases requires a 60% reduction in emissions.” The adverse effects of Global Warming, including fostering the foothold of West Nile Virus in the New World, might be something to contemplate as we build up our military forces around oil-rich Iraq.
Robert W. Lund 
, MD
Vice President and Medical Director
Munich American Reassurance Company
September 2002