Throughout history, stories of Cholera, Malaria, the Plague smallpox, diphtheria show pandemic disease has changed our world. Pandemics have changed the course of nations, begun and ended wars and very often changed the religious majorities of entire populations.
Because of common improvements in public health, plumbing and hygiene, and the increased knowledge of disease pathogens, most pandemics that occurred in the past likely cannot occur now. About the only existing disease that now has the ability to quickly infect large enough numbers of people to cause pandemic conditions is influenza. The nature of influenza viruses is that they mutate-constantly. Because the human organism develops immunity to a particular virus once the immune system has overcome it, the wily influenza virus mutates enough to secure its own continued existence by coming back in a slightly different form.
One of the main reasons influenza is so successful is that it has developed the ability to infect a variety of host animals and can recombine with viruses from other animals and humans at a later date to form still another, new form of disease. Because of this ability to fast-mutate, vaccines never appear to be able to get that far ahead of the next epidemic. That's why every year, millions of people make sure to get their flu shot-and get the flu anyway. And, as most of us are aware, the average case of the flu appears to have far more to do with the individual's immune system that the virus itself.
Although influenza viruses mutate every year, historically there is a major, unexperienced mutation about every forty years with the potential to infect huge numbers of people quickly as they don't have any residual immunity to the recombined viruses. This is the fear with the current H1N1 virus outbreak that began in Mexico. What began as a localized epidemic threatens to become pandemic only because of the unusual nature of this year's recombination of viruses and the increased global mobility of the population. Although there have been a number of deaths associated with the current flu in Mexico, many of the victims-as is common in most influenza deaths-may have had other serious health challenges. When, each year, we are force-fed horror stories of thousands of flu deaths as an encouragement to get vaccinated, we are never told that most of these deaths occurred in those with life-threatening or near-terminal health conditions and that flu was simply the final assault on an already failing body.
One reason there have been so many deaths in Mexico is likely that many of those first becoming ill already lived in reduced circumstances, with little clean water, heavily polluted air, a shortage of nutritious food and almost no medical care. Without an adequate medical care system, Mexico did not discover the outbreak in time to keep it from becoming a somewhat localized epidemic. It is likely that the current epidemic continued for a period of time, infecting large numbers of people who never sought medical care and never came to the attention of authorities. Our porous border, with constant traffic from Mexico, created the ideal scenario to become a widespread pandemic situation. As usual, Mexican citizens with serious illness headed for better medical treatment in the United States if they were close enough to the border or affluent enough to get on a plane-a sensible decision in the face of scarce local medical care. Because of a large tourist industry, visitors from around the globe were exposed to the virus before it was ever discovered to be a local problem.
Usually, the first "wave" of an influenza pandemic lasts from six to eight weeks among whatever population is exposed to the virus. In situations such as is presently occurring common sense tells us that this timeframe may be extended as the infected travel to new areas and spreads the virus among new victims. Therefore, the first wave might last three, four, five months before it peters out by having no new hosts to infect. Some areas may not experience any cases of this type of influenza at all. Already it appears many fears of a fast-spreading pandemic were overblown: the virus is not spreading like a brand-new, fast moving virus so it s likely at least some of the population in the United States already has enough residual immunity to some parts of the mix to prevent infection.
The reason vaccine makers are hurrying to create a vaccine is because flu has a bad habit lying low for a period of 6-12 months before coming back to infect those it missed the first time. This is the second, and in some ways, most dangerous wave. Often, while lying seemingly dormant within a few host victims, the virus may mutate enough to become virulent even to those that experienced infection during the first wave. A carefully crafted vaccine may work to protect victims from the second wave. However, haste in creating a vaccine can have unintended consequences such as we experienced in the 1975-6 swine flu outbreak. In a hurry to prevent a supposed pandemic due to the death of one soldier, the hastily-concocted vaccine killed over 500 people and left at least that number permanently impaired due to Guillian-Barre syndrome. Many, many had reactions resembling the flu to the vaccine itself.
So, a true pandemic can last over a year-but that does not mean there will be a year of continued infection. Small pockets may exist and burn through a local unexposed population then die down. The feared second wave may or may not cause an increase in illness and possibly death.
For those who fear a repeat of the Spanish Flu that killed millions in 1918, they should remember the circumstances of a world war, war-torn and displaced populations and poor war-time living conditions exacerbated the deaths. Even in the United States, the pandemic affected primarily populous cities with poor hygiene, unsanitary water supplies and over-crowding and a misunderstanding of the nature of disease pathogens. The Hong Kong Flu in 1968 killed about a million people worldwide, primarily in overcrowded, poor-sanitation conditions. Since that time, anti-viral medications have been developed to fight the virus itself and better antibiotics handle the attendant bacterial infections that are the primary cause of death among flu victims.
There is little to fear from this round of the influenza virus. It likely is nearing its peak in the United States-with little serious illness. We can pretty well guess it'll be back sometime next fall or winter. Will it be more dangerous? Probably not-and if it is, we have the resources to win the battle.