Our planet has
experienced several pandemics in the last millennium, all of which killed
several million people and all of which left some sort of documentary
record. The Black Death of 1346-50,
probably a mixture of bubonic plague and anthrax, was introduced to Europe via
the overland trade route to East Asia, and slaughtered over one-third of the
continent's population; by the end of the 1300s, the global
population had fallen by about 25% (or 100 million people). The epidemics of
smallpox and other illnesses that European mariners introduced to Mexico,
Brazil, and the Caribbean in the 16th century killed millions of Indians and probably reduced those regions' indigenous populations by 80%
before the century was out (see Crosby, Germs,
Seeds, and Animals [M.E. Sharpe, 1994]). Cholera
pandemics in the 19th and early 20th centuries killed
upwards of 10-15 million people. Spanish
flu killed at least 50 million people
worldwide at the end of the First World War. HIV/AIDS has killed 30 million people since
the 1980s, and as many more people are still living with the disease today.
History can tell us a great deal about the consequences of a large-scale epidemic. Massive die-offs, first of all, can result in the loosening of economic bonds, as surviving serfs or peasants use their scarcity to negotiate with landlords for freedom. They can also result in the stark curtailment of freedom. When labor is scarce, lords and conquistadors are just as likely to resort to slavery to provide it. Parts of Europe where slavery was in decline, like Italy, saw a resurgence of slave labor in the decades following the Black Death, and when Spanish and Portuguese colonists found that their Indian laborers were dying they replaced them with African slaves.
Epidemics can lead to medical breakthroughs, like the
development of public sanitation to fight cholera and of anti-retroviral drugs
to fight AIDS. They can also provoke
superstitious responses and violence: think of Europeans who blamed bubonic
plague on the Jews, Huron Indians who associated smallpox with Jesuit missionaries,
and evangelical Christians who attribute AIDS to divine displeasure with
homosexuality. And huge
die-offs generally don't have any long-term effects on the survivors. Given the relationship between long-distance
travel and large-scale epidemics, one might expect trade and travel to decline
after pandemics, but I know of no case where this has occurred. Humans still prefer to live in crowded
cities, sometimes in close proximity to livestock, an ideal environment for generating new illnesses. They tend to forget the need for prophylactic
measures, like vaccination or condom use, once a generation has passed
since the die-off. A realistic
novel or movie set after a future plague would have some of the survivors sold
into slavery or the equivalent; others killed as scapegoats; and the
rest forgetting anything ever happened – until the
next epidemic came along and killed another hundred million people.
To what species, finally, might our fictional (we hope) future superbug
belong? Damned if I know, though it's comforting
to realize that epidemics are to some degree self-limiting. Truly frightening and lethal diseases like
Ebola tend to kill their hosts before they have time to spread; those that are
both highly contagious and have a long incubation period, like smallpox or
influenza, can spread far and wide but kill only a fraction of those infected
with them (25%, in the case of untreated smallpox, less, in the case of
flu). There may be exceptions. Extreme drug-resistant tuberculosis is both contagious and very dangerous, and apparently one can only treat it with chemotherapy and quarantine, both of which are expensive. It is apparently also possible to create a
genetically engineered strain of smallpox that suppresses the host's immune response,
making it both highly contagious and 100% fatal. I can't imagine anyone setting a science
fiction novel in a post-immunosuppressant-smallpox world, however, because
there wouldn't be any humans left to write about…