Population growth is adding to the threat of massive epidemics,
two Stanford scientists told a meeting at the Beijer Institute
of Ecological Economics of the Royal Swedish Academy of Sciences
in Stockholm recently.
Speaking on "Development, Global Change, and the Epidemiological
Environment," ecologists Gretchen C. Daily and Paul R. Ehrlich
described the many changes, both positive and negative, that "enlarging
the scale of the human enterprise has produced in the epidemiological
Development changes some of those conditions for the better, by
improving water supplies, sanitation, and health care. But it
also can help create large cities with gigantic slums that promote
close contact, unsanitary conditions, promiscuous behavior, and
drug use that have led to them being called "graveyards of
humanity," the scientists said.
"Large human populations can maintain many infectious diseases
that small ones cannot, and large ones also are more likely to
be invaded by pathogens previously restricted to monkeys, mice,
or other nonhuman animals," Daily and Ehrlich said.
"Today's populations also contain many hungry people, and
hunger reduces the efficiency of the body's immune defenses. There
also are escalating numbers of people infected with the HIV virus.
Thus, humanity now amounts to a vast monoculture, increasingly
ripe for invasion by rapidly evolving germs. To make matters worse,
high-speed transport systems now can spread epidemics around the
world in a matter of days," they said.
The Stanford scientists found two trends especially threatening.
One is the increasing contact of growing human populations with
animal reservoirs of potentially lethal pathogens. "AIDS
is likely just to represent the tip of that epidemic iceberg,"
The second is the rapid, near catastrophic evolution of resistance
to antibiotics and other drugs by bacteria, malaria organisms,
and other dangerous parasites of human beings. Many strains of
bacteria, notably some of the kind that cause tuberculosis are
now resistant to essentially all antibiotics. Some strains of
malaria in Southeast Asia already are resistant to anti-malarial
drugs so new that they have yet to be approved for sale in the
United States, they said.
"This return to the preantibiotic era is rooted in the ignorance
of evolution that pervades both the medical community and the
general public," they said. "To this day, the United
States still allows the feeding of antibiotics in gigantic quantities
to farm animals--a sort of social suicide that helps disarm us
in our war against bacteria."
Further, the misuse of insecticides, both in attempts to control
disease-carrying insects and in the process of the intensification
of agriculture, has led to the evolution of resistant insect vectors-particularly
the Anopheles mosquitoes that transmit malaria, Daily and
Ehrlich said. "The evolution of resistance is simply the
inevitable consequence of the misuse of our chemical weapons,
something evolutionists have warned against for decades."
Various aspects of "global change" also can cause the
deterioration of the epidemiological environment. An example is
global warming, which has the potential of spreading tropical
diseases, such as malaria, into what are now the temperate zones.
The Stanford team recommended various strategies for improving
the epidemiological environment. "The most important is to
bring the growth of the human population to a halt as quickly
as is humanely possible, and then lower the birth rate below the
death rate to initiate a gradual decline," they said. "Not
only does the size of that population in itself constitute a degrading
of the epidemiological environment, but overpopulation is a major
cause of other changes, such as rapid urbanization and agricultural
intensification, which also degrade it."
They recommended that much more effort be put into disease warning
networks, medical infrastructure, national vaccination programs,
integrated management of resistance, upgrading of water and sanitary
systems and dwellings, and a general emphasis on disease prevention
rather than treatment.
"These steps will demand a substantial effort from society,
and getting them implemented constitutes a gigantic challenge
to physicians, ecologists, economists, political scientists, sociologists,
sanitary engineers, and others involved professionally in the
maintenance of public health. At the same time, this combination
of tasks could provide an unprecedented opportunity for interdisciplinary
cooperation," they said.