Geography Reference
In-Depth Information
spread from Asia via trade routes and peaked in 1348-1350 in Europe and led to
the deaths of 75-200 million people. This was between 30 and 60 % of Europe's
population—although it must be noted that the century also saw the end of the me-
dieval warming period and poor harvests which led to food shortages and a severely
weakened the population (Herlithy
1997
). More modern examples range from the
previous descriptions of the rapid global spread of HIV-AIDS, which contrasts with
the containment of SARS.
The mortality rates and ill-health effects of many tropical diseases are still far
too high. Many, not all, now have cures, but these are not often available in many
cities and regions. One of the biggest health problems is still associated with ma-
laria, spread by parasites carried by certain types of female mosquitoes in tropical
and subtropical areas. Although not in the top 20 causes of death in Table
13.1
it
has been argued that the 0.66 million deaths estimated by the WHO represent gross
underestimates, with the true figure being closer to 1.24 million, let alone the de-
bilitating effects on many people (Murray et al.
2012
). Certainly medicines such as
quinine, several recent drugs, and the use of nets over beds at dusk and night when
mosquitoes are flying have reduced the risk of the disease. So has the draining of
marshes and standing water pools in urban areas which reduce the number of places
where the insects breed. Snowden's (
2006
) detailed study of the effects of malaria in
Italy until it was finally eradicated in 1962 showed how the disease had previously
led to low productivity, premature death and economic backwardness in the coun-
try. It needed a multi-pronged state strategy from the early twentieth century to re-
move the scourge, one that involved medical breakthroughs, swamp draining, rural
clinics and education for preventative measures. In tropical areas the hoped-for final
solution by chemical spraying of marshes with DDT in the 1960s proved illusory,
as the parasites have bred resistance to particular drugs and the sprays used led to
the poisoning of the water which created other problems for a whole range of birds
and animals. So despite determined efforts to reduce its effects, through new drugs,
swamp draining and more recently through experiments with the mass inoculation
of populations in some areas to reduce the number of people acting as hosts to the
parasite, malaria still remains a significant cause of ill-health and premature deaths.
This may get worse as some of the malaria-giving parasites are becoming resistant
to the drugs used to treat them, which makes new treatment discoveries a priority.
These are only a few of the examples of death and disability caused by fac-
tors from the physical environment, especially from the hotter wetter environments
where a large number of other serious diseases lurk, such as dengue, yellow fever,
typhoid etc. Some people in these areas have increased tolerance to these infections,
but many of these diseases have an increased ability to harm people who have trav-
elled from other environments without the appropriate medical treatment. One of
the big emerging problems is the effect of global warming. This will probably lead
to lower yields from current crop varieties in an aggregate sense, leading to food
shortages given world population growth, unless new varieties can be developed. In
addition, the warming will allow many flies and insects, and hence the pathogens
they carry, to spread further north, infecting people with little immunity. So malaria
may be spread again to Europe, as West Nile disease is already becoming common
