Environmental Engineering Reference
In-Depth Information
Disease
as andrew Price-Smith and Yanzhong Huang note, public health victories peaked in
the mid 1970s. the world has been on the defensive ever since against the assaults
from HIv/aIDS, bovine spongiform encephalopathy (bSe), west nile virus, SarS,
and virulent H5n1 avian influenza. Caroline Khoubessarian confirms that there
has been a spike in new infectious diseases, with more than 30 unknown diseases
related to bacteria and viruses emerging since 1973. appendix 16-2 charts the most
salient cases in this deadly cadence. It shows that diseases are erupting faster, more
fully, and farther around the globe. communicable disease is no longer a problem
banished from a well-protected global economic north, but one that has erupted in,
and flowed between, both the rich North and poor South alike. Pathogens rapidly
evolve and colonise ecological niches, even in the most developed states. thus the
world is still battling the big five challenges of HIV/AIDS, tobacco, avian influenza,
and polio, and even a recently defeated SarS can easily re-emerge from its animal
reservoir.
even with SarS, the least prevalent case thus far, there is little cause for
celebration or complacency. SarS was a classic outbreak event. In the ten months
following 1 november 2002, 8096 humans were infected, ranging from 5327 in
china where it started, 1755 in neighbouring Hong Kong, 346 in nearby taiwan,
to 251 in distant canada and 27 in the much larger United States. SarS had high
virulence, transmissibility, and a rapid incubation period, along with an initially
unknown cause, transmission mode, and treatment. It infected not only neighbours
and fellow travellers but also a large number of medical personnel. It erupted in the
form of multiple, virtually simultaneous outbreaks around the world.
Avian influenza has thus far also been well contained. But complacency and
confidence are challenged by the growing consensus that it is an outbreak event about
to arrive in full force. the large number of birds and animals at its source and the great
growth in novel sub-types of avian influenza in humans make many feel the world is
on the verge of another influenza pandemic, comparable to those in 1968, 1957, and
1918. the frequency of such outbreaks is increasing. the next will probably be highly
virulent, transmissible, and deadly, like that in 1918. the H5n1 variant, appearing in
thailand and vietnam in January 2002, mutates rapidly, acquires genes from viruses
infecting other animal species, and has high virulence. but the precise timing, source,
and pathway of the next influenza pandemic are unpredictable. And like the 1976
swine influenza in the U.S., there is some chance it may never come.
HIv/aIDS is an attrition disease that the world has been battling for more than
a quarter of a century now. an estimated 33.2 million people live with the virus, for
which there is still no cure. From its epicentre in southern africa, where it affects
20 percent of those aged 15 to 49, its prevalence is rising in many countries. It
features a long incubation period, a high certainty of morbidity, and a few pathways
that are well known and capable of being controlled.
Polio, another attrition case, is the most promising, for the number of those
infected has dropped dramatically over the past 25 years. but its persistence in
 
 
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