Cholera (Deadly Diseases and Epidemics)

115 Pages·2003·6.02 MB·English

by  William Coleman

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CHOLERA
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Anthrax Meningitis
Avian Flu Mononucleosis
Botulism Pelvic Inflammatory
Campylobacteriosis Disease
Cholera Plague
Ebola Polio
Encephalitis Salmonella
Escherichia coli
SARS
Infections
Smallpox
Gonorrhea
Streptococcus
Hepatitis
(Group A)
Herpes
Staphylococcus
HIV/AIDS
aureus Infections
Influenza
Syphilis
Leprosy
Toxic Shock
Lyme Disease
Syndrome
Mad Cow Disease
Tuberculosis
(Bovine Spongiform
Encephalopathy) Typhoid Fever
Malaria West Nile Virus
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CHOLERA
William Coleman
CONSULTING EDITOR
I. Edward Alcamo
Distinguished Teaching Professor of Microbiology,
SUNY Farmingdale
FOREWORD BY
David Heymann
World Health Organization
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D e d i c a t i o n
We ded i c a te the books in the DE A D LYDI S E A S E SA N DEPI D E M I C Ss eries to Ed Al c a m o,
whose wi t ,ch a rm ,i n tell i gen ce ,and com m i tm ent to bi o l ogy edu c a ti on were
second to none.
Cholera
Copyright © 2003 by Infobase Publishing
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ISBN-10:0-7910-7303-3
ISBN-13:978-0-7910-7303-2
Library ofCongress Cataloging-in-Publication Data
Coleman,William,1934–
Cholera / William Coleman.
p.cm.—(Deadly diseases and epidemics)
Includes index.
ISBN 0-7910-7303-3
1.Cholera—Juvenile literature.[1.Cholera.] I.Title.II.Series.
RC126.C695 2003
616.9'32—dc21 2002155048
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Table of Contents
Foreword
David Heymann, World Health Organization 6
1. Discovering Cholera 8
2. Properties of Vibrio cholerae 16
3. Dr. Snow and Cholera 28
4. Transmission and Epidemiology of Cholera 36
5. Signs and Symptoms of Cholera 46
6. The Virulence of Vibrio cholerae 54
7. The Genome of Vibrio cholerae 64
8. Treatments for Cholera 72
9. Prevention and Vaccines 82
10. Cholera in the Future 90
Glossary 96
Bibliography 102
Further Reading 106
Websites 107
Index 108
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Foreword
In the 1960s, infectious diseases—which had terrorized generations—
were tamed.Building on a century of discoveries,the leading killers
of Americans both young and old were being prevented with new
vaccines or cured with new med i c i n e s . The risk of death from
pneumonia, tuberculosis, meningitis, influenza, whooping cough
and diphtheria declined dramatically. New vaccines lifted the fear
that su m m er would bring polio and a gl obal campaign was
a pproaching the gl obal erad i c a ti on of s m a ll pox .New pe s ti c i de s
l i ke DDT cleared mosquitoes from homes and fields,thus reducing
the incidence of malaria which was present in the southern United
States and a leading killer of children worldwide.New technologies
produced safe drinking water and removed the risk of cholera and
other water-borne diseases. Science seemed unstoppable. Disease
seemed destined to almost disappear.
But the euphoria ofthe 1960s has evaporated.
Microbes fight back.Those causing diseases like TB and malaria
evo lved re s i s t a n ce to cheap and ef fective dru gs .The mosqu i to evo lved
the ability to defuse pesticides. New diseases emerged including
AIDS,Legionnaires,and Lyme disease.And diseases which have not
been seen in decades re-emerge,as the hantavirus did in the Navajo
Nation in 1993. Technology itself actually created new health risks.
The global transportation network,for example,meant that diseases
likeWest Nile virus could spread beyond isolated regions in distant
countries and quickly become global threats. Even modern public
health pro tecti ons som etimes failed , as they did in Mi lw a u kee ,
Wisconsin in 1993 which resulted in 400,000 cases of the digestive
system illness cryptosporidiosis.And,more recently,the threat from
smallpox, a disease completely eradicated, has returned along with
other potential bioterrorism weapons such as anthrax.
The lesson is that the fight against infectious diseases wi ll
n ever en d .
In this constant struggle against disease we as individuals have a
weapon that does not require vaccines or drugs, the warehouse of
knowledge. We learn from the history of science that “modern”
beliefs can be wrong. In this series of books, for example, you will
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learn that diseases like syphilis were once thought to be caused
by eating po t a toe s .The inven ti on of the micro s cope set scien ce
on the ri ght path.Th ere are more po s i tive lessons from history.
For example,smallpox was eliminated by vaccinating everyone
who had come in contact with an infected person.This “ring”
approach to controlling smallpox is still the preferred method
for confronting a smallpox outbreak should the disease be
intentionally reintroduced.
At the same time,we are constantly adding new drugs,new
vaccines,and new information to the warehouse.Recently,the
entire human genome was decoded.So too was the genome of
the parasite that causes malaria. Perhaps by looking at the
m i c robe and the vi ctim thro u gh the lens of gen etics we wi ll
to be able to discover new ways of fighting malaria, still the
leading killer ofchildren in many countries.
Because of the knowl ed ge ga i n ed abo ut su ch diseases
as A I D S , en ti re new classes of a n ti - retrovi ral dru gs have
been developed. But resistance to all these drugs has already
been detected , so we know that AIDS drug devel opm en t
must con ti nu e .
E du c a ti on , ex peri m en t a ti on and the discoveries wh i ch
grow out of them are the best tools to protect health.Opening
this book may put you on the path of discovery. I hope so,
because new vaccines, new antibiotics, new technologies and,
most importantly, new scientists are needed now more than
ever if we are to remain on the winning side of this struggle
with microbes.
David Heymann
Executive Director
Communicable Diseases Section
World Health Organization
Geneva,Switzerland
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1
Discovering Cholera
What is cholera? Cholera is the term used to describe a specific
gastrointestinal disease as well as the bacterium which causes that disease.
In this case, the disease was known long before the microorganism that
causes it was even recognized. To understand this, it is necessary to go
back through history.
THE GERM THEORY OF DISEASE
Mi c roor ganisms were not wi dely recogn i zed as the causes of m a ny
diseases until late in the nineteenth cen tu ry. However, s ome early
s c i en tists did propose that living or ganisms caused ill n e s s e s . Th e
Italian physician Girolamo Frac a s toro (ca.1 4 78–1553) spo ke of“s eed s”
or “germ s” of d i s e a s e . Tra n s l a ti ons of Frac a s toro’s Latin wri ti n gs
i n d ic a te that he may have su rm i s ed that these “s eed s”were alive .Th i s
is the earliest known wri t ten record of the G e rm Theory of Disease–
i . e . , the con cept that microor ganisms cause some diseases. Th i s
concept was negl ected for many ye a rs ,h owever.
Over 300 years later,Agostino Bassi (1773–1856) described a disease
of silkworms known as muscardine as being the result of a fungal infec-
tion ofthe worms.He could see the fungusas white,powdery material on
silkworm eggs. It was identified as a fungus of the genus Botrytis. A
botanist of the day confirmed this identification and named the fungus
Botrytis bassianain honor ofAgostino Bassi.
LOUIS PASTEUR AND ROBERT KOCH
In the mid-nineteenth century the famous French scientist Louis Pasteur
( 1 8 22–1895) had proven that microor ganisms do not arise spon t a n eo u s ly.
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His cl a s s i c , s i m p l i s ti c , and ingenious ex peri m ent was to
de s i gn a flask with an S-shaped curve in its neck .The curve
tra pped microor ganisms that were pre s ent in the air before
t h ey could re ach the main part of the flask. He fill ed the
flasks with bro t h , h e a ted them , and then all owed them
to coo l . In previous ex peri m ents using flasks wi t h o ut
the S-shaped neck , m i c roor ganisms would grow in the
bro t h .This did not occur in Pa s teu r ’s ex peri m en t s . Cri ti c s
s t a ted that a “ vital force” h ad been rem oved from the
air by heati n g, so the microor ganisms could not grow.
Pa s teu r ’s flasks all owed the air to have access to the heated
bro t h , defusing this argumen t . His coo l ed flasks did not
become spoi l ed with bacterial growth because the micro-
organisms in the air had no means to ascend the tube leading
to the broth on ce they were tra pped in the dip, or curve ,of
the S-shaped flask. Pa s teur went on to show that wh en he
bro ke the spo ut of the flask,t h ereby de s troying the S-shaped
s po ut with the dip in it, the bacteria pre s ent in the air
qu i ck ly grew in the bro t h .This ex peri m ent establ i s h ed on ce
and for all that microor ganisms do not arise spon t a n eo u s ly.
Th ey can, h owever, be grown in labora tories just like any
o t h er living thing.
In ad d i ti on to this landmark ex peri m en t , Pa s teur wen t
on to make nu m erous con tri buti ons to unders t a n d i n g
m i c roor ga n i s m s .Am ong his many intere s t s ,Pa s teur reex a m-
i n ed the probl ems of s i l k worm infecti on , wh i ch had been
s tu d i ed by Bassi so many ye a rs before ,even though he was
u n aw a re ofBa s s i ’s work .Pa s teu r ’s ef forts were sparked by his
i n terest in the more gen eral qu e s ti on ofthe microbial ori gi n s
of i n fecti on s . He stu d i ed infecti ons in high er animals as a
re sult of these ef fort s . This occ u rred in the late 1800s, a
go l den era in microbi o l ogy. Pa s teu r, a l ong with his main
com peti tor,the German scien tist Robert Koch (1843– 1 9 1 0 ) ,
s tu d i ed nu m erous microor ganisms and the ef fects they
c a u s ed ,i n cluding diseases.
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