Cholera and its Implications for the Modern World

Essay by KDDOBA+, February 2004

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Travelers Beware! Do not drink the local water or milk. Cook all foods that may

have been exposed to water. Do not eat uncooked salads, fresh fruit, or shellfish. Why are

so many travelers to third world countries getting these warnings? The answer is simple,

due to the infectious bacterial disease known as Cholera.

Cholera is caused when the bacterium Vibrio cholerae infects the small intestine. A

more precise name for the region infected is the gastrointestinal area. The bacterium itself

is small, and comma-shaped (see appendix p.7 ). Vibrio cholerae is a gram-negative

bacteria that is a pathogen of humans. The bacteria moves by means of flagellum. The

bacterium produces a toxin that causes the small intestine to secrete fluids, leading to

vomiting and diarrhea. The life cycle of the cholera bacterium is simple; Vibrio cholera

reproduces by binary fission, a form of asexual reproduction. The genus, Vibrio, are

typically marine organisms that are found on the surface of the water.

The cholera bacteria

is usually found in the same water as feces. The bacteria, once ingested by humans, begins

to produce a Cholera toxin. Cholera toxin activates specific enzymes in intestinal cells,

which leads to the secretion of fluids into the small intestine, causing symptoms like

diarrhea. Most of the bacterium are not able to survive the secretions and low pH of the

stomach; after the release of the Cholera toxin, the bacterium usually die.

The first true case of cholera was recorded in Europe in 1830 and again, in 1848,

1854, 1865, 1884, and 1892. During the terrible London epidemic of 1854, John Snow,

proved cholera to be a waterborne disease, through epidemiological means. The first

major U.S. epidemic occurred in the Mississippi Valley from 1870-1873. In 1884, Robert

Koch, a German scientist, discovered Vibrio cholerae as the cause of the disease. An

outbreak in Hamburg, in 1892, was concluded to be caused by pollution of the Elbe River.

For the first half of this century, cholera was confined to Asia, except for an epidemic in

Egypt, in 1948. Control of cholera is still a major problem in several Asian counties.

Epidemics occurred in Calcutta, India in 1953; between 1964 and 1967 in South Vietnam;

and for the Indian refugees of the civil war of 1971, of which 6,500 people were killed. In

the early 1990's, an epidemic occurred in seven South American countries. There were

342,000 documented cases of the disease and 3,600 deaths. Cholera is rare in the United

States. The few cases that do arise each year involve travelers returning from Asia or

Africa, or from imported goods from the Gulf of Mexico area. Cholera occurs naturally in

the Gulf of Mexico, and each year several cases in the U.S. result from shellfish caught in

those waters. The first cholera vaccine was invented in 1981 in the United States. The

O139 variant of the cholera bacterium was discovered in 1992. This produces a more

active form of the disease. The people of India that have become immune to the earlier

strain of cholera have been infected by the O139 bacterium. In 1994, 10,000 refugees of

the Rwandan civil war died from cholera. Even though major outbreaks may not be likely

in the United States, in other countries a small outbreak may flare up to be a major


The symptoms for cholera usually first appear one to three days after initial contact

with the bacteria, usually through means of ingesting it. The first symptoms a carrier of the

disease might have are mild dehydration, nausea, dizziness, and anxiousness. The next set

of visible symptoms are watery diarrhea, and vomiting, which ranges in levels of

seriousness. As much as a pint of water an hour can be lost as the diarrhea continues. In

more serious and severe cases of cholera, symptoms include very intense vomiting, intense

thirst, painful cramps, and cold and withered skin. No matter how serious a case of

cholera is, there is usually no fever. Whenever the first symptoms start to appear, the

person should contact a physician immediately. If a physician suspects that you have

cholera, he will need a sample of your watery stool, which he will then send off to a

medical lab, in order to confirm if you have contacted the disease.

Treatment for cholera is almost one hundred percent successful. The key step in

the treatment is full replenishment of all the lost fluids. This rehydration must be prompt,

as not to cause further sickness or injury to the patient. Patients can be treated with an oral

rehydration solution, a pre-packaged mixture of sugar and salt that is mixed with water

and ingested in large amounts. This solution is used all over the world to treat diarrhea.

Severe cases of the disease require intravenous replacement of liquids. Fluid therapy must

be continued until all lost liquids are replaced and the diarrhea stops. Some medicines can

be purchased, such as Tetracycline, that shorten the duration of the diarrhea. With prompt

treatment, fewer than one percent of cholera patients die. Without treatment, death can

come as soon as forty-eight hours after initial infection, and in big epidemics, the death

rate has been known to exceed sixty percent.

A cholera vaccine is available; however, it is not normally recommended. Only fifty

percent of those that take the vaccine develop immunity to the disease, and for those who

do develop immunity, it only lasts a few (about two to six) months. Complete vaccination

against the disease requires two doses of vaccine taken one to four or more weeks apart.

Cholera doses are age specific. The cholera vaccine is not recommended for infants or

pregnant women. Reactions to the vaccine are: erythema, fever, malaise, and headaches.

Serious reactions are rare, but if experienced, it is strongly recommended not to

revaccinate. No country currently requires the cholera vaccine for entry and departure to

and from cholera-infected areas.

Prevention of cholera is very easy; just be educated and aware. In places where

there is adequate water purification and filtration, and where there is good food sanitation,

cholera is rare. However, in places that lack these qualities, travelers need to take

precautions. People should avoid drinking water from untreated areas (i.e. streams, lakes,

rivers, and ponds) or water from unknown sources. People should wash their hands

thoroughly with soap and cleanser after using the bathroom, changing diapers, and before

preparing foods. Travelers should remember to cook all foods, and to eat them promptly

after their preparation. Also, when available, drink bottled water over non-bottled.

Travelers should stay away from the local foods. Ice in drinks can be harmful as well.

Over the long term the surest prevention of cholera will come with improved sanitation.

Because cholera has a near one hundred percent recovery rate when treated

promptly, and treatment for the disease is easy, it is no wonder that there has not been a

major effect on world population or health from this disease. The most deadly epidemic of

cholera occurred in a worldwide chain of epidemics in the early 1800's, killing an

estimated three million people. This is very small considering the millions of people

that die from AIDS today. The second most deadly epidemic was in 1971, when

Bangladeshi refugees fled from India during their civil war. 6,500 people were killed. The

third most deadly epidemic was in 1991. Outbreaks of cholera in Peru quickly spread to

other South and Central American countries, including Mexico. In this epidemic 340,000

cases were reported, and 3,600 deaths were confirmed. Despite the large epidemics, the

world's population and health has not been greatly effected by cholera.

The immune system responds to the disease causing organism with a whole

spectrum of responses. The reasons for this big spectrum is not known. One response is

after infection, antibodies can be detected against cholera antigens including the Cholera

toxin that Vibrio cholerae makes. Antibodies detected against cholera antigens are

considered "Vibriocidal" antibodies because they will lyse V. cholerae cells along with

complement and serum components. Vibriocidal antibodies reach a peak 8-10 days after

initial infection, then decrease, returning to the baseline 2-7 months later. The presence of

V. antibodies goes along with a resistance to infection; however, the antibodies may not

be the relayer of this protection, and the role of circulating antibodies in natural infection is


The cholera bacterium evades the immune system simply by traveling too fast for

it. The bacteria is ingested, goes to the small intestine were it releases its toxin, and then is

killed by the stomach's low pH secretions, prior to the immune system having a chance to


There has not been an active case of cholera in the United States for nearly 90

years. The U. S. has had fewer than 80 proven cases of cholera ever, most of which

were brought into the country by travelers returning from South America. No major

outbreaks of this disease have occurred in the U.S. since 1911. However, small cases

occurred in 1973 and 1991, due to poorly prepared shellfish that were imported to the

United States from the Gulf of Mexico area. The excellent sanitation facilities in the U.S.

translate into the near elimination of the chance of an epidemic of cholera ever occurring.