Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.
What causes cholera, and how is cholera transmitted?
Cholera is caused by the bacterium V. cholerae. This bacterium is Gram
stain-negative and has a flagellum (a long, tapering, projecting part) for motility and pili (hairlike structures) used to attach to
tissue. Although there are many V. cholerae serotypes that can produce cholera
symptoms, the O groups O1 and O139, which also produce a toxin, cause the most
severe symptoms of cholera. O groups consist of different
lipopolysaccharides-protein structures on the surface of bacteria that are
distinguished by immunological techniques. The toxin produced by these V.
cholerae serotypes is an enterotoxin composed of two subunits, A and B; the
genetic information for the synthesis of these subunits is encoded on plasmids
(genetic elements not in the bacterial chromosome). In addition, another plasmid
type encodes for a pilus (a hollow hairlike structure that can augment
bacterial attachment to human cells and facilitate the movement of toxin from V.
cholerae into human cells). The enterotoxin causes human cells to extract water
and electrolytes from the body (mainly the upper gastrointestinal tract) and
pump it into the intestinal lumen where the fluid and electrolytes are excreted
as diarrheal fluid. The enterotoxin is similar to toxin formed by bacteria that
cause diphtheria in that both bacterial types secret the toxins into their
surrounding environment where the toxin then enters the human cells. The
bacteria are usually transmitted by people drinking contaminated water, but the
bacteria can
also be obtained in contaminated food, especially seafood such as raw oysters.
What is the history of cholera?
Cholera has likely been with humans for many
centuries. Reports of cholera-like disease have been found in India as early as
1000 AD. Cholera is a term derived from Greek khole (illness from bile) and
later in the 14th century to colere (French) and choler (English). In the 17th
century, cholera was a term used to describe a severe gastrointestinal disorder
involving diarrhea and vomiting. There were many outbreaks of cholera, and by
the 16th century, some were being noted in history. England had several in the
18th century, most notable being in 1854, when Dr. John Snow did a classic study
in London that showed a main source of the disease (resulting in about 500
deaths in 10 days) came from at least one of the major water sources for London
residents termed the "Broad Street pump." The pump handle was removed, and the
cholera deaths slowed and stopped. The pump is still present as a landmark in
London. Although Dr. Snow did not discover the cause of cholera, he did show how
the disease could be spread and how to stop a local outbreak. This was the
beginning of modern epidemiologic studies.
V. cholerae was first isolated as the cause of cholera by Filippo Pacini in
1854, but his discovery was not widely known until Robert Koch (who also
discovered the cause of tuberculosis), working independently 30 years later,
publicized the knowledge and the means of fighting the disease. The history of
cholera repeats itself. The U.S. National Library of Medicine houses original
documents about multiple cholera outbreaks in the U.S. from the 1820s to the
1900s, with the last large outbreak in 1910-1911. Since the 1800s, there have
been seven cholera pandemics (worldwide outbreaks).
Multiple outbreaks worldwide continue into the 21st century with outbreaks in
India, Iran, Vietnam, and several African countries in the last 10 years (most
recent outbreaks occurred in Haiti and Nigeria in 2010-2011). Why is cholera
history repeating itself? The answer can be traced back to Dr. Snow's studies
that show a source (water or occasionally food) contaminated with V. cholerae
can easily and rapidly transmit the cholera-causing bacteria to many people.
Until safe water and food is available to all humans, it is likely cholera
outbreaks will continue to happen.
Muscle cramps are involuntarily and forcibly contracted muscles that do not relax. Extremely common, any muscles that have voluntary control, including some organs, are subject to cramp. Since there is such variety in the types of muscle cramps that can occur, many causes and preventative medications are known. Stretching is the most common way to stop or prevent most muscle cramps.
Diarrhea is a change is the frequency and looseness of bowel movements. Cramping, abdominal pain, and the sensation of rectal urgency are all symptoms of diarrhea. Absorbents and anti-motility medications are used to treat diarrhea.
There are many causes of back pain. Pain in the low back can relate to the bony lumbar spine, discs between the vertebrae, ligaments around the spine and discs, spinal cord and nerves, muscles of the low back, internal organs of the pelvis and abdomen, and the skin covering the lumbar area.
Dehydration is the excessive loss of body water. There are a number of causes of dehydration including heat exposure, prolonged vigorous exercise, and some diseases of the gastrointestinal tract. The best way to treat dehydration is to prevent it from occurring.
Nausea is an uneasiness of the stomach that often precedes vomiting. Nausea and vomiting are not diseases, but they are symptoms of many conditions. The causes of vomiting differ according to age, and treatment depends upon the cause of nausea and vomiting.
Dry mouth is a common side effect of many prescription and non-prescription drugs. Symptoms of dry mouth include a sticky, dry feeling in the mouth, frequent thirst, sores in the mouth; sores or split skin at the corners of the mouth, cracked lips, a dry feeling in the throat, a b urning or tingling sensation in the mouth, and a dry, red, raw tongue.
Food poisoning is common, but can also be life threatening. The most common form of food poisoning is caused by bacteria and include symptoms such as fever, abdominal pain, diarrhea, nausea and vomiting.
Travelers' diarrhea is generally contracted by eating contaminated food or drinking contaminated water. Food is the primary source of travelers' diarrhea. Enterotoxigenic E. coli is the cause of up to 70% of all cases of travelers' diarrhea. There are five unique classes of E. coli that causes gastroenteritis. Other bacteria responsible for travelers' diarrhea include
Campylobacter, jejuni, shigella, and salmonella. Viruses such as rotavirus and Norwalk virus (norovirus) and giardia lamblia a parasite may cause travelers' diarrhea. Prevention is careful eating and drinking of water.
Travelers should prepare for their trip by visiting their physician to get the proper vaccinations and obtain the necessary medication if they have a medical condition or chronic disease. Diseases that travelers may pick up from contaminated water or food, insect or animal bites, or from other people include malaria, meningococcal meningitis, yellow fever, hepatitis A, typhoid fever, polio, and cholera.
Digestion is the complex process of turning food you eat into the energy you need to survive. The digestive process also involves creating waste to be eliminated, and is made of a series of muscles that coordinate the movement of food.
Bioterrorism is a form of terrorism where there is the intentional release of biological agents such as viruses, germs, or bacteria. Diseases caused by bioterrorism agents include anthrax, botulism, plague, smallpox, tularemia, brucellosis, food poisoning, Q fever, ricin toxin poisoning, cholera, epidemic typhus, viral encephalitis, XDR TB, and MDR TB.
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