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.
A: Food poisoning is a general term that refers to gastrointestinal illnesses
(usually diarrhea and/or
vomiting) caused by food that is contaminated with
bacteria, parasites, viruses, or toxic substances. The actual cause of most individual
episodes of food poisoning,
however,
never is pursued (for example, a culture is not done) since most episodes are mild
or moderate in severity and are over in a few hours to a few days. In fact, the
diagnosis of food poisoning usually is made only
presumptively, based on the patient's symptoms and the circumstances. Even in
outbreaks of suspected food poisoning that involve many people, when careful studies
are done, a specific cause is found no more than half of the time.
Bacteria are the cause of most outbreaks of food poisoning for which a specific cause is
determined. Bacteria cause food poisoning in three ways. After reaching the intestines,
they may multiply and produce toxic substances that enter the intestine and cause
diarrhea and/or vomiting without damaging the intestine itself. The
bacteria also may multiply within the intestines and produce toxic
substances that damage the lining
of the intestine or they may invade and damage the intestine directly. Finally, some
bacteria produce toxic substances that cause diarrhea and/or vomiting in the
food before it is eaten. These bacteria do not need to multiply within
the intestines, and the toxic substances they produce do not damage the intestine.
Listeriosis is a
disease caused by a gram-positive bacterium named Listeria that can penetrate
and replicate inside human cells.
Most people that are infected have few or no
symptoms; when symptoms are present, they usually consist of
fever, muscle
aches, nausea, or
diarrhea. Some people may develop more severe symptoms such as
meningitis,
mental changes, brain abscesses, or death.
Although most people
have self-limited disease, people with risk factors such as an altered or
depressed immune response (for example, pregnant females and their fetus or newborn,
cancer patients,
AIDS patients) are at higher risk for getting the
disease and some are more likely to have more severe disease.
Listeriosis is
usually diagnosed by discovering that a person was associated with an outbreak
of Listeria-contaminated food or fluid, or identified as a person associated
with the source of a known listeriosis outbreak. Definitive diagnosis is done
when Listeria bacteria are isolated from the patient's blood, cerebral spinal
fluid, or other body fluid.
Most normal people spontaneously clear the
infection and require no treatment. In contrast, people with risk factors should
be treated quickly with IV antibiotics.
People are exposed to Listeria
bacteria if they ingest contaminated food or fluid. Foods that are not cooked or
fluids that are not treated or pasteurized are frequently the sources of
infection. Pregnant females can transmit Listeria organisms to their fetus or to
their newborn.
Cooking foods, treating or pasteurizing fluids, and avoiding
food and fluids that may be contaminated with animal or human waste may prevent
infection.
The prognosis for most Listeria infections is excellent even if
people have consumed contaminated foods or fluid; however, the prognosis rapidly
declines in patients with risk factors if they are not quickly diagnosed and
treated.
U.S. government agencies are responsible for maintaining safe foods and
fluids for the U.S. population and may enforce regulations to ensure contaminated
products are reported, removed, recalled, and production and sales stopped until
processing meets acceptable standards of safety.
What is listeriosis?
Listeriosis is an infection caused by a gram-positive
motile bacterium named Listeria monocytogenes that produces fever, muscle aches,
and in many people, diarrhea. Severe infections can cause headaches, meningitis,
convulsions, and death. Most healthy people exposed to the bacteria have minor or
no symptoms, but a few people, especially the elderly, pregnant females and
their fetus, newborns, and anyone with a compromised immune system are especially
susceptible to these organisms. Listeria bacteria are widespread throughout the
world and are frequently associated with farm animals that infrequently show no
signs of infection. Research shows that many animals are uninfected carriers; in
addition, they suggest that about 5%-10% of all humans carry these organisms as
part of the human bowel flora. About 2,500 infections are diagnosed per year in
the U.S. with about 500 deaths per year. Except for pregnant females and their
fetus or newborn, there is no direct transfer of Listeria from human to human.
The organisms (Listeria monocytogenes) that cause listeriosis probably have been
infecting humans for centuries; Listeria was first isolated from an infected WWI
soldier in 1918 and had many different names until 1940, when the genus and
species names were firmly established. The bacteria were first recognized as a
food-borne pathogen in 1979. The bacteria can penetrate human cells and can
multiply inside them. People with altered or impaired immune systems have cells
that are less able to control the spread of these organisms into the blood or
into other cells. In 2010, a known species, Listeria ivanovii, thought only to
infect cattle, was found to infect humans.
There have been many outbreaks of the
disease over the world; the most recent occurred in Texas in October 2010,
tentatively related to locally processed celery; 10 people were diagnosed with
listeriosis and five died. Most people infected had underlying medical problems or
conditions.
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.
Headaches can be divided into two categories: primary headaches and secondary headaches. Migraine headaches, tension headaches, and cluster headaches are considered primary headaches. Secondary headaches are caused by disease. Headache symptoms vary with the headache type. Over-the-counter pain relievers provide short-term relief for most headaches.
Diabetes mellitus is a chronic condition characterized by high levels of sugar (glucose) in the blood. The two types of diabetes are referred to as type 1 (insulin dependent) and type 2 (non-insulin dependent). Symptoms of diabetes include increased urine output, thirst, hunger, and fatigue. Treatment of diabetes depends on the type.
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.
Although a fever technically is any body temperature above the normal of 98.6 degrees F. (37 degrees C.), in practice a person is usually not considered to have a significant fever until the temperature is above 100.4 degrees F (38 degrees C.). Fever is part of the body's own disease-fighting arsenal: rising body temperatures apparently are capable of killing off many disease- producing organisms.
A miscarriage is any pregnancy that ends spontaneously before the fetus can survive. Miscarriage usually occurs before the 13th week of pregnancy. The cause of a miscarriage cannot always be determined. The most common causes of a miscarriage in the first trimester are collagen vascular disease (lupus), hormonal problems, diabetes, chromosomal abnormalities, and congenital abnormalities of the uterus.
Epilepsy is a brain disorder in which the person has seizures. There are two kinds of seizures, focal and generalized. There are many causes of epilepsy. Treatment of epilepsy (seizures) depends upon the cause and type of seizures experienced.
Cancer is a disease caused by an abnormal growth of cells, also called malignancy. It is a group of 100 different diseases, and is not contagious. Cancer can be treated through chemotherapy, a treatment of drugs that destroy cancer cells.
Influenza (flu) is a respiratory illness caused by a virus. Flu symptoms include fever, cough, sore throat, runny nose, headache, fatigue, and muscle aches. The flu may be prevented with an annual influenza vaccination.
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.
Encephalitis is a brain inflammation that causes sudden fever, vomiting, headache, light sensitivity, stiff neck and back, drowsiness, and irritability. Meningitis is an infection that causes inflammation of the meninges that surround the brain and spinal cord. Symptoms of meningitis include high fever, headache, nausea, vomiting, and stiff neck.
AIDS is the advanced stage of HIV infection. Symptoms and signs of AIDS include pneumonia due to Pneumocystis jiroveci, tuberculosis, toxoplasmosis, seizures, weakness, meningitis, yeast infection of the esophagus, and Kaposi's sarcoma. Anti-retroviral therapy (HAART) is used in the treatment of AIDS.
Diarrhea
is an increase in the frequency of bowel movements or a decrease in the form
of stool (greater looseness of stool). Although changes in frequency of
bowel movements and looseness of stools can vary independently of each other,
changes often occur in both.
Diarrhea needs to be distinguished from four other conditions. Although these conditions may accompany
diarrhea, they often have different causes and different treatments than
diarrhea. These other conditions are:
incontinence of stool, which is the inability to
control (delay) bowel movements until an appropriate time, for example, until one can
get to the toilet
rectal urgency, which is a sudden urge to have a
bowel movement that is so strong that if a toilet is not immediately available
there will be incontinence
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