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.
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.
A reported outbreak of norovirus infection on a cruise ship has left many
would-be travelers worried about contracting the illness and wondering if they
can prevent it. Many people may not be familiar with the term norovirus, but
it's actually a relatively new term for an old disease. The many strains of
noroviruses cause a self-limited gastrointestinal illness that many refer to as
the "stomach flu." Outbreaks of norovirus infection have also been documented as
coming from restaurants, schools, and nursing homes.
Norovirus is now the official name for the group of viruses that, for a time,
were referred to as "Norwalk-like" viruses, after the original strain "Norwalk
virus," which caused an outbreak of gastroenteritis in a school in Norwalk,
Ohio, in 1968. Other names for this group of viruses have included caliciviruses
(the virus family name) and small round structured viruses (SRSVs).
After infection with one of the noroviruses, symptoms typically appear within
one to two days. The sudden onset of nausea and vomiting, watery diarrhea, and
abdominal cramping are the most common symptoms of norovirus infection. A
low-grade fever may be present. The illness typically resolves on its own within
24 to 60 hours without serious long-term effects. However, dehydration is a
potential complication, especially among children and the elderly, possibly
requiring medical treatment.
Norovirus is a small virus that is highly
contagious.
People acquire the virus by ingesting material contaminated with
small amounts of infected feces or fluids. Food and water may be contaminated
during processing or handling.
Noroviruses are the most common cause of
gastroenteritis in the United States.
Infected people usually experience
vomiting or watery diarrhea or both.
The illness usually lasts two to three days
and resolves by itself.
There is no specific treatment for norovirus, but it
is important that infected people stay well hydrated. Fluids containing sugar
and electrolytes should be encouraged. Intravenous fluids may be needed if the
person cannot maintain an adequate oral intake of fluids.
Complications are
related to the degree of dehydration. Young children and the elderly are at
special risk for dehydration.
Because the disease is highly contagious, it is
important for caretakers to clean their hands whenever they come into contact
with the ill person or his/her environment.
The risk of food-borne outbreaks or
outbreaks within hospitals or nursing homes may be minimized by following
established standards that include hand hygiene.
What is a norovirus?
A norovirus is a small virus that contains RNA and is
surrounded by a protein coating. By sequencing the RNA, scientists have
discovered that there are many different types of norovirus. Originally, strains
were named based on the city in which they were first identified. Thus, one
common strain used to be called Norwalk virus. Based on genetic typing, we now
know that there are at least 25 different strains of norovirus that affect
humans.
Norovirus infection is the most common cause of gastroenteritis outbreaks.
Although some people call this the "stomach flu," norovirus is not related to
the influenza virus. According to statistics from the CDC, there are 21 million
cases of norovirus infection annually in the U.S., of which one-quarter are
related to food-borne outbreaks. Outbreaks occur throughout the year but are
more common in the winter months. There is no specific treatment for norovirus.
Fortunately, the disease is self-limited and simple supportive measures are
sufficient to care for most people unless they become dehydrated.
Figure 1: Picture of norovirus particles seen using transmission electron microscopy.
SOURCE: CDC/Charles D. Humphrey
Abdominal pain is pain in the belly and can be acute or chronic. Causes include inflammation, distention of an organ, and loss of the blood supply to an organ. Abdominal pain can reflect a major problem with one of the organs in the abdomen such as the appendix, gallbladder, large and small intestine, pancreas, liver, colon, duodenum, and spleen.
Gastroenteritis (viral gastroenteritis, stomach flu) is an infection caused by a variety of viruses that results in vomiting and/or diarrhea. Even though it is often called the "stomach flu," it is not caused by the influenza viruses. Viruses that can cause gastroenteritis (stomach flu) include: rotaviruses, adenoviruses, caliciviruses, astroviruses, Norwalk virus, and a group of Noroviruses. Gastroenteritis is not caused by bacteria. The main symptoms of gastroenteritis include vomiting and watery diarrhea, however, headache, fever, and abdominal cramps (stomach ache) may also be present.
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.
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.
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.
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.
Recreational Water Illnesses (RWIs) are caused by germs spread by breathing in mists or aerosols, swimming, or having contact with contaminated water in hot tubs, water parks, water play areas, fountains, lakes, rivers, oceans, and swimming pools. Diarrhea is the most commonly reported recreational water illness. Diarrheal illnesses are caused by germs such as Crypto, Shigella, Norovirus, E. coli, and Giardia. Prevention of water born illnesses is key to avoid infection. Avoid swallowing water and practice good hygiene habits are a must.
Food poisoning is a common infection that affects millions of people in the
United States each year.
Most commonly, patients complain of vomiting, diarrhea, and crampy
abdominal pain.
People should seek medical care if they have an associated fever, blood
in their stool, signs and symptoms of dehydration, or if their symptoms do not
resolve after a couple of days.
Treatment focuses on keeping the patient well hydrated.
Most cases of food poisoning resolve on their own.
Prevention is key and depends upon keeping food preparation areas clean,
good hand washing, and cooking foods thoroughly.
What is food poisoning?
Food poisoning might be described as a food borne disease. Food that contains
a toxin, chemical or infectious agent (like a bacterium, virus, parasite, or
prion) and cause symptoms in the body are considered types of food pois...
A reported outbreak of norovirus infection on a cruise ship has left many
would-be travelers worried about contracting the illness and wondering if they
can prevent it. Many people may not be familiar with the term norovirus, but
it's actually a relatively new term for an old disease. The many strains of
noroviruses cause a self-limited gastrointestinal illness that many refer to as
the "stomach flu." Outbreaks of norovirus infection have also been documented as
coming from restaurants, schools, and nursing homes. 
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