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.
What causes a norovirus infection? How are norovirus infections transmitted?
Infection occurs when humans inadvertently ingest material contaminated with
small amounts of fluids or feces from an infected person. It only takes a small
number of viruses to cause infection, so even microscopic amounts of feces or
fluids can be contagious.
An infected person with vomiting or diarrhea can contaminate their
environment directly or spread virus particles through aerosolized droplets
when throwing up. Contamination may also occur in food and/or in water, which
has led to infection spreading widely in restaurants or aboard cruise ships.
Outbreaks in school systems occur regularly, sometimes spreading widely as was
the case with an outbreak in the Chicago public schools in 2010. The virus is
very hardy and can live for days or weeks on surfaces.
What are norovirus infection symptoms and signs in adults, children, and
babies?
Most people get sick within one day of ingesting norovirus (range 12-48 hours). Symptoms
and signs include vomiting or watery diarrhea or both. Fever occurs in
one-third to one-half of infected people. Cramping
abdominal or stomach pain and
a general feeling of tiredness, headache, and muscle aches are common.
People are usually thirsty, although they may have trouble keeping fluids
down. In general, patients who can orally ingest about the same amount of fluid
they lose through diarrhea, vomiting, or both do well. Symptoms in adults may be
different than symptoms in children. Young children and babies may not complain
of thirst but may appear listless or lethargic as they become dehydrated.
Symptoms may be more severe in debilitated, elderly patients. People who are unable to
replace their fluids and develop signs of dehydration need medical care.
Most people have a mild illness that lasts two to three days. In contrast to
bacterial diarrheas, such as those caused by Shigella or Campylobacter bacteria,
norovirus does not cause blood or pus in the stool. The length of infection may
be prolonged in patients who are in the hospital or in young children.
Norovirus has been associated with severe inflammation of the colon in
newborns and with disease flares in children who have inflammatory bowel
disease, but it is not yet clear what role norovirus is playing in these
conditions.
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.
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