Approximately 3 million to 6 million children throughout the world die every year from gastroenteritis, according to Dr. Thomas Boyce, associate professor of pediatrics at the Mayo Clinic College of Medicine, in "The Merck Manual for Healthcare Professionals." Most of the cases in the U.S. are mild. Physicians have various tests available to diagnose those cases which are not.
Definition
Acute gastroenteritis is the inflammation of the mucous membrane that lines the stomach and intestines. Boyce writes in "The Merck Manual" that various parasites, bacteria and viruses are the primary cause of this infection. For healthy adults, the inflammation causes some abdominal pain, nausea, vomiting and diarrhea. But it can be fatal to infants, the elderly and those suffering from other diseases because they all have weakened immune systems.
Parasites
Cryptosporidium parvum and Giardia lamblia are the two main parasites that cause acute gastroenteritis. In America, Cryptosporidium causes outbreaks of infection when cities have problems purifying drinking water, as explained by Dr. Warren Levinson, professor of microbiology at the University of California, in "Review of Medical Microbiology and Immunology." People with weakened immune systems will have symptoms for a longer time compared with healthy adults. Giardia can also cause outbreaks, but is a common infection in day-care centers and in hikers who drink water from streams. It causes a very smelly diarrhea.
Bacteria
Some bacteria cause acute gastroenteritis by invading the mucous membrane of the intestines, causing ulcers and bleeding. Others cause it by creating toxins. Still others attach to the intestinal mucous membranes, produce toxins there and interfere with the normal absorption function of the intestines. This makes the intestines release large amounts of water and electrolytes. The main bacteria that cause acute gastroenteritis are E. coli, Shigella, Campylobacter and Salmonella, according to Boyce in "The Merck Manual."
Viruses
In America, viruses are the primary cause of acute gastroenteritis, where approximately 30 percent to 40 percent of all cases are due to viruses, says Dr. Vicente Corrales-Medina, infectious diseases fellow at Baylor College of Medicine in the journal Current Medical Diagnosis and Treatment. The rotavirus is the main cause for young children, especially for those younger than 2. The Norwalk virus causes most of the cases in older children and adults. More than 90 percent of the cases of gastroenteritis that happen during the fall and winter are due to the Norwalk virus.
Diagnosis
The overwhelming majority of the cases are mild. As explained by Corrales-Medina in "Current Medical Diagnosis and Treatment," if people have diarrhea that lasts for 7 to 10 days, physicians have tests available for further diagnosis. A sample of the stool can be checked for white blood cells and red blood cells, as well as parasite eggs, called ova. In a culture, the lab will take a sample of the stool and check it under a microscope. A stool Giardia antigen test can check for Giardia parasites.
References
- "Current Medical Diagnosis and Treatment 2010"; Stephen McPhee, Dr. Maxine Papadakis; 2010
- "Review of Medical Microbiology and Immunology"; Dr. Warren Levinson; 2008
- Merck Manual for Healthcare Professionals: Gastroenteritis
