wall) reduces the small intestine’s ability to absorb
NUTRIENTSand fluid. People often refer to gastroen-
teritis as “stomach flu,” though this is inaccurate;
the “flu” or influenza is a viral infection of the
pulmonary system.
Symptoms and Diagnostic Path
Symptoms of gastroenteritis include DIARRHEA,
abdominal cramping, and occasionally ABDOMINAL
DISTENTION. Depending on the cause of the infec-
tion, the diarrhea can be profuse or bloody;
bloody diarrhea requires medical evaluation.
There may also be FEVERand VOMITING.
Symptoms that extend beyond two or
three days in children or the elderly, or
in a person of any age who cannot keep
any fluids down, require medical evalu-
ation to prevent DEHYDRATION.The diagnostic path may include laboratory
tests to determine the presence of pathogens
(agents of infection) in the stool and blood tests to
help identify the extent and nature of infection.
The doctor may take stool samples or a rectal swab
to determine whether bacterial or parasitic
pathogens are present, which would require treat-
ment with the appropriate medications. Bacterial
gastroenteritis most often results from consuming
contaminated food or water. The doctor may rec-
ommend ANTIEMETIC MEDICATIONSto quell nausea
and ANTIDIARRHEAL MEDICATIONSto reduce diarrhea,
depending on the cause and extent of the symp-
toms.
Noninfectious forms of gastroenteritis include
Crohn’s disease and radiation gastroenteritis.
Crohn’s disease is a component of INFLAMMATORY
BOWEL DISEASE(IBD), which many doctors believe is
an autoimmune disorder with a genetic com-
ponent in which the IMMUNE SYSTEMattacks the
intestinal mucosa. The attacks result in small
ulcerations that often bleed. The enteric symptoms
are chronic; treatment targets the underlying dis-
ease. Radiation gastroenteritis results from dam-
age to the intestinal mucosa that occurs with
RADIATION THERAPYto the abdomen, and may be
acute (limited to the course of radiation therapy)
or chronic (signaling permanent changes in the
intestinal mucosa).
COMMON ENTERIC PATHOGENS
Pathogen Type Route of Infection
astrovirus VIRUS contaminated food or water
person-to-personcalicivirus virus contaminated food or water
person-to-personCryptosporidium PARASITE contaminated water
animal-to-person
person-to-personCyclospora parasite contaminated food or water
cayetanensis person-to-person
enteric adenovirus virus contaminated food or water
person-to-personEscherichia coli BACTERIA contaminated food or water
person-to-personGiardia lamblia parasite contaminated water
person-to-personListeria bacteria contaminated food
person-to-personMicrosporidia parasite unknownrotavirus virus contaminated food or water
person-to-personSalmonella bacteria contaminated food
reptile-to-personStaphylococcus bacteria contaminated food
enterotoxin person-to-personTreatment Options and Outlook
Adequate fluid replacement and other supportive
measures are the only treatment necessary for
viral gastroenteritis, which typically runs its
course in three to five days. Young children, older
adults, and people who have serious chronic
health care conditions are at greatest risk for com-
plications from viral gastroenteritis, though most
people recover fully. Bacterial and parasitic gas-
troenteritis require treatment with the appropriate
medications to eliminate the causative PATHOGEN,gastroenteritis 49