Diarrheal Diseases 101

Diarrhea Got You Down in the Dumps?

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Gastrointestinal infections that cause diarrhea represent a huge public health problem in all parts of the world. In developing countries, diarrheal disease is the second-leading cause of death in children, particularly in children younger than 5 years of age. In developed countries, including the United States, diarrheal disease is under better control but still represents a common affliction, especially among children and the elderly.

Diarrheal diseases can be spread from person-to-person via the fecal-oral route, with greater rates of disease found in daycare centers, hospitals and nursing homes. In addition, these diseases are frequently reported in food-borne and water-borne outbreaks.


There are two main types of diarrheal disease:

  1. Noninflammatory: Intestinal infections, such as Cholera and Giardia, are caused by an alteration in intestinal absorption of fluids. These types of infections result in large volumes of watery diarrhea, accompanied by cramps and bloating, with mild or no fever.
  2. Inflammatory: Also known as dysentery, this kind of disease is characterized by smaller volumes of bloody diarrhea, accompanied with fever and pain. It is caused by microbes, such as Shigella and Entamoeba histolytica, that invade the colon and trigger an inflammatory immune response.


To diagnose your infection, your doctor may run a series of tests, including:

Stool Tests

  • Culture. A bacterial culture is used to identify bacterial species responsible for your infection.
  • Gram-stain. These stains can distinguish between the two major classes (gram-positive or gram-negative) bacteria and aid in narrowing down what kind of infection you have.
  • Ova + Parasites. A stool sample is examined for the presence of parasites and/or their eggs.
  • Fecal leukocytes. Identification of these white blood cells in your stool will inform your doctor that you have an inflammatory disease.
  • Toxin and Antigen Assay. Some infections can be detected through these substances.

Blood Tests

  • Serology. This method consists of drawing a blood sample and evaluating your antibodies to identify microbes with which you have recently been infected.
  • Culture. A blood sample is used to culture bacteria that may be responsible for your infection.


The following treatments can sometimes be used to treat diarrheal disease:

  • Antibiotics for bacterial infections
  • Over-the-counter diarrheal drugs
  • Oral Rehydration Therapy to prevent dehydration

Always ask your doctor about using any kind of drugs to treat diarrheal disease. Misuse of antibiotics can result in emergence of antibiotic-resistant superbugs, and some diarrheal drugs prevent "flushing out" of the infectious microbes and can actually do more harm than help.


  • Practice good personal hygiene. In developing countries, poor hygiene practice is the main reason for the high prevalence of diarrheal diseases. Use of clean water, flushed toilets and sanitary waste disposal habits in industrialized countries have limited the spread of diarrheal diseases. In addition, frequent hand washing with soap and good cooking and dining practices are important for preventing diarrheal diseases.
  • Make sure your vaccinations are up-to-date. Vaccines are available for several diarrheal diseases, including Cholera, Salmonella typhi, Hepatitis A and Rotavirus. People traveling to other countries should find out which diseases are common in their travel destination and ask their doctor for recommended vaccines.

When to Call a Doctor

Call your doctor if your diarrhea lasts more than 3 days, have a high fever, bloody stools, prolonged vomiting or signs of dehydration, such as thirst, dry lips or mouth, decreased urine output that is dark in color, flushed skin, sunken eyes, cramps and stiff joints, severe fatigue, irritability and headache.


Gastrointestinal infections can be caused by a variety of microbes, including several species of bacteria, viruses and protozoa.

Among the more common microbes that infect the GI tract are:


  • Norovirus
  • Rotavirus
  • Adenovirus
  • Calcivirus



  • Giardia lamblia
  • Entamoeba histolytica
  • Cryptosporidium parvum

Resources: Foodborne Illness. Centers for Disease Control and Prevention. Rehydrate.org. Rehydration Project

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