The National Academies

The National Academies: What You Need To Know About Infectious Disease

What You Need To Know About Infectious Disease

Diarrheal Diseases

Caused by virusesbacteria, or parasites, diarrheal diseases spread through contaminated food and water or because of insufficient hygiene practices. Many children with diarrheal diseases also have an underlying condition of malnutrition, making them more vulnerable. Diarrheal diseases are among the top ten leading causes of infectious diseaserelated deaths worldwide, accounting for 1.5 million deaths annually. 760,000 of those deaths are among children under the age of 5, making these diseases the second leading cause of death among young children.

Diarrhea is defined as having three or more loose stools per day. There are three main types of diarrhea: acute watery diarrhea, which typically lasts several hours or days and includes cholera; acute bloody diarrhea, also called dysentery; and persistent diarrhea, which lasts 14 days or longer. Diarrhea can cause dehydration, the loss of water and electrolytes—sodium, chloride, potassium, and bicarbonate. Signs of dehydration include thirst, irritability, decreased skin elasticity, and sunken eyes. If dehydration becomes severe other signs appear, such as loss of consciousness, faint pulse, low output of urine, cool and moist extremities, and low blood pressure. If left untreated, dehydration can result in death.

A three-pronged approach is used for treatment of these diseases. Zinc tablets are given to reduce the number of diarrheal episodes, followed by rehydration therapy. For severe dehydration, intravenous solutions are given. For mild or moderate dehydration, a solution of clean water, sugar, and salt is used. Eating a nutritious diet can treat diarrhea and prevent it from reappearing.

Education about personal and food hygiene and how infections spread, access to clean water, and improved sanitation can prevent the spread of diarrheal diseases. In addition, exclusive breastfeeding is recommended for the first 6 months of life. 


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What do you know about infectious disease?

Which are larger?

  • Correct!

    Bacteria are 10 to 100 times larger than viruses.

  • Sorry, that’s incorrect.

    Bacteria are 10 to 100 times larger than viruses.

Infectious Disease Defined


A type of protein produced by cells of the immune system that help keep viruses, bacteria, and cancer cells from growing.

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