Diarrhea can be caused by many conditions. Some types of diarrhea are contagious and can be spread between people and even from animals to people. Diarrhea can also be a symptom of a disease that is not infectious.
For healthy people, occasional diarrhea usually doesn't last long and gets better on its own without causing major problems. However, diarrhea is the second leading cause of death in children in the developing world. It's also a major contributor to work absenteeism and loss of productivity in the United States' workforce.
The elderly, very young children, and people with compromised immune systems are especially vulnerable to diarrheal infections. They are at an increased risk of complications related to severe diarrhea including dehydration and the need for hospitalization and fluid management. They may also be more likely to die from these complications.
This article will go over the types of diarrhea, the causes of diarrhea, how to tell if diarrhea is contagious, and how long infectious diarrhea usually lasts. You will also learn about infectious diarrhea treatments and how to prevent diarrhea.
The most common causes of diarrhea are viral, bacterial, and parasitic infections. Infectious diarrheal diseases are contagious, meaning that they can be spread between people.
Diarrheal infections are typically spread through the fecal-oral route. This means that fecal matter that has infectious particles in it gets on a surface or person. Things that people touch a lot, like doorknobs, buttons, and counters can be easily contaminated.
If people don't wash their hands after they use the bathroom, they can spread the infection when they touch other people (for example, by shaking hands). People can also catch infections that cause diarrhea if a sick person makes food for them.
Kids often spread infectious diarrhea easily because they tend to put their hands and objects in their mouths.
Animals can also contaminate sources of water and surfaces with pathogens that spread infectious diarrhea. These illnesses can also be transmitted if people don't wash their hands after touching an animal.
Two terms you may here associated with infectious diarrhea:
- Gastroenteritis refers to bacterial or viral infections that affect both the stomach and small/large intestines. These patients present with nausea, vomiting, and abdominal pain, as well as diarrhea.
- Dysentery refers to infectious or inflammatory diarrheal diseases that result in the frequent passage of smaller stools containing varying amounts of mucus and/or blood.
Infectious diarrhea often comes quickly and does not last longer than a few days, though some illnesses may cause diarrhea that lasts a week or two.
Once the cause is found, most infectious diarrheal diseases can be treated. However, some types of infectious diarrhea are harder to treat. People may have diarrhea that lasts a long time and leads to complications.
Viruses are the most common cause of diarrhea. There are four specific viruses that most often cause infectious diarrhea:
- Norovirus, also known as the "cruise ship virus," is the most common cause of food-borne gastroenteritis in the U.S.
- Rotavirus is the most common cause of diarrhea in American children and a leading cause of death in children in the developing world.
- Adenoviruses include a family of more than 50 subtypes. Types 40 and 41 are primarily responsible for causing diarrhea in humans. (Other adenoviral subtypes include cold viruses).
- Astroviruses are a common cause of diarrhea in the elderly, children, and people with compromised immune systems.
Infectious diarrhea caused by a virus is usually highly contagious.
Bacterial diarrhea is a major contributor to illness and death worldwide. Although less common in the U.S. than viral diarrhea, bacterial diarrhea disorders more often lead to dysenteric disease due to the development of ulcers and inflammation in the intestines. The bacteria that commonly cause infectious diarrheal disease include:
- Salmonella enteritidis can cause diarrhea, fever, and abdominal cramps within 12 to 72 hours of consuming contaminated food or beverage.
- Escherichia coli (especially E. coli 0157) is spread through contaminated food and dairy products and can lead to a condition known as hemorrhagic colitis.
- Shigella is common both in the U.S. and around the world and can often cause bloody diarrhea, particularly in children of preschool age.
- Campylobacter is among the most common bacterial foodborne infections and can cause bloody diarrhea due to acute intestinal inflammation
- Vibrio infection is often associated with eating raw seafood or sushi.
- Staphylococcus aureus can cause explosive diarrhea due to toxins released by the bacteria.
- Clostridium difficile is unique in that the rise of the infection is frequently linked to prior or concurrent antibiotic use. It is today the most common cause of hospital-acquired diarrhea.
- Yersinia is a species of bacteria that can cause a number of different diseases in humans. Yersinia enterocollitica is a common cause of infectious diarrhea. In contrast, Yersinia pestis has been isolated as a primary cause of the bubonic plague. Humans typically encounter Yersinia species in dairy products.
Bacterial infections that cause diarrhea can spread quickly between people, but it's more common for people to get sick after drinking water or eating food that is contaminated.
Protozoa are the primary cause of parasitic diarrhea both in the U.S. and around the world. These single-celled organisms come in many forms. Among the three most common causes of parasitic diarrhea:
- Giardia lamblia is passed through contaminated food or by person-to-person contact and can result in explosive diarrhea within two days of infection.
- Entamoeba histolytica is related to fecal-oral transmission and can cause bloody diarrhea as these invasive parasites bore their way into the intestinal wall.
- Cryptosporidium is known to cause both respiratory and gastrointestinal illness and is characterized by the development of watery stools.
Infectious diarrhea caused by parasites is usually transmitted through infected drinking water.
Diarrhea in Babies in Toddlers
Infants and young children who go to daycare or preschool are more likely to catch contagious diarrhea illnesses. Things like sharing toys, contact with others in confined spaces, diaper changing/potty training, and inadequate hand washing amongst kids make it easy for germs to spread.
Diarrhea can also be non-infectious. People with medical conditions affecting the digestive, immune, or endocrine (hormone) systems can have diarrhea as a symptom. Diarrhea caused by these conditions cannot be spread to other people.
Medical conditions that can cause non-infectious diarrhea include:
- Irritable bowel syndrome (IBS)
- Inflammatory bowel disease (IBD)
- Celiac disease
- Lactose intolerance
People with these conditions may have acute episodes of diarrhea when the disease flares up, or they may have chronic diarrhea that lasts a long time.
Diagnosis and Treatment
What is considered infectious diarrhea, how long infectious diarrhea will last, and what can be done to treat and prevent this kind of diarrhea depends on the cause.
To find out what that is, you'll need to see a healthcare provider. Because the symptoms of infectious diarrhea can be similar to non-infectious diarrhea, you may not be able to tell what you have based on how you feel. And if you have an infection that's causing diarrhea, you won't necessarily know which pathogen is causing it.
To diagnose infectious diarrhea, providers will gather information from a patient—for example, if they have been around sick people or traveled recently. They can also run a series of tests to identify the cause of diarrhea.
Finding out whether diarrhea is infectious or not has several steps:
- A stool culture is commonly used to diagnose bacterial infections
- A combination of microscopic and antigen-based tests can help identify protozoa in stool samples
- Viral infections can be diagnosed by running a PCR test on a person's stool, blood, or other body fluids
Infectious Diarrhea Treatment Guidelines
The treatment for diarrhea depends on the cause and how sick a person is.
For infectious diarrheal diseases, there are medications that can be given. For example, antibiotics and antivirals can treat bacterial and viral infections, respectively, while antimicrobial agents can treat diarrhea caused by protozoans.
Anti-diarrheal medications can be prescribed along with oral rehydration therapy to prevent or treat the loss of fluid from diarrhea. The fluid can also be delivered intravenously (through a vein) if the dehydration is especially severe.
You may have a fever with infectious diarrhea. If you have a fever and feel sick when you have diarrhea, an over-the-counter (OTC) fever-reducing or pain-relieving medication may help.
How Diarrhea Is Treated
An ounce of prevention is truly worth a pound of cure when it comes to avoiding diarrhea. Here are a few tips for preventing diarrhea infections at home and while you're out:
- Practice frequent proper handwashing with hot water and soap or use an antibacterial handwash
- Sanitize your bathroom, kitchen, and anywhere in your home where food is prepared and eaten
- Thoroughly cook all poultry, meat, or shellfish and use a kitchen thermometer to ensure the foods reach appropriate internal temperatures
- Clean all cutting boards and utensils immediately after coming into contact with raw meat, poultry, or seafood
- Wash all fruits and vegetables
- Avoid eating raw shellfish if you have any doubt about its origin or freshness
- If traveling overseas, make sure your vaccinations are up to date. If you're planning to visit a developing country, visit the travel health website managed by the Centers for Disease Control and Prevention (CDC) to learn which vaccinations are needed before you go. You can also review any information related to water and local food safety.
Frequently Asked Questions
What types of diarrhea are contagious?
Diarrhea is often caused by germs. A diarrheal illness that is caused by viruses, bacteria, and parasites is contagious.
Can infections that cause diarrhea be passed through the air?(Video) Infectious Diseases A-Z: How to tell if your upset stomach is a viral infection
Some of the germs that cause infectious diarrhea can be spread through the air, but transmission is more likely when someone vomits.
Is diarrhea contagious if there's no fever?
Some infectious illnesses that cause diarrhea do not always cause a fever. For example, you might not have a fever if you are sick with norovirus ("stomach flu"), which is highly contagious.
How long does infectious diarrhea last?
Acute diarrhea usually lasts a few days at most. Chronic diarrhea lasts for four weeks or longer. It can also come and go.
How long are you contagious with diarrhea?
How long you can spread infectious diarrhea to other people depends on what is causing it. You might start feeling better but still be able to spread the infection for a few more days.
Learn More:How Long to Stay Home With the Stomach Flu
How can you tell if diarrhea is viral or bacterial?
Your provider can test your stool and see if it has germs—like bacteria or parasites—in it. There are also blood tests that can help your provider see if you have a virus.(Video) Infectious Diarrhea 1
What antibiotics are used for infectious diarrhea?
Antibiotics are only used when diarrhea is caused by bacteria. Three examples of antibiotics that are used for acute diarrhea are ciprofloxacin, cephalosporin, and azithromycin.
Preventing Traveler's Diarrhea
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & Causes of Diarrhea.
Hodges K, Gill R. Infectious diarrhea: Cellular and molecular mechanisms.Gut Microbes. 2010;1(1):4–21. doi:10.4161/gmic.1.1.11036
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By Ingrid Koo, PhD
Ingrid Koo, PhD, is a medical and science writer who specializes in clinical trial reporting
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Exposure to pathogenic bacteria, such as E. coli or parasites through contaminated food or water, leads to diarrhea. When traveling in developing countries, diarrhea caused by bacteria and parasites is often called traveler's diarrhea.What type of diarrhea is contagious? ›
Norovirus is a very contagious virus that causes vomiting and diarrhea. Anyone can get infected and sick with norovirus.Can you pass diarrhea to someone else? ›
Viruses and bacteria can spread through contact with poo, vomit and contaminated objects, water or food. This means that it is very important to frequently wash your hands thoroughly with soap if you have acute diarrhea, in order to protect others from infection.Can diarrhea spread to others? ›
Other causes: Diarrhoeal disease can also spread from person-to-person, aggravated by poor personal hygiene. Food is another major cause of diarrhoea when it is prepared or stored in unhygienic conditions.