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Diseases » Giardia » Contagiousness

Is Giardia Contagious?

Transmission of Giardia from Person to Person

Giardia is considered to be contagious between people. Generally the infectious agent may be transmitted by saliva, air, cough, fecal-oral route, surfaces, blood, needles, blood transfusions, sexual contact, mother to fetus, etc.
Giardia, although infectious, is not a genetic disease. It is not caused by a defective or abnormal gene.
The contagious disease, Giardia, can be transmitted:

  • from person to person by saliva, air, coughing, contact, surfaces, fecal-oral route, etc.

Transmission of Giardia

Transmission of Giardia to a person can be by way of:

  • food borne pathogens.

Contagion summary:

Ingestion of one or more cysts may cause disease, as contrasted to most bacterial illnesses where hundreds to thousands of organisms must be consumed to produce illness. (Source: FDA Bad Bug Book)

Discussion about Contagion of Giardia:

Giardiasis: DPD (Excerpt)

Giardia lives in the intestine of infected humans or animals. Millions of germs can be released in a bowel movement from an infected human or animal. You can become infected after accidentally swallowing the parasite. Giardia may be found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals. Giardia is not spread by contact with blood. Giardia can be spread:

  • By putting something in your mouth or accidentally swallowing something that has come in contact with the stool of a person or animal infected with Giardia
  • By swallowing recreational water contaminated with Giardia. Recreational water is water in swimming pools, hot tubs, jacuzzis, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with sewage or feces from humans or animals.
  • By eating uncooked food contaminated with Giardia. Thoroughly wash with uncontaminated water all vegetables and fruits you plan to eat raw. See below for information on making water safe.
  • By accidentally swallowing Giardia picked up from surfaces (such as toys, bathroom fixtures, changing tables, diaper pails) contaminated with stool from an infected person.
(Source: excerpt from Giardiasis: DPD)

Giardiasis: DPD (Excerpt)

Giardia can be very contagious. Follow these guidelines to avoid spreading Giardia to others.

  • Wash your hands with soap and water after using the toilet, changing diapers, and before eating or preparing food.
  • Avoid swimming in recreational water (pools, hot tubs, lakes or rivers, the ocean, etc.) if you have Giardia and for at least 2 weeks after diarrhea stops. You can pass Giardia in your stool and contaminate water for several weeks after your symptoms have ended. This has resulted in outbreaks of Giardia among recreational water users.
  • Avoid fecal exposure during sex.
(Source: excerpt from Giardiasis: DPD)

Foodborne Infections General: DBMD (Excerpt)

Some common diseases are occasionally foodborne, even though they are usually transmitted by other routes.  These include infections caused by Shigella , hepatitis A, and the parasites Giardia lamblia and Cryptosporidia.  Even strep throats have been transmitted occasionally through food.  (Source: excerpt from Foodborne Infections General: DBMD)

Microbes in Sickness and in Health -- Publications, National Institute of Allergy and Infectious Diseases: NIAID (Excerpt)

People, including babies, with diarrhea caused by Cryptosporidia or other diarrhea- causing microbes, such as Giardia and Salmonella, can infect others while using swimming pools, waterparks, hot tubs, and spas. (Source: excerpt from Microbes in Sickness and in Health -- Publications, National Institute of Allergy and Infectious Diseases: NIAID)

About contagion and contagiousness:

Contagion and contagiousness refers to how easily the spread of Giardia is possible from one person to another. Other words for contagion include "infection", "infectiousness", "transmission" or "transmissability". Contagiousness has nothing to do with genetics or inheriting diseases from parents. For an overview of contagion, see Introduction to Contagion.


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