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Learn about Giardia duodenalis, a protozoan flagellate that causes giardiasis, a diarrheal disease. Find out how trophozoites and cysts are transmitted, infect, and multiply in the small intestine.
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Some people with giardia infection never develop signs or symptoms, but they still carry the parasite and can spread it to others through their stool. For those who do get sick, signs and symptoms usually appear one to three weeks after exposure and may include:
•Watery, sometimes foul-smelling diarrhea that may alternate with soft, greasy stools
•Fatigue
•Stomach cramps and bloating
•Gas
•Nausea
Call your doctor if you have loose stools, stomach cramping and bloating, and nausea lasting more than a week, or if you become dehydrated. Be sure to tell your doctor if you're at risk of giardia infection — that is, you have a child in child care, you've recently traveled to an area where the infection is common, or you've swallowed water from a lake or stream.
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Giardia parasites live in the intestines of people and animals. Before the microscopic parasites are passed in stool, they become encased within hard shells called cysts, which allows them to survive outside the intestines for months. Once inside a host, the cysts dissolve and the parasites are released.
Infection occurs when you accidentally swallow the parasite cysts. This can occur by swallowing unsafe water, by eating infected food or through person-to-person contact.
The giardia parasite is a very common intestinal parasite. Although anyone can pick up giardia parasites, some people are especially at risk:
•Children. Giardia infection is far more common in children than it is in adults. Children are more likely to come in contact with feces, especially if they wear diapers, are toilet training or spend time in a child care center. People who live or work with small children also are at higher risk of developing giardia infection.
•People without access to safe drinking water. Giardia infection is rampant wherever sanitation is inadequate or water isn't safe to drink. You're at risk if you travel to places where giardia infection is common, especially if you aren't careful about what you eat and drink. The risk is greatest in rural or wilderness areas.
•People who have anal sex. People who have anal sex or oral-anal sex without using a condom or other protection are at increased risk of giardia infection, as well as sexually transmitted infections.
Giardia infection is almost never fatal in industrialized countries. But it can cause lingering symptoms and serious complications, especially in infants and children. The most common complications include:
•Dehydration. Often a result of severe diarrhea, dehydration occurs when the body doesn't have enough water to carry out its normal functions.
•Failure to thrive. Chronic diarrhea from giardia infection can lead to malnutrition and harm children's physical and mental development.
•Lactose intolerance. Many people with giardia infection develop lactose intolerance — the inability to properly digest milk sugar. The problem may persist long after the infection has cleared.
No drug or vaccine can prevent giardia infection. But commonsense precautions can go a long way toward reducing the chances that you'll become infected or spread the infection to others.
•Wash your hands. This is the simplest and best way to prevent most kinds of infection. Wash your hands with soap and water for at least 20 seconds after using the toilet or changing diapers, and before eating or preparing food. When soap and water aren't available, you can use alcohol-based sanitizers. However, alcohol-based sanitizers aren't effective in destroying the cyst form of giardia that survives in the environment.
•Purify wilderness water. Avoid drinking untreated water from shallow wells, lakes, rivers, springs, ponds and streams unless you filter it or boil it for at least 10 minutes at 158 F (70 C) first.
•Wash produce. Wash any raw fruits and vegetables with safe, uncontaminated water. Peel the fruit before eating it. Avoid eating raw fruits or vegetables if traveling in countries where they may have contact with unsafe water.
•Keep your mouth closed. Try not to swallow water when swimming in pools, lakes or streams.
•Use bottled water. When traveling to parts of the world where the water supply is likely to be unsafe, drink and brush your teeth with bottled water that you open yourself. Don't use ice.
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Giardia infection is a parasitic intestinal infection that can cause diarrhea, bloating and fatigue. Learn how to avoid giardia by washing your hands, purifying water and avoiding contaminated food and sex.
Jun 29, 2018 · The life cycle of Giardia species is simple and it is included of two active trophozoite and cystic forms. This parasite transmits via fecal-oral route through direct or indirect ingestion of infectious cysts. The incubation period varies from 9 to 15 days after ingestion of cysts.
- Hossein Hooshyar, Parvin Rostamkhani, Mohsen Arbabi, Mahdi Delavari
- 2019
The trophozoite is the vegetative form and replicates in the small intestine, where it causes symptoms of diarrhea and malabsorption. After exposure to biliary fluid, some of the trophozoites form cysts in the jejunum and are passed in the feces, allowing completion of the transmission cycle by infecting a new host.
- Rodney D. Adam
- 10.1128/CMR.14.3.447-475.2001
- 2001
- Clin Microbiol Rev. 2001 Jul; 14(3): 447-475.
Nov 8, 2022 · Treatment. Preparing for your appointment. Diagnosis. To help diagnose giardia infection (giardiasis), your doctor is likely to test a sample of your stool. For accuracy, you may be asked to submit several stool samples collected over a period of days. The samples are then examined in a lab for the presence of parasites.
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Aug 11, 2021 · The trophozoite is the vegetative form and replicates in the small intestine of the host. The eight flagella provide motility, and the ventral disk mediates attachment to the intestinal wall, where it gains its nutrients.
Feb 16, 2024 · The traditional basis of diagnosis is identification of Giardia intestinalis trophozoites or cysts in the stool of infected patients via a stool ova and parasite...
