From the Guidelines
Giardiasis is an intestinal infection caused by the microscopic parasite Giardia lamblia, characterized by diarrhea, abdominal cramps, bloating, weight loss, or malabsorption, and can be asymptomatic in some cases. The infection is typically spread through contaminated water, food, or direct contact with infected feces. According to the Centers for Disease Control and Prevention 1, giardiasis is diagnosed by demonstrating G. lamblia cysts in stool.
Symptoms and Diagnosis
The symptoms of giardiasis include:
- Diarrhea
- Abdominal cramps
- Bloating
- Weight loss
- Malabsorption Some individuals may be asymptomatic, as noted in the case definitions for infectious conditions under public health surveillance 1.
Treatment
Treatment for giardiasis usually involves antiparasitic medications, with tinidazole being the first choice, followed by metronidazole as an alternative 1. Tinidazole is approved in the United States for children aged ≥3 years and is available in tablets that can be crushed. Metronidazole has a high frequency of gastrointestinal side effects and is not FDA approved for the treatment of giardiasis.
Prevention
Prevention of giardiasis involves practicing good hygiene, such as:
- Washing hands thoroughly after using the bathroom and before handling food
- Drinking only treated or bottled water in high-risk areas
- Washing fruits and vegetables carefully It is essential to stay hydrated during infection and avoid dairy products, which may temporarily worsen symptoms due to secondary lactose intolerance. Most people recover completely with treatment, though some may experience persistent symptoms requiring additional medical attention.
From the FDA Drug Label
1.2 Giardiasis Tinidazole is indicated for the treatment of giardiasis caused by Giardia duodenalis (also termed G. lamblia) in both adults and pediatric patients older than three years of age Giardiasis is an infection caused by Giardia lamblia (also termed Giardia duodenalis). 2
From the Research
Definition and Causes of Giardiasis
- Giardiasis is an intestinal infection caused by the parasite Giardia lamblia, also known as Giardia intestinalis 3.
- The infection can be asymptomatic or present with symptoms such as diarrhea, weight loss, abdominal cramps, and failure to thrive 3, 4.
- Giardiasis is most often diagnosed after recent travel or in day care centers, and can be transmitted through contaminated water or person-to-person contact 3, 4.
Life Cycle and Transmission of Giardia Lamblia
- The organism has two stages in its life cycle: a cyst stage and a trophozoite stage 3, 5.
- Infection occurs when an individual ingests as few as 10-25 cysts, which then excyst and attach to the small bowel wall 3, 6.
- The trophozoites can encyst and be shed in feces, allowing for future ingestion by another host 3, 5.
Diagnosis and Treatment of Giardiasis
- Diagnosis is typically made by stool examination, which may also eliminate other possible infectious agents 3, 6.
- Small bowel biopsy or stool ELISA may be necessary in difficult cases or for large population screening examinations 3.
- The mainstay of treatment is metronidazole, which is highly effective in curing over 90% of individuals 3, 7.
- Other treatment options include tinidazole, ornidazole, quinacrine, and furazolidone, although metronidazole is generally the preferred treatment 7, 6.