Giardiasis is a common protozoan gastroenteritis causing diarrhea lasting several weeks, usually without fever. Humans, cats, dogs, cattle, beaver and other animals may carry the infection. The disease is associated with poor sanitation and contaminated water/food.
CASES/YEAR
1,462,173 (US); 29,243,462 (Global)
INCUBATION
1 week to 10 days; range of 3-25 days or possibly longer; [CCDM]
INITIAL SYMPTOMS
Diarrhea lasting several weeks usually without fever; [PPID, p. 3391-2]
PRECAUTIONS
Standard; "Use Contact Precautions for diapered or incontinent persons for the duration of illness or to control institutional outbreaks." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
FINDINGS:
Many infections are asymptomatic. Acute symptoms include malodorous diarrhea, cramping, and nausea. Chronic symptoms include diarrhea, distention, flatus, and weight loss. [Merck Manual, p. 1648-9] About 1/4 of patients have vomiting and <20% have fever. Other findings occasionally described are urticaria and reactive arthritis. Patients may be lactose intolerant for several weeks after completion of treatment. Eosinophilia is not seen. [Guerrant, p. 623-30] Fever and blood in stool suggest another diagnosis. Patients with chronic infection may have episodes rather than continual symptoms. In some cases, diarrhea is less prominent than belching, flatulence, and weight loss. [Harrison ID, p. 1119] Giardiasis is associated with arthritis, uveitis, and urticaria, but it is not yet known if it causes these conditions. Giardiasis is an uncommon cause of cholecystitis and pancreatitis. [Cecil, p. 2106] Initial stool specimens may be negative because the incubation period can be shorter than the prepatent period (time necessary for cysts to be formed in the stool). Some patients have episodes of diarrhea along with normal bowel movements and constipation. [PPID, p. 3157]
EPIDEMIOLOGY:
Humans, cats, dogs, cattle, beaver and other animals may carry the infection. Children may become infected in daycare centers. Infection is also acquired by drinking or swimming in contaminated water or eating contaminated food. [CCDM, p. 235] Backpackers who drink untreated surface water are at risk. Certain sexual practices (fecal-oral contact) increase risk. [Cecil, p. 2105] Other mammals that may be infected are dogs, cats, sheep, cattle, beavers, gerbils, and mice. [PPID, p. 3528] As few as 10 cysts can cause infection. Cysts can remain viable for months in cold water and are not destroyed by standard techniques of water chlorination. Boiling or filtrating water eliminates viable cysts. [Harrison ID, p. 1118]
DIAGNOSTIC
Stool antigen detection with immunofluorescence (DFA) most sensitive/specific;. PCR available. [ABX Guide] Direct immunofluorescent microscopy is 90% sensitive on a single stool sample. [Cecil, 24th Ed, p. 2042]
SCOPE
Global; Increased risk for travelers who visit areas with contaminated food or water; Endemic worldwide; Risk increases with duration of travel; [CDC Travel, p. 213]
SIGNS & SYMPTOMS
-
>arthralgia
-
>fatigue, weakness
-
>fever
-
>myalgia
-
G abdominal pain
-
G constipation
-
G diarrhea
-
G nausea, vomiting
-
S urticaria
-
*arthritis
-
*erythema nodosum
-
*pancreatitis
-
*weight loss
ENTRY
Ingestion, Swimming, Sexual Contact
SOURCE
Person-to-Person, Human Fecal-Oral, Animal Excreta, Eating Contaminated Food, Waterborne (Ingesting, Inhaling, or Swimming)
RESERVOIR
Cattle, Goats and Sheep, Cats, Dogs, Rodents, Human, Wild Animals
RISK FACTORS
- AIDS patients
- Ingest infectious agents in food/water
- Swim in contaminated water (ingestion or inhalation)
- Travel to endemic area
REFERENCES FOR CASES/YEAR
1. (US) MMWR 2011: 16,747; Passive surveillance in 1997 was 22,907; Estimated total cases = 2 million; [Mead1999: PMID 10511517] Calculate16,747/22,907 X 2 million = 1,462,173;
2. (Global) Calculate:1,462,173 x 20 = 29,243,460;