In Washington

DOH receives approximately 550 to 750 reports of giardiasis per year, for an average rate of 11.7/100,000 persons. On average, 1 death is reported to be associated with Giardia infection each year.

Purpose of Reporting and Surveillance

• To identify sources of transmission (e.g., a public water source) and to prevent further transmission from such sources.
• When the source of infection appears to pose a risk of only a few individuals (e.g., an animal or a private meal), to inform those individuals how they can reduce their risk of exposure.
• To identify cases that may be a source of infection for others (e.g., a food handler) and prevent further transmission.
• To better characterize the epidemiology of this organism.

Reporting Requirements

• Health care providers: notifiable to Local Health Jurisdiction within 3 work days
• Hospitals: notifiable to Local Health Jurisdiction within 3 work days
• Laboratories: no requirements for reporting
• Local health jurisdictions: notifiable to DOH Communicable Disease Epidemiology within 7 days of case investigation completion or summary information required within 21 days

Clinical Criteria for Diagnosis

• Demonstration of G. lamblia cysts in stool, or
• Demonstration of G. lamblia trophozoites in stool, duodenal fluid, or small-bowel biopsy, or
• Demonstration of G. lamblia antigen in stool by a specific immunodiagnostic test (e.g., enzyme-linked immunosorbent assay).

Case Definition

• Probable: a clinically compatible case that is epidemiologically linked to a confirmed case.
• Confirmed: a case that is laboratory confirmed.

1. Identification

A protozoan infection principally of the upper small intestine; while often asymptomatic, it may be associated with a variety of intestinal symptoms, such as chronic diarrhea, steatorrhea, abdominal cramps, bloating, frequent loose and pale greasy stools, fatigue and weight loss. Malabsorption of fats or of fat soluble vitamins may occur. There is usually no extraintestinal invasion, but reactive arthritis may occur and in severe giardiasis, damage to duodenal and jejunal mucosal cells may occur.

Diagnosis is traditionally made by identification of cysts or trophozoites in feces (to rule out the diagnosis at least three negative test results are needed) or of trophozoites in duodenal fluid (by aspiration or string test) or in mucosa obtained by small intestine biopsy; the latter may be more reliable when results of stool examination are questionable but is rarely necessary. Because Giardia infection is usually asymptomatic, the presence of G. lamblia (either in stool or duodenum) does not necessarily indicate that Giardia is the cause of illness. Tests using EIA or direct fluorescent antibody methods for detection of antigen in the stool are commercially available and are generally more sensitive than direct microscopy.

2. Infectious Agent

3. Worldwide Occurrence

4. Reservoir

5. Modes of Transmission

6. Incubation Period

7. Period of Communicability

8. Susceptibility and Resistance

1. Preventive Measures

1. Educate families, personnel and inmates of institutions, and especially adult personnel of day care centers, in personal hygiene and the need for handwashing before handling food, before eating and after toilet use.
2. Filter public water supplies that are exposed to human or animal fecal contamination.
3. Protect public water supplies against contamination with human and animal feces.
4. Dispose of feces in a sanitary manner.
5. Boil emergency water supplies. Less reliable is chemical treatment with hypochlorite or iodine; use 0.1 to 0.2 ml (2 to 4 drops) of household bleach or 0.5 ml of 2% tincture of iodine per liter for 20 minutes (longer if the water is cold or turbid).

2. Control of Patient, Contacts and the Immediate Environment

1. Report to local health authority.
2. Isolation: Enteric precautions.
3. Concurrent disinfection: Of feces and articles soiled therewith. In communities with a modern and adequate sewage disposal system, feces can be discharged directly into sewers without preliminary disinfection. Terminal cleaning.
4. Quarantine: None.
5. Immunization of contacts: None.
6. Investigation of contacts and source of infection: Microscopic examination of feces of household members and other suspected contacts, especially those who are symptomatic.
7. Specific treatment: Metronidazole (Flagyl) or tinidazole (not licensed in the US) is the drug of choice. Quinacrine and albendazole are alternatives; furazolidone is available in pediatric suspension for young children and infants, paromomycin can be used during pregnancy. Drug resistance and relapses may occur with any drug.

3. Epidemic Measures

4. International Measures