GIARDIASIS

Giardiasis What exactly is Giardiasis?

Giardiasis is a serious diarrheal disease that affects people all over the world.

The causative agent, the flagellate protozoan Giardia intestinalis (previously known as G. lamblia or G. duodenalis), is the most commonly identified intestinal parasite in the United States and the most common protozoal intestinal parasite isolated globally.

Giardiasis is a zoonotic disease that can infect both animals and humans.

G. intestinalis can cause asymptomatic colonization as well as acute or chronic diarrhea.

The organism has been found in up to 80% of raw water supplies from lakes, streams, and ponds, and up to 15% of filtered water samples.

Pathophysiology Giardia intestinalis infection is most commonly caused by fecal-oral transmission or ingestion of contaminated water.

Person-to-person transmission is common, with 25% of family members of infected children becoming infected themselves.

Giardia has one of the simplest life cycles of any human parasite, with two stages: (1) the trophozoite, which exists freely in the human small intestine, and (2) the cyst, which is passed into the environment.

Excystation occurs in the stomach and duodenum in the presence of acid and pancreatic enzymes after ingestion of the cyst (see second image below), which was found in contaminated water or food.

The trophozoites enter the small bowel and multiply rapidly, with a doubling time of 9-12 hours; encystation occurs in the presence of neutral pH and secondary bile salts as the trophozoites enter the large bowel.

Causes Giardia intestinalis, a flagellate protozoan, causes giardiasis (formerly known as G lamblia).

Transmission from person to person. Person-to-person transmission, which is frequently associated with poor hygiene and sanitation, is the most common mode of infection; diaper changing and inadequate hand washing are risk factors for transmission from infected

children; children attending day care centers, as well as day-care workers, are at a higher risk of infection secondary to fecal-oral transmission.

Transmission via water. Water-borne transmission is responsible for a significant number of epidemics in the United States, most of which occur after ingesting unfiltered surface water; Giardia cysts can survive in cold water for up to 2-3 months.

Transmission via the genitalia. Venereal transmission occurs via fecal-oral contamination; food-borne epidemics have been reported, most frequently as a result of contamination by infected food-handlers.

Clinical Significance The following are clinical signs and symptoms of giardiasis: Diarrhea. Diarrhea is the most common symptom of acute Giardia infection, occurring in 90% of symptomatic subjects; histologic sections from asymptomatic infected individuals show marked or moderate partial villous atrophy in the duodenum and jejunum; in addition to disrupting the mucosal epithelium, effects in the intestinal lumen may contribute to malabsorption and diarrhea production.

Weakness, malaise Diarrhea causes malaise or weakness due to electrolyte loss.

Distention of the abdomen. In 70-75 percent of symptomatic patients, abdominal cramping, bloating, and flatulence occur.

Smelly, greasy stools. Stools become stinky, mushy, and greasy.

Weight loss and anorexia. Anorexia, fatigue, malaise, and weight loss are all common; weight loss affects more than half of patients and averages 10 pounds.

Assessment and Diagnostic Results The identification of Giardia intestinalis trophozoites or cysts in the stool of infected patients via a stool ova and parasite (O&P) examination is the traditional basis of diagnosis.

Examine the stool. The traditional method for diagnosing giardiasis is stool examination for trophozoites or cysts; at least three stools taken at 2-day intervals should be examined for ova and parasites; trophozoites can be found in fresh, watery stools but disintegrate quickly.

Antigen detection in feces. There are several commercially available tests to detect Giardia antigen in the stool; these use either an immunofluorescent antibody (IFA) assay or a capture enzyme-linked immunosorbent assay (ELISA) against cyst or trophozoite antigens; these tests have a sensitivity of 85-98 percent and a specificity of 90-100 percent.

Medical Direction Antibiotic therapy is the standard treatment for giardiasis.

Therapy with fluids. Appropriate fluid and electrolyte management is critical, especially in patients who have experienced significant diarrheal losses.

Diet. There is no need for a special diet; however, a significant number of patients have symptoms of lactose intolerance (cramping, bloating, diarrhea), and following a lactose-free diet for several months may be beneficial.

Activity. No restrictions on activity are recommended; however, infected subjects who are at risk of spreading the infection should be isolated and treated.

Pharmacologic Administration Antibiotic therapy is commonly used to treat giardiasis.

Antibiotics. Although most experts recommend metronidazole and tinidazole as the drugs of choice because the short treatment periods encourage good patient adherence, treatment failures occur in up to 20% of cases, most likely due to resistance; thus, treatment with a second-line drug (eg, mepacrine) may be necessary.

Administration of Pharmaceuticals Giardiasis is commonly treated with antibiotics.

Antibiotics. Although most experts recommend metronidazole and tinidazole as first-line drugs because the short treatment periods encourage good patient adherence, treatment failures occur in up to 20% of cases, most likely due to resistance; thus, treatment with a second-line drug (eg, mepacrine) may be required.

Nursing Illness The following are the major nursing diagnoses based on the assessment data:

Diarrhea caused by enteric infections Fluid volume deficit as a result of GI losses Pain caused by smooth muscle spasm impairs one's sense of comfort.

Hyperthermia caused by a decrease in circulation as a result of dehydration.

Nursing Care Planning and Objectives The following are the major nursing care planning objectives for patients with giardiasis:

The client will keep fluid and electrolyte balances in check.

The client's pain will be eliminated or reduced.

The client will have an increased appetite and will gain weight in accordance with his or her age.

The client will maintain normothermia, as evidenced by the absence of hyperthermic signs and symptoms.

Interventions in Nursing Nursing interventions for a giardiasis-infected child include the following:

Reestablish fluid and electrolyte balance. Weigh the patient daily and record the number and consistency of stools per day; use a fecal incontinence collector if desired for accurate measurement of output; monitor and record intake and output; note oliguria and dark, concentrated urine; discuss the importance of fluid replacement during diarrheal episodes.

Reduce any discomfort or pain. Assess the extent and characteristics of pain; apply a warm compress to the abdomen; teach the client and caregivers how to distract from the pain; and establish a pain-relieving position.

Enhance hyperthermia. Provide tepid sponge baths and antipyretics as directed.

Evaluation objectives are met, as evidenced by:

The client was able to reestablish normal fluid and electrolyte balance.

The client's pain was reduced.

The client had an increased appetite and weight for his age.

The client remained normothermic, as evidenced by the absence of hyperthermic signs and symptoms.

Documentation Procedures Documentation in a child with giardiasis includes the following:

Individual findings, such as factors influencing interactions, the nature of social exchanges, and the specifics of individual behavior Beliefs and expectations based on culture and religion Care strategy.

Plan of instruction Responses to interventions, instruction, and actions taken.

Attainment or progress toward achieving a goal.