Giardiasis Nursing Care Management: Study Guide

Giardiasis is the diarrheal illness you will see in the kid who just got back from a camping trip, the daycare toddler with greasy foul stools, or the family where one infected child has passed it around. It is a major diarrheal disease found worldwide.

What is Giardiasis?

The flagellate protozoan Giardia intestinalis (previously known as G. lamblia or G. duodenalis) is the cause. It is the most commonly identified intestinal parasite in the United States and the most common protozoal intestinal parasite isolated worldwide. Giardiasis usually represents a zoonosis with cross-infectivity between animals and humans, and G. intestinalis can cause asymptomatic colonization or acute or chronic diarrheal illness.

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

Pathophysiology

Infection most often results from fecal-oral transmission or ingestion of contaminated water. Person-to-person spread is common, with 25% of family members who have infected children becoming infected themselves.

Giardia has one of the simplest life cycles of all human parasites, made of two stages: the trophozoite, which exists freely in the human small intestine; and the cyst, which is passed into the environment. After a cyst in contaminated water or food is ingested, excystation occurs in the stomach and duodenum in the presence of acid and pancreatic enzymes. The trophozoites pass into the small bowel and multiply rapidly, with a doubling time of 9-12 hours. As they pass into the large bowel, encystation occurs in the presence of neutral pH and secondary bile salts. Cysts are passed into the environment, and the cycle repeats.

Statistics and Incidences

Giardia remains the parasite most commonly identified in stool specimens, causing about 1.2 million annual episodes of illness.

• From 1964-1984, G. lamblia caused at least 90 water-borne outbreaks of diarrhea, affecting more than 23,000 people, typically involving small water systems using untreated or inadequately treated surface water.
• Incidence is high among people who camp and backpack in mountainous Western states.
• Other groups at increased risk include children, homosexual men, and people with immunoglobulin deficiency states (inherited or acquired).
• Yoder et al reported the incidence is greatest in northern states, but this may reflect differences in state surveillance systems rather than a true higher incidence.
• Endemic infection occurs most commonly from July through October among children younger than 5 years and adults aged 25-39 years.
• Carrier rates as high as 30-60% have been documented among children in daycare centers, institutions, and on Native American reservations.
• The asymptomatic carriage rate in children may be as high as 20% in southern regions and in children younger than 36 months who attend daycare centers.
• In the 46 states reporting giardiasis, the mean number of cases per 100,000 population ranges from 0.1-23.5; most cases are reported between June and October, tied to the summer recreational water season and camping.
• Giardia has a worldwide distribution in both temperate and tropical regions. Prevalence rates vary from 4-42%; in the industrialized world, overall prevalence is 2-5%.
• In the developing world, G. intestinalis infects infants early in life and is a major cause of epidemic childhood diarrhea; prevalence rates of 15-20% in children younger than 10 years are common.
• Giardiasis has no race predilection, though Native American populations on reservations can have high carrier rates.
• It is slightly more common in males than females; a Canadian population study showed infection rates of 21.2 per 100,000 per year versus 17.9 per 100,000 per year for males and females, a relative risk of 1.19.
• Per 2003-2005 CDC data, the greatest number of reported cases occurred among children aged 1-4 and 5-9 years and adults aged 35-44 years.

Causes

Giardiasis is caused by the flagellate protozoan Giardia intestinalis (formerly G. lamblia).

• Person-to-person transmission. Often tied to poor hygiene and sanitation, this is a primary route. Diaper changing and inadequate handwashing are risk factors for spread from infected children. Children attending daycare centers, and daycare workers, carry a higher risk from fecal-oral transmission.
• Water-borne transmission. Responsible for a significant number of US epidemics, generally after ingestion of unfiltered surface water. Giardia cysts stay viable in cold water for as long as 2-3 months.
• Venereal transmission. Occurs through fecal-oral contamination. Food-borne epidemics have been reported, most commonly from contamination by infected food handlers.

Clinical Manifestations

• Diarrhea. The most common symptom of acute infection, occurring in 90% of symptomatic patients. Marked or moderate partial villous atrophy in the duodenum and jejunum can appear even in asymptomatic infected people. Beyond disrupting the mucosal epithelium, luminal effects contribute to malabsorption and diarrhea.
• Malaise, weakness. From loss of electrolytes with diarrhea.
• Abdominal distention. Cramping, bloating, and flatulence occur in 70-75% of symptomatic patients.
• Malodorous, greasy stools. Stools become malodorous, mushy, and greasy.
• Anorexia and weight loss. Anorexia, fatigue, malaise, and weight loss are common. Weight loss occurs in more than 50% of patients and averages 10 pounds.

Assessment and Diagnostic Findings

Diagnosis traditionally rests on identifying Giardia intestinalis trophozoites or cysts in stool via a stool ova and parasite (O&P) examination.

• Stool examination. The traditional method. At least 3 stools taken at 2-day intervals should be examined for ova and parasites. Trophozoites may be found in fresh, watery stools but disintegrate rapidly.
• Stool antigen detection. Several commercial tests detect Giardia antigen in stool using either an immunofluorescent antibody (IFA) assay or a capture enzyme-linked immunosorbent assay (ELISA) against cyst or trophozoite antigens. Sensitivity is 85-98% and specificity is 90-100%.
• String test. The string test (Entero-test) is a gelatin capsule containing a weighted nylon string. The patient tapes one end to the cheek and swallows the capsule. After the gelatin dissolves in the stomach, the weight carries the string into the duodenum. Mucus from the string is examined for trophozoites in an iodine or saline wet mount, or after fixation and staining.

Medical Management

Standard treatment is antibiotic therapy.

• Fluid therapy. Fluid and electrolyte management is critical, especially with large-volume diarrheal losses.
• Diet. No special diet is required. Many patients have lactose intolerance symptoms (cramping, bloating, diarrhea), and a lactose-free diet for several months may help.
• Activity. No activity restrictions are indicated. However, infected people at risk of spreading the infection should be isolated and treated.

Pharmacologic Management

The two major drug classes with proven benefit are nitroimidazole derivatives and acridine dyes. Most experts recommend metronidazole and tinidazole as drugs of choice because the brief treatment periods encourage adherence. Treatment failures occur in as many as 20% of cases, probably from resistance, so a second-line drug (eg, mepacrine) may be necessary.

Nursing Management

Nursing Assessment

• History. Overall clinical presentation is shaped by parasite load, virulence of the isolate, and the host immune response.
• Physical exam. Physical examination does not contribute to diagnosis. Weight loss may be evident, but there are no unique physical findings attributable to giardiasis.

Nursing Diagnosis

• Diarrhea related to enteric infections.
• Fluid volume deficit related to GI losses.
• Impaired sense of comfort: pain related to smooth muscle spasm.
• Hyperthermia related to decreased circulation secondary to dehydration.

Nursing Care Planning and Goals

• Client maintains fluid and electrolyte balance.
• Client's pain is lost or diminished.
• Client shows increased appetite and weight appropriate for age.
• Client maintains normothermia, shown by absence of signs and symptoms of hyperthermia.

Nursing Interventions

• Restore fluid and electrolyte balance. Weigh the patient daily and note any decrease. Record number and consistency of stools per day; use a fecal incontinence collector for accurate output if needed. Monitor and record intake and output, noting oliguria and dark, concentrated urine. Stress the importance of fluid replacement during diarrheal episodes.
• Reduce pain or discomfort. Assess the extent and characteristics of pain. Apply a warm compress to the abdomen, teach distraction methods, and position the child to reduce pain.
• Improve hyperthermia. Provide tepid sponge baths and give antipyretics as prescribed.

Evaluation

• Client restored normal fluid and electrolyte balance.
• Client's pain was diminished.
• Client showed increased appetite and weight appropriate for age.
• Client maintained normothermia, shown by absence of signs and symptoms of hyperthermia.

Documentation Guidelines

• Individual findings, including contributing factors, interactions, nature of social exchanges, and specifics of individual behavior.
• Cultural and religious beliefs and expectations.
• Plan of care.
• Teaching plan.
• Responses to interventions, teaching, and actions performed.
• Attainment or progress toward the desired outcome.