A 6-year-old male came to clinic with 5 days of diarrhea. They were loose watery stools occurring several times a day without blood or mucous. He denied abdominal pain or emesis but said sometimes he felt a little nauseous. He had recently been on vacation in the northern United States to visit his grandparents who lived on a farm with various animals and crops. He also had been swimming in 2 different lakes and had been to a family reunion potlock dinner during the past 2 weeks. He was drinking well and was urinating normally. The family wasn’t sure but maybe a cousin also had diarrhea. He had no recent antibiotic exposure. He was previously healthy and his review of systems revealed he had no fever, chills, or muscle aches.
The pertinent physical exam showed a well-appearing male in no distress. His vital signs were normal and his growth parameters were 25-50% for age. His mucous membranes were moist and he had good skin turgor. His abdominal examination showed slightly hyperactive bowel sounds. He had no abdominal tenderness, hepatosplenomegaly or masses. Genitourinary examination was normal as was his anus.
The diagnosis of diarrhea with significant exposure to potential infectious disease pathogens was made. As the patient was well hydrated, the family was counseled about prolonged diarrhea and recommendations for fluid intake and diet. A laboratory evaluation of stool studies for common bacterial pathogens along with stool for ova and parasites, Giardia and Clostridium difficile was made. The stool was positive for giardia and he was treated with Flagyl®. The diarrhea improved and repeated cultures were negative. The cousin had diarrhea but his resolved and he was not tested.
People often don’t think that developed countries have parasitic diseases but this is not true. The major parasitic infections endemic in the United States can be thought of as:
- Intestinal parasitic infections
- Seen throughout the US but especially in the northern states during the summer
- Often occur through recreational water use
- Cryptosprodiosis, Dientamoebiasis and Giardiasis are the most common.
- Neglected tropical diseases
- Seen especially in the southern states (especially Texas) and are linked to extreme poverty
- Chagas disease, Cutaneous Leishmaniasis, Toxocariasis, and Toxoplasmosis are the most common.
Giardia intestinalis (also known as Giardia lambia or Giardia duodenalis) is considered a zoonotic disease sometimes known as Beaver Fever. It was one of the first organisms Antonie van Leewenhoek saw under the microscope. It is a flagllated protozoan found globally that usually affects the cells in the duodenum and jejunum. It is most commonly found in children ages 1-9 years old. The number of cases is slightly decreasing in last few years in the U.S. with about 16-19,000 cases depending on the year. Cases cluster often in the northern states in the summer. Contaminated water and fecal-oral contamination of the cysts spread the disease. The cysts are difficult to kill as they are chlorine tolerant. Cysts can be killed by boiling water for more than 1 minute, or using a filter with an absolute pore size of 1 micron or smaller to remove the cysts. Incubation is 9-15 days.
The disease can be asymptomatic, have mild to severe diarrhea. Other symptoms can include anorexia, bloating, abdominal pain and cramping and explosive diarrhea. Unfortunately about 50% of patients may not clear the organisms and have chronic disease which may include anorexia, malabsorption, diarrhea and weight loss which can last years. Giardia should be considered when diarrhea lasts more than 3 days in the appropriate setting. Routine ova and parasite tests may not test for Giardia so specific testing should be ordered. Testing is by direct fluorescent antibody testing of the stool. Giardia is not continually shed and therefore 3 negative stool tests from different days are considered the standard for a negative test. Treatment is usually with nitroimidazole compounds such as metronidazole (Flagyl®), ornidazole, secnidazole or tinidazole. Other treatments are available to try if there is initial treatment failure.
Questions for Further Discussion
1. For what indications do you consider testing for stool pathogens?
2. When do you consider testing for Clostridium difficile?
3. What is in the differential diagnosis of diarrhea? Click here
- Symptom/Presentation: Diarrhea
- Age: School Ager
To Learn More
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Muhsen K, Levine MM. A systematic review and meta-analysis of the association between Giardia lamblia and endemic pediatric diarrhea in developing countries. Clin Infect Dis. 2012 Dec;55 Suppl 4:S271-93.
Barry MA, Weatherhead JE, Hotez PJ, Woc-Colburn L. Childhood parasitic infections endemic to the United States. Pediatr Clin North Am. 2013 Apr;60(2):471-85.
Painter JE, Gargano JW, Collier SA, Yoder JS; Centers for Disease Control and Prevention. Giardiasis surveillance — United States, 2011-2012. MMWR Suppl. 2015 May 1;64(3):15-25.
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital