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Investigation of patients with diarrhea, particularly infants, the elderly, and immunocompromised patients
Investigation of nosocomial diarrhea
See Parasitic Investigation of Stool Specimens Algorithm in Special Instructions for other tests that may be useful in the evaluation of a patient with diarrhea.
Rotavirus is a major cause of nonbacterial gastroenteritis, especially in infants and very young children (6 months-2 years of age). Infection may be entirely asymptomatic or produce a spectrum of disease ranging from mild gastroenteritis to severe diarrhea and vomiting with dehydration. Infection usually begins acutely and lasts for 4 to 8 days. In temperate climates, rotaviral infections are seasonal; they peak in frequency during the winter months and are uncommon during the summer. Rotaviral gastroenteritis is, therefore, sometimes called "winter vomiting disease."
Infection is more likely to be symptomatic in preterm infants, immunosuppressed patients and elderly individuals, especially those living in nursing homes or other confined quarters. In other children and adults, rotavirus infections are usually subclinical and may be associated with asymptomatic shedding of rotavirus in the feces.
Rapid and accurate detection of rotavirus antigens in stool specimens may lead to better patient management, particularly in hospitalized or institutionalized patients.
Peak viral counts are reported to occur on days 3 to 5 after onset of symptoms. The virus is eliminated from the infected individual within a few days following acute infection. Specimens collected 8 days or more after onset of symptoms may not contain enough rotavirus antigen to produce a positive reaction.
A prolonged carrier state has been recognized with rotavirus infection.
The rate of positive test results may vary due to age, weather, seasonal factors, geographic location, and the general health environment for the group under study.
See Parasitic Investigation of Stool Specimens Algorithm in Special Instructions for other diagnostic tests that may be of value in evaluating patients with diarrhea.
Stool specimens should be collected as soon after onset of symptoms as possible.
Do not collect specimens in containers having media, preservatives, animal serum, or detergent as any of these may interfere with the assay.
A positive result does not preclude the presence of other pathogenic organisms. While the relationship between rotavirus and gastroenteritis is well established, coinfection with bacterial or parasitic pathogens is possible. If suspected, testing for other enteric pathogens should be performed in parallel with the rotavirus antigen test.
Results of the rotavirus antigen assay must be interpreted with caution. A negative result does not exclude the possibility of rotavirus infection, as too small a quantity of virus or inadequate or improper sampling may cause a false-negative result.
This EIA antigen detection method has 100% sensitivity and 92% specificity when compared to transmission electron microscopy (EM), the method initially used to detect virus in fecal and intestinal biopsy specimens and the standard to which rotavirus diagnostic tests are compared. When compared to EM and RNA analysis, in combination, the specificity increases to 97%.
Mitchell DK, Jiang X, Matson DO: Gastrointestinal infections. In Essentials of Diagnostic Virology. Edited by GA Storch, Churchill Livingstone. 2000 pp 82-84