Clinical and Interpretive

This assay is used in the investigation of patients with diarrhea, particularly infants, the elderly, and immunocompromised patients and in the investigation of nosocomial diarrhea.

Rotavirus infection produces a spectrum of responses that vary from subclinical infection, to mild diarrhea, to a severe and occasionally fatal dehydrating illness.

Rotavirus is the major cause of nonbacterial gastroenteritis, especially in infants and very young children (6 months-2 years of age). Among children hospitalized for gastroenteritis, up to 50% of the patient specimens will give positive rotavirus test results. The shedding of rotavirus in feces is fairly common among asymptomatic neonates. Endemic rotaviral infection is more likely to be symptomatic in babies who require special care than in healthy, full-term infants.

Rotaviruses pose a special threat to individuals who are immunosuppressed for bone marrow transplantation and to elderly persons, especially those living in nursing homes or other confined quarters. In other adults, rotavirus infections usually are subclinical.

In temperate climates, rotaviral infections are seasonal; they peak in frequency during the winter months and are uncommon during the summer. Rotaviral gastroenteritis has sometimes been called “winter vomiting disease.” The disease is characterized by diarrhea of acute onset and a duration of 4 to 8 days. Vomiting is often the initial symptom. Some patients experience vomiting without diarrhea. Dehydration is the most common reason for hospitalization of patients infected with rotavirus.

Nosocomial transmission of rotavirus is often a costly and difficult problem to resolve; therefore, the rapid and accurate detection of rotavirus antigens may lead to better management of hospitalized 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.

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.

This assay does not preclude the presence of other pathogenic organisms. While the relationship between rotavirus and gastroenteritis is well established, coinfection with bacterial pathogens is possible.

Bacterial testing should be performed in parallel with the rotavirus antigen test to rule out bacterial etiology of the illness.

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%.