Rotavirus gastroenteritis in southern California.

The epidemiology of rotavirus infections in Southern California was analyzed over a three year period, from January 1, 1981 through December 31, 1983. Data was available from patients seen at the University of California Irvine Medical Center (UCIMC), in addition to referral testing provided to the community in Orange County. Over the 3 yr period the laboratory performed 1172 rotavirus assays. Out of these, 345 were positive for an overall positive rate of 29.4%. The 643 stool specimens from UCIMC corresponded to 508 patients, of which 31.1% (158/508) were positive for rotavirus. The majority of patients with a positive rotavirus test were under 1 yr of age (117/158), with only ten cases found in the 2-15 yr old group. The distribution of the positive rotavirus tests was similar for the female and male population. Approximately 70% of the positive results occur during October through December, with the month of November having the highest incidence. The distribution of positive rotavirus tests did not appear to correlate with either the coldest or the driest month of the year in Southern California.

Determination of immune status in patients with low antibody titers for rubella virus.

Three assays for detection of rubella antibodies, Rubella G (fluorescence immunoassay [FIA]), Rubacell (passive hemagglutination), and Rubaquick (passive hemagglutination with rotation), were compared with hemagglutination inhibition. A total of 100 serum specimens were selected, 68 of which had an FIA value of less than or equal to 25. On initial testing, among the four tests, there was agreement for 88 specimens for assignment of rubella immune status. On repeat testing, all the results agreed by the hemagglutination inhibition, passive hemagglutination, and passive hemagglutination rotation methods, and only one discrepant specimen remained by FIA.

Evaluation of five cell types for the isolation of herpes simplex virus.

Five cells were evaluated in a comparative analysis for sensitivity, specificity, and rapidity in detecting the presence of herpes simplex virus HSV-1 and HSV-2. Included in this study were human embryonic kidney (HEK), rabbit kidney (RK), MRC-5, mink lung (ML), and Microtus agrestis (UMMA). A total of 274 specimens from genital, throat, skin, or other sources that were submitted for HSV isolation were used in the study. The sensitivity of the different cells was assessed by the total number of positive cultures detected by all the cells under evaluation. At 48 hr, HEK and RK detected 80% of the positives, ML detected 79%, MRC-5 detected 73%, and UMMA detected 60%. All cells tested were satisfactory; however, the choice of which cell to use for isolation of HSV depends upon the needs of the specific laboratory.

Comparison of cultureset to a conventional tissue culture-fluorescent-antibody technique for isolation and identification of herpes simplex virus.

The isolation and identification of herpes simplex virus types 1 and 2 from clinical specimens with a 48-h system was compared with a conventional tissue culture detection method.

Fluorescence immunoassay and passive latex agglutination as alternatives to hemagglutination inhibition for determining rubella immune status.

Three different assays for detection of rubella antibodies, hemagglutination inhibition (HAI), fluorescence immunoassay (FIA), and passive latex agglutination (PLA) were used to test 297 human serum samples. Overall agreements for immune status were as follows: HAI versus FIA, 95.3% (283 of 297); HAI versus PLA (1:10 dilution), 96.3% (286 of 297); HAI versus PLA (undiluted), 93.9% (279 of 297); PLA (1:10 dilution) versus FIA, 94.9% (282 of 297); and PLA (undiluted) versus FIA, 97.9% (291 of 297). The HAI test is the most time consuming, subjective, and technically difficult to perform. The FIA and PLA tests are very rapid and less labor intensive. In addition, the FIA offers an objective determination of the patient's rubella antibody level.