HIV antibody testing: Genito-Urinary Clinic or additional site same-day testing service.

It has been suggested that different groups of individuals, possibly those at greater risk, may choose to attend anonymous HIV services not attached to Genito-Urinary Medicine Clinics. This paper reports the results of a comparative study of documented sociodemographic profile and risk category for individuals having HIV antibody tests at a Genito-Urinary Medicine Clinic and at an additional site same-day HIV antibody testing service not attached to a Genito-Urinary Medicine Clinic but within the same hospital. A retrospective case record analysis for 12 months from 1.10.93 to 30.9.94 was performed. During the 12-month study period 954 people had HIV testing at the additional site HIV antibody testing service and 803 had HIV antibody testing at the Genito-Urinary Medicine Clinic. Of those attending the additional site testing service 218 (22.9%) were homosexual/bisexual males as compared with 128 (15.9%) of the Genito-Urinary Medicine Clinic attendees (p < 0.01). A total of 22 (2.3%) of the individuals attending the additional site service gave a history of sexual contact in Africa as compared with 52 (65%) attending the Genito-Urinary Medicine Clinic (p < 0.001). There was no significant difference in the gender or age of those having HIV antibody tests at the two locations (p = 0.82 and p = 0.39 respectively). Four hundred and seventeen (52%) of the tests performed at the Genito-Urinary Medicine Clinic were performed on those who had not already decided to have a test before attending the clinic. Of those individuals who had decided to have a test before attending, 2.5 times as many attended the Same-Day Service as attended the Genito-Urinary Medicine Clinic (954 additional site attenders compared with 384 Genito-Urinary Medicine Clinic attenders). The results suggest that to optimize patient choice and benefit from a HIV antibody testing service this should be available at both Genito-Urinary Medicine Clinics and at additional site testing services.

Screening tests for antibodies to cytomegalovirus: an evaluation of five commercial products.

Four hundred and ninety two samples of serum from blood donors were screened for the presence of antibodies specific to cytomegalovirus using radioimmunoassay, a modified complement fixation test, and five commercially available tests: the Cetus CMV IHA, Abbott CMV total AB EIA, Cytomegalisa Stat EIA, Enzygnost EIA, and Virenz G-CMV EIA. A wide variation in results was found, with only 53.5% of the sera giving total concordance by all methods. Rates of seropositivity in the different tests ranged from 34.9% to 59.3%, with sensitivities ranging from 75.2% to 99.1% compared with the radioimmunoassay. Of 211 sera which gave positive results with four or more of the tests, none was negative by the radioimmunoassay and Abbott EIA, three were negative in Cetus IHA and Enzygnost EIA, and 11 were negative in the modified complement fixation test. Virenz G and Cytomegalisa Stat EIAs, however, gave 40 (19%) and 49 (23.2%), respectively, as negative. The results confirmed the reliability of the radioimmunoassay for the detection of the antibody status to CMV, but this test is too elaborate for a screening procedure. The Abbott EIA and Cetus IHA were found to be the most suitable for this purpose in spite of high false positive rates.

Improving the varicella-zoster virus: IgG radioimmunoassay procedure by the use of purified antigen.

The indirect radioimmunoassay (RIA) for detecting and assaying IgG class antibodies against varicella-zoster virus (VZV) can be improved by simple purification of the viral antigen. This is achieved by reducing binding to cellular components present in crude antigens. The purified antigen is particularly useful for testing sera that either bind excessively to normal control antigen or give equivocal results when crude antigens are used.

Hotting-up the complement-fixation test.

A detailed investigation into the effect of modifying the incubation temperature of the complement-fixation (CF) test is described. For varicella-zoster virus cytomegalovirus and rubella virus, increasing the incubation temperature progressively increased the sensitivity of the CF test to reach a maximum at 15 degrees C, at which temperature the geometric mean titre of seropositive samples was significantly greater than that found at 4 degrees C. For these three viruses, each serum shown to contain IgG antibodies by ultrasensitive radioimmunoassay procedures was detected by CF following incubation at 15 degrees C. No false-positive reactions occurred at 15 degrees C, but it was our impression that anticomplementary activity was enhanced at this temperature. Significant increases in antibody titre at 15 degrees C were also seen when measles virus, respiratory syncytial virus, adenovirus and Mycoplasma pneumoniae were employed as CF antigens. The results demonstrate that the CF test should be performed at 15 degrees C if optimum sensitivity is to be achieved. The ability of the test to detect significant rises in antibody titre was not impaired at the higher incubation temperature.

A prospective study of influenza infections during pregnancy.

Serological evidence of infection with influenza A and B viruses was sought during three successive winters. Paired sera from 1595 pregnant women were studied and 79 infections occurred in 77 women (4.8%). A further 77 women who had no serological evidence of recent influenza infection were selected from the study population to serve as a control group. Cases and controls were comparable with respect to age, race, marital status, and number of previous pregnancies. Their offspring had virtually identical mean birth weights, skull circumferences, lengths, and incidences of neonatal jaundice. Although all the infections occurred in either the second or the third trimesters of pregnancy, the cases delivered more babies with congenital abnormalities than did the controls. The possibility was considered that the presence of an abnormal fetus made these women more susceptible to influenza infection. Unexpectedly, the women experiencing influenza infection during pregnancy delivered an excess of male babies, and an excess of females was born to the controls. Although this difference was statistically highly significant (P < 0.01), a biological explanation for the results was not readily apparent and it is suggested that future studies of influenza during pregnancy should particularly look for evidence of an altered sex ratio.