ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This study compares AIDS incubation in different geographic areas, calendar time of infection, exposure group and age at exposure. Investigators from North America, Europe and Australia contributed data from 1891 people for whom dates of HIV seroconversion were known. We excluded subjects not enrolled in prospective studies at entry and those with more than 25 months between last negative and first positive sera; we also censored subjects at the time last seen and excluded all follow-up after 1987 in order to minimize the impact of newly developed prophylactic therapies. The final analysis cohort contained 1171 subjects. Using actuarial methods, no differences in incubation times were found among homosexual men infected in different continents or in different years (prior to and after 1 January 1985). Among hemophilic people, children developed AIDS more slowly than adults (P = 0.02), and hemophilic adults developed AIDS more slowly than homosexual men (P < 0.05), mainly because homosexual men had an added risk of Kaposi's sarcoma. Progression time to AIDS was significantly faster in older hemophilic men, but not in older homosexual men. These data illustrate that AIDS incubation may differ in different exposure groups, probably because of different exposures to potential opportunistic pathogens.

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Data on sexual practices, collected during studies of hepatitis B virus (HBV) infection in 1978 and 1979, were analyzed for 4910 homosexual and bisexual men from Chicago, Denver, Los Angeles, San Francisco, and St Louis. Data on sexual practices in 1978 showed that white participants had larger numbers of non-steady male sexual partners and engaged in oral-genital activities more frequently but were equally likely to engage in anal intercourse as black and Hispanic participants. San Francisco participants had more non-steady sex partners and were more likely to engage in receptive anal intercourse with non-steady partners than participants from all other sites. Analysis of data on 606 HBV-antibody-negative men interviewed on three occasions in 1978 and 1979 showed no changes in risk indices for insertive and receptive anal intercourse between these years, except in San Francisco where significant declines occurred in insertive anal intercourse and receptive anal intercourse without ejaculation in a small, highly select group of participants.

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Previous studies have reported that intravenous drug users (IVDUs) have made considerable drug-use risk reduction, but less sexual risk reduction. This paper presents findings about sexual risk reduction by street-recruited IVDUs in New York City, and examines the predictors of sexual risk reduction. Sixty-one per cent of these street-recruited IVDUs have initiated deliberate sexual risk reduction in order to avoid AIDS. For the total sample (n = 568), as well as for the male IVDUs, specific health belief and social influence factors were significant predictors of sexual risk reduction. For female IVDUs, drug-risk reduction, having a friend or acquaintance who practices sexual risk reduction, and wanting to have a(nother) child were significant predictors of sexual risk reduction. These findings suggest the importance of social support and community organization to promote risk reduction.

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A population-based survey was carried out in the Kagera region of the United Republic of Tanzania in 1987 to determine the magnitude of HIV-1 infection and to study associated risk factors. The region was divided into one urban and three rural zones. A multistage cluster sampling technique was adopted. Antibodies to HIV-1 were determined by enzyme-linked immunosorbent assay and confirmed by Western blot analysis. A total of 2475 adults (aged 15–54 years) and 1 961 children (aged 0–14 years) was studied. The overall prevalence of HIV-1 infection among adults was 9.6%, with a higher prevalence in the urban zone (24.2%) than in the three rural zones (10.0, 4.5 and 0.4%, respectively). The corresponding figures for children were 1.3% overall: 3.9% in the urban area and for the rural areas 1.2, 0.8 and 0.0%, respectively. The age-specific seroprevalence for adults was highest in the age group 25–34 years. The age-standardized sex-specific prevalence was higher among women than men in the urban zone, while it was the same in the rural zones. Change of sexual partners among adults was associated with an increased risk of HIV-1 seropositivity. Travelling outside the region but within the country was also found to be associated with increased risk of HIV-1 infection but only in the rural population.

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

We carried out a case-control study to investigate the role of sexually transmitted diseases (STDs), including infection with HIV, as risk factors for adverse outcome of pregnancy. Overall, 1507 women were enrolled within 24 h of delivery. Cases (n = 796) were mothers of low-birthweight infants (< 2500g) or of stillborns. Low-birthweight infants were divided into preterms (n = 373) and neonates small for gestational age (n = 234). Stillborns were separated into intrauterine fetal deaths (n = 120), and intrapartum fetal deaths (n = 69). Controls were selected from mothers delivering a live baby of ≥ 2500 g (n = 711). The maternal HIV seroprevalence in the control group was 3.1%. Prematurity was associated with maternal HIV antibody [8.6% seropositive; adjusted odds ratio (OR) 2.1; 95% confidence interval (CD 1.1–4.0], as was being born small for gestational age (7.7% seropositive; adjusted OR 2.3; 95% Cl 1.2–4.2). In mothers who delivered a stillborn baby, both intrauterine fetal death (11.7% seropositive; adjusted OR 2.7; 95% Cl 1.3–5.5) and intrapartum fetal death (11.6% seropositive; adjusted OR 2.9; 95% Cl 1.3–6.5) were independently associated with HIV seropositivity in the mother. Maternal syphilis was confirmed as an important risk factor for intrauterine fetal death (14.3% positive; adjusted OR 4.8; 95% Cl 2.4–9.5). No significant association was found between other STDs, including gonococcal and chlamydial infection, and adverse obstetrical outcome. These results suggest an association between maternal HIV infection and adverse obstetrical outcome, defined as low birthweight and stillbirth.

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This paper presents a theory to explain the development of immunodeficiency disease after a long and variable incubation period of infection with HIV-1. Two assumptions are central to the theory: (1) mutation via reverse transcription during viral replication can generate viral strains resistant to neutralization by antibodies specific to earlier mutants in a particular host; (2) the virus can kill the CD4-positive lymphocytes that play a role in mounting an immunological attack directed at the virus. The theory is examined via the development of a mathematical model which reveals that an increasing number of antigenically distinct viral strains may overwhelm the immune system of the host. As the viral diversity increases beyond a certain level the immune system is unable to suppress the population growth of all the strains simultaneously. The intuitive explanation of this pattern of model behaviour lies in the assumption that each virus can kill CD4-positive lymphocytes that are specific to any of the viral strains, but each lymphocyte only directs immunological attack against a single viral strain. The model captures several observed features of the interaction between HIV-1 and the human immune system: (1) an early peak in viraemia (primary HIV-1 infection) following infection; (2) a long and variable incubation period with low viral abundance for much of the period; (3) an increase of viral density in the final phase of infection as the failing immune system fails to control viral population growth (the appearance of the disease AIDS); (4) coevolution and coexistence of many viral mutants in one infected person, and (5) a positive correlation between the presence of high replicative viral strains and the rate of progression to disease (AIDS).

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A hospital-based surveillance of HIV infection was implemented in the Bordeaux Regional University Hospital (France). This reporting system, initiated by the Croupe d'Epidámiologie Clinique du SIDA en Aquitaine, identified and followed-up 89 adult patients with transfusion-associated HIV-1 infection (7.2% of all reported cases). Contamination occurred between August 1981 and June 1985 and diagnosis was made between 1985 and 1989. By 30 June 1990, 43 patients (48.3%) had full-blown AIDS, and 28 of them had died. The mean follow-up period was 66 months (s.d. 16 months). The mean incubation period, i.e. The time interval between the contaminating transfusion and the development of full-blown AIDS, was 62 months [median 73 months; 95% confidence interval (CD 66–82 months]. Five years after contamination, the cumulative probability of reaching the AIDS stage was 34.2% (95% Cl 20.3–49.3%), and the probability of survival was 81.7% (95% Cl 72.5–90.0%). From this surveillance system we estimate that in south-western France at the end of 1989 the cumulative incidence of transfusion-associated HIV-1 infection was at least 126 cases (45.6 per million inhabitants). Although we anticipate an increase in transfusion-associated AIDS cases over the next 5 years, there have been no reports of contamination after 1 August 1985, when systematic screening of HIV antibodies was implemented in French blood banks. This confirms the efficacy of screening in countries like France where the risk of contamination through blood products is now minimal.

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Length of survival was analysed in relation to year of diagnosis, AIDS-indicative disease, age, risk behaviour, zidovudine therapy, and CD4 cell count and serum immunoglobulin (Ig) levels at the time of diagnosis in a group of 231 consecutive adult Danish AIDS patients reported before 1 January 1988. The cumulative survival rate was 53% (95% confidence interval 47–59%) at 1 year, 29% (22–36%) at 2 years and 18% (10–26%) at 3 years. Length of survival increased significantly (P < 0.001) over time for patients who were initially diagnosed with Pneumocystis carinii pneumonia (PCP), 17% (3–31%) at 2 years prior to 1986, 32% (16–49%) in 1986 and 52% (34–69%) in 1987, whereas survival remained stable for patients with other AIDS-indicative diseases. Survival was similar for patients who were diagnosed with Kaposi's sarcoma alone and PCP alone. Independent predictors of a shortened survival were a CD4 cell count < 200 ± 106/I, a serum IgA level >4g/I, and an initial diagnosis with opportunistic infections other than PCP. In addition, the multivariate analysis suggested an improved survival in recent years for patients diagnosed with PCP, independent of other factors examined. We conclude that length of survival in AIDS patients is highly variable. Determinants of progression include CD4 cell count, serum IgA level, and presenting disease. Survival has increased markedly for patients with PCP and median survival now exceeds 24 months.

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Statistical modelling is applied to routine AIDS surveillance data to assess recent trends and to provide a range of short-term predictions. Several alternative functions have been fitted to half-yearly incidence data reported by the countries of the European Community by 31 December 1989 and adjusted for reporting delays. Among homosexual/bisexual men, recent trends in AIDS incidence are more nearly linear than exponential. Higher though less than exponential rates of growth are observed among intravenous drug users and among those presumed infected by heterosexual contact. Extrapolations to the end of 1991 using each of five functions provide a range of forecasts. Projections of total cumulated cases to the end of 1991 lie in the range 60000–78000, with 24000–30000 projected cases among homosexual/bisexual men, 23000–33000 among intravenous drug users, and 6000–8000 in the heterosexual transmission group. With the possible exception of the latter group, the lower parts of these ranges appear more probable.

ISSN:0269-9370    

出版商:OVID    

年代:1990

数据来源: OVID