Partner notification as a tool for research in HIV epidemiology: behaviour change, transmission risk and incidence trends.

OBJECTIVE: To assess whether routinely collected data from partner notification for HIV infection could be used to study HIV epidemiology. The issues addressed were measures of contact patterns and behaviour change, variables influencing transmission risks, and indications of HIV incidence. DESIGN: We collected anonymous questionnaire data from all partner notifications performed from seropositive patients diagnosed in Sweden between 1 January 1989 and 30 June 1990. METHOD: A structured questionnaire was completed by the physician or counsellor interviewing newly diagnosed seropositive patients and counselling their reported partners. The questions focused on temporal and behavioural aspects of all contacts between index patients and partners. RESULTS: Questionnaires were completed for 365 of the 403 (91%) index patients diagnosed during the study period, for 350 of the 390 (90%) located partners, and for 274 of the 297 (92%) relationships where results of HIV testing were known for index patient and partner. Seropositive individuals diagnosed in 1989 or later reported less risk behaviour than those diagnosed earlier. Risk of transmission in sexual contact increased when the infectious partner developed symptoms of HIV infection. Anal intercourse was found to be approximately twice as infectious as vaginal, and transmission risk from a seropositive insertive partner approximately twice as high as from a receptive. The total HIV incidence in Sweden appears to be declining, as does the number of newly diagnosed infected homosexual men. CONCLUSION: Carefully collected data acquired from a partner notification programme are well suited to describe and follow the epidemiology of HIV infection.

Partner notification in context: Swedish and Zambian experiences.

Partner notification is a public health strategy in which sexual partners of persons with a sexually transmitted disease (STD) are notified, counselled and offered services. According to recommendations published by the World Health Organization, partner notification should be voluntary, confidential and only undertaken when appropriate services are available. This paper communicates experiences from studies on partner notification in Sweden and Zambia and emphasizes the need for a contextualized approach to partner notification. In Sweden as well as in Zambia partner notification is an acknowledged strategy to prevent STDs. Methods must, however, be adjusted to the practical and cultural context in each country.

A survey of patients with Chlamydia trachomatis infection: sexual behaviour and perceptions about contact tracing.

The aim of this study was to evaluate how patients with Chlamydia trachomatis infection perceived the legal enforcement of partner notification and to seek their views on legislation impinging on their own sexual behaviour. The investigation was performed at STD clinics in Stockholm, Sweden in 1997. Consecutive patients (n=192) answered a questionnaire about sexual behaviour and contact tracing. More men (40%) than women (21%) had had sexual intercourse during the past 6 months with an occasional partner. The mean number (6 months prior to this) was 2.3 partners (1-15) for men and 2.2 partners (1-21) for women. Eighteen per cent admitted to having avoided disclosing the name of their partner(s). Ninety per cent considered it beneficial that chlamydial infection was regulated and that a named partner could be forced to undergo STD testing. Partly based on this report, the government has recommended police enforcement to be removed from the legislation as a tool for contact tracing in chlamydial infections.

Contact tracing in the control of genital Chlamydia trachomatis infection.

Four different types of contact tracing for partners of Chlamydia trachomatis infected patients were compared with respect to reinfections during two 15-month periods in 1979/80 and in 1983/84. Between the two study periods a gradual improvement in contact tracing occurred. No reduction in overall reinfections was observed in the second period, reinfections occurring within 12 weeks were similar in the two periods. Treatment of the regular partner (by giving the woman a prescription for her partner) without examination or further partner follow-up resulted in few reinfections. A system of partner referral without verification that partners actually appeared for examination resulted in significantly more reinfections by the regular partner than a system with non-mandatory verification: 60 of 997 women (6%) compared with 6 of 645 (1%). The addition of C. trachomatis infection to the existing STD legislation resulted in fewer identified partners refusing examination than previously, one of 254 men (0.4%) compared with 40 of 223 (18%) before legal inclusion.

Choice of sexual partner according to rate of partner change and social class of the partners.

Models for the spread of sexually transmitted diseases, including AIDS, rely on sexual partner mixing patterns in the population. From data acquired through partner notification for infection with Chlamydia trachomatis among young people in Gothenburg, Sweden, it was possible to construct contact matrices for the variables 'rate of partner change' and 'social class' of the partners in pair formations. These matrices show a restricted mixing between these two variables for young heterosexual women. Therefore random mixing models will probably overestimate rate of spread and possibly final size of an epidemic of a sexually transmitted disease.

Risk factors for Chlamydia trachomatis infection in 6810 young women attending family planning clinics.

Screening programmes are important for the control of Chlamydia trachomatis (Ct) infection, a disease spread mainly by asymptomatic carriers. Risk factors for Ct infection were assessed in 6810 consecutive asymptomatic young women seeking contraceptive advice. All women filled in a questionnaire and were offered Ct testing. Of the 5785 who consented to testing, 425 (7.3%) were Ct culture positive. Four variables were significantly related to increased risk of being infected: age 18-23 years, duration of present relationship less than 1 year, non-use of condoms, and a history of not having had a previous genital infection. It is not possible to devise screening criteria that would effectively identify women at high risk. Therefore a screening programme should be targeted at all sexually active young people. However, if after some years the programme succeeds in lowering general Ct prevalence, these factors may be important when selecting patients for Ct testing.

PIP: Screening programs are important for the control of Chlamydia trachomatis (CT) infection, a disease spread mainly by asymptomatic carriers. Risk factors for CT infection were assessed in 6810 consecutive asymptomatic young women seeking contraceptive advice. All women filled in a questionnaire and were offered CT testing. Of the 5785 who consented to testing, 425 (7.3%) were CT culture positive. 4 variables were significantly related to increased risk of being infected; ages 18-23 years, duration of present relationship 1 year, nonuse of condoms, and a history of not having had a previous genital infection. It is not possible to devise screening criteria that would effectively identify women at high risk. Therefore, a screening program should target all sexually active young people. However, if after some years the program succeeds in lowering general CT prevalence, these factors may be important when selecting patients for CT testing.

Estimation of a preference matrix for women's choice of male sexual partner according to rate of partner change, using partner notification data.

Data from a study of partner notification for venereal chlamydial infection are used to estimate the contact preference matrix, according to sexual contact activity levels of the male partners, of young heterosexual women. A method for correcting data for the bias introduced by studying infected women only is presented. Results indicate that an overall proportional mixing model is not an adequate description of the mixing pattern.

An epidemiological approach to sexually transmitted diseases--with special reference to contact tracing and screening.

Sexually Transmitted Diseases (STD) are a major health problem all over the world. The diseases are often spread by unsuspecting asymptomatic individuals. One important means of controlling STD is thus the identification of asymptomatic persons. The purposes of this thesis were a) to describe methods of identifying infected individuals through contact tracing and screening, b) to evaluate contact tracing routines, c) to compare epidemiological characteristics of two different groups of chlamydia-infected women and their partners and d) to see if data from contact tracing could be used in a model describing partner choice and STD spread. A microepidemic of penicillinase-producing gonococci was effectively controlled through contact tracing by cooperating counsellors. Serotyping of gonococci and graphic description proved of great help in mapping the contact chain. Contact tracing integrated in the psychosocial long-term care of HIV-infected patients resulted in identification of a great number of previously unidentified individuals. Screening for Chlamydia trachomatis (Ct) among asymptomatic patients of family planning clinics revealed a 7.3% Ct prevalence. Four factors were significantly correlated to the risk of being infected: age 18-23, duration of present relationship less than 1 year, failure to use condoms and no previous history of genital infection. Abstention from testing was especially high in areas with low socio-economic status. In these areas, increased resources for health care are needed. Five different levels of management of Ct infections were compared. Increased measures to verify that reported partners were examined decreased reinfections and after Ct was included in the STD Act more reported partners than before came for examination. Index patients found by chlamydia screening and their partners have a lower average number of recent partners than index patients visiting an STD clinic and their partners. Partners of female patients in the STD clinic group were also more often Ct-positive. The differences between the groups are small and do not justify different ambitions in partner management. Choice of steady partner was rather restricted and choice of casual partner followed a more random pattern. Our data thus do not support a pure random mixing model for STD spread.

Screening for human T cell leukaemia/lymphoma virus among blood donors in Sweden: cost effectiveness analysis.

OBJECTIVE: To analyse the cost effectiveness of a national programme to screen blood donors for infection with the human T cell leukaemia/lymphoma virus. DESIGN: Three models for calculating the costs and benefits of screening were developed. The first model analysed the cost of continuously testing all donations; the second analysed the cost of initially testing new blood donors and then retesting them after five years; the third analysed the cost of testing donors only at the time of their first donation. Patients who had received blood components from donors confirmed to be infected with the virus were offered testing. SETTING: Sweden. MAIN OUTCOME MEASURES: Prevalence of infection with the virus among blood donors, the risk of transmission of the virus, screening costs, and the outcome of infection. RESULTS: 648 497 donations were tested for the virus; 1625 samples tested positive by enzyme linked immunosorbent assay. 6 were confirmed positive by western blotting. The prevalence of infection with the virus was 2/100 000 donors. 35 patients who had received blood infected with the virus were tested; 3 were positive. The cost of testing every donation was calculated to be $3.02m (1.88m pounds); this is 18 times higher than the cost of testing new donors only, and only 1 additional positive donor would be discovered in 7 years. Regardless of the model used, screening was estimated to prevent only 1 death every 200 years at a minimum cost of $36m (22.5m pounds). CONCLUSION: Based on these estimates the Swedish National Board of Health and Welfare decided that only new blood donors would be screened for infection with the virus.

[A questionnaire study in the county of Stockholm on transmission control of chlamydia infections. Too many physicians neglect the contact tracing]. / Enkätstudie i Stockholms län över smittskyddsåtgärder vid klamydiainfektion. Alltför många läkare försummar smittspårning.

Since 1989 the reporting of chlamydia infections is regulated by the Contagious Diseases Act, which stipulates that a physician who detects chlamydia is obliged to trace the patient's sexual partner(s). Up to 1994 the annual decrease in the number of chlamydia cases was 20 percent, which did not meet the goal stipulated by the County Council. A questionnaire study was carried out concerning diagnosis, treatment and public health intervention in chlamydia patients seen by general and private practitioners. While the clinical management was seen to adhere to the recommendations of the National Board of Health, adequate tracing of sexual contacts was not carried out in 20-45 per cent of the cases. In a major urban area, such as the County of Stockholm, referral of all chlamydia cases to specialist clinics could possibly improve not only the care of the patients but also the success rate in reaching their sex partners.

Epidemiologic characteristics of two different populations of women with Chlamydia trachomatis infection and their male partners.

Two groups of women under the age of 26 with chlamydial infection (A-asymptomatic women from a screening program, B-traditional STD clinic patients) and their partners were compared with respect to history of STD, sexual behavior, contraception, and indices for income and social welfare expense. The mean number of partners was 1.3 in group A and 1.8 in group B. Women in group B, in spite of more frequent condom use, demonstrated greater risk behavior both with respect to STD and to unwanted pregnancy and also had higher indices for social welfare expense. More group A partners than group B partners were asymptomatic and chlamydia negative. Group B partners also more often had low income as well as high social welfare expense indices. In both groups, complicated chains of transmission were found, and the need for expert contact tracing in both types of patient groups is stressed.

The risk of transmission of genital Chlamydia trachomatis infection is less than that of genital Neisseria gonorrhoeae infection.

A total of 211 men with 237 female sexual partners and a total of 155 women with 156 male consorts were examined for genital infection with Chlamydia trachomatis and Neisseria gonorrhoeae. The index patients had either single chlamydial or gonococcal infections or dual infections with both microorganisms. Analysis of recovery rates for groups of sexual consorts indicated that gonorrhea was contracted more frequently than chlamydial infection. Thus, when index patients had dual infections, 45% and 28% of their female and male consorts, respectively, had chlamydial infection, but 64% and 77%, respectively, had gonorrhea. When index patients had single infections with C. trachomatis or N. gonorrhoeae, chlamydial infections were observed in consorts of 45% (women) and 28% (men), but gonococcal infections were observed in 80% (women) and 81% (men). Moreover, a significantly larger proportion of consorts of patients with chlamydial infection eluded infection than did partners of patients with gonorrhea. Women who used an intrauterine contraceptive device had chlamydial and gonococcal infections more often than those who used other forms of contraception, or no contraceptive.

PIP: A total of 211 men with 237 female sexual partners and a total of 155 women with 156 male consorts were examined for genital infection with Chlamydia trachomatis and Neisseria gonorrhoeae. The index patients had either single chlamydial or gonococcal infections or dual infections with both microorganisms. Analysis of recovery rates for groups of sexual consorts indicated that gonorrhea was contracted more frequently than chlamydial infection. Thus, when index patients had dual infections, 45% and 28% of their female and male consorts, respectively, had chlamydial infection, but 64% and 77%, respectively, had gonorrhea. When index patients had single infections with C. trachomatis or N. gonorrhoeae, chlamydial infections were observed in consorts of 45% (women) and 28% (men), but gonococcal infections were observed in 80% (women) and 81% (men). Moreover, a significantly larger proportion of consorts of patients with chlamydial infection eluded infection than did partners of patients with gonorrhea. Women who used an IUD had chlamydial and gonococcal infections more often than those who used other forms of contraception or no contraception at all.

Efficacy of partner notification for HIV infection.

Since 1985, partner notification has been part of Swedish policy to prevent the spread of human immunodeficiency virus (HIV) infection. Potentially infected partners of a newly diagnosed seropositive patient are notified either by the index patient or by the physician and referred for counselling. The efficacy of this strategy was assessed over 18 months in 1989-90. 365 HIV-seropositive index patients (91% of the 403 patients diagnosed in Sweden during the study period) reported 564 sexual or needle-sharing contacts. 390 contacts were located and counselled and HIV test results are known for 350 of them. In 53 of the 350 cases, previously unknown seropositivity was diagnosed. Partner notification for HIV should be viewed as a strategy to offer counselling and testing to a high-prevalence group of people. In a country where general HIV prevalence is low, the strategy is cost-effective for location and counselling of unknowingly seropositive individuals.