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Contact tracing for hepatitis C: perspectives of people with experience of substance use and hepatitis C on intervention acceptability.

INTRODUCTION: Chronic hepatitis C (HCV) is a major cause of cirrhosis and hepatocellular carcinoma. In the UK, the principal risk factor for HCV is injecting drug use. The introduction of direct acting anti-virals (DAA's) have transformed HCV care, with cure rates of over 95%. However, HCV is often asymptomatic, and reinfection is a concern. Modelling and real-life studies demonstrate the potential effectiveness of a contact tracing approach for finding people who have acquired HCV through injecting drug use. However, it is not used routinely in the UK. This qualitative study was undertaken to assess the acceptability of a contact tracing approach to identify people who have injected drugs with an index patient recently diagnosed with HCV. METHODS: Twelve people with lived or living experience of injecting drug use and an HCV diagnosis were interviewed using semi-structured interview topic guides. Participants were purposefully selected according to the inclusion criteria and to ensure there was an even spread of male and female participants. Sekhon's Theoretical Framework of Acceptability, incorporating seven components (affective attitude, burden, ethicality, intervention coherence, opportunity cost, perceived effectiveness, and self-efficacy) was used to analyse data from interview transcripts. RESULTS: A sample of 12 people who inject drugs in the UK indicated that a contact tracing approach was acceptable across two components of Sekhon's acceptability framework: affective attitude and ethicality. Participants broadly found the idea of tracing people who may be at risk of contracting HCV acceptable, and the approach aligned with their value systems. A contact tracing approach would help alleviate concerns about putting other people's lives at risk through HCV transmission and was seen as a 'sensible' way of finding people at risk. However, there were caveats to this acceptability. Contact tracing approaches delivered by mainstream health, or governmental organisations increased burden, opportunity costs and perceived effectiveness of a contact tracing approach for HCV, particularly within contexts of exclusion and criminalisation of people who inject drugs. Burden and opportunity costs were also affected by individual experiences and risks of violence, sexual violence and abuse. There was a lack of knowledge of contact tracing approaches amongst respondents, leading to a lack of intervention coherence and misunderstandings of what contact tracing was and how it would work. Trusted relationships with NGOs and HCV specialist nurses reduced burden and increased confidence and ability (self-efficacy) to engage with a contact tracing approach. CONCLUSION: People who inject drugs broadly perceive contact tracing as an acceptable method of finding people who are at risk of HCV. However, this acceptability is based on specific modes of delivery through trusted organisations. Findings further highlight the importance of naming and describing contact tracing approaches appropriately, as well as assessing and mitigating against potential risk to index patients, to increase self-efficacy and capacity to engage. Considering these findings, the potential for expanding existing contact tracing approaches should be explored to ensure the UK reaches and maintains its elimination targets.

Humans↗

Contact tracing for genital Chlamydia trachomatis in a Swedish county.

BACKGROUND: Contact tracing is one of the measures used to control genital Chlamydia trachomatis infections. GOAL OF THIS STUDY: To assess important variables of contact tracing in an everyday clinical setting. STUDY DESIGN: Patients reported according to the STD Act were studied in a prospective, consecutive county-based study. RESULTS: A total of 149 patients had a mean of 2.2 partners. The social worker's patients reported significantly more partners than the physicians' patients. The median number of patients at the 26 involved institutions was 3. Treatment without a prior examination was prescribed to 4% of the partners; 95% of all notified partners were examined, and a majority of them were chlamydia-infected. CONCLUSION: The requirements of the STD Act in Sweden are being followed reasonably well by health providers responsible for contact tracing, although an experienced social worker seems to get better results.

Chlamydia Infections↗

Do the factors associated with successful contact tracing of patients with gonorrhoea and Chlamydia differ?

OBJECTIVE: To assess and compare factors which may be associated with successful contact tracing in patients with gonorrhoea and chlamydia. STUDY DESIGN: Prospective observational study of patients attending a genitourinary medicine clinic with a diagnosis of gonorrhoea or chlamydia. Multivariate analysis model including demographic, socioeconomic, and behavioural variables. RESULTS: The attendance of at least one sexual contact was associated with naming more contacts for patients with gonorrhoea (OR 1.44, 95% CI 1.04-2.01). A history of gonorrhoea was associated with successful contact tracing for patients with chlamydia (OR 1.46, 95% CI 1.12-1.9). Successful contact tracing, as defined by at least one confirmed contact attendance after the index case, was not associated with age, sex, sexual orientation, history of chlamydia, use of condoms, marital status, ethnicity, or socioeconomic status for either gonorrhoea or chlamydia. CONCLUSIONS: Differences in the composition of the core groups infected with gonorrhoea and chlamydia are not explained by differences in contact tracing success. In the clinic setting studied, the outcome of contact tracing was not associated with a variety of demographic, socioeconomic, and behaviour factors.

Adult↗

[Contact tracing a year back is worthwhile. Follow the Vasterbottens example to prevent Chlamydia transmission in Sweden!].

UNLABELLED: Contact tracing is proved to be a good way to prevent asymptomatic sexually transmitted infections, such as Chlamydia trachomatis, from spreading. According to the Swedish law a physician has to report all cases of genital C. trachomatis to the County Medical Officer of Health and to the National institute for Infectious Disease Control and perform contact tracing. An evaluation of the sexual history 6 months back in time is recommended and standard in most of the country. The county of Västerbotten has one of the lowest incidenses of C. trachomatis in Sweden though the population is younger than the Swedish average. During year 2002 the contact tracing in Västerbotten was evaluated by sending a questionnaire to everyone who reported a case of genital C. trachomatis. We recived 534 (98%) out of 544 questionnaires. The patients reported 1360 partners, 2.5 on average, 1129 were identified. 761 had a known test result and 497 of them were positive, 0.9 on average. 72% of the contact tracers evaluated the sexual history > or = 12 months back in time. 78% of the contact tracings were performed by four social workers. Their patients reported 2.5 partners on average and 80% evaluated > or = 12 months back in time. 14 persons did only one contact tracing, 1.3 partners/index on average, 40% evaluated > or = 12 months back in time. 82% of the partners had sex with the infected patient 0-6 months before the patients was diagnosed with C. trachomatis, 75% out of those with a known test result were infected, 16% had sex 7-12 months before diagnosis, 30% infected. (The C. trachomatis prevalence in Sweden is estimated to be 2.7-4.9% among young women.) CONCLUSION: A few experienced persons tracing for at least 12 month back in time is probably two important reasons why Västerbotten has such a small C. trachomatis incidence.

Adolescent↗

UK National Audit of Early Syphilis Management. Case-notes audit: contact tracing, information giving, follow-up and outcomes.

Contact tracing was provided for 683/781 (87%, regional range 57-97%) cases, and identified 997 traceable contacts of whom 511 (51%) were seen, short of the recommended standard of 60%. However, the performance range for this standard was 26-70%, with seven regions achieving 60% or more. Of 511, 215 (42%, range 3-73%) contacts had syphilis. Treatment completion was recorded for 691 (88%, range 71-100%) cases, and resolution of lesions for 348/469 (74%, range 40-96%) cases. Nationally, 419/764 (55%, range 37-70%) cases were recorded as having a two dilution (four-fold) or greater decrease in non-treponemal test titre within 3-6 months after treatment; not achieving this titre decrease was mainly attributable to non-attendance for follow-up and failure of titre levels to fall. Follow-up of infectious syphilis in UK genitourinary medicine clinics is poor and falls far short of that recommended by National Guidelines. Only 16 (2%) cases had follow-up at intervals approximating to 1, 2, 3, 6 and 12 months, and only 312 (40%, range 5-61%) cases attended at least two follow-up visits. Only 17 (7%) of all 236 oral treatments (including switches to oral treatment), and 33 (27%) of 123 cases with HIV infection were recorded as designated annual follow-up. Further work is needed to determine factors that account for the wide variation between regions in contact tracing and follow-up performance.

Anti-Bacterial Agents↗

Measuring the outcome of contact tracing. 2. The responsibilities of the health worker and the outcome of contact investigations.

The previous paper (Satin and Mills, 1978) concerned information on patients who were interviewed by health workers in five selected clinics; information on the contacts named by these patients was similarly analysed. This paper describes and evaluates the activities of the health workers and the outcome of contact investigations. At all stages of the contact tracing process, differences were observed between men and women. It was found that more than half of the male contacts and half the female contacts were known to have been examined. Of those contacts examined, at least two-thirds of them attended the same clinic as the patient who had named them, and 85% of these contacts were found to have a treatable condition. It will be seen that the concept of success or effectiveness of contact tracing is complex in definition and measurement.

Allied Health Personnel↗

Contact tracing: comparing the approaches for sexually transmitted diseases and tuberculosis.

SETTING: Literature review for the process of contact tracing for sexually transmitted diseases (STD) and for tuberculosis (TB), focusing on articles that report results of studies or commentary. OBJECTIVE: To compare and contrast contact tracing in order to highlight emerging commonalities. DESIGN: A descriptive review, based on Medline search with augmentation from other published and unpublished sources. RESULTS: Contact tracing for STD and TB have some obvious differences because of differing routes of transmission, differing sensibilities required to work with the affected populations, a different potential for anonymous contacts, and a major difference in the epidemiologic value of biomarkers. Nonetheless, the convergence of these processes on disadvantaged populations where drug use and sexual activity are important social factors has engendered an increasing similarity. CONCLUSION: A broadened approach to both, with greater attention to how ancillary contacts and associates may be of use in interrupting deeply embedded endemic disease transmission, deserves further study. Some newer approaches in the use of network-informed methods to elicit contacts and investigate the community dynamics of transmission may be of particular value in TB case investigation. These strategies will be enhanced by the availability of DNA fingerprinting, a powerful biomarker of recent Mycobacterium tuberculosis transmission and case association (a technology not available for STD contact tracing).

Contact Tracing↗

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.

Adolescent↗

Improved contact tracing of Chlamydia trachomatis in a Swedish county--is genotyping worthwhile?

The vast majority of genital Chlamydia trachomatis infections are non-symptomatic or mildly symptomatic. Efficient contact tracing and screening programmes are the most effective means to reveal these infections. We conducted a prospective study on the effects of contact tracing performed by specially trained midwives in a centralized municipality-based organization during one year. In order to improve the efficiency of the contact tracing, all C. trachomatis-positive isolates in the county during one year were typed by sequencing the ompA gene. Contact tracing in two municipalities the year prior to the study revealed 1.6 partners for each index case (n = 110). The corresponding figure for the whole county during the study period was 2.1 partners per index case (n = 2065). Genotyping added valuable information in mapping individual sexual networks, but was not essential for achieving satisfactory contact tracing results.

Bacterial Outer Membrane Proteins↗

Outcome of contact tracing for Chlamydia trachomatis in a district general hospital.

The outcome of contact tracing (partner notification) for Chlamydia trachomatis in a district general hospital during the 5-year period between 1991-1995 was surveyed. During the 5-year period 1027 cases of C. trachomatis were diagnosed. The health adviser saw 928 (90%) of cases who reported 1132 (1.2) sexual contacts. Out of 682 sexual contacts sought by the health adviser, 472 (69.5%) were seen. Following a consultation with the health adviser, over two-thirds (86%) of index cases chose to inform their contacts themselves. Over two-thirds (71%) of contacts informed by these index cases were seen. A higher proportion of regular and first or most immediate contacts were seen as a result of contact tracing. A significantly higher proportion of partners of index cases who themselves returned for test of cure were seen. A consultation with the health adviser facilitated uptake of partner notification by the index patients. Patient referral led to a majority of contacts being seen in a genitourinary medicine (GUM) clinic. Follow-up visits by index patients may improve outcome of contact tracing and should continue irrespective of need for test of cure.

Chlamydia Infections↗

A record system for contact tracing.

A system for recording information on patients and contacts was developed during a research project designed to measure the effectiveness of contact tracing. The record system has proved valuable in contact tracing, cross-referencing patients and their contacts, defining the characteristics of the patient and contact populations, and providing information for research and management. The value of a standardised system has been accepted by health workers who appreciate that its purpose is to increase efficiency and improve the care of infected persons. By October 1976 health workers in 16 clinics in the United Kingdom had started to use the system.

Humans↗

Digital imaging versus conventional contact tracing for the objective measurement of venous leg ulcers.

OBJECTIVE: This study aimed to compare the accuracy and inter-observer reproducibility of leg ulcer measurements made using digital images and conventional contact tracing. METHOD: The accuracy of measurements made with these two methods by four observers of 11 shapes with a known area was assessed. The time taken to do this was also measured. Following this, the accuracy and inter-observer reproducibility of the two methods was measured for patients with leg ulcers presenting to the vascular clinic, with contact tracing as the reference. RESULTS: For the reference shapes, both methods had a mean error of less than 5%. Contact tracing significantly underestimated the area by 3.9% (p < 0.05), while digital tracing showed no significant error. Digital tracing was quicker than contact tracing, especially for larger shapes (p < 0.05). For leg ulcers, there was no significant difference between area measurements made by the two methods. Inter-observer variation of digital tracing was greater for the ulcers than the reference shapes. This was due to differences in subjective interpretation and technical problems in recording some images. CONCLUSION: Measurement of leg ulcer area using computer-aided tracing of digital camera images is more accurate and quicker than contact tracing provided that appropriate care is taken when taking the pictures. Digital images offer considerable advantages in the shared hospital-community care of patients with leg ulcers.

Humans↗

Endemic versus non-endemic gonorrhoea in Stockholm: results of contact tracing.

The aim of the present study was to characterize endemic versus non-endemic gonorrhoea to identify risk groups for transmission and to evaluate the effects of intensified contact tracing performed by specially trained social workers at venereal clinics. A total of 671 gonorrhoea patients (283 women and 388 men) comprised the study group. Seventy percent of the women and 48% of the men had an endemic infection (P < 0.001). Men without a steady partner had an increased risk of non-endemic infection. A decrease from 75% to 40% was noted in the proportion of endemic infection in Stockholm from the first quarter of the study period (2 years) to the last. Contact tracing resulted in 1.2 identified partners per patient. A total of 736 partners were examined either as a result of contact tracing efforts or because they had sought medical care on their own prior to intervention. Forty-seven percent of these partners were infected, 44% were not infected and 9% were examined outside the study with results unknown to us. The partner notification efforts yielded 161 new untreated cases. Contact tracing of women generated one new case per 4.0 interviewed women and contact tracing of men one new case per 4.3 interviewed men. Interviewing index patients with endemic infection yielded the highest number of new cases. Forty-three percent of the patients were infected outside Stockholm but only a smaller part of these patients spread their infection further into the community.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Contact tracing and population screening for tuberculosis--who should be assessed?

BACKGROUND: The aim of the study was to investigate the relative effectiveness of four strategies in detecting and preventing tuberculosis: contact tracing of smear-positive pulmonary disease, of smear-negative pulmonary disease and of non-pulmonary disease, and screening new entrants. METHODS: An analysis of patient records and a TB database was carried out for an NHS Trust-based tuberculosis service in a socio-economically deprived area. Subjects were contacts of all patients treated for TB between 1997 and 1999. New entrants were screened in 1999. Outcomes measured were numbers of cases of active tuberculosis detected and numbers of those screened given chemoprophylaxis. RESULTS: A total of 643 contacts of 227 cases of active TB were seen, and 322 new entrants to the United Kingdom. The highest proportion of contacts requiring full treatment or chemoprophylaxis were contacts of smear-positive index cases (33 out of 263 contacts; 12.5 per cent). Tracing contacts of those with smear-negative pulmonary tuberculosis (12 out of 156; 7.7 per cent) and non-pulmonary disease (14 out of 277; 6.2 per cent) was significantly more effective in identifying individuals requiring intervention (full treatment or chemoprophylaxis) than routine screening of new entrants (10 out of 322; 3.1 per cent). CONCLUSIONS: Screening for TB of new entrants to the United Kingdom is part of the national programme for control and prevention of TB, whereas tracing contacts of those with smear-negative and non-pulmonary disease is not. This study demonstrates that, in our population, the contact-tracing strategy is more effective than new entrant screening. It is not likely that the contacts have caught their disease from the index case, but rather that in high-incidence areas such as ours such tracing selects extended families or communities at particularly high risk.

Antitubercular Agents↗

[Typhoid fever in Amsterdam, 1991-2000, and the simplification of the national protocol for source and contact tracing].

OBJECTIVE: To determine the incidence of patients reported with typhoid fever in Amsterdam (1991-2000) and to evaluate the contact tracing for those patients with the specific objective of examining whether contact tracing can be simplified. DESIGN: Retrospective. METHOD: From an automated database, data were collected on all reported typhoid fever patients in Amsterdam during the period 1991-2000 and on their contact persons. RESULTS: One hundred and one patients with typhoid fever were reported during the study period, and Salmonella typhi infection was diagnosed in 12 of the 281 household contacts. For 96 of the 101 index patients, travelling abroad was the most likely source of infection. In 8 of the 12 contact persons with an S. typhi infection, the index person was the most likely source of infection, which is equivalent to a secondary transmission rate of 2.8% (8/277). Seven of the 8 secondary infected persons had symptoms indicative of typhoid fever infection and S. typhi was found in all their first stool samples. CONCLUSION: Supported by these results, the national guidelines for source and contact tracing in the case of typhoid fever have been amended. In the case of index patients with bad toilet hygiene or who are responsible for food preparation, the faeces of all household contacts must be examined once. If the contact persons have symptoms indicative of an S. typhi infection and/or if their work involves food preparation, their faeces should also be tested once. The changes to the national protocol will markedly reduce the labour-intensity of tracing and testing the contacts of patients with typhoid fever, thereby maintaining the quality of the process. Tracing the source of infection in the case of patients with typhoid fever will also remain important in the future in order to detect potential transmission within the Netherlands at an early stage.

Adolescent↗

Accounting for contact tracing in epidemiological birth-death models.

Phylodynamics bridges the gap between classical epidemiology and pathogen genome sequence data by estimating epidemiological parameters from time-scaled pathogen phylogenetic trees. The models used in phylodynamics typically assume that the sampling procedure is independent between infected individuals. However, this assumption does not hold for many epidemics, in particular for such sexually transmitted infections as HIV-1, for which contact tracing schemes are included in health policies of many countries. We extended phylodynamic multi-type birth-death (MTBD) models with contact tracing (CT), and developed a simulator to generate trees under MTBD and MTBD-CT models. We proposed a non-parametric test for detecting contact tracing in pathogen phylogenetic trees. Its application to simulated data showed that it is both highly specific and sensitive. For the simplest representative of the MTBD-CT family, the BD-CT(1) model, where only the last contact can be notified, we solved the differential equations and proposed a closed form solution for the likelihood function. We implemented a maximum-likelihood program, which estimates the BD-CT(1) model parameters and their confidence intervals from phylogenetic trees. It performed accurate parameter inference on BD and BD-CT(1) simulated data, and detected contact tracing in HIV-1 B epidemics in Zurich and the UK. Importantly, we showed that not accounting for contact tracing when it is present, leads to bias in parameter estimation with the BD model (overestimation of the becoming-non-infectious rate). This bias is also present, but greatly reduced, when the BD-CT(1) model is used on data where multiple contacts can be notified. Our CT test, MTBD-CT tree simulator and BD-CT(1) parameter estimator are freely available at GitHub (evolbioinfo/treesimulator and evolbioinfo/bdct).

Contact Tracing↗

Urogenital Chlamydia trachomatis infections in general practice: diagnosis, treatment, follow-up and contact tracing.

BACKGROUND: Patients with urogenital Chlamydia trachomatis infection are frequently seen in general practice. It is, therefore, important to assess GPs' management of these patients in order to ensure adequate control of the disease. OBJECTIVE: We aimed to evaluate the GPs' routines in diagnosis, medical treatment, follow-up and contact tracing according to knowledge/attitude (criteria) and actual performance. METHODS: The study comprised the 388 GPs in the County of Aarhus. Two questionnaires were used. The first questionnaire was mailed to each of 252 GPs who had attended a patient with urogenital C. trachomatis infection 4 weeks previously. Each GP was asked about his/her actual performance for that particular patient. In order to elucidate the GPs' criteria, the second questionnaire was mailed to each of the 388 GPs in the County of Aarhus, asking about their usual intended routines (criteria) for managing urogenital C. trachomatis infections. The questionnaires covered the same topics. RESULTS: Great variations among the GPs' management of urogenital C. trachomatis infection according to sampling-site, medical treatment, follow-up and contact tracing were found. Furthermore, a discrepancy between criteria and actual performance for obtaining an urethral swab-sample in women and for contact tracing of previous partners were demonstrated. The GPs stated that they had intended to obtain more urethral swab-samples and do more contact tracing than they actually did. CONCLUSIONS: We conclude that increasing the collection of urethral samples from women combined with greater emphasis on contact tracing procedures might limit the prevalence of the infection. In order to achieve this, continuous medical education and auditing procedures on urogenital chlamydial infections may be helpful.

Anti-Bacterial Agents↗

The characterisation of a recent syphilis outbreak in Sheffield, UK, and an evaluation of contact tracing as a method of control.

OBJECTIVE: To explore the factors around and the success of contact-tracing in a recent major outbreak of infectious syphilis in Sheffield, and to evaluate the effectiveness of it, our hitherto standard strategy of control. METHOD: Retrospective chart review RESULTS: Over a period of 18 months, an outbreak of 21 cases was, on closer inspection, the result of several, discrete "micro" outbreaks in different groups. Two major patterns emerged, a relatively straightforward and more accessible cluster in heterosexual persons (a "spread" network), and more sporadic, "starburst" networks in men who have sex with men. CONCLUSION: Our traditional method of control, contact-tracing, was seen to be most effective in the spread network in heterosexuals. In the face of an apparent outbreak, clinicians should explore the nature and parameters of their local epidemic and engage a mixture of control methods. These may include, but not excusively so, contact-tracing to interrupt transmission by case-finding and by treatment.

Adult↗