Contact Tracing Rate Research Articles

Qualitative analysis of a Mathematical model of COVID-19 with intervention strategies in the Philippines

This paper focuses on the development of a mathematical model to analyze the transmission dynamics of COVID-19 in the Philippines, where the pandemic has significantly impacted the population despite several quarantine measures, testing, contact tracing, and vaccinations. The model considers the impact of contact tracing and vaccination campaigns on disease transmission. The model is analyzed qualitatively and numerically, and the results show that increasing the contact tracing rate and vaccination rate can effectively reduce the reproduction number of the virus. The disease-free equilibrium is found to be locally asymptotically stable when the basic reproduction number is less than one, and the disease-endemic equilibrium is locally asymptotically stable when the basic reproduction number is greater than one. The study suggests that a contact tracing rate greater than 0.08847694 is required to effectively manage the transmission of COVID-19 in the target population. These findings provide insights for policymakers and public health officials in developing effective strategies to mitigate the impact of the pandemic.

Effects of contact tracing and non-Markovian awareness process on the spread of air-borne diseases

Contact tracing is an important tool to contain the spread of many airborne diseases. We develop an approximated pairwise model to investigate the impact of non-Markovian awareness process among infectious individuals represented by pairwise endemic models. We derive the basic reproduction number and the final epidemic size, which are dependent on the tracing rate and the distribution of awareness process. The model analysis provides the threshold of contact tracing rate. When the contact tracing rate is greater than the threshold, the basic reproduction number will be less than one, then the epidemic will eventually die out. The analysis further shows that, higher variance in the awareness process generates smaller basic reproduction number, lower tracing threshold, and larger final epidemic size, when the mean awareness period is fixed. Extensive numerical analysis show the comprehensive effects of tracing rates and non-Markovian awareness processes on human behavior and the transmissibility ability of epidemic. It turns out that large tracing rates and high variances in awareness process lead to obvious reductions in contacts between susceptible and infectious individuals, so as to curb the transmission of infectious diseases. Moreover, contact tracing is more effective in reducing the number of infected individuals and the contacts between susceptible and infected individuals when the awareness process has a larger variance.

Contact tracing of syphilis-seropositive pregnant women and syphilis-infection among their male partners in Bao'an district, Shenzhen, China

BackgroundUntreated male partners are a critical source of maternal re-infection. Contact tracing is a good way to identify infection among partners and reduce risk of mother-to-child transmission related to maternal re-infection. This study aimed to analyze the current situation and related factors of contact tracing of syphilis-seropositive pregnant women and syphilis-infection among their male partners.MethodData of syphilis-seropositive pregnant women and their male partners attending clinic for syphilis-screening were obtained from the Shenzhen Program for Prevention of Congenital Syphilis. Contact tracing rate of syphilis-seropositive pregnant women and syphilis prevalence among male partners were counted, and related factors were also analyzed using a random-effects logistic regression model.ResultOf the 1299 syphilis-seropositive pregnant women, 74.1% (963/1299) had their male partners receiving syphilis-screening and 19.1% (184/963) of male partners were syphilis-infected. For pregnant women, being divorced (adjusted odds ratio [AOR] =0.39; 95%CI: 0.17–0.87), seeking for emergency services at their first antenatal clinics visits (AOR = 0.58; 95%CI: 0.44–0.77), reporting willingness to notify partner(AOR = 7.65; 95%CI: 4.69–12.49), multi-partners (AOR = 1.38; 95%CI:1.03–1.86) and having a history of drug abuse (AOR = 0.37; 95%CI: 0.14–1.00)were independently associated with successful contact tracing. For male partners, of minority ethnicity (AOR = 4.15; 95%CI: 1.66–10.34), age at first sex>20(AOR = 0.57; 95%CI: 0.37–0.87), reporting multi-partners (AOR = 1.60; 95%CI: 1.04–2.46), having a history of drug abuse (AOR = 4.07; 95%CI: 1.31–12.64) were independently associated with syphilis-infection. In addition, pregnant women with TRUST titer ≥1:8 (AOR = 2.81; 95%CI: 1.87–4.21), having a history of adverse pregnancy outcomes (AOR = 1.70; 95%CI: 1.14–2.53), reporting multi-partners (AOR = 0.43; 95%CI: 0.29–0.64) and reporting the current partner as the source of syphilis (AOR = 5.05; 95%CI: 2.82–9.03) were independently associated with partners’ syphilis-infection.ConclusionContact tracing is feasible and effective in identifying syphilis-infected partners among syphilis-seropositive pregnant women. Contact tracing is associated with many factors such as women’s marital status, services at their first antenatal clinics visit and willingness of partner notification. Partners’ ethnicity, age at first sex, multi-partners and history of drug abuse as well as women’s levels of TRUST titer were associated with partners’ syphilis-infection.

Factors influencing health care workers' implementation of tuberculosis contact tracing in Kweneng, Botswana.

IntroductionTB contact tracing rates remain low in high burden settings and reasons for this are not well known. We describe factors that influence health care workers' (HCW) implementation of TB contact tracing (CT) in a high TB burden district of Botswana.MethodsData were collected using questionnaires and in-depth interviews in 31 of the 52 health facilities in Kweneng East Health District. Responses were summarized using summary statistics and comparisons between HCW groups were done using parametric or non-parametric tests as per normality of the data distribution.ResultsOne hundred and four HCWs completed questionnaires. Factors that influenced HCW TB contact tracing were their knowledge, attitudes and practices as well as personal factors including decreased motivation and lack of commitment. Patient factors included living further away from the clinic, unknown residential address and high rates of migration and mobility. Administrative factors included staff shortages, lack of transport, poor reporting of TB cases and poor medical infrastructure e.g. suboptimal laboratory services. A national HCW strike and a restructuring of the health system emerged as additional factors during in-depth interviews of TB coordinators.ConclusionMultiple factors lead to poor TB contact tracing in this district. Interventions to increase TB contact tracing will be informed by these findings.

Contact tracing of pregnant women infected with syphilis and the associated factors

To investigate the current status of contact tracing among pregnant women infected with syphilis and to analyze the associated factors from patients' perspective. Pregnant women who aged 18 years old, receiving prenatal care services in Shenzhen, diagnosed with syphilis according to national diagnostic criteria (WS 273-2007) from 2008 to 2011 were recruited and the total number was 3 551. Information of both pregnant women (including demographic information, laboratory results, syphilis diagnosis, and personal life history) and their partners (including results of partner tracing and laboratory examination) were collected with structured questionnaire by face-to-face interview. Multivariate non-conditional logistic regression model was applied to analyze the factors associated with partners' contract tracing. Odds ratio (OR) and its 95% confidential interval (95%CI) were calculated. The average age was 28.72 among recruited 3 551 syphilis-infected pregnant women, with standard deviation of 5.21 and range of 18 to 40. Totally 2 550 partners attended antenatal clinics and received syphilis examination, with a contact tracing rate of 71.81%. The OR(95%CI) was 1.70(1.26-2.30) for pregnant women with college or above education when comparing with those with senior high school or below education. The OR(95%CI) was 0.57(0.45-0.71) for those unmarried or divorce when comparing with those married. The OR (95% CI) was 0.73(0.56-0.94) and 0.65(0.53-0.81) for those screened in 28-36 gestational weeks and those screened in >36 gestational weeks or right before delivery separately, when comparing with those screened in ≤27 gestational weeks. The OR (95% CI) was 1.45(1.14-1.84) for those having received sufficient treatment before pregnancy when comparing with those diagnosed with latent syphilis. The OR(95%CI) was 0.31 (0.24-0.39) for those having no treatment or not standardized treatment when comparing with those having standardized penicillin treatment. The OR(95%CI) was 0.53 (0.43-0.65) for those terminating the pregnancy when comparing with those giving birth to a baby. The OR(95%CI) was 1.24 (1.05-1.46) for those having two or more love histories when comparing with those having only one love history. The OR(95%CI) was 4.74 (3.54-6.35) for those intending to disclose the serostatus to their partner when comparing with those showing unwillingness to disclose the serostatus. The successful rate of contact tracing among pregnant women infected with syphilis was high. The implementation of contact tracing may be affected by many factors, including patients' education levels, marital status, gestational weeks of screening, stage of syphilis, treatment status, outcome of pregnancy, number of love histories, and willingness of serostatus disclosure.

Tuberculosis Case Finding: Evaluation of a Paper Slip Method to Trace Contacts

SettingSouth Africa has the third highest tuberculosis (TB) burden in the world. Intensified case finding, recommended by WHO, is one way to control TB.ObjectiveTo evaluate the effectiveness and acceptability of a paper slip method for TB contact tracing.MethodTB patients were offered paper slips to give to their contacts, inviting them for TB screening. The number of contacts screened and the proportion diagnosed with TB was calculated. Contacts that returned to the clinic after receiving the slips were interviewed. A focus group discussion (FGD) with TB patients was held to determine their acceptability.ResultsFrom 718 paper slips issued, a 26% TB contact tracing rate was found, with a 12% case detection rate. The majority (68%) of contacts were screened within 2 weeks of receiving the slip. Age and gender were not significantly associated with time to screening. 16% of the contacts screened did not reside with the TB patients. 98% of the contacts said the method was acceptable. FGD findings show that this method is acceptable and may prevent stigma associated with TB/HIV.ConclusionThis simple, inexpensive method yields high contact tracing and case detection rates and potentially would yield additional benefits outside households.

Audit of syphilis treatment, follow-up and contact-tracing rates

An audit of diagnoses of syphilis infection managed at the Edinburgh genitourinary (GU) medicine clinic for the period 1 October 2001-31 October 2004. In all, 101 patients were identified as untreated carriers or contacts requiring treatment, partner notification and follow-up. Treatment rate was 100% in the audit population. Among this patient group, 90% were offered testing for other sexually transmitted infections (STIs) with a positivity rate of 24%. The HIV testing rate was 85%, resulting in five new diagnoses.

Audit of treatment and contact-tracing rates in immediate (presumptive) versus delayed (polymerase chain reaction) diagnosis of chlamydial infection

An audit of all cases of chlamydial infection diagnosed in men at the Edinburgh genitourinary (GU) medicine clinic over a six-month period from January 2003 is reported. In all, 189 men identified as requiring treatment for possible chlamydial infection on first attendance (because of contact with a partner with chlamydia or the diagnosis of non-gonococcal urethritis [NGU] on microscopy), who later proved chlamydia-positive by polymerase chain reaction (PCR), were compared with 83 men in whom infection was identified only on receipt of a PCR result. Treatment rates were 100% in the first group and 97.6% in the second group (chi(2) 0.046, P<0.05). In men presumptively diagnosed and treated, 88.6% of contacts identified were confirmed as traced, compared with 90% confirmed as traced in the group diagnosed by PCR alone. Our audit suggests that identifying men with chlamydial NGU by routine microscopy may carry a small but significant advantage in increasing treatment rates, but makes no difference to contact-tracing success rate.