Specificity of notification for tuberculosis among screened refugees in NSW

Quality and Utility of Information Captured by Surveillance Systems Relevant to Antimicrobial Resistance (AMR): A Systematic Review

Health surveillance systems are considered vital for combatting antimicrobial resistance (AMR); however, the evidence-base on the effectiveness of these systems in providing information that can be used by healthcare professionals, or the acceptability of these systems by users, has not been reviewed. A systematic review was conducted of a number of databases to synthesise the evidence. The review identified 43 studies that met the inclusion criteria, conducted in 18 countries and used 11 attributes in their assessment of surveillance systems. The majority of systems evaluated were for monitoring the incidence of tuberculosis. The studies found that most surveillance systems were underperforming in key attributes that relate to both effectiveness and acceptability. We identified that two features of systems (ease of use and users' awareness of systems) were associated with greater acceptability and completeness of systems. We recommend prioritising these for the improvement of existing systems, as well as ensuring consistency in the definition of attributes studied, to allow a more consistent approach in evaluations of surveillance systems, and to facilitate the identification of the attributes that have the greatest impact on the utility of data produced.

A polymorphism in the P2X7 gene increases susceptibility to extrapulmonary tuberculosis

RATIONALE

Genetic variation influences susceptibility to clinical tuberculosis (TB). Activation of the P2X(7) receptor on human macrophages induces killing of mycobacteria. We have identified polymorphisms in the P2X(7) gene that markedly reduce this killing.

OBJECTIVE

To determine if polymorphisms in P2X7 are associated with increased risk of TB, the prevalence of four polymorphisms was assessed in individuals from Southeast Asia, where the majority of patients with TB in our study originate. The association of these polymorphisms with clinical TB was subsequently investigated in two separate case-control cohorts and the function of P2X(7) was assessed in subjects from one cohort.

METHODS

Genotyping of P2X7 polymorphisms was performed from subjects in a nested case-control study of a longitudinal refugee cohort and a separate case-control study. The functional capacity of P2X(7) was investigated by measuring ATP-mediated mycobacterial killing and apoptosis.

RESULTS

Only the 1513A-C polymorphism was present in Southeast Asians and the allele was associated with reduced killing of Mycobacterium tuberculosis. The 1513C allele was strongly associated with extrapulmonary, but not pulmonary, TB in the first (odds ratio, 3.8; 95% confidence interval, 1.6-9.0) and second cohorts (odds ratio, 3.7; 95% confidence interval, 1.7-8.0). ATP-mediated killing of mycobacteria was ablated in macrophages from subjects homozygous for the 1513C allele and significantly impaired in macrophages from heterozygous subjects. There was strong correlation between the degree of mycobacterial killing and ATP-induced apoptosis.

CONCLUSIONS

The 1513C allele increases susceptibility to extrapulmonary TB, and this defect is associated with the reduction in the capacity of macrophages to kill M. tuberculosis.

Effectiveness of postmigration screening in controlling tuberculosis among refugees: a historical cohort study, 1984-1998

OBJECTIVES

This study assessed the effectiveness of postmigration screening for the control of tuberculosis (TB) among refugee migrants.

METHODS

We conducted a historical cohort study among 24 610 predominantly Southeast Asian refugees who had arrived in Sydney, Australia, between 1984 and 1994. All had been screened for TB before arrival and had radiologic follow-up for 18 months after arrival. Incident cases of TB were identified by record linkage analysis with confirmatory review of case notes.

RESULTS

The crude annual incidence rate over 10-year follow-up was 74.9 per 100 000 person-years. Only 29.6% of the cases were diagnosed as a result of routine follow-up procedures.

CONCLUSIONS

Enhanced passive case finding is likely to be more effective than active case finding for the control of TB among refugees.

The incidence of tuberculosis in a cohort of South-East Asian refugees arriving in Australia 1984-94

We have used record linkage analysis to describe the incidence of tuberculosis in a cohort of 24 652 predominantly south-east Asian refugees who arrived in Sydney, Australia during the period 1984 to 1994. Cases that had been registered with the State Department of Health were confirmed by examination of case records. After an average follow-up interval of 10.3 years there were 189 cases of tuberculosis, equivalent to an average incidence rate of 74.9 cases per 100 000 person-years. The highest incidence rate was in 40-49 year olds and 47% of cases were in women. One hundred and twenty seven cases (67%) were pulmonary and, of these, 64 (50%) were direct smear positive. The incidence of tuberculosis in this cohort is similar to that observed among Vietnamese migrants to Australia and the USA and substantially higher than the incidence among people born in Australia. It is important to maintain awareness of the diagnosis of tuberculosis, especially in countries such as Australia, where the incidence in the general population is low but where there are large populations of migrants and refugees in whom a higher incidence is expected.

Incidence of tuberculosis among a cohort of tuberculin-positive refugees in Australia: reappraising the estimates of risk

Estimates of the lifetime risk of tuberculosis have varied widely and may not be applicable in all current settings. The aim of this study was to measure the incidence of reactivation of latent tuberculosis in a cohort of 15,489 predominantly Southeast Asian refugees aged 12 yr and over who arrived in Sydney, Australia during the period 1984 to 1994 and who had a clear chest X-ray on arrival. Tuberculin skin test (TST) reaction size and the presence of a BCG scar were recorded at entry. Incident cases of tuberculosis, occurring before June 1998, were identified by record linkage analysis with confirmatory review of case notes. There were 122 cases of tuberculosis over an average 10.3 yr of follow-up (crude annual incidence, 76.2/100,000). There was a linear increase in risk with increasing TST reaction size above 10 mm. The risk, and the relation of risk to TST reaction size, were unrelated to BCG scar status. Among those whose initial TST reaction was >/= 15 mm, the annual incidence rate in the first 3 yr was 213 (95% CI, 150 to 300) per 100,000 person-years and in the subsequent 10 yr the rate averaged 122 (95% CI, 90 to 165) per 100,000 person-years. The observed rates are similar to those estimated in the general population of the United States in the 1950s and 1960s. Further data on the prognosis of tuberculosis and the effects of isoniazid preventive therapy in Southeast Asian migrants to Western countries are required to inform policy and practice for the prevention of tuberculosis in this population.