What's driving the decline in tuberculosis in Arkansas? A molecular epidemiologic analysis of tuberculosis trends in a rural, low-incidence population, 1997 2003

Incident cases of tuberculosis may result from a recently acquired Mycobacterium tuberculosis infection or from the reactivation of a latent infection acquired in the remote past. The authors used molecular fingerprinting data to estimate the relative contributions of recent and remotely acquired infection to the yearly incidence of tuberculosis in Arkansas, a state with a largely rural population where the incidence of tuberculosis declined from 7.9 cases per 100,000 population to 4.7 cases per 100,000 between 1997 and 2003. The authors used a time-restricted definition of clustering in addition to the standard definition in order to increase the specificity of the clustering measure for recent transmission. The greatest overall declines were seen in non-Hispanic Blacks (from 13.8 cases per 100,000 in 1997 to 6.5 cases per 100,000 in 2003) and persons aged 65 years or more (from 19.9 cases per 100,000 in 1997 to 8.5 cases per 100,000 in 2003). In both groups, the incidence of nonclustered cases declined more dramatically than the incidence of clustered cases. This suggests that the decline in rates resulted primarily from declining rates of disease due to reactivation of past infections. Declines in the overall incidence of tuberculosis in a population may not necessarily result from declines in active transmission.     

Childhood tuberculosis: out of sight,out of mind?

Despite significant improvements in tuberculosis (TB) management under the WHO directly observed treatment, short course (DOTS) strategy, childhood TB has been relatively neglected. Children are at high risk of severe disease, and reactivation of latent infection in adulthood perpetuates the epidemic. Almost a million cases of childhood TB are estimated to occur annually, but good-quality epidemiological data are scarce due to inherent difficulties diagnosing paediatric TB. There remains an urgent need both for better diagnostic tests and for robust regional data on the true burden of disease, otherwise childhood TB will remain an essentially 'invisible' and therefore neglected disease.     

Notified tuberculosis among Singapore residents by ethnicity, 2002–2011

Setting:

The National Tuberculosis Programme in Singapore where, among resident cases, higher tuberculosis (TB) rates have been reported in ethnic Malays.

Objective:

To describe the socio-demographic and clinical characteristics of resident TB cases by ethnicity, and to assess whether Malays differ from other groups in terms of the above parameters.

Design:

Cross-sectional review of records from the tuberculosis registry’s electronic database.

Results:

Among 15 622 resident cases notified, 72.2% were Chinese, 18.7% Malay, 5.8% Indian and 2.9% were from other minorities. Compared to other ethnicities, Malays were more likely to be incarcerated at the time of notification (odds ratio [OR] 3.70, 95%CI 3.03–4.52) and clustered at the same residential address (OR 1.65, 95%CI 1.44–1.89), but were less likely to be aged ≥65 years (OR 0.61, 95%CI 0.54–0.70) or to reside in high-cost housing (OR 0.11, 95%CI 0.07–0.17). In terms of disease characteristics, more Malays had diabetes mellitus (OR 1.54, 1.37–1.73), a highly-positive acid-fast bacilli smear (OR 1.64, 95%CI 1.47–1.83) and cavitary disease on chest X-ray (OR 1.41, 95%CI 1.28–1.55).

Conclusion:

Compared to other ethnicities, reported TB cases among Malays were more severe and were likely to be more infectious. Increased vigilance in case management and contact investigations, as well as an improvement in the socio-economic conditions of this community, are required to reduce TB rates in this ethnic group.     

Can tuberculosis be controlled?

BACKGROUND: Tuberculosis (TB) is nearly 100% curable. However, the ability of medical and public health interventions to control TB, particularly in developing countries, is often doubted. METHODS: We reviewed data for the amenability of TB to control. We considered separately control of deaths, prevalence, rate of infection and incidence. RESULTS: Tuberculosis mortality can be reduced by more than 80% in less than 5 years. The prevalence of TB can be reduced by 30% or more annually; sustained annual decreases of 17% have been documented in a developing country. The TB infection rate can be reduced by 15% annually. In the absence of human immunodeficiency virus (HIV), TB incidence can be decreased by as much as 25% per year and up to 10% annually in developing countries. A high prevalence of untreated HIV infection in the adult population of a developing country will inevitably result in a significant increase in TB incidence despite optimal use of currently available technologies. CONCLUSIONS: Tuberculosis can be controlled if appropriate policies are followed, effective clinical and public health management is ensured, and there are committed and co-ordinated efforts from within and outside the health sector. However, in the context of a large epidemic of AIDS, TB incidence will inevitably increase. By 2001, less than 30% of global TB cases were reported to have received effective diagnosis, treatment and monitoring. Rapid expansion of effective TB control services is urgently required, both to avert the continued high burden of morbidity and mortality from TB and because of the HIV pandemic.     

Mycobacterium tuberculosis Genotype and Case Notification Rates, Rural Vietnam, 2003�C2006

Tuberculosis case notification rates (CNRs) for young adults in Vietnam are increasing. To determine whether this finding could reflect emergence of Mycobacterium tuberculosis Beijing genotype, we studied all new sputum smear–positive pulmonary tuberculosis patients registered for treatment in 3 rural districts in Vietnam during 2003–2006. Beijing strain infections were more frequent in younger patients (15–24 years of age, 53%) than in older patients (31%; p<0.001). The increase in CNRs for youngest patients was larger for disease caused by the Beijing genotype than by other genotypes, but the difference was not significant. For patients 15–24 years of age, 85% of fluctuations in CNRs between years was caused by fluctuations in Beijing genotype infections compared with 53% and 23% in the groups 25–64 and >65 years of age, respectively (p<0.001). These findings suggest that young adults may be responsible for introducing Beijing strains into rural Vietnam.     

Beijing Lineage of MDR Mycobacterium tuberculosis in Bulgaria, 2007–2011

To assess the spread of the Mycobacterium tuberculosis Beijing genotype among patients with multidrug-resistant and extensively resistant tuberculosis in Bulgaria, we genotyped 188 (72%) of 261 microbiologically confirmed resistant isolates obtained during 2007–2011. The estimated prevalence of the Beijing genotype among these patients was 3.2%.     

Follow-up examinations: are multidrug-resistant tuberculosis patients in Uttar Pradesh,India, on track?

Setting: All multidrug-resistant tuberculosis (MDR-TB) patients who had completed 6 months of treatment under the Revised National Tuberculosis Control Programme (RNTCP) in Uttar Pradesh, the largest state in northern India.Objective: To determine the proportion of MDR-TB patients with regular follow-up examinations, and underlying provider and patient perspectives of follow-up services.Methods: A retrospective cohort study was undertaken involving record reviews of 64 eligible MDR-TB patients registered during April–June 2013 in 11 districts of the state. Patients and programme personnel from the selected districts were interviewed using a semi-structured questionnaire.Results: A total of 34 (53.1%) patients underwent follow-up sputum culture at month 3, 43 (67.2%) at month 4, 36 (56.3%) at month 5 and 37 (57.8%) at month 6. Themes associated with irregular follow-up that emerged from the interviews were multiple visits, long travel distances, shortages of equipment at the facility and lack of knowledge among patients regarding the follow-up schedule.Conclusion: The majority of the MDR-TB patients had irregular follow-up visits. Provider-related factors outweigh patient-related factors on the poor follow-up examinations. The programme should focus on the decentralisation of follow-up services and ensure logistics and patient-centred counselling to improve the regularisation of follow up.     

Evaluation of tuberculin skin testing in tuberculosis contacts in Victoria,Australia, 2005–2013

Aim: To review the programmatic use of the tuberculin skin test (TST) following tuberculosis (TB) exposure in Victoria, Australia.Methods: A retrospective review of data collected for public health surveillance was performed to identify contact demographic factors, including bacille Calmette-Guérin (BCG) status and age and outcomes of TST.Results: Contact tracing was performed for 15 094 people, of whom 13 427 (89.0%) had a TST performed. The TST was positive in 31.4% (95%CI 30.6–32.2) of all contacts, and 48.8% of contacts born outside of Australia. Amongst contacts who were TST-negative at baseline, the conversion rate following exposure was 14.8%. Conversion was most common in those aged 45–54 years, with <12% positivity in both the youngest (<5 years) and oldest (⩾65 years) age groups. Active TB developed in 1.1% of all contacts. Contacts aged <5 years had the highest risk of developing active TB following exposure (3.8%), while low risk was seen in those aged ⩾65 years (0.3%).Conclusion: Overall, contact tracing and TST in this setting appear to yield a high proportion of people at risk for the development of active TB. The yield of testing in some groups, particularly those aged ⩾65 years, was low, and investigation of alternative strategies should be considered.     

Mycobacterium tuberculosis drug resistance in HIV patients in Baixada Santista, São Paulo, Brazil

Since the early 1990s, an increase in Mycobacterium tuberculosis drug resistance has been reported, with high prevalence among HIV+ patients. We evaluated the sensitivity patterns of M. tuberculosis, resistance rate, and predisposing factors among HIV+ patients in Santos, S?o Vicente, Cubat?o, Praia Grande, and Guarujá, S?o Paulo State, Brazil. The medical charts of 301 patients with positive cultures for M. tuberculosis from 1993 to 2003 were reviewed. Resistance occurred in 57 patients (18.9%), as follows: 32 (10.6%) displayed multidrug-resistant tuberculosis (resistant to at least Rifampicin and Isoniazid); 4 (1.3%) were resistant to two or more drugs; and 21 (7%) were resistant to a single drug. Acquired resistance was observed in 70.1% of cases. Drug resistance was significantly associated with previous tuberculosis treatment, duration of HIV diagnosis, and previous hospitalization. In logistic regression analysis, only previous tuberculosis treatment adjusted by age remained as an independent risk factor (OR = 5.49; 95%CI: 2.60-11.60). Drug resistance to at least one drug in 18.9% and multidrug resistance in 10.6% of cases highlight the relevance of this problem in HIV patients in the Baixada Santista.     

What's new in tuberculosis vaccines?

Over the past 10 years, tuberculosis (TB) vaccine development has resurged as an active area of investigation. The renewed interest has been stimulated by the recognition that, although BCG is delivered to approximately 90% of all neonates globally through the Expanded Programme on Immunization, Mycobacterium tuberculosis continues to cause over 8 million new cases of TB and over 2 million deaths annually. Over one hundred TB vaccine candidates have been developed, using different approaches to inducing protective immunity. Candidate vaccines are typically screened in small animal models of primary TB disease for their ability to protect against a virulent strain of M. tuberculosis. The most promising are now beginning to enter human safety trials, marking real progress in this field for the first time in 80 years.     

Are HIV-positive presumptive tuberculosis patients without tuberculosis getting the care they need in Zimbabwe?

Setting: Emakhandeni Clinic provides decentralised and integrated tuberculosis (TB) and human immunodeficiency virus (HIV) care in Bulawayo, Zimbabwe.Objectives: To compare HIV care for presumptive TB patients with and without TB registered in 2013.Design: Retrospective cohort study using routine programme data.Results: Of 422 registered presumptive TB patients, 26% were already known to be HIV-positive. Among the remaining 315 patients, 255 (81%) were tested for HIV, of whom 190 (75%) tested HIV-positive. Of these, 26% were diagnosed with TB and 71% without TB (3% had no TB result recorded). For the 134 patients without TB, antiretroviral treatment (ART) eligibility data were recorded for 42 (31%); 95% of these were ART eligible. Initiation of cotrimoxazole preventive therapy (CPT) and ART was recorded for respectively 88% and 90% of HIV-positive patients with TB compared with respectively 40% and 38% of HIV-positive patients without TB (P < 0.001).Conclusion: Presumptive TB patients without TB had a high HIV positivity rate and, for those with available data, most were ART eligible. Unlike HIV-positive patients diagnosed with TB, CPT and ART uptake for these patients was poor. A ‘test and treat’ approach and better service linkages could be life-saving for these patients, especially in southern Africa, where there are high burdens of HIV and TB.     

High Rates of Mycobacterium tuberculosis among Socially Marginalized Immigrants in Low-Incidence Area, 1991–2010, Italy

Migration from low- and middle-income countries to high-income countries increasingly determines the severity of tuberculosis (TB) cases in the adopted country. Socially marginalized groups, about whom little is known, may account for a reservoir of TB among the immigrant populations. We investigated the rates of and risk factors for Mycobacterium tuberculosis transmission, infection, and disease in a cohort of 27,358 socially marginalized immigrants who were systematically screened (1991–2010) in an area of Italy with low TB incidence. Overall TB and latent TB infection prevalence and annual tuberculin skin testing conversion rates (i.e., incidence of new infection) were 2.7%, 34.6%, and 1.7%, respectively. Prevalence of both TB and latent TB infection and incidence of infection increased as a function of the estimated TB incidence in the immigrants’ countries of origin. Annual infection incidence decreased with time elapsed since immigration. These findings have implications for control policy and immigrant screening in countries with a low prevalence of TB.     

Institutions and conflicts in tuberculosis teaching in Córdoba, 1920-1955

The purpose of this paper is to analyze the process of institutionalizing tuberculosis research and teaching in the Faculty of Medical Sciences of the State University of Cordoba. The province of Cordoba, especially the capital and the northwestern region, was considered an area suitable for climatic cure. This caused an important flow of migration of infected people and at the same time an increasing interest of the argentine physicians in studying this disease. The analysis of the different actors that participated in the creation process of teaching institutions in this area will be studied with basis on Bourdieu's concept of 'field'. From this perspective, this paper approaches the stages of the disease, the development of teaching institutions, and the tensions and disagreements that were involved in their constitution.