Recent transmission of tuberculosis in a cohort of HIV-1-infected female sex workers in Nairobi, Kenya

Evaluation of the Isoniazid Preventive Therapy Care Cascade Among HIV-Positive Female Sex Workers in Mombasa, Kenya

BACKGROUND

Kenyan female sex workers (FSWs) have a high HIV prevalence, increasing their tuberculosis (TB) risk. Despite recommendations that HIV-positive individuals be offered isoniazid preventive therapy (IPT), uptake has been limited.

METHODS

In this longitudinal cohort of HIV-positive FSWs, we retrospectively characterized the IPT care cascade between March 2000 and January 2010, including reasons for cascade loss or appropriate exit. Cascade success required completion of 6 months of IPT. Baseline characteristics were assessed as potential correlates of cascade loss using multivariable logistic regression.

RESULTS

Among 642 HIV-positive FSWs eligible for IPT evaluation, median age was 31 years (IQR 26-35) with median CD4 lymphocyte count of 409 (IQR 292-604) cells per cubic millimeter. There were 249 (39%) women who successfully completed 6 months of IPT, 157 (24%) appropriately exited the cascade, and 236 (37%) were cascade losses. Most cascade losses occurred at symptom screen (38%, 90/236), chest radiograph evaluation (28%, 66/236), or during IPT treatment (30%, 71/236). Twenty-nine women were diagnosed with tuberculosis, including one after IPT initiation. Most women initiating IPT completed the course (71%, 249/351); <5% had medication intolerance. Younger women [<25 and 25-35 vs. >35 years; adjusted odds ratio (AOR) 2.65, 95% confidence interval (CI): 1.46 to 4.80 and AOR 1.78, 95% CI: 1.13 to 2.80, respectively], and those evaluated for IPT after antiretroviral availability in 2004 (AOR 1.92, 95% CI: 1.31 to 2.81), were more likely to be cascade losses.

CONCLUSIONS

Implementation of IPT among HIV-positive FSWs in Kenya is feasible. However, significant losses along the IPT care cascade underscore the need for strategies improving retention in care.

Predominant Mycobacterium tuberculosis Families and High Rates of Recent Transmission among New Cases Are Not Associated with Primary Multidrug Resistance in Lima, Peru

Sputum samples from new tuberculosis (TB) cases were collected over 2 years as part of a prospective study in the northeastern part of Lima, Peru. To measure the contribution of recent transmission to the high rates of multidrug resistance (MDR) in this area, Mycobacterium tuberculosis complex (MTBc) isolates were tested for drug susceptibility to first-line drugs and were genotyped by spoligotyping and 15-locus mycobacterial interspersed repetitive-unit (MIRU-15)-variable-number tandem repeat (VNTR) analysis. MDR was found in 6.8% of 844 isolates, of which 593 (70.3%) were identified as belonging to a known MTBc lineage, whereas 198 isolates (23.5%) could not be assigned to these lineages and 12 (1.4%) represented mixed infections. Lineage 4 accounted for 54.9% (n = 463) of the isolates, most of which belonged to the Haarlem family (n = 279). MIRU-15 analysis grouped 551/791 isolates (69.7%) in 102 clusters, with sizes ranging from 2 to 46 strains. The overall high clustering rate suggests a high level of recent transmission in this population, especially among younger patients (odds ratio [OR], 1.6; P = 0.01). Haarlem strains were more prone to cluster, compared to the other families taken together (OR, 2.0; P < 0.0001), while Beijing (OR, 0.6; P = 0.006) and LAM (OR, 0.7; P = 0.07) strains clustered less. Whereas streptomycin-resistant strains were more commonly found in clusters (OR, 1.8; P = 0.03), clustering rates did not differ between MDR and non-MDR strains (OR, 1.8; P = 0.1). Furthermore, only 16/51 MDR strains clustered with other MDR strains, suggesting that patients with primary MDR infections acquired the infections mostly from index cases outside the study population, such as retreated cases.

Impact of isoniazid preventive therapy for HIV-infected adults in Rio de Janeiro, Brazil: an epidemiological model

BACKGROUND

The potential epidemiological impact of isoniazid preventive therapy (IPT), delivered at levels that could be feasibly scaled up among people living with HIV (PLHIV) in modern, moderate-burden settings, remains uncertain.

METHODS

We used routine surveillance and implementation data from a cluster-randomized trial of IPT among HIV-infected clinic patients with good access to antiretroviral therapy in Rio de Janeiro, Brazil, to populate a parsimonious transmission model of tuberculosis (TB)/HIV. We modeled IPT delivery as a constant process capturing a proportion of the eligible population every year. We projected feasible reductions in TB incidence and mortality in the general population and among PLHIV specifically at the end of 5 years after implementing an IPT program.

RESULTS

Data on time to IPT fit an exponential curve well, suggesting that IPT was delivered at a rate covering 20% (95% confidence interval: 16% to 24%) of the 2500 eligible individuals each year. By the end of year 5 after modeled program rollout, IPT had reduced TB incidence by 3.0% [95% uncertainty range (UR): 1.6% to 7.2%] in the general population and by 15.6% (95% UR: 15.5% to 36.5%) among PLHIV. Corresponding reductions in TB mortality were 4.0% (95% UR: 2.2% to 10.3%) and 14.3% (14.6% to 33.7%). Results were robust to wide variations in parameter values on sensitivity analysis.

CONCLUSIONS

TB screening and IPT delivery can substantially reduce TB incidence and mortality among PLHIV in urban, moderate-burden settings. In such settings, IPT can be an important component of a multi-faceted strategy to feasibly reduce the burden of TB in PLHIV.

Tuberculosis screening among Bolivian sex workers and their children

Bolivian sex workers were more likely than other employed women to report tuberculosis screening only if they reported HIV screening. Of all women with household tuberculosis exposure, <40% reported screening for themselves or their children. Coupling tuberculosis screening with sex workers’ mandatory HIV screenings may be a cost-efficient disease-control strategy.

Modeling the dynamic relationship between HIV and the risk of drug-resistant tuberculosis

The emergence of highly drug-resistant tuberculosis (TB) and interactions between TB and HIV epidemics pose serious challenges for TB control. Previous researchers have presented several hypotheses for why HIV-coinfected TB patients may suffer an increased risk of drug-resistant TB (DRTB) compared to other TB patients. Although some studies have found a positive association between an individual's HIV status and his or her subsequent risk of multidrug-resistant TB (MDRTB), the observed individual-level relationship between HIV and DRTB varies substantially among settings. Here, we develop a modeling framework to explore the effect of HIV on the dynamics of DRTB. The model captures the acquisition of resistance to important classes of TB drugs, imposes fitness costs associated with resistance-conferring mutations, and allows for subsequent restoration of fitness because of compensatory mutations. Despite uncertainty in several key parameters, we demonstrate epidemic behavior that is robust over a range of assumptions. Whereas HIV facilitates the emergence of MDRTB within a community over several decades, HIV-seropositive individuals presenting with TB may, counterintuitively, be at lower risk of drug-resistant TB at early stages of the co-epidemic. This situation arises because many individuals with incident HIV infection will already harbor latent Mycobacterium tuberculosis infection acquired at an earlier time when drug resistance was less prevalent. We find that the rise of HIV can increase the prevalence of MDRTB within populations even as it lowers the average fitness of circulating MDRTB strains compared to similar populations unaffected by HIV. Preferential social mixing among individuals with similar HIV status and lower average CD4 counts among HIV-seropositive individuals further increase the expected burden of MDRTB. This model suggests that the individual-level association between HIV and drug-resistant forms of TB is dynamic, and therefore, cross-sectional studies that do not report a positive individual-level association will not provide assurance that HIV does not exacerbate the burden of resistant TB in the community.

6-month versus 36-month isoniazid preventive treatment for tuberculosis in adults with HIV infection in Botswana: a randomised, double-blind, placebo-controlled trial

BACKGROUND

In accordance with WHO guidelines, people with HIV infection in Botswana receive daily isoniazid preventive therapy against tuberculosis without obtaining a tuberculin skin test, but duration of prophylaxis is restricted to 6 months. We aimed to assess effectiveness of extended isoniazid therapy.

METHODS

In our randomised, double-blind, placebo-controlled trial we enrolled adults infected with HIV aged 18 years or older at government HIV-care clinics in Botswana. Exclusion criteria included current illness such as cough and an abnormal chest radiograph without antecedent tuberculosis or pneumonia. Eligible individuals were randomly allocated (1:1) to receive 6 months' open-label isoniazid followed by 30 months' masked placebo (control group) or 6 months' open-label isoniazid followed by 30 months' masked isoniazid (continued isoniazid group) on the basis of a computer-generated randomisation list with permuted blocks of ten at each clinic. Antiretroviral therapy was provided if participants had CD4-positive lymphocyte counts of fewer than 200 cells per μL. We used Cox regression analysis and the log-rank test to compare incident tuberculosis in the groups. Cox regression models were used to estimate the effect of antiretroviral therapy. The trial is registered at ClinicalTrials.gov, number NCT00164281.

FINDINGS

Between Nov 26, 2004, and July 3, 2009, we recorded 34 (3·4%) cases of incident tuberculosis in 989 participants allocated to the control group and 20 (2·0%) in 1006 allocated to the continued isoniazid group (incidence 1·26% per year vs 0·72%; hazard ratio 0·57, 95% CI 0·33-0·99, p=0·047). Tuberculosis incidence in those individuals receiving placebo escalated approximately 200 days after completion of open-label isoniazid. Participants who were tuberculin skin test positive (ie, ≥5 mm induration) at enrolment received a substantial benefit from continued isoniazid treatment (0·26, 0·09-0·80, p=0·02), whereas participants who were tuberculin skin test-negative received no significant benefit (0·75, 0·38-1·46, p=0·40). By study completion, 946 (47%) of 1995 participants had initiated antiretroviral therapy. Tuberculosis incidence was reduced by 50% in those receiving 360 days of antiretroviral therapy compared with participants receiving no antiretroviral therapy (adjusted hazard ratio 0·50, 95% CI 0·26-0·97). Severe adverse events and death were much the same in the control and continued isoniazid groups.

INTERPRETATION

In a tuberculosis-endemic setting, 36 months' isoniazid prophylaxis was more effective for prevention of tuberculosis than was 6-month prophylaxis in individuals with HIV infection, and chiefly benefited those who were tuberculin skin test positive.

FUNDING

US Centers for Disease Control and Prevention and US Agency for International Development.

Isoniazid tuberculosis preventive therapy in HIV-infected adults accessing antiretroviral therapy: a Botswana Experience, 2004-2006

OBJECTIVES

To describe reasons for exclusion from isoniazid tuberculosis preventive therapy (IPT) and outcomes of persons living with HIV (PLWH) during 6 months of IPT.

METHODS

In a clinical trial conducted in government clinics, first screening (screen 1) used National IPT Program guidelines and a second screening (screen 2) was trial specific. Adherence was defined as attending 6 monthly visits.

RESULTS

Between 2004 and 2006, at 4018 screening visits, 2934 (73%) PLWH met screen 1 criteria; 1995 (68%) met screen 2 criteria and were enrolled. Major reasons for exclusion were illness (66%) at screen 1 and abnormal chest radiographs (36%) at screen 2. Tuberculin skin tests were > or = 5 mm in 24% of those enrolled and 31% had CD4 lymphocyte counts <200 cells/mm(3). During the 6 months, 8 (0.40%) developed tuberculosis disease, 28 (1.4%) had severe adverse events (19/28 were hepatitis including one death probably isoniazid-associated), 20 others died, and 22% initiated antiretroviral therapy (ART). Although adherence was 86%, being on ART improved adherence: relative risk 1.41 (95% confidence limits 1.04-1.91). In multivariate analysis, ART was associated with a 4.38 greater odds of adherence to IPT.

CONCLUSIONS

Six months of IPT was relatively safe and well-tolerated by PLWH. Adherence to IPT was significantly better among those receiving ART with IPT.

Tuberculosis rates among HIV-infected persons in New York City, 2001-2005

We calculated population-based tuberculosis (TB) rates among HIV-infected persons in New York City from 2001 through 2005 using data from the city's TB and HIV/AIDS surveillance registries, and we examined those rates using linear trend tests and incidence rate ratios (IRRs). HIV-infected individuals had 16 times the TB rate of a "non-HIV" population (HIV status negative or unknown; IRR = 16.0; 95% confidence interval = 14.9, 17.2). TB rates declined significantly among the US-born HIV-infected population (P (trend) < .001) but not among the foreign-born HIV-infected population (P (trend) = .355). Such disparities must be addressed if further declines are to be achieved.

The persistence of tuberculosis in the age of DOTS: reassessing the effect of case detection

OBJECTIVE

To investigate whether short-term annual declines of 5-10% in the incidence of tuberculosis (TB) can be sustained over the long term by maintaining high case detection rates (CDRs).

METHODS

We constructed a compartmental difference-equation model of a TB epidemic in a hypothetical population of constant size with a treatment success rate of 85%. The impact of CDR on TB incidence was then investigated by generating an equilibrium population with no TB case detection and increasing the smear-positive CDR under two scenarios: (i) rapid expansion by 10% per year to a CDR of 80% after 8 years, and (ii) gradual expansion by 1% per year to a CDR of 90% after 90 years. The model was applied in two hypothetical populations: one without HIV and the other with a stable HIV incidence representative of the African Region. The CDR for smear-negative TB was assumed to be a constant fraction of the smear-positive CDR.

FINDINGS

In the absence of a TB control programme, the projected annual incidence of TB was 513 cases per 100 000 population, with a point prevalence of 1233 per 100 000 and an annual TB-specific mortality rate of 182 per 100 000. Immediately increasing the TB CDR from 0% to 70% caused a 74% reduction in TB incidence within 10 years. However, once case detection stabilized at any constant level < 80%, projected TB incidence also stabilized. Ten years after a CDR of 70% was reached, the annual decline in TB incidence was < 1.5%, regardless of how rapidly case detection was scaled up and despite wide variation of all model parameters.

CONCLUSION

While improved CDRs have a dramatic short-term effect on TB incidence, maintaining those rates, even at current target levels, may not reduce long-term incidence by more than 1-2% per year. TB control programmes and researchers should vigorously pursue improvements in case detection, regardless of current CDRs.

Effects of duration of HIV infection and secondary tuberculosis transmission on tuberculosis incidence in the South African gold mines

BACKGROUND

HIV increases the risk of tuberculosis directly, through immunosuppression, and indirectly, through onward transmission of Mycobacterium tuberculosis from the increased caseload. We assess the contribution of these two mechanisms by time since seroconversion to HIV.

METHODS

The incidence of new pulmonary tuberculosis was estimated in a retrospective cohort study of South African gold miners over 14 years. HIV tests were done in random surveys in 1992-1993, and in clinics. One thousand nine hundred fifty HIV positive men with seroconversion intervals of less than 3 years were identified and linked to medical, demographic and occupational records. They were compared with men who were HIV-negative in a survey, with no later evidence of HIV. Analyses were censored when men were diagnosed with tuberculosis, died or left the mine.

RESULTS

Tuberculosis incidence rose soon after HIV infection, reaching 1.4/100 person-years (95% confidence interval 1.1-1.9) within 2 years, and 10.0/100 person-years (95% confidence interval 6.5-15.5) at 10 or more years. By 11 years from seroconversion, nearly half the men had had tuberculosis. Among 5702 HIV-negative men, tuberculosis incidence was 0.48/100 person-years (95% confidence interval 0.33-0.70) in 1991-1993 and doubled over the period of the study (after adjusting for age). Age-adjusted model estimates suggest that half the increase in tuberculosis incidence by time since HIV infection was attributable to increasing incidence over calendar period--the indirect effect.

CONCLUSION

For the first time, we have shown that the increase in tuberculosis risk by time since seroconversion reflects both direct effects of HIV increasing susceptibility, and indirect effects due to onward transmission. Innovative and sustained public health measures are needed to reduce Mycobacterium tuberculosis transmission.

Morbidity before and after HAART initiation in Sub-Saharan African HIV-infected adults: a recurrent event analysis

The incidence and determinants of severe morbidity recurrence in sub-Saharan African HIV-infected adults on antiretroviral therapy (ART) have never been reported. In a prospective cohort study of HIV-infected adults in Abidjan the association of severe morbidity occurrence and recurrence with follow-up CD4 counts and ART on/off status was analyzed by means of multivariate failure analysis for recurrent events (Prentice, Williams, and Peterson model). A total of 608 patients (median CD4 290/mm3 ) was followed off ART for 1824 person-years (PY). Of these 187 started HAART (median CD4 174/mm3 ) and were followed for 328 PY. The incidence of first, second, and third severe morbidity events was 40.6/100 PY, 68.4/100 PY, and 93.9/100 PY during the off-ART period, and 28.4/100 PY, 39.4/100 PY, and 37.6/100 PY during the on-ART period, respectively. The rates of recurrences were higher than the rates of first episodes for almost all diseases, even after stratifying by CD4 count and by ART on/off status. In multivariate analysis, the time-updated CD4 count was independently associated with increasing rates of morbidity first events and recurrences, after adjustment on other covariates (p > 10(4) ). By contrast, there was no association between the ART on/off status and the morbidity rates after adjustment for CD4 count (p = 0.37). Introducing ART led to a clear reduction in morbidity, mainly related to the ART-induced increase in CD4 count. In HIV-infected patients on ART, the incidence of severe morbidity varied with the past history of morbidity. The past history of morbidity should be taken into account when comparing HIV morbidity rates before and after ART initiation.

Tuberculosis transmission in a high incidence area: a retrospective molecular epidemiological study of Mycobacterium tuberculosis in Casablanca, Morocco

Like in most developing countries, tuberculosis represents a major public health problem in Morocco. This paper describes the first study combining molecular and conventional epidemiology of tuberculosis in Casablanca, the economic capital of this country. Molecular fingerprinting of the genomic DNA recovered from cultures of sputum of 150 patients was performed by MIRU-VNTR. This molecular marker revealed that 53.1% of the total cases were clustered. These cases were classified into 23 clusters ranging in size from 2 to 13 patients, suggesting a rate of 37% of recent transmission in the sample under study. In a multivariate analysis, there were no independent predictors of clustering. However, the clinical form was associated with drug resistance (odds ratio=9.9; P value=0.0006). The phylogenetic analysis showed that the heterogeneity found in this population includes also the members from a same patient family, and that the 2 major families distributed in Casablanca were the Latin-American-Mediterranean (LAM) and Haarlem families. All the results of this work allow to understand better the tuberculosis transmission in Casablanca, and suggest that different clones of M. tuberculosis seem to circulate in this city, and that the reactivation of latent infections would be mainly responsible for the endemic situation of this disease. These findings indicate also that the transmission of TB in Morocco is not optimally controlled, and that efforts for control strategies should be sustained in all developing countries where the incidence of TB is high and still raising.

The Independent Effect of Highly Active Antiretroviral Therapy on Severe Opportunistic Disease Incidence and Mortality in HIV-Infected Adults in Côte D'Ivoire

Background

Studies in developed countries have shown highly active antiretroviral therapy (HAART) decreases incidence of severe opportunistic diseases (ODs) in HIV-infected patients beyond that which is expected from changes in CD4+T-cell count.

Objective

To estimate the independent impact of HAART on reducing ODs and mortality in Côte d'Ivoire.

Methods

Within two longitudinal studies of HIV-infected adults (1996–2003), we identified time on ‘cotrimoxazole alone’ and ‘HAART plus cotrimoxazole’. WHO stage 3–4 defining events and severe malaria were divided into those preventable and not preventable with cotrimoxazole. Incidence of ODs by CD4 count stratum was estimated using incidence density analysis. CD4+ T-cell count at time of OD was estimated using linear interpolation. Using Poisson regression, we estimated the effect of HAART on OD incidence and mortality by CD4 count stratum.

Results

Totals of 446 and 135 adults were followed during 6,216 and 3,412 person-months in the cotrimoxazole alone and HAART plus cotrimoxazole periods, respectively. There was a CD4+ T-cell-independent risk reduction for ODs and mortality during the HAART plus cotrimoxazole period compared with cotrimoxazole alone, which varied by time on HAART, CD4 count stratum and OD type. It was mainly seen after 6 months on HAART and for ODs not preventable by cotrimoxazole. The HAART effect differed significantly by CD4 count stratum ( P=0.02), but was significant in all strata after 6 months on HAART.

Conclusions

In these sub-Saharan African adults, HAART initiation reduced ODs and mortality beyond that which was expected through the HAART-induced CD4+ T-cell increase. Further studies should examine practical implications of this independent ‘HAART effect’ on clinical outcomes in patients on HAART.

CD4 Decline and Incidence of Opportunistic Infections in Cape Town, South Africa

OBJECTIVES

To determine the rate of CD4 decline and the incidence of opportunistic infections (OIs) among antiretroviral therapy-naive South African HIV-infected patients and inform timing of OI prophylaxis.

METHODS

We used mixed-effect models to estimate CD4 cell decline by CD4 cell count strata in HIV-infected patients in the Cape Town AIDS Cohort between 1984 and 2000. Stratum-specific OI incidence per 100 person-years of observation was determined using incidence density analysis.

RESULTS

Nine hundred seventy-four patients with 2 or more CD4 cell counts were included. CD4 counts declined by 47.1 cells/microL per year in the stratum with more than 500 cells/microL stratum, 30.6 cells/microL per year in the stratum with 351 to 500 cells/microL, and 20.5 cells/microL per year in the stratum with 201 to 350 cells/microL. Tuberculosis and oral candidiasis were the only OIs that occurred frequently in the stratum with more than 200 CD4 cells/microL. Rates of chronic diarrhea, wasting syndrome, tuberculosis, and oral and esophageal candidiasis increased in the stratum with less than 200 cells/microL, and rates of all OIs were highest in the stratum with 50 cells/microL or less.

CONCLUSIONS

: CD4 cell count declines were dependent on CD4 strata and can inform timing of clinic visits and treatment initiation in South Africa. Incidence rates of OIs suggest that targeted OI prophylaxis could prevent substantial HIV-related morbidity in South Africa.

Sex-work harm reduction

Sex work is an extremely dangerous profession. The use of harm-reduction principles can help to safeguard sex workers' lives in the same way that drug users have benefited from drug-use harm reduction. Sex workers are exposed to serious harms: drug use, disease, violence, discrimination, debt, criminalisation, and exploitation (child prostitution, trafficking for sex work, and exploitation of migrants). Successful and promising harm-reduction strategies are available: education, empowerment, prevention, care, occupational health and safety, decriminalisation of sex workers, and human-rights-based approaches. Successful interventions include peer education, training in condom-negotiating skills, safety tips for street-based sex workers, male and female condoms, the prevention-care synergy, occupational health and safety guidelines for brothels, self-help organisations, and community-based child protection networks. Straightforward and achievable steps are available to improve the day-to-day lives of sex workers while they continue to work. Conceptualising and debating sex-work harm reduction as a new paradigm can hasten this process.

Exogenous reinfection in tuberculosis

Whether the development of active tuberculosis in people with previous tuberculous infection represents an episode of endogenous reactivation or exogenous reinfection has been debated for decades. Articles proposing the unitary concept of pathogenesis of tuberculosis in the 1960s initiated a period in which reinfection was considered to be an uncommon cause of tuberculosis. To review evidence demonstrating the occurrence of tuberculosis due to exogenous reinfection, we did a literature search covering publications from 1966 until the present, and found that there was substantial evidence--both experimental and epidemiological--supporting the role of exogenous reinfection in tuberculosis. However, only models based on estimates of the annual risk of infection and the incidence of tuberculosis provided a quantitative estimate of the relative contribution of exogenous reinfection to the burden of tuberculosis. Better estimates of the contribution of exogenous reinfection to new cases of tuberculosis may need to be considered in tuberculosis control strategies.

Risk factors for active tuberculosis after antiretroviral treatment initiation in Abidjan

RATIONALE

In sub-Saharan Africa: (1) tuberculosis is the first cause of HIV-related mortality; (2) the incidence of tuberculosis in adults receiving highly active antiretroviral therapy (HAART) is lower than in untreated HIV-infected adults but higher than in HIV-negative adults; and (3) factors associated with the occurrence of tuberculosis in patients receiving HAART have never been described.

OBJECTIVE

To look for the risk factors for active tuberculosis in HIV-infected adults receiving HAART in Abidjan.

METHODS

Seven-year prospective cohort of HIV-infected adults, with standardized procedures for documenting morbidity. We analyzed the incidence of active tuberculosis in patients who started HAART and the association between the occurrence of tuberculosis and the characteristics of these patients at HAART initiation.

MAIN RESULTS

A total of 129 adults (median baseline CD4 count 125/mm(3)) started HAART and were then followed for 270 person-years (P-Y). At HAART initiation, 31 had a history of tuberculosis and none had current active tuberculosis. During follow-up, the incidence of active tuberculosis was 4.8/100 P-Y (95% confidence interval [CI], 2.5-8.3) overall, 3.0/100 P-Y (95% CI, 1.1-6.6) in patients with no tuberculosis history, and 11.3/100 P-Y (95% CI, 4.1-24.5) in patients with a history of tuberculosis (adjusted hazard ratio, 4.64; 95% CI, 1.29-16.62, p = 0.02).

CONCLUSION

The risk of tuberculosis after HAART initiation was significantly higher in patients with a history of tuberculosis than in those with no tuberculosis history. If confirmed by others, this finding could lead to assessment of new patterns of time-limited tuberculosis secondary chemoprophylaxis during the period of initiation of HAART in sub-Saharan African adults.

Transmission of tuberculosis among patients with human immunodeficiency virus at a university hospital in Brazil

This study evaluated the IS6110-RFLP patterns of 109 Mycobacterium tuberculosis isolates of patients with HIV cared for at a Brazilian university hospital. Thirteen clusters involving 35 (32.1%) individuals were identified. Nosocomial transmission was possible in 5 cases. Strategies to prevent M. tuberculosis transmission should be implemented in hospitals in developing countries.

High rates of clustering of strains causing tuberculosis in Harare, Zimbabwe: a molecular epidemiological study

We examined the pattern of tuberculosis (TB) transmission (i.e., reactivation versus recent transmission) and the impact of human immunodeficiency virus (HIV) infection in Harare, Zimbabwe. Consecutive adult smear-positive pulmonary TB patients presenting to an urban hospital in Harare were enrolled. A detailed epidemiological questionnaire was completed, and tests for HIV type 1 and CD4 cell counts were performed for each patient. Molecular fingerprinting of the genomic DNA recovered from cultures of sputum was performed by two molecular typing methods: spacer oligonucleotide typing (spoligotyping) and analysis of variable number of tandem DNA repeats (VNTRs). A cluster was defined as isolates from two or more patients that shared the same spoligotype pattern or the same VNTR pattern, or both. DNA suitable for typing was recovered from 224 patients. The prevalence of HIV infection was 79%. Of 187 patient isolates (78.6%) typed by both spoligotyping and analysis of VNTRs, 147 were identified as part of a cluster by both methods. By spoligotyping alone, 84.1% of patient isolates were grouped into 20 clusters. The cluster size was generally <8 patient isolates, although three large clusters comprised 68, 25, and 23 patient isolates. A total of 89.4% of the patient isolates grouped into 12 clusters defined by analysis of VNTRs, with 2 large clusters consisting of 127 and 13 patient isolates, respectively. Thirty-six percent of patient isolates with a shared spoligotype and 17% with a shared VNTR pattern were geographically linked within Harare, but they were not linked on the basis of the patient's home district. In a multivariate analysis, there were no independent predictors of clustering, including HIV infection status. Comparison with the International Spoligotype database (Pasteur Institute, Pointe a Pitre, Guadeloupe) demonstrated that our three largest spoligotype clusters are well recognized and ubiquitous in Africa. In this epidemiologically well characterized urban population with a high prevalence of HIV infection, we identified a very high level of strain clustering, indicating substantial ongoing recent TB transmission. Geographic linkage could be detected in a proportion of these clusters. A small group of actively circulating strains accounted for most of the cases of TB transmission.

Effects of human immunodeficiency virus infection on recurrence of tuberculosis after rifampin-based treatment: an analytical review

We reviewed 47 prospective studies of recurrence of pulmonary tuberculosis (TB) after cure to assess the influence of human immunodeficiency virus (HIV) infection and rifampin treatment. Multivariate regression revealed that the recurrence rate for HIV-uninfected persons increased with decreasing duration of therapy: it was 1.4 cases per 100 person-years for recipients of >or=7 months of rifampin therapy and 2.0 and 4.0 cases per 100 person-years for recipients of 5-6 and 2-3 months of rifampin therapy, respectively (trend P=.00014), over a mean follow-up duration of 34 months, at a TB incidence of 250 cases per 100,000 person-years. Relative risks of recurrence associated with HIV infection at these 3 treatment durations were 2.2, 2.1, and 3.4, respectively, with a significant interaction between HIV infection status and treatment duration (P=.025). The recurrence rate increased with the background TB incidence (P=.048), and it decreased over time since completion of treatment in HIV-uninfected but not in HIV-infected patients (overall trend, P=.00008; difference by HIV infection status, P=.025). In countries where HIV infection is endemic, TB recurrence may be reduced by administration of rifampin-based treatment for at least 6 months, in accordance with World Health Organization recommendations.

Tuberculosis risk varies with the duration of HIV infection: a prospective study of European drug users with known date of HIV seroconversion

BACKGROUND

It is not known whether the risk of active tuberculosis disease varies with the length of time that individuals are infected with HIV.

OBJECTIVE

To study how, independently of CD4 T cell count, the risk of tuberculosis varies with the duration of HIV infection.

METHODS

Using Poisson regression analysis, the incidence of and risk factors for tuberculosis were studied in 683 injecting drug users (IDU) with a documented date of HIV seroconversion followed in seven cohorts in six European countries until 1998.

RESULTS

Overall incidence was 11.5/1000 person-years. Adjusted for CD4 T cell count and geographic region, the risk ratio (RR) for tuberculosis (both pulmonary and extrapulmonary), compared with the first 3 years of HIV infection, was 2.8 for years 4 to 6 of HIV infection [95% confidence interval (CI), 1.3-6.3], 1.2 for year 7 to 9 (95% CI, 0.3-4.2) and 4.6 after 9 years (95% CI, 1.4-15.0). The adjusted RR for geographic region was 13.1 (95% CI, 4.3-40.0) for Amsterdam and 15.8 (95% CI, 4.8-52.0) for the Valencian region of Spain compared with all other sites combined.

CONCLUSION

The risk of tuberculosis is increased relatively early in HIV infection (year 4 to 6) and also later (after year 9) with possibly a relatively silent period between. As expected, IDU in Southern Europe have a substantially higher risk of tuberculosis than IDU in Northern and Central Europe. Amsterdam forms an exception for Northern Europe, with very high incidence rates.

Evaluation and utilization as a public health tool of a national molecular epidemiological tuberculosis outbreak database within the United Kingdom from 1997 to 2001

The aim of this study was to develop a national model and analyze the value of a molecular epidemiological Mycobacterium tuberculosis DNA fingerprint-outbreak database. Incidents were investigated by the United Kingdom PHLS Mycobacterium Reference Unit (MRU) from June 1997 to December 2001, inclusive. A total of 124 incidents involving 972 tuberculosis cases, including 520 patient cultures from referred incidents and 452 patient cultures related to two population studies, were examined by using restriction fragment length polymorphism IS6110 fingerprinting and rapid epidemiological typing. Investigations were divided into the following three categories, reflecting different operational strategies: retrospective passive analysis, retrospective active analysis, and retrospective prospective analysis. The majority of incidents were in the retrospective passive analysis category, i.e., the individual submitting isolates has a suspicion they may be linked. Outbreaks were examined in schools, hospitals, farms, prisons, and public houses, and laboratory cross-contamination events and unusual clinical presentations were investigated. Retrospective active analysis involved a major outbreak centered on a high school. Contact tracing of a teenager with smear-positive pulmonary tuberculosis matched 14 individuals, including members of his class, and another 60 cases were identified in schools clinically and radiologically and by skin testing. Retrospective prospective analysis involved an outbreak of 94 isoniazid-resistant tuberculosis cases in London, United Kingdom, that began after cases were identified at one hospital in January 2000. Contact tracing and comparison with MRU databases indicated that the earliest matched case had occurred in 1995. Subsequently, the MRU changed to an active prospective analysis targeting linked isoniazid-monoresistant isolates for follow up. The patients were multiethnic, born mainly in the United Kingdom, and included professionals, individuals from the music industry, intravenous drug abusers, and prisoners.

Review of human immunodeficiency virus type 1-related opportunistic infections in sub-Saharan Africa

Understanding the natural history of human immunodeficiency virus type 1 (HIV-1) and opportunistic infections in sub-Saharan Africa is necessary to optimize strategies for the prophylaxis and treatment of opportunistic infections and to understand the likely impact of antiretroviral therapy. We undertook a systematic review of the literature on HIV-1 infection in sub-Saharan Africa to assess data from recent cohorts and selected cross-sectional studies to delineate rates of opportunistic infections, associated CD4 cell counts, and associated mortality. We searched the MEDLINE database and the Cochrane Database of Systematic Reviews and Cochrane Clinical Trials Register for English-language literature published from 1990 through April 2002. Tuberculosis, bacterial infections, and malaria were identified as the leading causes of HIV-related morbidity across sub-Saharan Africa. Of the few studies that reported CD4 cell counts, the range of cell counts at the time of diagnosis of opportunistic infections was wide. Policies regarding the type and timing of opportunistic infection prophylaxis may be region specific and urgently require further study.

Controlling tuberculosis in India

BACKGROUND

Tuberculosis kills nearly 500,000 people in India each year. Until recently, less than half of patients with tuberculosis received an accurate diagnosis, and less than half of those received effective treatment.

METHODS

We analyzed the effects of new policies introduced in 1993 that have resulted in increased resources, improved laboratory-based diagnosis, direct observation of treatment, and the use of standardized antituberculosis regimens and reporting methods.

RESULTS

By September 2001, more than 200,000 health workers had been trained, and 436 million people (more than 40 percent of the entire population) had access to services. About 3.4 million patients had been evaluated for tuberculosis, and nearly 800,000 had received treatment, with a success rate greater than 80 percent. More than half of all those treated in the past 8 years were treated in the past 12 months.

CONCLUSIONS

India's tuberculosis-control program has been successful in improving access to care, the quality of diagnosis, and the likelihood of successful treatment. We estimate that the improved program has prevented 200,000 deaths, with indirect savings of more than $400 million--more than eight times the cost of implementation. It will be a substantial challenge to sustain and expand the program, given the country's level of economic development, limited primary health care system, and large and mostly unregulated private health care system, as well as the dual threats of the human immunodeficiency virus and multidrug-resistant tuberculosis.

HIV infection and silicosis: the impact of two potent risk factors on the incidence of mycobacterial disease in South African miners

OBJECTIVE

To investigate the combined effects of HIV infection and silicosis on mycobacterial disease.

DESIGN AND SETTING

A retrospective cohort of 1374 HIV-positive and 2648 HIV-negative miners who attended a South African gold mining hospital and primary health clinics.

PARTICIPANTS

Miners who had been tested for HIV, with consent, at primary health clinics during 1991-1996, predominantly because of a symptomatic sexually transmitted disease.

RESULTS

Tuberculosis (TB) incidence was 4.9 and 1.1 per 100 person-years in HIV-positive and HIV-negative miners respectively. The incidence of Mycobacterium kansasii disease was also high (0.32 and 0.10 per 100 person-years, respectively). Silicosis was highly prevalent, implying inadequate dust control, and was a significant TB risk factor among both HIV-positive and HIV-negative men (adjusted incidence rate ratios 1.4-2.5 according to radiological severity). The data were consistent with the risks of silicosis and HIV combining multiplicatively, but did not fit an additive model. The incidence of HIV-associated TB increased significantly during the study, with no corresponding change in HIV-negative rates, to reach 16.1 per 100 person-years among HIV-positive silicotics.

CONCLUSIONS

The risks of silicosis and HIV infection combine multiplicatively, so that TB remains as much a silica-related occupational disease in HIV-positive as in HIV-negative miners, and HIV-positive silicotics have considerably higher TB incidence rates than those reported from other HIV-positive Africans. The increasing impact of HIV over time may indicate epidemic TB transmission with rapid disease development in HIV-infected miners. Similar but currently unrecognized interactions may be contributing to TB control problems in other industrializing countries affected by the HIV epidemic.

Tuberculosis: associations with HIV and socioeconomic status in rural Malawi

Tuberculosis (TB) is associated with human immunodeficiency virus (HIV) infection, increasing age and male sex, but less is known about other risk factors in developing countries. As part of the Karonga Prevention Study in northern Malawi, we conducted a retrospective cohort study in the general population to assess risk factors for the development of TB. Individuals were identified in 1986-89 and TB cases diagnosed up to 1996 were included. TB was confirmed in 62/11,059 (0.56%) HIV negative individuals and 7/182 (3.9%) HIV positive individuals (relative risk 7.1, 95% confidence interval 3.2-15.7). This association was little altered by adjustment for age, sex or socioeconomic factors. The risk of TB was higher in those aged over 30 years than in younger individuals, in men than in women, in those engaged in occupations other than farming than in subsistence farmers, in those living in households with burnt brick dwellings than in those with less well built dwellings, and in those with some schooling than in those with none. These associations persisted after adjusting for age, sex, HIV status and population density. The absolute risks of TB were low in this study due to the passive follow-up and strict diagnostic criteria. The relative risk with HIV was of a similar magnitude to that measured elsewhere. Increased risks of TB with age and in men are expected. Associations with measures of higher socioeconomic status were unexpected. They may reflect a greater likelihood of diagnosis in this group.