Decline in overall, smear-negative and HIV-positive TB incidence while smear-positive incidence stays stable in Guinea-Bissau 2004-2011

Tobacco smoking impact on tuberculosis treatment outcome: an observational study from West Africa

OBJECTIVE

Both tuberculosis (TB) and tobacco smoking are preventable health hazards. Few studies have examined the relationship between TB and tobacco smoking in an African setting, where the two health burdens collide heavily. This study aimed to describe the severity of TB disease and treatment outcomes among smokers with TB compared with nonsmokers with TB in Guinea-Bissau.

METHODS

We conducted a prospective follow-up study between 2003-2017 in Guinea-Bissau, enrolling adult patients with TB classified as nonsmokers or smokers. Disease severity was assessed using the Bandim TBscore. Multivariate logistic and Cox proportional hazard regressions were used to analyse treatment outcomes.

RESULTS

Of 1780 included patients, 385 were smokers who had smoked for a median 10 years (interquartile range [IQR] 5-20). No difference in disease severity at the time of diagnosis was observed. Smokers were not significantly more prone to a nonsuccessful treatment outcome, although a trend was seen (adjusted odds ratio [OR] 1.24, 95% confidence interval [CI] 0.91-1.70), and smokers tended to be more often lost to follow-up, but this also was not a significant finding (adjusted hazard ratio [HR] 2.09, 95% CI 0.89-4.94).

CONCLUSION

In a TB high-endemic setting with few tobacco smokers, smoking was not associated with disease severity or worse outcome, possibly because of socioeconomic confounders.

Assessing gender differences among presumed and diagnosed patients with pulmonary TB: observations from Guinea-Bissau

BACKGROUND

Globally, more males than females are diagnosed with pulmonary TB (PTB); however, the cause of this gender disparity remains unknown. We aimed to assess gender differences in an observational cohort of patients with presumed PTB (prePTB) at the Bandim Health Project, Guinea-Bissau.

METHODS

Adult patients with signs and symptoms suggestive of PTB seeking medical care were invited to participate and were referred to comprehensive diagnostic work-up.

RESULTS

We included 2020 patients with prePTB; 54.6% were female. Females were younger than males and more often infected with HIV. More male patients with prePTB were diagnosed with PTB and the proportion of smear-positive cases was greater among males. There was no gender difference in loss to follow-up during the diagnostic process. Of 219 patients with PTB, 205 started treatment, with no difference between genders regarding pretreatment loss to follow-up or treatment outcome.

CONCLUSIONS

More women sought help for symptoms indicative of PTB, yet more men were diagnosed. Women did not have more clinically severe disease at presentation, did not drop out of diagnostic procedures more frequently and did not experience a worse outcome than men. This suggests that the gender gap in PTB is unlikely to be due solely to differences in care-seeking behaviour or diagnostic procedures in our setting.

Increasing smear positive tuberculosis detection using a clinical score - A stepped wedge multicenter trial from Africa

BACKGROUND

The Bandim TBscore is a clinical score that predicts treatment outcome in Tuberculosis (TB) patients and proved useful as an indicator of which healthcare-seeking adults to refer for sputum smear microcopy. We aimed to test in a randomized trial if the TBscore could be used to enhance the detection of smear positive (SP) TB.

METHODS

We carried out a stepped wedge cluster-randomized trial at six health centers in Bissau, Guinea-Bissau, and Gondar, Ethiopia. The primary outcome was diagnostic yield for SP TB. Secondary outcomes were successful treatment and effect on overall 12 months mortality. The study was registered at the Pan African Clinical Trials Registry (PACTR201611001838365).

RESULTS

We included 3571 adults. Overall, there was no effect of the intervention on SP PTB detected (OR 1.39 (95%CI 0.75 - 2.56). Analysis stratified by country, showed that the TBscore increased case detection in Gondar (OR 4.05 (95%CI 1.67 - 9.85)) but no effect was found in Bissau (OR 0.47 (95%CI 0.22 - 1.05)) where take-up was much lower. Overall mortality decreased during the intervention (HR 0.31 (95%CI 0.13-0.72)).

CONCLUSION

Using the TBscore for triage before smear microscopy may improve case detection and decrease mortality if there is sufficient laboratory capacity to increase sputum smears.

CLEC4E (Mincle) genetic variation associates with pulmonary tuberculosis in Guinea-Bissau (West Africa)

Tuberculosis (TB) is the leading cause of death from a single infectious agent. According to the WHO, 85% of cases in 2018 were pulmonary tuberculosis (PTB), making it the most prevalent form of the disease. Although the bacillus responsible for disease, Mycobacterium tuberculosis (MTB), is estimated to infect 1.7 billion people worldwide, only a small portion of those infected (5-10%) will transition into active TB. Because such a small fraction of infected people develop active disease, we hypothesized that underlying host genetic variation associates with developing active pulmonary disease. Variation in CLEC4E has been of interest in previous association studies showing either no effect or protection from PTB. For our study we assessed 60 SNPs in 11 immune genes, including CLEC4E, using a case-control study from Guinea-Bissau. The 289 cases and 322 controls differed in age, sex, and ethnicity all of which were included in adjusted models. Initial association analysis with unadjusted logistic regression revealed putative association with seven SNPs (p < 0.05). All SNPs were then assessed in an adjusted model. Of the six SNPs that remained significant, three of them were assigned to the CLEC4E gene (rs12302046, rs10841847, and rs11046143). Of these, only rs10841847 passed FDR adjustment for multiple testing. Adjusted regression analyses showed that the minor allele at rs10841847 associated with higher risk of developing PTB (OR = 1.55, CI = 1.22-1.96, p-value = 0.00036). Based on these initial association tests, CLEC4E seemed to be the predictor of interest for PTB risk in this population. Haplotype analysis (2-SNP and 3-SNP windows) showed that minor alleles in segments including rs10841847 were the only ones to pass the threshold of global significance, compared to other haplotypes (p-value < 0.05). Linkage disequilibrium patterns showed that rs12302046 is in high LD with rs10841847 (r2 = 0.67), and all other SNPs lost significance when adjusted for rs10841847 effects. These findings indicate that rs10841847 in CLEC4E is the single best predictor of pulmonary tuberculosis risk in our study population. These results provide evidence for the hypothesis that genetic variation of CLEC4E influences risk to TB in Guinea-Bissau.

Neonatal BCG vaccination and child survival in TB-exposed and TB-unexposed children: a prospective cohort study

OBJECTIVES

To assess the association between neonatal BCG vaccination and mortality between 28 days and 3 years of age among tuberculosis (TB)-exposed and TB-unexposed children.

DESIGN

Prospective cohort study.

SETTING

Bandim Health Project runs an urban Health and Demographic Surveillance site in Guinea-Bissau with registration of mortality, vaccination status and TB cases.

PARTICIPANTS

Children entered the analysis when their vaccination card was inspected after 28 days of age and remained under surveillance to 3 years of age. Children residing in the same house as a TB case were classified as TB-exposed from 3 months prior to case registration to the end of follow-up.

METHODS

Using Cox-proportional hazards models with age as underlying time scale, we compared mortality of children with and without neonatal BCG between October 2003 and September 2017.

MAIN OUTCOME MEASURE

HR for neonatal BCG compared with no neonatal BCG by TB-exposure status.

RESULTS

Among the 39 421 children who entered the analyses, 3022 (8%) had observation time as TB-exposed. In total, 84% of children received neonatal BCG. Children with neonatal BCG had lower mortality both in TB-exposed (adjusted HR: 0.57 (0.26 to 1.27)) and in TB-unexposed children (HR: 0.57 (95% CI 0.47 to 0.69)) than children without neonatal BCG. Children exposed to TB had higher mortality than TB-unexposed children if they had not received neonatal BCG.

CONCLUSION

Neonatal BCG vaccination was associated with lower mortality among both TB-exposed and TB-unexposed children, consistent with neonatal BCG vaccination having beneficial non-specific effects. Interventions to increase timely BCG vaccination are urgently warranted.

Feasibility and Effectiveness of Tuberculosis Active Case-Finding among Children Living with Tuberculosis Relatives: a Cross-Sectional Study in Guinea-Bissau

Background and objectives

The World Health Organization End tuberculosis (TB) Strategy, approved in 2014, aims at a 90% reduction in TB deaths and an 80% reduction in TB incidence rate by 2030. One of the suggested interventions is the systematic screening of people with suspected TB, belonging to specific risk groups. The Hospital Raoul Follereau (HRF) in Bissau, Guinea-Bissau, is the National Reference Hospital for Tuberculosis and Lung Disease of the country. We performed an active case-finding program among pediatric age family members and cohabitants of admitted adult TB patients, from January to December 2013.

Methods

Newly admitted adult patients with a diagnosis of TB were invited to bring their family members or cohabitants in childhood age for clinical evaluation in a dedicated outpatient setting within the hospital compound. All the children brought to our attention underwent a medical examination and chest x-ray. In children with clinical and/or radiologic finding consistent with pulmonary TB, a sputum-smear was requested.

Results

All admitted adult patients accepted to bring their children cohabitants. In total, 287 children were examined in 2013. Forty-four patients (15%) were diagnosed with TB. The number needed to screen (NNS) to detect one case of TB was 7. 35 patients (80%) had pulmonary TB; 2 of them were sputum smear-positive. No adjunctive personnel cost was necessary for the intervention.

Conclusions

A hospital-based TB active case-finding program targeted to high-risk groups like children households of severely ill admitted patients with TB can successfully be implemented in a country with limited resources.

Genomics of human pulmonary tuberculosis: from genes to pathways

Purpose of review

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), remains a major public health threat globally. Several lines of evidence support a role for host genetic factors in resistance/susceptibility to TB disease and MTB infection. However, results across candidate gene and genome-wide association studies (GWAS) are largely inconsistent, so a cohesive genetic model underlying TB risk has not emerged.

Recent Findings

Despite the difficulties in identifying consistent genetic associations, genetic studies of TB and MTB infection have revealed a few well-documented loci. These well validated genes are presented in this review, but there remains a large gap in how these genes translate into better understanding of TB. To address this, we present a pathway based extension of standard association analyses, seeding the results with the best validated genes from candidate gene and GWAS studies.

Summary

Several pathways were significantly enriched using pathway analyses that may help to explain population patterns of TB risk. In conclusion, we advocate for novel approaches to the study of host genetic analysis of TB that extend traditional association approaches.

Tuberculosis elimination in the post Millennium Development Goals era

The Millennium Development Goal for tuberculosis (TB) is to stop the increase in incidence and halve the mortality of TB between 1990 and 2015. This goal has now been reached on a global scale, although not in the most affected region of Africa. The new target is TB elimination, defined as one case of active TB per one million population per year, which is to be reached before 2050. This review will discuss the main tools in play, namely case-finding and new diagnostics, increased access and effectiveness of anti-TB therapy (directly observed therapy, short course (DOTS)), preventive therapy for latent infection, and vaccination. Each approach is discussed and a way forward in research and management is suggested.

Diabetes mellitus prevalence in tuberculosis patients and the background population in Guinea-Bissau: a disease burden study from the capital Bissau

BACKGROUND

Data regarding the association between diabetes mellitus (DM) and tuberculosis (TB) in Africa are scare. We did a DM screening survey among TB patients and non-TB controls in Guinea-Bissau.

METHODS

The study was conducted at the Bandim Health Project (BHP) in the capital Bissau. From July 2010 to July 2011, newly diagnosed TB cases were identified through a TB notification system. Concurrently, non-TB controls were selected randomly from the BHP's demographic surveillance database and visited at home. Participants were tested using fasting blood glucose (FBG) measurements. DM was diagnosed as FBG ≥ 7 mmol/l. Our survey was linked to the patient database at the only existing Diabetes Clinic in Bissau.

RESULTS

TB patients (n=110) were older than the controls (n=572) (35 vs 31 years; p=0.02), more often male (55% vs 37%; p<0.001) and had a lower body mass index (18.7 vs 24.2 kg/m(2); p<0.001). The prevalence of DM was 2.8% (3/107) for TB patients and 2.1% (11/531) for controls (p=0.64). Excluding two controls already receiving anti-diabetic treatment, the prevalence of DM was 2.8% (3/107) vs 1.7% (9/529) (p=0.44).

CONCLUSIONS

The prevalence of DM was low, also among TB patients. No association between DM and TB was found.

Impact of HIV-1, HIV-2, and HIV-1+2 dual infection on the outcome of tuberculosis

BACKGROUND

HIV-1 infection has been shown to impact the outcome of patients with tuberculosis (TB), but data regarding the impact of HIV-2 on TB outcomes are limited. The aim of this study was to assess the impact of HIV types on mortality among TB patients in Guinea-Bissau and to examine the predictive ability of the TBscoreII, a clinical score used to assess disease severity.

METHODS

In a prospective follow-up study, we examined the prevalence of HIV-1, HIV-2, and HIV-1+2 co-infection in TB patients in Guinea-Bissau, and the impact on outcomes at 12 months of follow-up. We included all adult TB patients in an observational TB cohort at the Bandim Health Project (BHP) in Guinea-Bissau between 2003 and 2013 and assessed survival status at 12 months after the start of treatment.

RESULTS

A total 1312 patients were included; 499 (38%) were female (male/female ratio 1.6). Three hundred and seventy-nine patients were HIV-infected: 241 had HIV-1, 93 had HIV-2, and 45 were HIV-1+2 dual infected. The HIV type-associated risk of TB was 6-fold higher for HIV-1, 7-fold higher for HIV-1+2 dual infection, and 2-fold higher for HIV-2 compared with the HIV-uninfected. Of the patients included, 144 (11%) died, 62 (12%) among females and 82 (9%) among males (hazard ratio (HR) 0.91, 95% confidence interval (CI) 0.64-1.30; p=0.596). Compared to male patients, female patients were younger (1 year younger, 95% CI 0.5-2; p=0.04), reported a longer duration of symptoms (14 days longer, 95% CI 4-25; p=0.003), and had a higher TBscoreII (0.5 points more, 95% CI 0.3-0.7; p<0.001). More females than males were HIV-infected (36% vs. 25%; p<0.001) and more females had a body mass index (BMI) <15 kg/m(2) (11% vs. 6%; p<0.001) and a mid upper arm circumference (MUAC) <200 mm (13% vs. 7%; p < 0.001). HIV infection increased the mortality risk, with HIV-1 infection displaying the highest HR (5.0, 95% CI 3.5-7.1), followed by HIV-1+2 (HR 4.2, 95% CI 2.2-7.8) and HIV-2 (HR 2.1, 95% CI 1.2-3.8). A TBscoreII ≥4 was associated with increased mortality (HR 2.2, 95% CI 1.5-3.1). Significantly increased HRs were found for signs of wasting; a BMI <18 kg/m(2) was associated with a HR of 1.8 (95% CI 1.3-2.6) and a MUAC <220 mm with a HR of 3.8 (95% CI 2.7-5.2).

CONCLUSION

The HIV type-associated risk of TB was much higher for HIV-1 patients and higher but less so for HIV-2 patients, compared with the HIV-uninfected. Clinical severity at presentation was also higher for HIV-infected patients, although less so for HIV-2-infected patients, and all HIV-infected patients had a poorer outcome than the uninfected; mortality was 4-5-fold higher for HIV-1 and dually infected patients and two-fold higher for HIV-2-infected patients. These differences between HIV types did not disappear after adjusting for CD4 count.