Trends in tuberculosis in the UK

Review canine tuberculosis - An emerging concern

Canine mycobacterial disease was first recognised over 100 years ago but is now an emerging concern. All reported cases of tuberculous disease in dogs have been caused by infection with one of three Mycobacterium tuberculosis-complex (MTBC) organisms (M. tuberculosis, Mycobacterium bovis, and Mycobacterium microti). Molecular PCR and interferon-gamma release assays offer alternative or complementary diagnostic pathways to that of specialist culture, which is limited by availability, sensitivity, and the time it takes to get a result. Optimised triple antimicrobial protocols offer an excellent chance of a successful outcome in dogs where treatment can be considered and is attempted. In this review, the clinical presentation, diagnosis, treatment, and prognosis of canine tuberculosis are discussed.

Canine tuberculosis: A review of 18 new and 565 previously reported confirmed cases

Cases of canine tuberculosis, a zoonotic infection of significant public health significance, are typically only sporadically reported in the literature. For this observational study, case details were collated both retrospectively and prospectively for dogs infected with Mycobacterium tuberculosis-complex (MTBC) organisms. A total of 18 previously unreported cases as well as 565 historically reported confirmed cases were reviewed. A variety of diagnostic techniques were used to make a confirmed diagnosis of tuberculosis (culture, interferon-gamma release assay [IGRA], and PCR). The reference standard for diagnosis is culture; however, this was negative or not attempted in some dogs. Where fully speciated, all cases were caused by infection with one of three MTBC organisms: M. tuberculosis, Mycobacterium bovis, or Mycobacterium microti. This study includes the first documented canine infections with M. microti in the UK. All cases were assigned to one of four clinical groups based on the presenting signs: 44.1% were primarily pulmonary, 14.5% were primarily abdominal, and the remainder were disseminated or miscellaneous. The development of adjunctive tests remains necessary to support early treatment decisions pending reporting of culture for MTBC organisms, which can take weeks to months. Definitive treatment, where attempted, was successful in most cases. Of the 13 dogs treated by the authors with triple combination antimicrobial therapy, a good clinical outcome was seen in 12 (92%) of them.

Accuracy of upper respiratory tract samples to diagnose Mycobacterium tuberculosis: a systematic review and meta-analysis

BACKGROUND

Pulmonary tuberculosis due to Mycobacterium tuberculosis can be challenging to diagnose when sputum samples cannot be obtained, which is especially problematic in children and older people. We systematically appraised the performance characteristics and diagnostic accuracy of upper respiratory tract sampling for diagnosing active pulmonary tuberculosis.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, Cinahl, Web of Science, Global Health, and Global Health Archive databases for studies published between database inception and Dec 6, 2022 that reported on the accuracy of upper respiratory tract sampling for tuberculosis diagnosis compared with microbiological testing of sputum or gastric aspirate reference standard. We included studies that evaluated the accuracy of upper respiratory tract sampling (laryngeal swabs, nasopharyngeal aspirate, oral swabs, saliva, mouth wash, nasal swabs, plaque samples, and nasopharyngeal swabs) to be tested for microbiological diagnosis of tuberculous (by culture and nucleic acid amplification tests) compared with a reference standard using either sputum or gastric lavage for a microbiological test. We included cohort, case-control, cross-sectional, and randomised controlled studies that recruited participants from any community or clinical setting. We excluded post-mortem studies. We used a random-effects meta-analysis with a bivariate hierarchical model to estimate pooled sensitivity, specificity, and diagnostics odds ratio (DOR; odds of a positive test with disease relative to without), stratified by sampling method. We assessed bias using QUADAS-2 criteria. This study is registered with PROSPERO (CRD42021262392).

FINDINGS

We screened 10 159 titles for inclusion, reviewed 274 full texts, and included 71, comprising 119 test comparisons published between May 13, 1933, and Dec 19, 2022, in the systematic review (53 in the meta-analysis). For laryngeal swabs, pooled sensitivity was 57·8% (95% CI 50·5-65·0), specificity was 93·8% (88·4-96·8), and DOR was 20·7 (11·1-38·8). Nasopharyngeal aspirate sensitivity was 65·2% (52·0-76·4), specificity was 97·9% (96·0-99·0), and DOR was 91·0 (37·8-218·8). Oral swabs sensitivity was 56·7% (44·3-68·2), specificity was 91·3% (CI 81·0-96·3), and DOR was 13·8 (5·6-34·0). Substantial heterogeneity in diagnostic accuracy was found, probably due to differences in reference and index standards.

INTERPRETATION

Upper respiratory tract sampling holds promise to expand access to tuberculosis diagnosis. Exploring historical methods using modern microbiological techniques might further increase options for alternative sample types. Prospective studies are needed to optimise accuracy and utility of sampling methods in clinical practice.

FUNDING

UK Medical Research Council, Wellcome, and UK Foreign, Commonwealth and Development Office.

Changing patterns of household transmission of tuberculosis in an eastern state of India: The impact of COVID19 pandemic

BACKGROUND

The COVID-19 Pandemic has affected many components of the Tuberculosis (TB) control program. Due to lockdown and restrictions, people, including TB patients, might have spent more time in the household. There might be an increased TB transmission among the household contacts (HHC). The current study was conducted to measure the household transmission of TB and also find out the relationship with several clinico-social factors.

METHODS

Contact tracing data of West Bengal, India, was extracted from Nikshay portal of Central TB Division, Government of India. The anonymized data was divided into two parts, firstly before the lockdown initiation in India and secondly during the lockdown. A modified Poisson regression model was developed to determine the statistical association between clinico-social variables and the pandemic with household-level secondary TB cases.

RESULTS

There was a 30% reduction in daily TB case notification, but the proportion of HHC screened was 4% higher during the pandemic than the pre-pandemic period. The secondary attack rate of household TB disease transmission was 34% lower during the pandemic period. Index TB patients aged under ten years, microbiologically positive, Drug-Resistant TB, having three or more HHCs, treatment delay more than seven days, notified from the private sector, and diagnosis during the pre-pandemic period was found to be independently associated with a higher risk of having a secondary TB case at household.

CONCLUSION

The risk of household TB transmission was significantly lower during the pandemic period compared to the pre-pandemic period, which may be due to better infection prevention and control practices.

Nutritional Supplementation Would Be Cost-Effective for Reducing Tuberculosis Incidence and Mortality in India: The Ration Optimization to Impede Tuberculosis (ROTI-TB) Model

BACKGROUND

Undernutrition is the leading cause of tuberculosis (TB) in India and is associated with increased TB mortality. Undernutrition also decreases quality of life and economic productivity.

METHODS

We assessed the cost-effectiveness of providing augmented rations to undernourished Indians through the government's Targeted Public Distribution System (TPDS). We used Markov state transition models to simulate disease progression and mortality among undernourished individuals in 3 groups: general population, household contacts (HHCs) of people living with TB, and persons living with human immunodeficiency virus (HIV). The models calculate costs and outcomes (TB cases, TB deaths, and disability-adjusted life years [DALYs]) associated with a 2600 kcal/day diet for adults with body mass index (BMI) of 16-18.4 kg/m2 until they attain a BMI of 20 kg/m2 compared to a status quo scenario wherein TPDS rations are unchanged. We employed deterministic and probabilistic sensitivity analyses to test result robustness.

RESULTS

Over 5 years, augmented rations could avert 81% of TB cases and 88% of TB deaths among currently undernourished Indians. Correspondingly, this intervention could forestall 78% and 48% of TB cases and prevent 88% and 70% of deaths among undernourished HHCs and persons with HIV, respectively. Augmented rations resulted in 10-fold higher resolution of undernutrition and were highly cost-effective with (incremental cost-effectiveness ratio [ICER] of $470/DALY averted). ICER was lower for HHCs ($360/DALY averted) and the HIV population ($250/DALY averted).

CONCLUSIONS

A robust nutritional intervention would be highly cost-effective in reducing TB incidence and mortality while reducing chronic undernutrition in India.

Population-based sequencing of Mycobacterium tuberculosis reveals how current population dynamics are shaped by past epidemics

Transmission is a driver of tuberculosis (TB) epidemics in high-burden regions, with assumed negligible impact in low-burden areas. However, we still lack a full characterization of transmission dynamics in settings with similar and different burdens. Genomic epidemiology can greatly help to quantify transmission, but the lack of whole genome sequencing population-based studies has hampered its application. Here, we generate a population-based dataset from Valencia region and compare it with available datasets from different TB-burden settings to reveal transmission dynamics heterogeneity and its public health implications. We sequenced the whole genome of 785 Mycobacterium tuberculosis strains and linked genomes to patient epidemiological data. We use a pairwise distance clustering approach and phylodynamic methods to characterize transmission events over the last 150 years, in different TB-burden regions. Our results underscore significant differences in transmission between low-burden TB settings, i.e., clustering in Valencia region is higher (47.4%) than in Oxfordshire (27%), and similar to a high-burden area as Malawi (49.8%). By modeling times of the transmission links, we observed that settings with high transmission rate are associated with decades of uninterrupted transmission, irrespective of burden. Together, our results reveal that burden and transmission are not necessarily linked due to the role of past epidemics in the ongoing TB incidence, and highlight the need for in-depth characterization of transmission dynamics and specifically tailored TB control strategies.

A Spatial Analysis of Tuberculosis Related Mortality in South Africa

Background: South Africa, with an estimated annual tuberculosis (TB) incidence of 360,000 cases in 2019, remains one of the countries with the largest burden of TB in the world. The identification of highly burdened TB areas could support public health policy planners to optimally target resources and TB control and prevention interventions. Objective: To investigate the spatial epidemiology and distribution of TB mortality in South Africa in 2010 and its association with area-level poverty and HIV burden. Methods: The study analysed a total of 776,176 TB deaths for the period 2005-2015. Local and global and spatial clustering of TB death rates were investigated by Global and Local Moran's Indices methods (Moran's I). The spatial regression analysis was employed to assess the effect of poverty and HIV on TB mortality rates. Results: There was a significant decrease in TB mortality rate, from 179 per 100,000 population in 2005 to 60 per 100,000 population in 2015. The annual TB mortality rate was higher among males (161.5 per 100,000 male population; (95% confidence interval (CI) 132.9, 190.0) than among females (123.2 per 100,000 female population; (95% CI 95.6, 150.8)). The 35-44 age group experienced higher TB mortality rates, regardless of gender and time. Hot spot clusters of TB mortality were found in the South-Eastern parts of the country, whereas cold spot clusters were largely in the north-eastern parts. Tuberculosis death rates were positively associated with poverty, as measured by the South African Multidimension Poverty Index (SAMPI) as well TB death rates in the neighbouring districts. Conclusion: The findings of this study revealed a statistically significant decrease in TB deaths and a disproportionate distribution of TB deaths among certain areas and population groups in South Africa. The existence of the identified inequalities in the burden of TB deaths calls for targeted public health interventions, policies, and resources to be directed towards the most vulnerable populations in South Africa.

Non-neoplastic Soft Tissue Tumors and Tumor-like Lesions

Clinicians are commonly faced with patients presenting with a solitary palpable soft tissue mass. Most soft tissue lesions are benign, and not every mass is due to a neoplastic process. Many pathologies can mimic a malignant tumor. Despite appropriate clinicoradiologic assessment, these lesions can be mistaken for a soft tissue sarcoma and can lead to multiple investigations or an intervention, inconveniencing patients and leading to an increased health care cost. With the relevant clinical history, clinical examination, and specific imaging characteristics, the diagnosis can be narrowed. We present a pictorial review of soft tissue sarcoma mimics with guidance on appropriate differential diagnoses.

Social determinants of tuberculosis: context, framework, and the way forward to ending TB in India

INTRODUCTION

Social determinants are involved in the causation of TB and its adverse outcomes. This review was conducted to evolve a framework for action on social determinants with special reference to India in the context of the new END TB strategy.

AREAS COVERED

We reviewed the social context of TB in India as a neglected disease of the poor, its emergence in epidemic form in the colonial period, and the factors that resulted in its perpetuation and expansion in post-independence India. We examined the role of social determinants in two key pathways - the pathway of TB causation and its outcomes, and the care cascade for patients with TB, and its consequences. We reviewed the most important social determinants of TB including poverty, membership of certain castes and indigenous population, undernutrition and poor access to healthcare, especially in rural areas.

EXPERT OPINION

We suggest that TB elimination will require an optimal mix of enhanced biomedical and social interventions. TB elimination strategy in India needs a pro-poor model of patient - centered care inclusive of nutritional, psycho-social and financial support, universal health coverage, and social protection; and convergence with multi-sectoral efforts to address poverty, undernutrition, unsafe housing, and indoor pollution.

Impact of the COVID-19 Pandemic on Tuberculosis Control: An Overview

Throughout history, pandemics of viral infections such as HIV, Ebola and Influenza have disrupted health care systems, including the prevention and control of endemic diseases. Such disruption has resulted in an increased burden of endemic diseases in post-pandemic periods. The current coronavirus disease 2019 (COVID-19) pandemic could cause severe dysfunction in the prevention and control of tuberculosis (TB), the infectious disease that causes more deaths than any other, particularly in low- and middle-income countries where the burden of TB is high. The economic and health crisis created by the COVID-19 pandemic as well as the public health measures currently taken to stop the spread of the virus may have an impact on household TB transmission, treatment and diagnostic services, and TB prevention and control programs. Here, we provide an overview of the potential impact of COVID-19 on TB programs and disease burden, as well as possible strategies that could help to mitigate the impact.

Homozygosity for TYK2 P1104A underlies tuberculosis in about 1% of patients in a cohort of European ancestry

The human genetic basis of tuberculosis (TB) has long remained elusive. We recently reported a high level of enrichment in homozygosity for the common TYK2 P1104A variant in a heterogeneous cohort of patients with TB from non-European countries in which TB is endemic. This variant is homozygous in ∼1/600 Europeans and ∼1/5,000 people from other countries outside East Asia and sub-Saharan Africa. We report a study of this variant in the UK Biobank cohort. The frequency of P1104A homozygotes was much higher in patients with TB (6/620, 1%) than in controls (228/114,473, 0.2%), with an odds ratio (OR) adjusted for ancestry of 5.0 [95% confidence interval (CI): 1.96-10.31, P = 2 × 10-3]. Conversely, we did not observe enrichment for P1104A heterozygosity, or for TYK2 I684S or V362F homozygosity or heterozygosity. Moreover, it is unlikely that more than 10% of controls were infected with Mycobacterium tuberculosis, as 97% were of European genetic ancestry, born between 1939 and 1970, and resided in the United Kingdom. Had all of them been infected, the OR for developing TB upon infection would be higher. These findings suggest that homozygosity for TYK2 P1104A may account for ∼1% of TB cases in Europeans.