Deaths due to respiratory tract infections in Africa: a review of autopsy studies

Incidence and mortality of tuberculosis before and after initiation of antiretroviral therapy: an HIV cohort study in India

INTRODUCTION

India has the highest burden of tuberculosis (TB) in the world, but the epidemiology of HIV-associated TB is not well known.

METHODS

We describe the incidence and the mortality of TB from HIV diagnosis to antiretroviral therapy (ART) initiation (pre-ART group) and after ART initiation (on-ART group) in an HIV cohort study in Anantapur, India. Multivariable analysis of factors associated with TB was performed using competing risk regression and restricted cubic spline methods.

RESULTS

A total of 4590 patients and 3133 person-years (py) of follow-up were included in the pre-ART group, and 3784 patients and 4756 py were included in the on-ART group. In the pre-ART group, the incidence of TB was high during the first month after HIV diagnosis and dropped nearly four times soon after. In the on-ART group, the incidence of TB increased after ART initiation reaching a peak in the third month. The probability of having TB within 30 months was 22.3% (95% confidence interval [CI], 21.1-23.6) in the pre-ART group and 17.8% (95% CI, 16.3-19.3) in the on-ART group. In a multivariable analysis, women had a lower risk of TB in both groups. Poor socio-economical conditions were associated with an increased risk of TB in the pre-ART group, but not in the group on-ART. While the association between low CD4 counts and TB was strong in the pre-ART group, this association was weaker in the on-ART group, and the highest risk of TB was seen in those patients with CD4 counts around 110 cells/mm3. The cumulative incidence of mortality at 12 months in patients with TB was 29.6% (95% CI, 26.9-32.6) in pre-ART TB and 34.9% (95% CI, 31-39.1) in on-ART TB. Half deaths before ART initiation and two thirds of deaths after ART initiation occurred in patients with TB.

CONCLUSIONS

The high incidence and mortality of TB seen in this study underscore the urgent need to improve the prevention and diagnosis of HIV-associated TB in India. We found substantial differences between TB before and after ART initiation.

Emerging novel and antimicrobial-resistant respiratory tract infections: new drug development and therapeutic options

The emergence and spread of antimicrobial-resistant bacterial, viral, and fungal pathogens for which diminishing treatment options are available is of major global concern. New viral respiratory tract infections with epidemic potential, such as severe acute respiratory syndrome, swine-origin influenza A H1N1, and Middle East respiratory syndrome coronavirus infection, require development of new antiviral agents. The substantial rise in the global numbers of patients with respiratory tract infections caused by pan-antibiotic-resistant Gram-positive and Gram-negative bacteria, multidrug-resistant Mycobacterium tuberculosis, and multiazole-resistant fungi has focused attention on investments into development of new drugs and treatment regimens. Successful treatment outcomes for patients with respiratory tract infections across all health-care settings will necessitate rapid, precise diagnosis and more effective and pathogen-specific therapies. This Series paper describes the development and use of new antimicrobial agents and immune-based and host-directed therapies for a range of conventional and emerging viral, bacterial, and fungal causes of respiratory tract infections.

Tuberculosis in children

Tuberculosis (TB) is a major, but often unrecognised, cause of disease and death in young children from countries with high TB incidence rates among adults. It is also relevant to paediatricians in low-incidence countries, such as Australia, because of increased international travel, immigration and refugee resettlement. This manuscript provides a brief overview of the global TB disease burden, the natural history of disease in children, and offers guidance on the prevention, diagnosis and treatment of TB in children.

Rapid point of care diagnostic tests for viral and bacterial respiratory tract infections--needs, advances, and future prospects

Respiratory tract infections rank second as causes of adult and paediatric morbidity and mortality worldwide. Respiratory tract infections are caused by many different bacteria (including mycobacteria) and viruses, and rapid detection of pathogens in individual cases is crucial in achieving the best clinical management, public health surveillance, and control outcomes. Further challenges in improving management outcomes for respiratory tract infections exist: rapid identification of drug resistant pathogens; more widespread surveillance of infections, locally and internationally; and global responses to infections with pandemic potential. Developments in genome amplification have led to the discovery of several new respiratory pathogens, and sensitive PCR methods for the diagnostic work-up of these are available. Advances in technology have allowed for development of single and multiplexed PCR techniques that provide rapid detection of respiratory viruses in clinical specimens. Microarray-based multiplexing and nucleic-acid-based deep-sequencing methods allow simultaneous detection of pathogen nucleic acid and multiple antibiotic resistance, providing further hope in revolutionising rapid point of care respiratory tract infection diagnostics.

Tuberculosis in children

Many clinicians regard tuberculosis as an adult pulmonary disease, but tuberculosis (TB) is a major cause of disease, both pulmonary and extrapulmonary, and death in young children from TB-endemic countries, especially in areas affected by poverty, social disruption, and human immunodeficiency virus (HIV) infection. This article reviews the disease burden and the natural history of disease in children with TB. It also provides guidance regarding the diagnosis, treatment, and prevention of TB in children.

The role of rapid diagnostic tests in managing adults with pneumonia in low-resource settings

In well-resourced settings the systematic use of rapid diagnostics tests (e.g. pneumococcal urinary antigen test) that define the causal pathogen to direct therapy has not resulted in significantly improved outcomes in adults withpneumonia. The management of pneumonia in many low-resource settings is complicated by a substantial burden of tuberculosis and HIV-associated opportunistic infections, in addition to the usual spectrum of pathogens seenin well-resourced settings. Clinical features alone do not reliably distinguish between these different aetiologiesand physicians often have to treat empirically. Given the limitations in diagnostic laboratory capability present inmost low-resource settings, rapid and point-of-care diagnostic tests could become valuable tools to guide treatment decisions. Pneumococcal and Legionella urinary antigen tests are specific and moderately sensitive, but their utilityin low-resource settings is uncertain. The Xpert MTB/RIF (Cepheid, USA) platform and rapid assays for urinary lipoarabinomannan can substantially speed up tuberculosis diagnosis; the current challenge is to translate this intoearlier treatment and hopefully improve patient outcome. In HIV-infected patients, 1-3-β-D-glucan is a serum marker of Pneumocystis jirovecii infection with excellent sensitivity. Further studies are needed to assess the clinical utilityand cost-effectiveness of these rapid diagnostic assays when they are incorporated into treatment algorithms.

A prospective study of the prevalence of tuberculosis and bacteraemia in Bangladeshi children with severe malnutrition and pneumonia including an evaluation of Xpert MTB/RIF assay

BACKGROUND

Severe malnutrition is a risk factor for pneumonia due to a wide range of pathogens but aetiological data are limited and the role of Mycobacterium tuberculosis is uncertain.

METHODS

We prospectively investigated severely malnourished young children (<5 years) with radiological pneumonia admitted over a 15-month period. Investigations included blood culture, sputa for microscopy and mycobacterial culture. Xpert MTB/RIF assay was introduced during the study. Study children were followed for 12 weeks following their discharge from the hospital.

RESULTS

405 eligible children were enrolled, with a median age of 10 months. Bacterial pathogens were isolated from blood culture in 18 (4.4%) children, of which 72% were Gram negatives. Tuberculosis was confirmed microbiologically in 7% (27/396) of children that provided sputum - 10 by culture, 21 by Xpert MTB/RIF assay, and 4 by both tests. The diagnostic yield from induced sputum was 6% compared to 3.5% from gastric aspirate. Sixty (16%) additional children had tuberculosis diagnosed clinically that was not microbiologically confirmed. Most confirmed tuberculosis cases did not have a positive contact history or positive tuberculin test. The sensitivity and specificity of Xpert MTB/RIF assay compared to culture was 67% (95% CI: 24-94) and 92% (95% CI: 87-95) respectively. Overall case-fatality rate was 17% and half of the deaths occurred in home following discharge from the hospital.

CONCLUSION AND SIGNIFICANCE

TB was common in severely malnourished Bangladeshi children with pneumonia. X-pert MTB/RIF assay provided higher case detection rate compared to sputum microscopy and culture. The high mortality among the study children underscores the need for further research aimed at improved case detection and management for better outcomes.

Understanding the contribution of common childhood illnesses and opportunistic infections to morbidity and mortality in children living with HIV in resource-limited settings

OBJECTIVE

Although antiretroviral treatment (ART) has reduced the incidence of HIV-related opportunistic infections among children living with HIV, access to ART remains limited for children, especially in resource-limited settings. This paper reviews current knowledge on the contribution of opportunistic infections and common childhood illnesses to morbidity and mortality in children living with HIV, highlights interventions known to improve the health of children, and identifies research gaps for further exploration.

DESIGN AND METHODS

Literature review of peer-reviewed articles and abstracts combined with expert opinion and operational experience.

RESULTS

Morbidity and mortality due to opportunistic infections has decreased in both developed and resource-limited countries. However, the burden of HIV-related infections remains high, especially in sub-Saharan Africa, where the majority of HIV-infected children live. Limitations in diagnostic capacity in resource-limited settings have resulted in a relative paucity of data on opportunistic infections in children. Additionally, the reliance on clinical diagnosis means that opportunistic infections are often confused with common childhood illnesseswhich also contribute to excess morbidity and mortality in these children. Although several preventive interventions have been shown to decrease opportunistic infection-related mortality, implementation of many of these interventions remains inconsistent.

CONCLUSIONS

In order to reduce opportunistic infection-related mortality, early ART must be expanded, training for front-line clinicians must be improved, and additional research is needed to improve screening and diagnostic algorithms.

T cell susceptibility to HIV influences outcome of opportunistic infections

During HIV infection, the timing of opportunistic infections is not always associated with severity of CD4 T cell depletion, and different opportunistic pathogens reactivate at different CD4 T cell thresholds. Here, we examine how differences in the phenotype and function of pathogen-specific CD4 T cells influence susceptibility to HIV infection. By focusing on three common opportunistic infections (Mycobacterium tuberculosis, human papillomavirus, and cytomegalovirus), we investigate how differential depletion of pathogen-specific CD4 T cells impacts the natural history of these pathogens in HIV infection. A broader understanding of this relationship can better inform treatment strategies against copathogens.