Obesity, diabetes and pneumonia: the menacing interface of non-communicable and infectious diseases.
OBJECTIVE
To review current knowledge on the epidemiological, clinical and biological impact of the pandemic of obesity and diabetes on pneumonias.


METHODS
We conducted a literature review using PubMed and EMBASE, supplemented by various sources. Given the disparate and fragmented nature of the literature, a formal systematic review was not possible.


RESULTS
In 2008, globally 10% of men and 14% of women were obese and an estimated 371 million had diabetes; half undiagnosed and many obese. Numbers are rising rapidly in low- and middle-income countries where the majority reside, but reliable data are lacking. The most frequent pneumonias in obesity and diabetes are tuberculosis, influenza and pneumococcal, staphylococcal and opportunistic pathogens. Diabetes impacts tuberculosis control and increases drug resistance and mortality. Mortality and morbidity from pneumococcal pneumonia and influenza are increased in obesity and diabetes. In addition to mechanical and physiological effects, there are considerable immunological abnormalities characterised by chronic, low-grade inflammation. Simultaneous up-regulation and dysregulation of both innate and adaptive immune responses impair control and killing of invading organisms. Prevention in those at risk is poorly practised, although screening for tuberculosis in diabetes is beginning in high-burden settings.


CONCLUSIONS
Pneumonia is a threat globally in obesity and diabetes with increased incidence and severity of disease. There is uncertainty about whether vaccines are equally effective in those with obesity and diabetes. Increased epidemiological, clinical and biological knowledge will be crucial to face this 21st century challenge.
Division of Epidemiology, Human Genetics and Environmental Sciences, University of Texas School of Public Health, Brownsville, TX, USA.
Susan P
SP
Fisher-Hoch
Christine E
CE
Mathews
Joseph B
JB
McCormick
D048909:Diabetes Complications / Q000276:immunology / Q000382:microbiology*; D003920:Diabetes Mellitus / Q000453:epidemiology; D005260:Female; D014943:Global Health; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology / Q000209:etiology; D008297:Male; D009765:Obesity / Q000150:complications* / Q000453:epidemiology / Q000276:immunology; D018410:Pneumonia, Bacterial / Q000453:epidemiology / Q000209:etiology*; D011024:Pneumonia, Viral / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology / Q000209:etiology
chronic inflammation; diabetes; obesity; pneumonia