Infectious diseases in children and body mass index in young adults

Association of underweight status with the risk of tuberculosis: a nationwide population-based cohort study

In studies evaluating the association between body mass index (BMI) and risk of tuberculosis (TB), the data for the underweight population has been limited and results were conflicting. Our study aimed to evaluate whether being underweight increases the risk of TB using a nationwide representative sample from the Republic of Korea. A large population-based cohort study of over ten million subjects who participated in the health screening in 2010 was performed using the Korean National Health Insurance database 2010–2017. We evaluated the incidence and risk of TB by BMI category (kg/m²) for Asians using a multivariable Cox regression model, adjusting for age, sex, smoking, alcohol consumption, regular exercise, low-income state, and underlying hypertension, diabetes mellitus, and dyslipidemia. To evaluate the association between BMI and TB risk, the underweight population was further subdivided according to the degree of thinness. During 70,063,154.3 person-years of follow-up, 52,615 of 11,135,332 individuals developed active TB with an incidence of 0.75 per 1000 person-years. Overall, there was a log-linear inverse relationship between TB incidence and BMI, within the BMI range of 15–30 kg/m² (R² = 0.95). The estimated adjusted hazard ratio (HR) for incident TB in the underweight population (BMI < 18.5) was 2.08 (95% confidence intervals, CI 2.02–2.15), overweight (23 ≤ BMI < 25) was 0.56 (0.55–0.58) and obese (BMI ≥ 25) was 0.40 (0.39–0.41) relative to the normal weight population. Among the underweight population, TB risk increased as the degree of thinness increased (adjusted HR = 1.98, 1.91–2.05; 2.50, 2.33–2.68; and 2.83, 2.55–3.15, for mild, moderate and severe thinness, respectively) (p for trend < 0.001). We found a significant inverse relationship between BMI and TB incidence, which was especially profound in the underweight population. Public health strategies to screen TB more actively in the underweight population and improve their weight status may help reduce the burden of TB.

Twenty-five years of research about adipogenic adenoviruses: A systematic review

Infectious etiology is implicated in chronic diseases such as gastric ulcer or atherosclerosis. However, "infection" is a recent term in the field of obesity. Since the first report in 1982 of obesity due to infection, several microbes have been linked to obesity. Among the adipogenic microbes, avian adenovirus SMAM-1 and human adenovirus Ad36 have been studied most extensively for the past 25 years. Here, we present a systematic review of literature about SMAM-1 and Ad36. Reports from North America, Europe, and Asia reveal strong evidence that Ad36 causes obesity in animals and paradoxically improves glycemic control, and in vitro data provides mechanistic explanation. Considering that experimental Ad36 infection of humans is unlikely, its causative role in human obesity or glycemic control has not been demonstrated unequivocally. Nonetheless, most, but not all, observational studies in children and adults link Ad36 infection to obesity and improvement in glycemic control. The E4orf1 gene of Ad36 was identified as responsible for better glycemic control. Overall, 25 years have considerably advanced knowledge about the role of infection in obesity. Potential translational benefits include the development of vaccines to prevent Ad36-induced obesity and drug development based on the E4orf1 protein to improve glycemic control.