Tuberculosis : Understanding risk factors and lung health

Introduction to tuberculosis-

TB involves the pathogenesis of Mycobacterium tuberculosis infection. It comes with a complex course including potential long latency periods, unrecognized re-infections, asymptomatic disease onset, lengthy treatment with multiple drugs. It is also associated with a widespread problem of drug resistance.

Associated comorbidities-

Co-infection with HIV and diabetes greatly increases mortality and risk of treatment failure of TB. TB management therefore needs an integrated approach. Every TB patient should be investigated for HIV and diabetes, and also vice versa.

Diabetes mellitus increases the risk of developing TB 2-3 times. It also comes with a risk of TB treatment failure, relapse and death.

Public Health Issues

increased risk of TB lies especially in low incidence countries, where infection control is very difficult.

 Co-morbidities like HIV, diabetes mellitus, viral hepatitis and alcohol, drug and cigarette use, psychological care are important components for optimal patient management, this thus ensures compliance.

 Understanding risk factors-

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The primary aim is to reduce transmission from infectious cases. In about 5% of infected cases, rapid progression occurs within 2 years. Also, The risk of progression is much higher in immunocompromized individuals.

The risk of infection following exposure is caused due to exogenous factors . it also depends on behavioural risk factors including smoking, alcohol, and indoor air pollution. In settings of overcrowding transmission will be high. Similarly,  delay in diagnosis, causes prolonged exposure to an infected person. coinfection, Diabetes, alcohol, malnutrition, tobacco smoke, and indoor air pollution are factors which accelerate progression to TB disease.

  • Malnutrition
  • Age
  • Smoking
  • Alcohol
  • Indoor pollution
  • Diabetes
  • Healthcare workers
  • Socioeconomic and behavioural factors


 malnutrition increases the risk of TB because of an impaired immune response. TB itself causes malnourishment because of decreasing appetite. malnourished children are twice as likely to contract TB.

Young Age

Children are at higher risk of contracting infection and disease. children less than 2 years of age get infected from the household source case, whereas, with children more than 2 years of age, majority get infected in the community. Household sputum positive source case is the single most important risk factor for children.


diabetic patients have a threefold increased risk of developing TB. Also poorer outcomes  are associated among diabetic patients

diabetes directly impairs the adaptive immune response. Also,There is a Decreased production of IFN-γ and other cytokines diminished T-cell immunity of diabetics

 Healthcare Workers

Healthcare workers are at increased risk of exposure to TB.

 Socioeconomic and Behavioural Factors

Rapid urbanization  and socioeconomic status influence  a person’s susceptibility to infection. People are exposed to several risk factors discuss which increases their risk. Due to a higher likelihood of being exposed to crowded, less ventilated places and have limited safe cooking practicing facilities.

Tobacco Smoke

There is an increased association between tobacco smoke and risk of TB. Smoking impairs clearance of mucosal secretion. It is also known to reduced phagocytic ability of alveolar macrophages  and decrease the immune response  due to nicotine.


Alcohol is a strong risk factor for TB disease . Reasons for increased risk include alteration in the immune system, specifically in altering the molecules responsible for cytokine production.

Indoor Air Pollution

  Firewood is as an independent risk factor for disease. Also biomass combustion is shown to release large carbon monoxide (CO), nitrogen oxide, formaldehyde, and polyaromatic hydrocarbons which can deposit in lung alveoli.


Screening for TB can reduce the risk of progression to disease among high risk individuals (close contacts, HIV infected individuals, health care workers, etc

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