Tuberculosis risk factors

The risk factors for developing tuberculosis include: living or traveling to endemic areas for TB, elderly people and infants, immunosuppression, history of frequent or prolonged contact with infected patients, IV drug users, smoking, bad hygiene, and poor nutrition. In addition, the risk factors for multidrug-resistant TB include: non-adherence to treatment regimen, inadequate treatment for that bacterial strain, and contact with patients with multidrug-resistant TB.

Primary TB, which represents 1-5% cases, occurs after infection. However, most of the cases occur with latent infection which is asymptomatic. The dormant bacilli can cause tuberculosis in 2 to 23% of the latent cases, usually several years following the primary infection.^[1] The risk of reactivation is much higher with immunosuppression, such as HIV. In patients with HIV coinfection, the risk of reactivation increases reaching up to 10% per year.

The following are risk factors for active TB:^[2][3]

• Living or traveling to endemic areas (Sub-saharan African, Russia, India, Pakistan, China)
• Elderly
• Infants
• IV drug users
• Immunosuppression:

• AIDS
• Diabetes
• Silicosis
• Malignancy, such as head and neck cancers

• Hematologic and reticuloendothelial disease, such as leukemia and Hodgkin’s disease

• End-stage kidney disease
• History of gastrectomy
• Malabsorption syndrome

• Or those taking medications, such as:

• Chemotherapy
• Immunosuppressive medications, such as prolonged corticosteroid therapy, tumor necrosis factor-alpha blockers^[4]
• Tocilizumab

The risk of contracting TB increases in cases where there is:^[2]

• Frequent or prolonged contact with people who have TB
• Poor nutrition
• Smoking
• Bad hygiene

The following factors may increase the rate of TB infection in a population:^[2]

• Chest X-ray with evidence of previous TB disease (fibrotic lesions and nodules)
• Increased number of HIV infections
• Increased number of homeless people
• The appearance of drug-resistant strains of TB

• Treatment with the following drugs have been reported with increased risk of reactivation of latent tuberculosis.

• Adalimumab
• Alemtuzumab
• Belatacept
• Certolizumab pegol
• Canakinumab
• Etanercept
• Fluocortolone
• Golimumab
• Infliximab
• Rilonacept
• Ruxolitinib
• Saxagliptin
• Teriflunomide
• Tocilizumab
• Tofacitinib
• Vedolizumab

Drug resistance is more common in people who:^[5]

• Do not take their TB medicine regularly
• Do not take all of their TB medicine as told by their doctor or nurse
• Develop TB disease again, after having taken TB medicine in the past
• Come from areas of the world where drug-resistant TB is common
• Have spent time with someone known to have drug-resistant TB disease

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