Tuberculosis risk factors
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Progression from TB infection to TB disease occurs when the TB bacilli overcome the immune system defenses and begin to multiply.
Risk Factors
Primary TB disease occurs soon after infection, however, the majority of cases occur with a latent infection, where there are no obvious symptoms. The dormant bacilli can cause tuberculosis in 2 to 23% of the latent cases, often many years after infection.[1] The risk of reactivation increases with immunosuppression, such as that caused by infection with HIV. In patients co-infected with HIV, the risk of reactivation increases to 10% per year.
The following people are at higher risk for active TB:
- Elderly
- Infants
- People with weakened immune systems, such as:
- Hematologic and reticuloendothelial disease
- End-stage kidney disease
- History of gastrectomy
- Or those taking medications, such as:
- Immunosuppressive medications, such as corticosteroids, tumor necrosis factor-alpha blockers[2]
The risk of contracting TB increases in cases where there is:
The following factors may increase the rate of TB infection in a population:
- Chest X-ray with evidence of previous TB disease
- Increase in HIV infections
- Increase in number of homeless people
- The appearance of drug-resistant strains of TB
Multidrug-Resistant Tuberculosis
Drug resistance is more common in people who:[3]
- 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
References
- ↑ Parrish N, Dick J, Bishai W (1998). "Mechanisms of latency in Mycobacterium tuberculosis". Trends Microbiol. 6 (3): 107–12. PMID 9582936.
- ↑ Mutlu G, Mutlu E, Bellmeyer A, Rubinstein I (2006). "Pulmonary adverse events of anti-tumor necrosis factor-alpha antibody therapy". Am J Med. 119 (8): 639–46. PMID 16887405.
- ↑ "Multidrug-resistant tuberculosis".