What is the difference between the transmission of tuberculosis (TB) and viral infections?

From the Guidelines

Tuberculosis (TB) is spread differently from most viral infections primarily because it is caused by a bacterium, Mycobacterium tuberculosis, which is transmitted through airborne particles, as opposed to viral infections which can spread through multiple routes such as direct contact, fomites, or bodily fluids 1. The key differences in transmission between TB and viral infections can be summarized as follows:

• Airborne transmission: TB is transmitted through airborne particles, whereas many viral infections can spread through multiple routes.
• Prolonged exposure: TB typically requires prolonged exposure in enclosed spaces to transmit, whereas many viruses can spread through brief encounters.
• Latent phase: TB has a latent phase where infected individuals carry the bacteria without symptoms and aren't contagious, while viral infections typically have shorter incubation periods followed by contagious phases.
• Treatment: TB requires specific drug combinations for treatment, such as isoniazid, rifampin, ethambutol, and pyrazinamide, for 6-9 months, whereas viral infections often have no specific treatment or require different antiviral medications 1. Some of the key factors that influence the transmission of TB include:
• The virulence of the infecting strain of M. tuberculosis
• The characteristics of the source-case and the person exposed to the source-person
• The environment in which the exposure takes place
• The use of effective chemotherapy, which can rapidly reduce the transmission of TB, including drug-resistant strains 1. It's worth noting that the transmission of TB can be reduced through the use of effective infection control measures, such as isolation, respirators, and cough etiquette, as well as through the rapid diagnosis and treatment of TB cases 1.

From the Research

Transmission of Tuberculosis

• Tuberculosis is caused by Mycobacterium tuberculosis, transmitted primarily by inhalation of aerosolized droplets containing the organisms 2.
• The infection occurs in the respiratory tract and the tubercle bacilli spread via the lymphatic system and bloodstream to many different organs 2.

Comparison with Virus Transmission

• Unlike viral transmission, which can occur through various routes such as skin contact, contaminated food and water, and vector-borne transmission, tuberculosis is primarily spread through inhalation of aerosolized droplets 2.
• The mode of transmission of tuberculosis is more similar to that of other bacterial infections, such as pneumonia, which is also spread through respiratory droplets 2.

Key Differences

• Tuberculosis has a longer incubation period compared to many viral infections, with approximately 10% of infected individuals developing active disease 2.
• The risk of developing tuberculosis is increased by immunosuppression caused by systemic diseases or medication, which is not typically a factor in viral transmission 2.
• Tuberculosis can affect many organs and systems, including lymph nodes, larynx, middle ear, genitourinary tract, musculoskeletal system, central nervous system, gastrointestinal tract, pericardium, and skin, whereas viral infections often have more specific target organs 2.

Treatment and Prevention

• The treatment of tuberculosis typically involves a combination of antibiotics, such as isoniazid, rifampicin, pyrazinamide, and ethambutol, which is different from the treatment of viral infections, which often relies on antiviral medications or supportive care 3, 4.
• The prevention of tuberculosis transmission relies on public health measures, such as directly observed therapy (DOT) and contact tracing, which are not typically used for viral infections 3, 4.