What is the pathogenesis of tuberculosis?

What is the pathogenesis of tuberculosis?

Infection occurs when a person inhales droplet nuclei containing tubercle bacilli that reach the alveoli of the lungs. These tubercle bacilli are ingested by alveolar macrophages; the majority of these bacilli are destroyed or inhibited.

How does HIV affect tuberculosis?

People living with HIV are more likely than others to become sick with tuberculosis (TB). This is because HIV weakens the immune system, which makes it harder for the body to fight TB germs.

What is pathogenesis mechanism of HIV infection?

The pathogenesis of HIV is basically a struggle between HIV replication and the immune responses of the patient, via cell-mediated and immune-mediated reactions. The HIV viral burden directly and indirectly mediates CD4+ T-cell destruction.

How does HIV infection induces extreme susceptibility to tuberculosis?

HIV infection drives depletion of gut-associated Th17 CD4+ T cells. A major hallmark of HIV infection is chronic T-cell activation and progressive loss of CD4 T lymphocytes, which is considered to predispose the host to active TB (Geldmacher et al, 2012).

What is the pathogenesis of secondary tuberculosis?

Secondary tuberculosis begins if primary complex or minor disseminated lesions worsened by unknown cause such as cavity formation following softening or new productive typed necrosis formation based on the original lesion. Recently reinfection tuberculosis was seen among old aged persons.

What are the 4 stages of pathogenesis?

To cause disease, a pathogen must successfully achieve four steps or stages of pathogenesis: exposure (contact), adhesion (colonization), invasion, and infection.

What is the pathogenesis process?

Pathogenesis is the process by which an infection leads to disease. Pathogenic mechanisms of viral disease include (1) implantation of virus at the portal of entry, (2) local replication, (3) spread to target organs (disease sites), and (4) spread to sites of shedding of virus into the environment.

How does HIV affect the pathogenesis of tuberculosis?

Impact of HIV Infection on the Pathogenesis of Tuberculosis. 35) Although TB can be a relatively early manifestation of HIV infection, it is important to note that the risk of developing TB, and of disseminated infection, increases as the CD4 cell count decreases. Even with effective immune reconstitution with ART,…

When does the risk of TB increase with HIV?

TB can occur early in the course of HIV infection and throughout all stages of HIV infection. The risk of TB increases soon after infection with HIV; in a South African study of gold miners, the risk of TB doubled during the first year after HIV seroconversion.

How does TB spread from person to person?

TB can develop through progression of recently acquired infection (primary disease), reactivation of latent infection, or exogenous reinfection. Infection with M tuberculosis can occur when an individual exposed to an infectious case of TB inhales particles (<5 µm in size) containing the tubercle bacilli.

How many people are infected with tuberculosis in the world?

The World Health Organization (WHO) estimates that one third of the world’s population is infected with Mycobacterium tuberculosis, resulting in an estimated nearly 9 million new cases of active TB in 2010. Worldwide, 14.8% of TB patients have HIV coinfection, and as many as 50-80% have HIV coinfection in parts of sub-Saharan Africa ( Figure 1 ).