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Since they were previously exposed, the immune system’s memory T cells quickly release cytokines to try and control the new outbreak, which forms more areas of caseous necrosis, this time, though, it tends to cavitate, or form cavities, which can allow the bacteria to disseminate, or spread through airways and lymphatic channels to other ...
If TB bacteria gain entry to the blood stream from an area of damaged tissue, they can spread throughout the body and set up many foci of infection, all appearing as tiny, white tubercles in the tissues. [96] This severe form of TB disease, most common in young children and those with HIV, is called miliary tuberculosis. [97]
A misconception is that M. tuberculosis can be spread by shaking hands, making contact with toilet seats, sharing food or drink, or sharing toothbrushes. However, major spread is through air droplets originating from a person who has the disease either coughing, sneezing, speaking, or singing. [17]
Bacteria enter the body through inhalation and are ingested by white blood cells called macrophages. [1] Surviving bacteria multiply and can spread to other areas of the body. This can occur through the lymphatic system , blood, or via direct spread from infected tissues.
Respiratory droplet transmission is the usual route for respiratory infections. Transmission can occur when respiratory droplets reach susceptible mucosal surfaces, such as in the eyes, nose or mouth. This can also happen indirectly via contact with contaminated surfaces when hands then touch the face. Respiratory droplets are large and cannot ...
An infectious disease agent can be transmitted in two ways: as horizontal disease agent transmission from one individual to another in the same generation (peers in the same age group) [3] by either direct contact (licking, touching, biting), or indirect contact through air – cough or sneeze (vectors or fomites that allow the transmission of the agent causing the disease without physical ...
Fecal–oral transmission is primarily considered as an indirect contact route through contaminated food or water. However, it can also operate through direct contact with feces or contaminated body parts, such as through anal sex. [2] [3] It can also operate through droplet or airborne transmission through the toilet plume from contaminated ...
Miliary tuberculosis is a form of tuberculosis that is characterized by a wide dissemination into the human body and by the tiny size of the lesions (1–5 mm). Its name comes from a distinctive pattern seen on a chest radiograph of many tiny spots distributed throughout the lung fields with the appearance similar to millet seeds—thus the term "miliary" tuberculosis.