Disseminated tuberculosis (infectious)
Alternative names:
miliary tuberculosis; tuberculosis - disseminated
Definition:
A chronic, contagious
bacterial infection caused by mycobacterium tuberculosis,
which has spread to other organs of the body by the blood
or lymph system.
Causes, incidence, and risk factors:
The infection can develop after inhaling droplets sprayed
into the air as from a cough
or sneeze by someone infected with mycobacterium tuberculosis.
The disease is characterized by the development of granulomas
(granular tumors) in the infected tissues. The usual site
of the disease is the lungs, but other organs may be involved.
Primary infection is usually asymptomatic.
In the US, 95% of individuals will have healing of their primary
tuberculous lesions with no further evidence of disease. Disseminated
disease develops in the minority whose immune systems do not
successfully heal the primary infection. The disease may occur
within weeks after the primary infection, or may lie dormant
for years before causing illness. Infants and the elderly
are at higher risk for rapid progression to disease.
In disseminated disease, organs and tissues affected can include
the lining of the heart (pericardium), lining of the abdominal
cavity (peritoneum), larynx, bronchus, cervical lymph nodes,
bones and joints, organs of the male or female urinary and
reproductive (genitourinary) system, eye, stomach, lining
of the brain and spinal cord (meninges), and skin. The risk
of contracting TB increases
with the frequency of contact with people who have the disease,
crowded or unsanitary living conditions and poor nutrition.
Hispanics, Native Americans, and blacks are at higher risk
for developing the disease. An increased incidence
of TB has been seen recently in the United States. Factors
that may be causing this increase are tuberculous infection
in people with AIDS and
HIV infection, and increasing
number of homeless people. Another factor is the development
of drug-resistant strains of TB. Incomplete treatment of TB
infections (such as not taking medications for the prescribed
length of time) can contribute to the proliferation
of drug-resistant strains of bacteria. The incidence is 4
out of 10,000 people and increasing. Disseminated TB is more
common in AIDS patients. About half of AIDS patients with
a CD4 count less than 200 who develop TB will have disseminated
disease.
Update Date: 02/09/00
Updated by: J. Gordon Lambert, MD, Associate Medical Director,
Utah Health Informatics and adam.com
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