Tuberculosis (TB) is a disease caused by certain bacteria and can be spread
through the air from person to person. A person can easily contract TB when
their immune system is weak. Since HIV destroys the body’s immune system,
HIV positive people become highly vulnerable to TB. It is estimated that about
one third of the 34.4 million people living with HIV worldwide are co-infected
with TB.
How is TB spread?
TB is spread from person to person through the air. When a person with pulmonary
(lung) or laryngeal (throat) TB coughs or sneezes, droplets containing the bacteria
are released into the air. These tiny particles can stay in the air for several
hours. If another person inhales air containing these particles, transmission
of TB may occur.
The bacteria can then settle in the lungs for many years, or for life. They
can begin to multiply and can spread through the blood stream to cause disease
in other parts of the body, such as the lymph nodes, kidneys, spine and brain.
People at the highest risk of becoming infected with TB are close contacts
of someone who has infectious TB like family members, roommates, friends, or
co-workers.
What are the differences between TB infection and TB disease?
TB infection:
Most people who inhale TB bacteria and become infected are able to fight the
bacteria and stop them from causing disease. People with a TB infection usually
have no symptoms, do not feel sick, and cannot spread TB to others. Because
these bacteria are not active and can later become active, people with TB infection
can develop TB disease if their immune system is, or becomes weak, due to illness
or age. But, most people who have TB infections never develop TB disease.
TB disease:
TB bacteria can become active and start to grow if the immune system cannot
keep them under control. Some individuals may develop TB disease soon after
becoming infected, before their immune system can fight the bacteria. Others
may get sick later, if their immune system becomes weak for some reason, such
as illness or age. People infected with HIV are at high risk for TB infection
and TB disease due to their weakened immune systems.
How do HIV and TB infections affect each other?
Up to 50% of people living with HIV develop TB. Also, HIV is considered the
leading risk factor for reactivation of latent (dormant) TB infections. HIV-infected
people who become newly infected with TB progress rapidly to active TB. Studies
show that HIV speeds up the progress of TB infection, and having TB can make
HIV replicate more quickly in the body of an infected person.
Are there medication problems?
It can be difficult to take drugs for both TB and HIV at the same time. Many
anti-HIV drugs have an effect on the drugs used to fight TB, and vice versa.
Drugs commonly used to fight TB can decrease the levels of HIV drugs in the
blood to a level too low to control HIV. HIV drugs can raise the levels of TB
drugs high enough to cause serious side effects. If you are being treated for
both TB and HIV, you will need to work with your doctor or health care provider
to follow special
guidelines.
Additional information:
Measuring
Up A Health Surveillance Update on Canadian Children and Youth
For more information, contact your local
AIDS service organization or health care practitioner.
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