health

1. What Is Tuberculosis?
2. How Is Tuberculosis Spread?
3. Who Gets Tuberculosis?
4. Symptomes.
5. Diagnosis.
6. Treatment.
7. How Can the Spread of Infection Be Stopped?

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Hippocrates (c.460–c.377 b.c.e.), a Greek physician who in modern
times is called “the father of medicine,” accurately described tuberculosis
(TB) about 2,400 years ago when he coined the term “phthisis,” which
means to melt and to waste away. In later years, tuberculosis was called
consumption because people with TB tended to waste away as if they
were being slowly consumed.

Tuberculosis (too-ber-ku-LO-sis) is a bacterial infection that spreads
through the air and usually affects the lungs. Worldwide, it kills more
people than any other infectious disease.
Tuberculosis is a potentially serious infection caused by Mycobacterium
tuberculosis bacteria. The bacteria are spread mainly through the air from
an infected person to others nearby. TB usually infects the lungs, but it
can also cause symptoms that affect the whole body.
Not everyone who is infected with tuberculosis bacteria (called primary
infection) gets sick or infects other people. About 10 million people in
the United States are infected with tuberculosis, but only 1 out of every
10 of these people develops active TB (called secondary infection). Of the
10 percent of infected people who ultimately develop active disease, about
one-third to one-half manifest illness in the first two months to two years
after they are initially infected; the remainder develop active TB later in life.
People with primary TB infection are protected from developing
active TB by their body’s immune system*, but they still carry the bacteria
in their bodies. As long as the infection is inactive, they cannot spread
TB. They can, however, develop active (secondary) TB years later if their
immune systems are weakened by other diseases such as HIV/AIDS or
diabetes, or by alcohol or drug abuse. Most people with active TB who
are treated can be cured. If left untreated, however, TB is fatal 40 to
60 percent of the time. Importantly, individuals discovered to have TB
infection can be given preventive therapy, which can reduce the lifetime
risk of developing active disease by at least 70 percent.

An Ancient Disease

When people with active tuberculosis of the lungs or throat cough or
sneeze, they spread bacteria through the air. Other people who breathe
the same air may become infected with the bacteria, which can lodge in
the lungs and begin to grow. From there, the bacteria can move through
the blood and settle in almost any other part of the body, including the
urinary tract, brain, kidneys, lymph nodes*, bones, joints, peritoneum*,
and heart.
Spending lots of time in close quarters with a person who has untreated
active TB is the most common way to becoming infected. Even with close
contact, however, only one-third of people who are exposed to TB infection
become infected. Within a few weeks of the start of effective treatment,
patients are no longer contagious. TB in parts of the body other than the
lungs and throat usually is not contagious. People who have primary tuberculosis
cannot spread it to others.

Tuberculosis can strike anyone, but some people are more likely to get it
than others:

• Babies and young children who have weak immune systems
• People with medical problems, such as HIV (the virus that causes
  AIDS) infection, alcohol or drug abuse, poor nutrition, diabetes,
  certain types of cancer, or severe kidney diseases that weaken their
  immune systems
• People who take certain medications, such as corticosteroid drugs
  that weaken their immune systems
• People who have had organ transplants and take drugs to suppress
  their immune systems
• People who do not get good medical care due to poverty or
  homelessness.
  

Archeologists have found evidence of tuberculosis in skeletons
from Peru that are 1,300 years old and in Egyptian skeletons
dating back 3,400 years. But TB apparently did not emerge as a
major killer until the 1600s in Europe.
By the 1800s the Industrial Revolution had created ideal conditions
for TB to spread—overworked, underfed people crowded together in
tenements and factories with poor ventilation. TB became the leading
killer in many European and U.S. cities. It even took on an aura
of romance, as it sapped the life from many literary fi gures, both real
(British poet John Keats, 1795–1821) and fi ctional (Mimi, the heroine
of the opera La Boheme).
It was unclear whether TB was inherited or infectious until the
1880s, when the German physician Robert Koch (1843–1910) identifi
ed the TB bacterium. Treatment consisted of rest, rich food, and fresh
air, often provided in special TB hospitals called sanatoriums that were
built in mountain areas.
Streptomycin, an antibiotic that kills TB bacteria, was introduced
in the 1940s. Isoniazid, another eff ective antibiotic, came into use in the
1950s. Th ese drugs dramatically lowered the number of TB cases over
the next few decades. Both remained in use in the early 2000s, along
with other drugs. As drug-resistant strains of TB continued to emerge,
research toward better treatment continued.

Primary tuberculosis does not cause any symptoms. The symptoms of
secondary (active) tuberculosis depend on where in the body the tuberculosis
bacteria are growing.
Tuberculosis of the lungs may cause a cough that does not go away,
pain in the chest, and coughing up blood or sputum*. Other common
symptoms include feeling tired all the time, weight loss, lack of appetite,
fever, chills, and sweating at night. People with secondary TB may feel
sick quickly or develop symptoms gradually over weeks or months, and
they may be highly contagious until treated. However, some people with
active TB feel well and only cough occasionally.
Tuberculosis bacteria typically infect the lungs, but they can infect
almost any part of the body:

• Urinary tract. Symptoms may include repeated urinary tract infections,
  repeated fevers, or pus or blood in the urine for which there
  is no other explanation.
• Brain. Tuberculosis bacteria can infect the membranes surrounding
  the brain and spinal cord (the meninges), especially in babies and
  young children. Symptoms of tuberculosis meningitis may include
  headaches, seizures, or abnormal behavior.
• Lymph nodes. Tuberculosis bacteria can infect the small organs
  commonly known as lymph nodes. Symptoms may include inflammation
  and swelling of the nodes anywhere in the body, including
  in the neck.
• Bones and joints. Tuberculosis bacteria can infect the skeleton,
  especially in the elderly. Symptoms may include fever; pain; and
  stiff, swollen joints. The lower spine and weight-bearing joints are
  most often affected.
• Peritoneum. Tuberculosis bacteria can infect the inner lining of
  the abdomen. Symptoms may include a fever and buildup of fluid
  inside the abdomen, which often goes along with a buildup of fluid
  around the lungs.
• Heart. Tuberculosis bacteria can infect the sac enclosing the heart.
  Although this is extremely rare, the death rate is high when it does
  occur. Symptoms may include shortness of breath, chest pain, and
  fever.

Tuberculosis Timeline

A skin test known as the Mantoux or PPD (purified protein derivative)
test is used to diagnose primary tuberculosis. For this test, a small amount
of testing fluid is injected with a fine needle just beneath the skin on the
lower part of the arm. Two to three days later, a healthcare professional
checks the arm to see if a bump has formed at the site of the injection.
If a bump wider than a certain size is present (for most people, 10 to 15
millimeters of a half inch), the patient most likely has been infected by
TB bacteria; this is known as a positive test. Doctors may order more
tests, such as a chest x-ray and a test of sputum that is coughed up, to see
if secondary (active) tuberculosis is present.

Primary tuberculosis People with primary tuberculosis who are in
high-risk groups for developing active TB may be given medication to
help ward off the illness. This treatment is called preventive therapy. People
under age 35 with primary tuberculosis who are not in high-risk groups also
may benefit from preventive therapy. The goal is to kill the bacteria that are
not doing any harm now but that could cause active TB in the future. The
medication usually given for this purpose is called isoniazid (INH). To kill
these bacteria, however, INH must be taken every day for 6 to 12 months.

Secondary (active) tuberculosis Secondary (active) tuberculosis
can often be cured with medication. People with secondary TB usually
take several different drugs because doing so is more effective at killing all
the bacteria and preventing the formation of resistant bacteria that cannot
be killed by drugs.
Although they usually feel better after a few weeks of treatment, people
with active TB must continue to take their medication correctly for
the full length of the treatment or they can become sick again. Because
people with tuberculosis of the lungs or throat can spread the infection
to others, they need to stay home from school or work until they are no
longer infectious to others, which usually takes several weeks.
People with tuberculosis who are sick enough to go to the hospital
may be put in a special room with an air vent system that keeps the bacteria
from spreading. Doctors, nurses, and others who work in such rooms
must wear special facemasks to protect themselves from breathing the
bacteria.

The Centers for Disease Control and Prevention recommends that certain
people at risk for getting tuberculosis get the skin test yearly so that treatment
can begin immediately if they are found to have TB. These include:

• People who have spent a lot of time with other people who are
  infected with TB
• People who think they may have caught the disease for other reasons
• People who have HIV infection or other medical problems that put
  them at high risk for getting tuberculosis
• People who inject street drugs
• People who come to the United States from countries where tuberculosis
  is more common (most countries in Latin America and the
  Caribbean, Africa, and all of Asia except for Japan)
• People who live in the United States in environments in which
  tuberculosis is common (homeless shelters, migrant farm camps,
  prisons, and some nursing homes)

People who have tuberculosis can keep from spreading the infection
by taking all their medication exactly as prescribed; visiting their doctors
regularly; staying away from people until they are no longer infectious to
others; covering their mouths with a tissue when they cough, sneeze, or
laugh; and airing out the room often.
Tuberculosis bacteria can only be spread through the air. Other people
cannot be infected by shaking hands, sitting on toilet seats, or sharing
dishes or personal items with people who have tuberculosis. If close
contact with someone who has TB is necessary, a special type of facemask
(called a respirator) should be worn.
Bacillus Calmette-Guerin (BCG) is a vaccine* that can help protect
people against tuberculosis infection. It does not always work and may
cause a positive reaction to the tuberculosis skin test, making it harder to
tell if people become infected despite the vaccine. BCG is not widely used
in the United States, but it often is given to babies and young children in
countries where tuberculosis is common.