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transmitted through direct contact with the infected person, especially their nasal discharges.
This is particularly difficult to prevent since a person is infectious before they begin to show
symptoms. The viruses usually establish contact with the cells of the nose, which then
produce clear liquid to trap these microorganisms and expel them from the body. This is
followed by sneezing and coughing, especially if the virus travels deeper into the airway.
Thick, yellow or green sputum being coughed is a sign of these microbes being attacked by
the host’s immune system. Antibiotics are useless against viral infections and the symptoms
usually subside after a week.
Tuberculosis
On the other end of the spectrum of infectious diseases of the respiratory tract is
tuberculosis, or TB. It is a bacterial infection caused by Mycobacterium tuberculosis and
until the advent of powerful antibiotics, could often lead to death after a painful illness. The
infection spreads by the transmission of live bacteria from the infected person, especially
through oral and nasal discharges. Since the bacterium is hardy and can exist in a desiccated
form for many months, the illness can quickly reach epidemic proportions in regions where
population density is high, or there is a prolonged cold season where people stay indoors and
interact closely with one another. Many healthy children and adults can overcome an
infection without obvious symptoms, where only a blood test can confirm that a infection
had occurred.
The disease is named after the hard nodules that form within the lungs, called tubercles.
These tubercles can not only erode respiratory tissue, they can attack the blood vessels as
well, leading to the patient coughing up blood – a dramatic symptom indicative of an
advanced stage of the disease. The advent of HIV and AIDS brought tuberculosis to the
forefront, with the original tubercles of a resolved infection breaking down and releasing
bacteria into the blood stream. Immunocompromised individuals, whether infants, the
elderly, or those with immune deficiencies, become susceptible to the recurrence of this
ailment. Treatment usually involves multiple antibiotics over an extended period of time.
Caregivers need to be vaccinated.
Lung Cancer
Lung cancer is the development of a malignant tumor in the lungs, associated with
uncontrolled cell growth within the tissues and the metastasis of these cells to other organs
within the body. Smoking, especially when begun at an earlier age, is the highest risk factor
for developing lung cancer. Passive smoking is often equally dangerous. In recent history,
King George VI died of complications relating to lung cancer, brought on by years of heavy
smoking. Though tobacco smoking accounts for over 80% of lung cancer cases, any
chemical substance that repeatedly irritates the delicate inner linings of the lung can lead to
the formation of a tumor. These include asbestos, chromium, nickel, radon gas, uranium
dust, coal dust. The most common organ for the metastasis of lung cancer is the bone.
Therefore advanced stages of the disease also involve pain in the bones.