TB (Tuberculosis) is caused by bacteria, (Mycobacterium tuberculosis) that most often affect the lungs. Tuberculosis is curable and preventable. TB is spread from person to person through air. Person suffering from Tb transmits its germs through spitting, cough, sneezing. Only few germs are required to get infected with this disease. Latent Tb is safe because people can neither transmit germs, nor they are ill. When a person develops active Tb, symptoms may be mild for many months. This leads to delay in seeking care and so transmission of bacteria to many others.  People suffering with Tb can infect to fifteen more person in close contact with them over course of years.  Without proper treatment, most people ill with Tb will die. Medicine when properly taken is the best cure of Tb.

PPD Skin test

PPD skin test is used to diagnose latent tuberculosis. Ppd stands for purified protein derivative. It is the best way to detect the person suffering from tuberculosis.

How the test is performed

At first, the health care provider cleans skin under forearms. An injection containing PPD is injected. A needle is gently placed under the top layer of skin where a bump is formed.  As the material gets absorbed, the bump vanishes. After 48 to 72 hrs, the doctor will again check the area to detect whether a person has strong reaction to the test. Swelling or bump is also called indurations. The diameter of indurations is measured transversely to the long axis of forearm and measured in mill meter. It is important to note that redness is not measured. If blisters are present then also it is considered positive skin test. According to the centre of disease control and prevention it gives the following results.

How to understand the results of the Tb test

In some group of people test is considered positive, if indurations less than 15mm is present. 15 mm is considered positive for people of all background.

Area of indurations of 10 mm is considered positive for following groups.

• People suffering from diabetes, kidney failure and any other similar type of disease.
• Recent immigrant from high prevalence area.
• Residents and employees of high risk areas.
• Children under 4 years old
• Paediatric patients exposed to high risk adult
• Exposure to mycobacterium in the laboratory.
• IV Drug abusers

Indurations of 5mm are considered positive for the following groups.

• People whose immune system is suppressed.
• HIV infected people
• Recent contacts of people with tuberculosis.
• People with changes seen on chest x ray that are consistent with previous Tb.
• People having organ transplant.

If prone to high risk category a reaction of 5mm is considered positive, Chest x ray and other necessary test carried on to test how much the disease has spread in the body,  and to check the activeness and severity of the disease. It is also used to detect whether the Tb is still dormant inside the body. If the infection is dormant, the focus should be to prevent the dormant infection. If the infection is active, necessary treatment should be carried on for proper cure of infection.

 How the test feels

A sting will be felt, as the needle gets injected below the skin surface.

How to take care of arms after Tb skin test:

• Do not cover the spot with a bandage or a tape.
• Be careful not to rub or scratch it.
• If there is itching, cold cloth should be kept on it.
• Arms should be washed and dried gently.

What to do if Tb skin test comes positive?

The test becomes positive if bumps appear where fluid was injected. This means there is a presence of Tb germs in the body. Most people with positive Tb skin test have latent Tb infection.  For surety consultation of doctor is must for giving chest x ray or some other tests followed if necessary.

People who should have Tb skin test

• On coming in contact with active tuberculosis patients, Tb skin test is a must to be performed.
• Person living in a country where many people are infected with tuberculosis. In that condition, there is a great risk of to be caught with this disease.
• Working or living near a clinic, in the vicinity of hospitals, working in a nursing home, or spending life in prison.
• Adult, old or children who are homeless and do not have shelter. Those who are spending their night and day on roadside, and those people who are living in dingy hovels.

 Symptoms of tuberculosis

After knowing the results of the Tb test, we must know about the symptoms of tuberculosis. Inactive Tb test does not exhibit symptom because it is not harmful.  But active Tb test certainly exhibits some symptoms. Following are the symptoms of person suffering from active tuberculosis.

• Continuous coughing
• Appearance of blood in coughing
• Appearance of constant fever
• Excessive sweat emerges
• Person becomes fatigue soon
• Acute chest pain appears

These symptoms do not always point to Tb. It may be due to some other reasons. But persons exhibiting such symptoms should certainly make their body examine and undergo necessary test, under a certified doctor.