Question

The Mantoux Test

The summer orientation for freshmen nursing students at Ohio Northern University gave Elena a chance to meet her academic advisor, register for fall semester classes, and mingle with her future classmates. At the concluding session, Elena was given a form with instructions to have her family physician verify the results of her Mantoux test and return the document when school started.

As Elena was wondering what a Mantoux test was, La'Davia, the student next to her, leaned over and asked exactly that. “I have no idea,” said Elena. “It must be important if they won't let us start the nursing program without it.”

The girls were startled as Dr. Woodfield came up behind them and said, “It is important! I overheard your conversation and I thought you might have some questions. The Mantoux test is used to determine whether you've got tuberculosis. If you're infected, of course, we want to get you treated so you're healthy… but we also want to be sure you don't infect any of your future patients. That's why you need your Mantoux test now.”

• “Tuberculosis!” the girls responded in unison.
• “No one gets that anymore,” Elena replied.
• “Yeah, we're not even coughing,” said La'Davia.
• “It sounds like you know a little bit about this deadly disease, but you're missing some important details,” said Dr. Woodfield.

1. What pathogen causes tuberculosis?
2. How is it spread?
3. What are the signs of infection?

“Although the incidence of tuberculosis (TB) is lower in the United States than in other parts of the world (Figure a), TB is second only to AIDS as the greatest infectious disease killer globally. Every year 8.5 million people become infected and more than 1 million die of this

isease. Did you know TB is the third leading cause of death in women ages 15 to 44?”

4. Why do you think South Africa has a much higher tuberculosis incidence than China when China has a much larger population than South Africa?

I guess I see why we need to be tested,” said a surprised Elena. “Is this a blood test?”

“No,” Dr. Woodfield responded. “The Mantoux test involves subcutaneously injecting a tiny amount of tuberculin or purified protein derivative (PPD) on the subject's inner forearm . This harmless material is derived from the pathogen that causes TB. If the patient has been exposed to the microbe, then the immune system will launch a vigorous attack. Within a couple of days, a bump called an induration forms at the injection site. If this bump filled with immune active cells is more than 5 mm in diameter, then the Mantoux test is positive for TB. Because uninfected patients lack memory T_H cells against this pathogen, they will not be able to respond to the injection and no bump forms.”

b. The Mantoux test is performed by subcutaneously injecting PPD in the patient's inner forearm.

5. define the term subcutaneous.

“What are memory cells and how are they connected to the Mantoux test?” asked a confused La'Davia.

“Oh, I think I know this,” said Elena. “We talked about the immune system in my AP Bio class this year. The foreign PPD would be engulfed, partially degraded, and presented on the surface of a phagocyte so it can bind to a memory T_H cell. The memory cell secretes chemicals called cytokines that recruit more phagocytes to the antigen injection site where they work to eliminate the foreign material.”

6. Finish answering La'Davia's question: What is a memory cell?

c. An induration filled with immune-active cells develops approximately 48 hours after PPD injection in patients with past exposure to the tuberculosis pathogen.

7. induration is 2 cm large, what does this indicate about whether this patient has been exposed to the tuberculosis pathogen?

“Not bad,” Dr. Woodfield replied. “Immunology is a very complicated subject. You'll study it during your sophomore physiology class. As you learn more about how your body defends itself against pathogen invasion, you'll discover other diagnostic tests that are based on immunologic principles.”

As the students finished their conversation and said their goodbyes, Dr. Woodfield called after Elena and La'Davia, “Enjoy the rest of your summer ladies, and I'll see you back here in the fall with your test results….and ladies, this is the only test I want to

Answer 1

Ans. Pathogen causing tuberculosis is

Mycobacterium tuberculosis.

Mode of spread - transmitted mainly by droplet infection. Coughing or sneezing produces droplets containing M. Tuberculosis to be expelled into air. On inhalation of these droplets the bacterium enters the respiratory tract and travel to lungs.

Can also spread through ingestion of dairy contaminated with the bacteria.

Signs and symptoms of TB.

Fever

Coughing

Sputum

Loss of appetite

Chronic latigue

Pain while breathing or say pleural pain in the chest.

Severe weigh loss.

Swollen lymph nodes.

South Africa might have higher incidence of TB due to poverty, malnutrition, crowding Immuno compressed patients. These factors increase the risk of transmission.

Subcutaneous. Refers to a layer of skin below epidermis. It is a mode of administration of drugs.

A memory cell is a lymphocyte which is cpable of recognising an antigen which had caused an infection earlier memory cells are B Cells.On reexposure to the same antigen encountered previously memory cells proliferates in large numbers to produce specific antibodies against the invading antigen.

Size of induration 2cm indicates that the patient has been exposed to the pathogen. It is PPD positive. For mantoux test to be positive the transverse diamtere of the induration has to be 15mm or larger . So 2cm would be 20mm. And positive for the test

Hope this helps, if it does please give it a positive rating. Thank you.