Life sciences Grade 11 CAPS structured, clear, practical - Helping teachers unlock the power of NCS KNOWLEDGE AREA: Diversity, change and continuity TOPIC 1: Biodiversity and Classification of Micro-organisms Tuberculosis

Summary of presentation Pathogenic bacteria Causes Transmission Effects Tests for TB Management Treatment

Pathogenic bacteria Pathogenic bacteria is the bacteria that causes disease. Pathogenic bacteria are also parasitic. They bring about disease in one of two ways. They may secrete enzymes that break down the host’s protein or They secrete poisonous substances (toxins) that are harmful to the host. Some diseases caused by bacteria are tuberculosis, diphtheria, anthrax, plague, meningitis, pneumonia and tetanus.

Pathogenic bacteria Bacteria are successfully destroyed by antibiotics. However antibiotics are ineffective in killing virus. Can you explain why antibiotics can kill bacteria and not viruses?

solution Bacteria are living and can therefore be killed by antibiotics, virus can’t be killed by antibiotics because they are non-living

Causes of tuberculosis: Tuberculosis is caused by a bacteria called Mycobacterium tuberculosis. This bacteria can attack any part of the body, such as the brain, kidney and spinal cord. But it usually attacks the lungs. If the disease is not treated properly it can lead to death.

transmission We will discuss 2 types of TB. These are active TB and latent TB. CHARACTERISTICS OF ACTIVE TB The person feels sick. Can spread to other people. Produces a positive skin test. Can have an abnormal chest x-ray. The sputum smear is positive. Symptoms are present.

transmission CHARACTERISTICS OF LATENT TB: Patient does not feel sick. This TB does not spread to other people. Sputum test is negative. Normal chest x-ray. But skin test is positive. There are no symptoms.

transmission If a person is infected with active TB, sneezes or coughs then the TB bacteria gets into the air. Anyone who is nearby may breathe in the bacteria. The bacteria settles and grows in the lungs. Hereafter the bacteria can be carried by the blood to other parts of the body For example it can be carried to the kidney, brain and spinal cord.

transmission TB in these parts of the body (brain, spinal cord and kidney) does not usually spread. Active TB spreads to people who are close to the victim, like their family, friends and co-workers. Over-crowding and poor sanitation increases the rate at which TB is spread.

Symptoms: Active TB has the following symptoms: Weakness or extreme tiredness. Loss of appetite. Weight loss. Chills and fever. Sweating at night. If the TB is in the lungs then the following symptoms show: A cough that lasts for more than 2 weeks. Chest pains. Coughing up blood.

Symptoms: When the TB bacteria enters the person’s body it develops into active TB. Usually the immune system fights the bacteria and stops them from growing. This causes the bacteria to become inactive. This is called Latent TB. Latent TB shows no symptoms. The characteristics of latent TB was discussed earlier. If a person with a very strong immune system has latent TB they never usually develop active TB.

Symptoms: However people who have weak immune systems the latent TB can develop into active TB.

Effects of TB bacteria It destroys the body tissue when it attacks the body. If it settles in the lung, then it grows a hole in the lung. WHO IS AFFECTED BY THE BACTERIA: TB is an opportunistic disease. It attacks when the immune system is weak. These people would develop active TB. If the bacteria enters the body of a person with a strong immune system then the immune system fights the bacteria.

Effects of TB bacteria The bacteria becomes inactive and the person develops Latent TB. People who develop active TB usually are: Babies and young children because their immune systems are still developing. Poor people because they have weak immune system due to a lack of good nutrition. People with HIV/AIDS. Drug abusers. People with other diseases e.g. Diabetes. Organ transplant patients.

Tests FOR TB: There are 3 tests for TB. They are: X-rays TB skin tests Tissue Culture X-RAYS: The lungs are x-rayed. If the person is infected with TB then the holes in the lungs are visible on the x-ray. These holes are visible as patches.

Tests FOR TB: TB SKIN TEST: This is also called the Mantoux test. A small amount of a liquid called tuberculin in injected into the skin of the lower arm. A positive reaction to the test means that the TB bacteria is in your body and you could have latent TB.

Tests FOR TB: TISSUE CULTURE: A sample of phlegm is collected. It is then grown (cultured) in the laboratory. The culture is then examined under the microscope, to look for the TB bacteria. If the TB bacteria are present then the person has TB. This test can take about 4 to 6 weeks.

Management of TB TB can be prevented with the use of a vaccine called BCG. The BCG vaccines was developed by two scientists called Calmette and Guerin. They were French scientists.

Treatment: People with active TB can be treated with medication. The medication works in 3 ways. These are: They cure the active TB infection. Stop the latent TB from developing into active TB in patients with latent TB. It also prevents the spread of the disease from person to person.

Treatment: The type of medication and the amount administered differs from person to person. It depends on factors like age, health of the infected person, the state of their immune system, the organ infected and how advanced the disease is. The medication must be taken everyday for about 6 months. However the cure rate for TB in South Africa is only 62%, this below the WHO target of 85%.

Treatment The main reason for this low cure rate is that patients do not complete their treatment. They feel well after just a few doses and stop their medication. It is too expensive to keep them in hospital for the duration of their treatment. When patients stop their medication before the treatment is complete, the can become re-infected. This is called a relapse. There is also a very great danger that the TB can become drug resistant.

Treatment This means that the medication will not be able to kill the bacteria. In order to prevent this problem a new therapy called DOT or DOTS was established. This therapy ensures that patients complete their treatment and in this way prevent drug-resistant TB. DOT is Directly Observed Therapy. DOTS is Directly Observed Therapy Short Course.

Treatment In this therapy health workers meet the patient and watch them take their medication everyday until their treatment is complete! The meeting place is usually the patients home or place of work. The advantage of this therapy is that it eliminates the cost of a hospital stay, while at the same time ensuring the patient completes their treatment. This prevents drug resistant TB.

TERMINOLOGY Pathogenic bacteria: disease causing bacteria. Toxins: are poisonous substances. Mycobacterium tuberculosis: is the bacteria that causes TB. Phlegm: fluid from deep in the lung that is used for the TB test. Mantoux test: another name for the TB skin test. Tuberculin: is the liquid that is injected into a person’s lower arm during the Mantoux test. Relapse: when a patient is re-infected with the TB bacteria.

TERMINOLOGY DOTS: is Directly Observed Therapy Short Course. DOT: is Directly Observed Therapy. Drug resistant: the type of pathogen that can no longer be cured by the medication.

The therapy in which health workers help patients take their medication. A. DOT B. ABC C. Both A and B D. None of the above QUESTION 1

QUESTION 2 The TB cure rate for South Africa is… A. 60% B. 85% C. 100% D. 55% QUESTION 2

When the person is cured of the infection but becomes re-infected, this is called a… A. DOT B. BCG C. Relapse D. Re-infection QUESTION 3

QUESTION 4 The bacterium that causes TB… A. Human immune B. Mycobacterium tuberculosis C. BCG D. Streptococcus QUESTION 4

QUESTION 5 The test for TB is… A. Skin test B. X-ray C. Both A and B D. None of the above QUESTION 5

Symptoms of latent TB is… A. No symptoms B Symptoms of latent TB is… A. No symptoms B. Weight loss, chills and fever and a rash C. Weight gain and chills and fever D. Both B and C QUESTION 6

The symptoms of active TB are… A. No symptoms B The symptoms of active TB are… A. No symptoms B. Weight loss, chills and fever and a bad cough C. Weight gain and chills and fever D. Both B and C QUESTION 7

Vaccine against TB is called… A. DOT B. DOTS C. BCG D. CBG QUESTION 8

The latent TB tests positive during the… A. Skin test B The latent TB tests positive during the… A. Skin test B. Tissue culture C. X-rays D. None of the above QUESTION 9

Tuberculin is … A. Vaccine against TB B Tuberculin is … A. Vaccine against TB B. Liquid injected in the skin during the skin test C. Nutrient used to grow the TB culture D. A treatment for TB QUESTION 10

The pathogen that is no longer killed by the medication is called… A The pathogen that is no longer killed by the medication is called… A. Tuberculin B. Relapse C. Drug resistant D. BCG QUESTION 11

The reason for South Africa’s cure rate is… A. No cure for TB B The reason for South Africa’s cure rate is… A. No cure for TB B. Patients do not complete their treatment C. The medication is expensive D. Some patients are allergic to the medication QUESTION 12

The organs that can be attacked by the TB bacteria are… A The organs that can be attacked by the TB bacteria are… A. Kidney, lung, brain and spinal cord. B. Lung only C. Kidney only D. Alimentary canal QUESTION 13

QUESTION 14 Pathogenic bacteria is… A. Harmless B. Disease causing C. Extinct D. Not found in South Africa

Solution: A C B C B A