Tuberculosis

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A simple explanation of what tuberculosis is and what causes it. this is based on content that is needed for the A2 edexcel biology specifications.

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TUBERCULOSIS

STARTER – TRUE OR FALSE TB is caused by a virus TB spreads through the air HIV Patients are less likely to get TB than

others TB can affect other parts of the body besides

the lungs TB bacteria have a hard time living in fresh

air and sunlight

WHAT IS TUBERCULOSIS? Tuberculosis is also called TB for

short. The TB bacteria become active if

the immune system can't stop them from growing.

When TB bacteria are active (multiplying in your body), this is called TB disease.

People with TB disease are sick. They may also be able to spread

the bacteria to people they spend time with every day.

Figure 1

WHAT SORT OF PATHOGEN IS INVOLVED?

The pathogen involved is a bacterium called Mycobacterium tuberculosis (M. Tuberculosis).

LIFE CYCLE:• M. tuberculosis divides every 15–20

hours, which is slow compared to other bacteria.

• It survive in dry states for many weeks due to its cell wall which is rich in lipids.

HOW IS TB SPREAD? TB is spread through the air from one person

to another. The TB bacteria are put into the air when a

person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings.

People nearby may breathe in these bacteria and become infected. [1]

TB IS NOT SPREAD BY THE FOLLOWING…

shaking someone’s hand sharing food or drink sharing toothbrushes kissing

WHO IS MOST AT RISK FROM TB?

Those at high risk:- Elderly- Infants- People with a weak immune system- People who spend time around those who suffer

from TB- People with low nutrition People that have the HIV virus infection are also at

high risk of getting TB.

SYMPTOMS Symptoms of TB disease: • A bad cough that lasts 3 weeks or longer • Pain in the chest• Coughing up blood or sputum • Weakness or fatigue • Weight loss • No appetite • Fever• Sweating at night

HOW TO TEST FOR TB? Biopsy – a sample of tissue is taken from the

affected site and is tested for TB. Chest CT Scan – a series of images are put

together to see whether the TB disease is present in the body or not.

HOW CAN TB BE TREATED? Drug Therapy:• Current treatment involves 3 – 4 different kinds of

antibiotics given in combination over 6 – 9 months.• Multi-antibiotics are necessary to prevent the

emergence of drug resistance in the bacteria.• A combination of isoniazid and rifampicin for 6

months with pyrazinamide and ethambutol for the first 2 months is usually used, as this provides the highest antibacterial activity as well as having the capacity to inhibit the development of resistance.

• It results in a 90 % cure rate. Patients stop being infectious to others after 2 weeks. After 1 month patients should feel well and start to regain weight.

Vaccinations:• The control of infectious disease through

vaccination has been one of the most successful accomplishments of public health in the 20th century, enabling the eradication of smallpox and virtual eradication of polio from the world.

• Today, vaccination remains our most effective and cost-effective tool in the fight against infectious disease and must be considered as an integral part of any global effort to control infections.

HOW CAN TB BE TREATED?

WHAT IMPACT DOES TB HAVE ACROSS THE WORLD?

TB is very common in poorer countries. Areas in which the illness is still widespread are; Eastern Europe, South East Asia and Sub-Saharan Africa.

Approximately 1/3 of the worlds population is affected by TB.

Rate of 5,000 deaths a day caused by TB.

Annually – 2 million people die due to TB.

HOW CAN IT BE PREVENTED? Can be prevented by: Getting the BCG vaccine Balanced diets Exercise Breathing fresh air Avoidance of smoking Personal Hygiene

TB STATISTICSIt is common to get TB in these countries because they are LEDC, which means less likely to get treatment and a high population so TB can spread easily through the air.

TEST YOUR KNOWLEDGE Exam Question – January 2011

ANSWERS

THANK YOU FOR LISTENING

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