This is a global infectious disease.

Over 1/3 of the world population is now infected with this bacterium and new infections are occurring at a rate of one per second.

It kills approx 2 million people each year, more than any other infectious disease.

Not everyone infected develops the disease, however 1 in 10 will progress to actively have the disease, which if left untreated will kill more then half of its victims.

In 1993 the WHO declared a global emergency.

WHAT IS THIS DISEASE?

4.4 Lung disease – pulmonary

tuberculosis

Learning outcomesStudents should be able to understand the

following:The course of infection, symptoms and

transmission of pulmonary tuberculosis. Candidates should be able to

explain the symptoms of diseases and conditions affecting the lungs in terms of gas exchange and respiration

interpret data relating to the effects of pollution and smoking on the incidence of lung disease

analyse and interpret data associated with specific risk factors and the incidence of lung disease

recognise correlations and causal relationships.

TUBERCULOSISUsed to be called consumption.

Caused by rod shaped bacteria• Mycobacterium tuberculosis• Mycobacterium bovisSlow growing organism (divides every 16-

20hrs)

Most commonly affects the lungs

Transmission Droplet infection – cough, sneeze, laughing, even talking. People with prolonged, frequent or intense contact are at highest risk.

About 90% of those infected have asymptomatic latent TB and cannot pass on the infection.

There is a 10% lifetime chance that latent infection will progress to the active TB disease. If untreated the death rate is >50%.

Transmission

TB can also be spread from cows to humans because Mycobacterium bovis affects cattle.

Herds are regularly checked and affected cattle destroyed.

Milk is pasteurised killing the bacterium.

Some groups are at greater risk of contracting TB:

Those in close contact with infected individuals over long periods

Work or reside in long-term care facilities

Are from countries where TB is common

Have reduce immunity:

• Very old / very young• AIDS sufferers• People with other medical conditions that make their bodies less able to resist disease eg diabetes

• Those undergoing treatment with immunosuppressant drugs• Malnourished • Alcoholics or injecting drug users• Homeless

Course of infectionBacteria grow and divide in upper regions of

lungs.

Body’s immune system responds and white blood cells accumulate at the site of infection.

This leads to inflammation of lungs and enlargement of lymph nodes (Primary infection – usually in children)

In a healthy person there are few symptoms and infection is controlled within a few weeks.

However some bacteria usually remain

Course of infectionMany years later the bacteria may re-emerge

(Post –primary tuberculosis – typically in adults).

Also arises in upper regions of lungs but is much harder to control.

Bacteria destroy lung tissue, this results in cavities and scar tissue. Sufferers cough up damaged lung tissue and blood.

Without treatment TB spreads to rest of body and can be fatal.

Treatment Latent TB - usually single antibiotics.

Active TB - combinations of several antibiotics to reduce the risk of bacteria developing resistance. Most common antibiotics are Rifampicin and isoniazid need to be taken for 6-12 months.

Problems – people often feel better before the course is finished and stop taking the drugs. This can lead to an increase in resistant bacteria.The WHO introduced a scheme DOTS (Direct Observation Therapy) to tackle this problem.

Prevention and control1. People with TB and there contacts are

identified and treated.

2. Children are routinely vaccinated. The BCG vaccine is 80% effective in children.

3. Social and economic measures.• Better education• Improved health facilities• Better housing and nutrition

Worldwide importance

In Eastern Europe and Africa the disease is now on the increase after 40years of decline. largely as a result of the AIDS epidemic.

But also due to• Increased movement of people• Poorly managed TB treatment and prevention

programmes• Increase in drug resistant forms• Increased number of people living rough• Larger proportion of elderly people (with

suppressed immune systems)

Leicester

2001 Outbreak at Crown Hills Community College

67 people diagnosed with TB – reflecting the high proportion of the local population originating in the Indian subcontinent where TB rates are high.

Not linked to the suspension of routine TB vaccinations.

160 children tested +ve, only 3 had not been previously vaccinated at birth.

TASKProduce an A3 size leaflet for the Regional

Health Authority on Tuberculosis. To include

Cause and transmissionProgression of diseaseTreatmentPrevention and controlWorldwide importance