Tuberculosis

BY DR. ASHOK JAISINGANI

TUBERCULOSIS

Tuberculosis

Tuberculosis is the specific communicable disease caused by the mycobacterium tuberculosis Primarily affecting the lungs But also affecting secondarily Intestine MeningesBones Joints Lymph Nodes Skin and other tissues of the body

Causative Agents

Mycobacterium Tuberculosis of three types a) Humane types b) Bovine type c) Atypical type

Host Factors

Man is the host of the infection Age: Extreme of the age I.e. very old and too young are more prone Sex: More in male because of the more exposure to the work places (Occupational disease) Nutritional Status: In poor nutrition state the chances of the infection is increase Endocrine Disorder: In Case of the DM the chances of the TB are increased Environment: Overcrowding, poor hygiene and housing Poor living condition all increase the risk of the tuberculosis infections

Reservoir

Infected persons (Cases)

Infected animals

Source of the infection: Humane sources such as sputum or excreta of the TB pts Bovine source such as infected milk from the cow suffering from the TB

Period Of The Communicability & Incubation Period

Period Of the Infectivity: Patients are infected as long as they are untreated

Incubation Period: 3 – 6 weeks (it may be week, month or year)

Mode Of The Transmission

Droplet infection (within the range of the 30 cm) Dust loaded with the sputum (M – Tuberculosis survive for the year in dry sputum) Food handled by the infected persons ( Food borne) Flies sitting on the infected material (Fomite – borne) Directly by contact with the patients (By kissing the TB pt) Use of the common smoking huqqa Contaminated milk

Portal Of The entry

1) By inhalation through the nose and throat from there reach the alveoli causing the tuberculosis of the respiratory tract

2) By ingestion through the mouth causing the tuberculosis of the alimentary tract

Pathology Of The Primary Tuberculosis

Bacteria on reaching the alveoli are taken up by the the phagocytes and multiply Exudation of the cells takes place and pneumonic focus is formed this is called primary focus or Ghon focus Tubercle bacilli are carried by the lymphatic to related hilar lymph nodes which enlarge and the cessation takes place The Ghon focus, tuberculous lymphaginitis and the hilar glandular lesion together constitute “primary complex”

Factors Responsible In The Occurrence Of The TB

1) Dose and virulence of the bacteria

2) Resistance of the host

3) Environmental factors

Dose & Virulence Of Bacteria

The larger the number of the bacilli in the infecting dose More likely to be it cause the infection

Resistance Of The Host

Natural Resistance: Species resistance, Racial Resistance and individual resistance are depend upon the Heredity: Age: TB in the children under 2 – years tend to be acute and generalized miliary tuberculosis and tuberculosis meningitis Sex: No difference before the puberty At puberty girls are more prone than boys At 60 years of the age males are more than female Diet: Economic Status: Mental State:

Acquired Resistance Of The Host

a) Produced by the natural infection

b) Also produced by the BCG vaccination

Environmental factors

a) Unhygienic living condition b) Overcrowding c) Malnutrition d) Poverty e) Mental stress f) Intercurent infection and concomitant disease g) Diabetes h) Repeated Pregnancies I) Occupational Lung Diseases

Metastasis Of The Tuberculosis

1) Laryngeal Tuberculosis

2) Cervical Lymph node tuberculosis

3) Intestinal Tuberculosis & perianal fistula

4) Urogenital tuberculosis

5) Bone & Joints Tuberculosis

Tuberculin Test

A positive reaction to the test is generally accepted as evidences of the past or present infection by M – Tuberculosis

Tuberculin & Types Of The Tuberculin Tests

Tuberculin: It is a antigen or test material used for the tuberculin test it is of the two types a) Old tuberculin b) Purified Protein Derivatives

Types Of The Tuberculin Test: 1) Heat Test: It is usually preferred for the testing the large groups of the peoples because it is quick and easy to performs thus reliable and cheep 2) Montoux Test: It is favorable when a more precise measurement of the tuberculin sensitivity is required

Old Tuberculin

A six week old culture of the tubercle bacilli, in beef broth is heated to kill the bacilli and is then filtered

The filtrate is evaporated by the heat to 1/10th of its volume until appear golden yellow syrups liquid thus obtained is called old tuberculin

As the old tuberculin consist of the beef broth in addition to the products of the bacillary bodies

Occasionally non – specific reaction to the proteins of the beef broth may be elicited

Purified Protein Derivatives

This is obtained by the precipitating the proteins by adding the excess of the tubercle bacilli in the synthetic medium PPD is pure it gives few non – specific reactions PPD is standardized, in terms of the biological reactivity as tuberculin unit (TU) The standard PPD contain 50,000 tuberculin units per mg One TU is equal to 0.01 ml of OT or 0.0002 mg of PPD The WHO advocate a PPD tuberculin known as PPD – RT –23

Montoux Test

It is carried out by the injecting intradermally on the flexor surface of the forearm 1 TU of PPD in 0.1 ml The result of the test is read after 48 – 72 hours

Positive Montoux Test

The person is infected with the M – Tuberculosis not necessarily suffering from the tuberculosis thus having the infection not the disease

Children below the 2 – years has an active tuberculous lesion in the body even if it is not manifested

BCG vaccination has been done

Negative Montoux Test

The person is not suffering from the tuberculosis The person is suffering from the TB but he is immunocompromised The dermal hypersensitivity to the tuberculin can also be lost in malignancy, Hodgkin’s Disease

The Person is taking the INH if the previously positive

Interpretation Of The Result

Tuberculin reaction consist of the erythema & induration Erythema is disregarded and only induration is measured Reaction exceeding 10 mm are consider as positive Reaction less than 6 mm are considered as negative Reaction between the 6 & 9 mm are considered doubtful thus these reaction may be due to the M – Tuberculosis or atypical mycobacterium

Control Of The Tuberculosis

Aim Of The National T.B Control Program: 1) Reducing the reservoir of the infection

2) Improvement of the resistance

3) Minimizing the chance of the spread

Reducing The Reservoir Of The Infection

It is carried out by the

Case finding

Treatment

Case Finding

Case: The first step in TB control program is early detection of the sputum positive cases

Target Group: Person having the persistent cough and fever is the most fertile group for case finding

Case Finding Technique

There are three case finding techniques

1) Sputum Examination

2) Mass Miniature Radiotherapy (MMR)

3) Tuberculin Test

Sputum Examination

Direct microscopy of the sputum smear of the tubercle bacilli is the method of the choice

Examination Of The two consecutive specimen is sufficient to detect a large number of the infectious cases in community

Culture examination of the sputum is only second in importance

Mass Miniature Radiotherapy

It is now stopped due to

Lack of the definitives thus more presence of the X- ray shadow is not indicative of the case unless the presence of the tubercle bacilli are demonstrated

High Cost

Very low yield of the cases

Treatment

1) Two – phase chemotherapy

2) Different Regimen

a) 6 – Month Durations

b) 9 – Months Duration

c) 12 – Month Duration

Two – Phase Chemotherapy

1) The first is short aggressive or intense phase, early in the course of the treatment, lasting 1 – 3 months During this phase three or more drugs are combined to kill of as many bacilli as possible

2) The second or continuation phase is aimed at sterilizing the smaller number of the dormant or persisting bacilli

Treatment Of The 6 – Months Duration

Initial Phase: (2 – Months) Ethambutol or streptomycin + Isoniazed + Rifampicine + Pyrazinamide

Continuation Phase: (4 – Months) Isoniazed + Rifampicine

Treatment Of The 9 – Months Duration

Initiative Phase: (2 – Months) Ethambutol or Streptomycin + Isoniazed + Rifampicine + Pyrazinamide

Continuation Phase: (7 – Months) Isoniazed + Rifampicine

Treatment Of The 12 – Months Duration

Daily Dose: Isoniazed + Thiocetazone

Twice Weekly Dose: Streptomycin 1 gm intramuscularly

Isoniazed + pyridoxine orally

Improving The Resistance

BCG Vaccination: Stimulate a acquired resistance to possible subsequent infection with the virulent tubercle bacilli and thus reduce the morbidity & mortality from the primary tuberculosis among those at most risk.

The Vaccine & Its Dosage

BCG is only widely used bacterial vaccine derived from an attenuated bovine strain of the tubercle bacilli

Types Of The Vaccine: 1) Liquid Vaccine (Fresh) 2) Freeze – Dried Vaccine

Dosage: 1) The usual strength is 0.1 mg in 0.1 ml volume 2) The dose to new borne aged below 4 weeks in 0.05 ml

Administration Of The vaccine

The vaccine is injected intradermally, using a tuberculin syringe just above the insertion of the deltoid muscle without using an antiseptic or detergent

Age: Early in infancy either at birth or at 6 – weeks of the age simultaneously with the DPT & Polio

Phenomenon After The Vaccine

1) A papule is develop at the site of the vaccination after the 2 – 3 weeks 2) It increase in size, reach to about 4 – 8 mm in about 5 – weeks 3) It then subside or heals in to shallow ulcer, usually seen covered with the crust 4) Healing occurs spontaneously within 6 – 12 weeks leaving a permanent, tiny round, scar typically 4 – 8 mm in diameter

Complication

1) Prolong severe ulceration at the site of the vaccination 2) Supurative Lymphadenitis 3) Osteomyelitis 4) Disseminated BCG infection 5) It may cause the death

Contraindication

1) Generalized Eczema

2) Infected Dermatosis

3) Hypogammaglobulinemia

4) H/O deficient immunity

Minimizing The Chance OF The Spread

Isolation Care of the patient in the home Destruction of the sputum Visit by the health Visitors Promoting the health education Improving the living standard Chemoprophylaxis with INH for one year or INH plus ethambutol for 9 – months