Tuberculosis pdf - د. ناديا

EPIDEMIOLOGY &PREVENTION OF

PULMONARY TUBERCULOSIS

ICD-10 A15-A19

Dr. Nadia Aziz

C.A.B.C.M

Department of community medicine

Baghdad medical college

Objectives

1- Define the tuberculosis

2- Identify the causative agent

3- Identify the mode of transmission & the high
risk group

4- Identify the ways of prevention &
management

Identification

TUBERCULOSIS

is a major cause of

disability

and

death

in most of the world,

especially developing countries.
The

initial infection

usually goes

unnoticed

tuberculin skin test sensitivity appears within

2–10 weeks.
Early lung lesions commonly

heal

, except

occasional

pulmonary

tracheobronchial

lymph node calcifications

TUBERCULOSIS

10%

of those initially infected will eventually

develop active disease

, half of them during the

first 2 years following infection.

90%

of untreated infected individuals will

never

develop active TB.

TUBERCULOSIS

infants

and in

immunosuppressed

individuals

(HIV-positive) initial infection may

progress

rapidly to active tuberculosis

infants

the disease is often

disseminated

(miliary) or

meningeal

TUBERCULOSIS

Extra pulmonary

TB occurs less commonly (

30%

)

than

pulmonary

TB (

70%

TB disease may affect any organ or tissue, in
order of frequency:

lymph nodes

pleura

pericardium

, kidneys, bones

and joints, larynx, middle ear, skin, intestines,
peritoneum, eyes.

TUBERCULOSIS

65%

of patients with sputum smear-positive

pulmonary tuberculosis, if untreated will die
within

5 years

, most of them within

2 years

TUBERCULOSIS

smear positive

for acid-fast bacilli (AFB) is

indicative of

high infectiousness

Fatigue, fever, night sweats and

weight loss

may occur early or late.

Localizing symptoms

of cough, chest pain,

hemoptysis and hoarseness become prominent
in

advanced stages

Diagnosis

Radiography

of the chest reveals pulmonary

infiltrates

cavitations

and

fibrotic

changes with

volume loss, almost commonly in the

upper

segments of the lobes

Diagnosis

Tuberculin skin test

Immunocompetent people who are or have
been infected with Mycobacterium

Tuberculosis usually react to an intermediate
strength

tuberculin skin test.

Diagnosis

A positive reaction

of tuberculin skin test is

defined as a 5, 10, or 15 mm induration
according to the risk of exposure or disease.
Among persons with active TB disease
10%–20% may have no reaction to PPD(purified
protein derivative) a

negative skin test does not

therefore rule out active TB disease.

Diagnosis

An induration of tuberculin skin test of

5 mm

more is considered positive among

•

HIV

-infected persons

•

Persons on

immunosuppressive treatment

•

Persons showing

fibrotic lesions

on chest X-rays

•

Recent

close contacts

of infectious TB patients.

Diagnosis

A diameter of

10 mm or more

is considered

positive among persons with

high-risk

conditions

(e.g. diabetes mellitus,

hematological disorders, injection drug use,
end-stage renal disease, rapid weight loss).

Diagnosis

Any reaction of

15 mm

or more should be

considered positive among

low-risk persons

Tuberculin skin test

In some persons with TB infection, delayed

hypersensitivity to tuberculin may

wane with

time

& they may show a negative reaction

The skin test may

boost

to react to tuberculin and

cause a positive reaction in subsequent tests.

Boosted reaction

The “boosted” reaction may be mistaken for a new

infection.

Boosting also reported in persons who have

received

BCG.

A 2-step testing procedure 1–3 weeks apart will

distinguish boosted reactions and reactions due to

new infection.

Tuberculin skin test

Two-step testing should be used for initial skin

testing of adults who will be

retested

periodically

(e.g. health care workers)

Diagnosis

3- Demonstration of

acid-fast bacilli

stained smears from sputum or other body
fluids in a clinical and epidemiological
situation suggestive of TB.

Diagnosis

Isolation of organisms

of the Mycobacterium

tuberculosis complex on culture confirms the
diagnosis.

In the absence of bacteriological confirmation,

active disease can be presumed if clinical,
histological or radiological evidence is
suggestive of TB

Infectious agents

Mycobacterium tuberculosis complex includes:

M. tuberculosis

M. africanum
M. canettii

all primarily from humans
and

M. bovis

primarily from cattle.

Occurrence

Worldwide

with a

high prevalence of HIV infection

prevalence of tuberculosis have increased.

TB mortality and morbidity rates increase with

age

, and higher in

males

than in females.

Occurrence

In regions with rising incidence, morbidity is

highest among

working-age adults

MDR-TB

Multidrug-resistant TB

is resistance to at least

Isoniazid

and

Rifampicin

MDR-TB

Effective measures in combating and

preventing

multidrug resistant

strains includ:

1- Strict enforcement of

infection control

guidelines

Case-finding

Contact

investigations

4- Measures to

ensure completion

of appropriate

treatment regimens

Reservoir

Primarily

humans

, rarely

primates

, diseased

cattle, badgers, swine and other mammals
can be infected.

Mode of transmission

Exposure to tubercle bacilli in

airborne

droplet nuclei

, 1 to 5 microns in diameter,

produced by people with

pulmonary or respiratory tract tuberculosis during

expiratory efforts (coughing, singing or
sneezing).

Mode of transmission

Health care workers

are exposed during

procedures such as

bronchoscopy

intubation

and at

autopsy

Laryngeal

tuberculosis is

highly contagious

but

rare.

Mode of transmission

Bovine tuberculosis

, a rare event, results from

exposure to tuberculous cattle, usually
through ingestion of unpasteurized milk or
dairy products

Extrapulmonary

tuberculosis (other than

laryngeal) is generally

not communicable

Incubation period

From infection to demonstrable primary lesion

or significant tuberculin reaction, about

2–10

weeks

latent infection may persist for a

lifetime

Period of communicability

Theoretically, as long as

viable tubercle bacilli are

discharged in the sputum

The degree of communicability depends on:

•

Number of bacilli

discharged

•

Virulence

of the bacilli

•

Adequacy of

ventilation

•

Exposure of bacilli to

sun or UV light

Period of communicability

Effective antimicrobial chemotherapy

usually eliminates communicability within

2–4

weeks

Children

with primary tuberculosis are

generally

not infectious

TUBERCULOSIS

The risk of developing disease is

highest in

children under 3

, lowest in later childhood,

and high again among

young adults

, the

very

old

and the

immunosuppressed

TUBERCULOSIS

For adults with latent TB infection also infected

with HIV, This has resulted in a

parallel

pandemic of TB disease

In some urban sub-Saharan African areas, where

10–15% of the adult population are co-infected

with both HIV and TB, annual TB disease rates

have increased
Under such conditions, the risk of multi-drug-

resistant (MDR) TB is high.

Methods of control

A. Preventive measures

1) Promptly

identify

diagnose

and

treat

potentially infectious patients

with TB disease.

Establish

case-finding

and treatment

facilities for infectious cases to

reduce

transmission.

Methods of control

2) Ensure

medical

laboratory

and

X-ray

facilities, ensure provision of

drugs

and

facilities for early and complete treatment of
cases and people at high risk of infection, and
of

beds

for those needing hospitalization.

Methods of control

Educate

the public in mode of spread and

methods of control

4) Reduce or

eliminate those social conditions

that increase the risk of infection.

Methods of control

Preventive chemotherapy with

isoniazid

for

6–12 months has been effective in preventing
the progression of latent TB infection to TB
disease.

Methods of control

It is important to

rule out active TB disease

before starting treatment for latent TB
infection

, especially in immunocompromised

persons such as HIV-infected individuals, in
order to

avoid the development of drug

resistance.

Methods of control

irectly

bserved

reatment

upervised (

DOTS

strategy) should be used when possible and can
be administered

twice weekly

Not more than 1 month’s supply

of medication

should be given at any one time.

Methods of control

Persons with

HIV

infection and a positive PPD

who do not have active TB disease should

receive treatment for latent TB infection

Methods of control

All people with evidence of

TB disease

should

be considered for counselling and

tested for

HIV infection

if appropriate counselling is

available.

Methods of control

6) BCG

immunization

is considered for persons

from areas of high tuberculosis prevalence.

BCG

immunization

protect

against

meningitis

and

disseminated disease

in children

under 5

Methods of control

protection from BCG vaccine may persist for as
long as 20 years in high incidence situations,
others have shown no protection at all.
Efforts to develop a vaccine

more effective than

BCG

have identified candidate vaccines that are

currently undergoing testing in humans for
safety and immunogenicity

Methods of control

7) Take measures to

prevent silicosis

among

those working in industrial plants and mines.

Methods of control

B. Control of patient, contacts and the

immediate environment

control of infectivity is best achieved through

prompt specific drug treatment

, usually

leading to sputum conversion within 2-4 weeks.
Hospitalization is necessary only for patients
with severe illness

B. Control of patient, contacts and the

immediate environment

Patients should be taught to

cover both mouth

and nose

when coughing or sneezing.

Patients whose sputum is bacteriologically
negative, who

do not cough

do not require

isolation, nor do

children

with active TB

disease.

B. Control of patient, contacts and the

immediate environment

Proper

patient support

ensuring that drugs are

taken as prescribed, including

DOTS

(the

internationally recommended strategy for TB
control), is essential, especially for persons
with suspected drug resistance

B. Control of patient, contacts and the

immediate environment

Decontamination of air may be achieved by

ventilation

& by

ultraviolet light

B. Control of patient, contacts and the

immediate environment

Management of contacts:

Chemoprophylaxis

or treatment of latent TB

infection—TLTBI) is usually recommended for
persons who are in

contact

with TB infection

and in whom TB disease has been ruled out.

Control of patient, contacts and the

immediate environment

PPD testing

of all members of the

household

and other

close contacts

is recommended. If

negative, a

repeat skin

test should be

performed

2–3 months after exposure

has

ended.

Control of patient, contacts and the

immediate environment

Specific treatment:

For drug-susceptible disease, a

6-month regimen

is recommended, including isoniazid (

INH

rifampicin (

RIF

), pyrazinamide

(

PZA

) and ethambutol (

EMB

) for the first

months

, followed by

INH

and

RIF

for

4 months

Control of patient, contacts and the

immediate environment

HIV-associated TB

, Rifampicin lowers serum

levels of many protease inhibitors and some
nucleoside reverse transcriptase inhibitors and
its replacement by

rifabutin

can be considered

Control of patient, contacts and the

immediate environment

Treatment for

9 to 12

months for:

1- Children with

meningitis

Miliary

disease

Bone/Joint

disease

HIV

infection

Treatment failure

Sputum smear positivity at 5 months

from start of

treatment
can be due to

irregular drug-taking

the presence of

drug-resistant bacilli

If INH or RIF cannot be included, treatment
should continue for at least

18 months

after

cultures have become negative.

Thank You