Concept of prevention

Concept of prevention

By

Prof. Dr. Refaat Raouf Sadek

Professor

Community Medicine

Faculty of Medicine, Minia University

Prevention of Infectious Diseases

The goals of medicine are to promote health, to preserve health, to restore health when it is impaired, and to minimize suffering and distress. These goals are come to life in the word "prevention".

Definition and Concept of prevention:

Actions aimed at eradicating, eliminating or minimizing the impact of disease and disability, or if none of these are feasible, retarding the progress of the disease and disability.

The concept of prevention is best defined in the context of levels, traditionally called primary, secondary and tertiary prevention.

A fourth level, called primordial prevention, was later added.

Determinants of Prevention:

Successful prevention depends upon:

1. Knowledge of causation.

2. Dynamics of transmission.

3. Identification of risk factors and risk groups.

4. Availability of prophylactic or early detection and treatment measures.

5. An organization for applying these measures to appropriate persons or groups,

6. Continuous evaluation of and development of procedures

applied

Primordial Quaternary

Levels of prevention

Primordial Quaternary

Primordial prevention:

•It is the prevention of the emergence or development of risk factors (environmental, economic, social, behavioral conditions) in countries or population groups in which they have not yet appeared.

•For example, many adult health problems (e.g., obesity, hypertension) have their early origins in childhood, because this is the time when lifestyles are formed (for example, smoking, eating patterns, physical exercise).

•In primordial prevention, efforts are directed towards

discouraging children from adopting harmful lifestyles

Primary prevention:

-Primary prevention can be defined as the action taken previous to the onset of disease, which removes the possibility that the disease will ever occur.

-Primary prevention may be accomplished by measures

of “Health promotion” designed to promote general

health and well-being, and quality of life of people or by

specific protective measures.

General measures

Health promotion is “The process of enabling people to increase control over their health and its determinants, and thereby improve their health”. consists of all the activities which are not aimed at any specific diseases but serve to improve the host factor in epidemiologic triangle.

I.Health education.

II.Environmental modification (reducing air pollution, safe water, refuse and sewage sanitation, control of insects and rodents, improving housing).

III.Genetic counseling (to prevent congenital diseases, i.e. Thalassemia).

IV.Increasing the standard of living (i.e. income, education and occupational status).

II. Specific measures (artificial immunization, chemoprophylaxis→ antimicrobial drugs administered for specific prevention of certain infectious diseases.

It is given to prevent the development of disease, or carrier state, either Pre or Post exposure).

III. International measures (Quarantinable diseases):

Plague, yellow fever, Cholera, Smallpox

Secondary prevention:

•It is defined as “action which stops the progress of a disease at its initial stage and prevents complications

•Secondary prevention attempts to arrest the disease process, restore health by seeking out unrecognized disease and treating it before irreversible pathological changes take place, and decrese communicability of infectious diseases.

•It thus protects others from in the community from acquiring the infection and thus provides at once secondary prevention for the infected ones and primary prevention for their potential contacts.

The specific interventions are:

a- Early diagnosis

b- Proper treatment

Tertiary prevention:

•It is used when the disease process has advanced beyond its early stages.

•It is defined as “all the measures available to reduce or limit impairments and disabilities, and to promote the patients’ adjustment to permanent conditions.”

•Intervention that should be accomplished in the stage of tertiary prevention are disability limitation, and rehabilitation.

•Rehabilitation is “the combined and coordinated use of medical, social,

educational, and vocational measures for training and retraining the

individual to the highest possible level of functional ability.”

Quaternary Prevention:

•Is defined as «action taken to identify patient at risk of over

medicalisation, to protect him from new medical invasion, and to suggest to him interventions, which are ethically acceptable».

It can also be looked at as the «rehabilitation or restoration of

functions in those patients suffering from serious disease

complications to avoid severe incapacity »

Relationship between the stages of the natural history of a disease

and the three types of prevention

Control Elimination Eradication

– Is reducing the transmission of disease agent to such a low level that it ceases to be a public health problem

– Is complete interruption of transmission of disease in a defined geographical area, but the causative organism may be persisting in environment

– precursor of eradication

–Is complete ‘extermination’ of organism

–Is ‘tearing out by roots’

of a disease

–Exhibits ‘All or none phenomenon’

Disease elimination is a

‘geographical term’, i.e. can be used only for a country or a region

– Disease eradication is a ‘global term’, i.e. can be used only for whole planet

It aims at reducing:

-Incidence of the disease

-Duration of the disease

-Effects of infection -Financial burden to the community

No Reported Cases but the causative agent is not necessarily eliminated

No Reported cases, nor Reservoir of Infection

– World has eradicated ONLY 1 disease till date: Small pox (declared eradicated on 8 May, 1980)

– next target diseases for eradication, globally^: Polio, Measles,

Control measures include:

1-Control of Reservoir of Infection:

•Control of animal reservoir:

1- Eradication (of rodent, stray dogs), mass tuberculin of cattle.

2-Control of animals (sanitary environment, adequate feeding, veterinary care, vaccinations, sanitation of slaughtering houses).

•Control of human reservoir:

a.Control of carriers: difficult to control b.Control of cases

Community measures vaccinations, sanitation of slaughtering houses).

Prevention of infectious diseases

1- Primary prevention:

1- General measures (water sanitation, refuse and sewage sanitation, food sanitation, health education)

2-Specific measures (artificial immunization, Chemoprophylaxis)

3- International measures (Quarantinable diseases):

- Plague

- Yellow fever - Cholera

- Smallpox

2- Secondary prevention: (control) a- Early diagnosis

b- Proper treatment

3- Tertiary prevention: Rehabilitation.

Control of cases :

1. Case finding:

Clinical diagnosis, laboratory confirmation, health consciousness and cooperation of the population.

2. Notification:

Sanitary regulations (enforced notification of

infectious diseases to local health office within

24 hours).

3. Isolation:

Infectious diseases are classified into 3 section according to the place of isolation:

Section I (Quarantinable measures)

Cholera. -Plague. – Typhus - Meningoccal meningitis - H5N1 Relapsing fever - Anthrax - Yellow fever - Poliomyelitis

This section should be:

It is obligatory isolation in special places (Quarantine or fever hospital). Or sanitary cordon prepared on the border of infected area. These diseases require immediate notification.

Section II

-Typhoid Brucellosis Scarlet fever Paratyphoid Tuberculosis -Infective hepatitis Diphtheria Encephalitis

This section can be:

- Segregation after approval of health office when sanitary requirement of segregation are fulfilled,

otherwise the cases should be isolated at hospital. These diseases require weekly notification.

Section III

- Measles Pertussis Mumps Dysentries Rubella Influenza Varicella Malaria Puerperal sepsis Tetanus Bacterial food poisoning Filariasis

Cases are free to choice the place of isolation, either at home or at hospital and this depend on availability of nursing services and requirements used for minimizing the risk of cross infection.

These require monthly notification.

Value of isolation :

- To prevent spread of infection .

- To protect the patient himself against risk of secondary infection from contact or visitors

Period of isolation :

The period of isolation depends mainly on:

1- Time of recovery of case

2- Satisfactory general condition of the case.

3- Cessation of infectivity in disease having a convalescent carriers through :

Bacteriological examination for: stool, throat and

nose swabs (three consecutive successive negative results)

why? - To confirm elimination of infection

- To safeguard against sampling and technical defect .

-To exclude possibility of intermittent discharge of organism

4 - Disinfection :

a ) Terminal disinfection :

- Is application of disincentive measures after the patient has been removed by death or to a hospital or stopped to be a source of infection

After cure or death of case

Responsibility of local health office

Examples: For place (cleaning, airing, sunning of rooms, linen, furniture, floor)

b ) Concurrent disinfection :

Is application of disincentive measures as soon as possible after discharge of infectious material from body of an infected person

During illness

Responsibility of nursing

Example: Disinfection of urine, faeces, vomit, contaminated linen, clothes, hands, dressings

5 - Treatment

a- Specific therapy

b- Proper feeding ( diet therapy) c- Symptomatic treatment

d- Prevention and control of complications

6 - Release :

Means permission of the case to leave the isolation place and return to school or work .

time for release:

- Recovery of the case (clinically free) - Satisfactory general condition

- Cessation of infectivity

7 - Follow up :

- To spot early manifestation of relapses - To make sure of curability of cases.

8 - Rehabilitation:

Rehabilitation of patient becomes disable

(handicapped due to complications of disease)

Control of contacts:

A contact is a person who has been in association with the patient during the incubation period and until discovered and isolated.

Control measures were taken by local health office including:

1. Enlistment (name, age, sex, occupation, address, work) 2. Examination

3. Prevent contact with the case for benefit of both.

4. Put contacts under surveillance, segregation or isolation

5. Laboratory examination in diseases having Incubatory and contact carriers.

Excluded from work and examined until giving three consecutive negative results (Examination: food handler and school children for diphtheria.

6-Specific protection by immunization and chemoprophylaxis (contacts of meningococcal meningitis→ oral Rifampicin, cholera→ oral tetracycline)

7- Health education

Surveillance of contact:

Medical supervision during the usual incubation period.

Examined every day (they can perform their activities as going to school or

work),

health sanitarians at local health office are responsible for surveillance of

contact of infectious diseases (meningitis).

Segregation of contact:

Exclusion from work, in disease having incubatory carriers and contact carriers (diphtheria, streptococci) in children, teachers, food handlers.

Isolation of contact, only in:

Pneumonic plague (during incubation period 10 days) Pneumonic anthrax (during incubation period 7 days)

Isolation

Separation of Cases (known to be ill) Healthy contacts of cases Level of

Prevention

Secondary (Treatment) Primary (Specific Protection)

Duration

Till recovery (period of

communicability) Till maximum incubation period Quarantine currently has been

‘replaced with active surveillance’

III. Community measures In epidemics:

I.Control of environment:

1.Superchlorination of water.

2.Food sanitation 3.Fly control

II.Health education.

III.Specific prevention: mass immunization and chemoprophylaxis.

IV.Control measures (segregation in cases of cerebrospinal meningitis).

V.Epidemiological investigation (to trace the source and channels).