بسم الله الرحمن الرحيم 1 dr. malik muhammad abdul razzaq

الرحيم الرحمن الله الرحيم بسم الرحمن الله بسم

1 Dr. Malik Muhammad Abdul Razzaq

Dr. Malik Muhammad Abdul Razzaq Assistant Professor

Department of Community MedicineSheikh Zayed Medical College Rahim Yar Khan


CHAIN OF INFFECTON

THE CHAIN OF INFFECTION


Agent factorsIt is a substance, living or non-living, or

a force tangible or intangible, the excessive presence or relative lack of which may initiate or perpetuate a disease process.

A disease may have a single agent, a number of independent alternative agents or a complex of two or more factors whose combined presence is essential for the development of the disease.


Types of Causative AgentsBiological agentsNutrient agentsPhysical agentsChemical agentsMechanical agentsAbsence or insufficiency or excess of a

factor necessary to healthSocial agents


Host factors

Demographic : age, sex, ethnicity Biological: genetic factors, Biochemicals

levels of blood, hormones, functions of organs.

Social and economic: socio-economic status, education, occupation, stress, marital status, housing, etc.

Lifestyle factors: personality traits, living habits, nutrition, physical exercise, use of alcohol, drugs and smoking etc.


Environmental factors

All that which is external to the individual human host, living and non living and which he is in constant

interaction.Physical Environment Biological EnvironmentPsychosocial Environment.


Psychosocial EnvironmentThose factors affecting personal health,

health care and community wellbeing that stem from the psychosocial make up of individuals and structure and functions of social groups.

Cultural values, customs, habits, beliefsAttitude, morals, religion, educationLife style, Community Life, Health

servicesSocial & political Organization.


POSITIVE IMPACT Improve HealthProvide opportunitiesImprove quality of Life

NEGATIVE IMPACT:Poverty, Urbanization, Migration, Stressful

Conditions, bereavement, desertion, loss of employment, handicapped child, anxiety, depression, Anger, frustration.


Risk factors

An attribute or exposure that is significantly associated with the development of a disease

A determinant that can be modified by intervention, thereby reducing the possibility of occurrence of a disease or other specified outcome.

Non –Modifiable ( immutable) Age, Sex, Genetic Factors & ethnicity.

Modifiable Factors ( mutable) Smoking, hypertension, elevated serum cholesterol,

physical inactivity, obesity, etc..


Risk ApproachSomething for all, but more

for those in need - in proportion to the need"

Therefore it is stated that risk factor is a proxy for

need'- indicating the need for promotive and

preventive health services.


Prominent Risk Factors

DiseasesDiseases Risk FactorsRisk FactorsHeart diseaseHeart disease Smoking, high blood Pressure, elevated Smoking, high blood Pressure, elevated

serum cholesterol, diabetes, obesity, lack of serum cholesterol, diabetes, obesity, lack of exercise, type A personalityexercise, type A personality

CancerCancer Smoking, alcohol, solar radiation, ionizing Smoking, alcohol, solar radiation, ionizing radiation, work-site hazards, environmental radiation, work-site hazards, environmental pollution, medications, infectious agents, pollution, medications, infectious agents, dietary factors.dietary factors.

StrokeStroke High blood pressure, elevated cholesterol, High blood pressure, elevated cholesterol, smoking.smoking.

Motor vehicle Motor vehicle accidentsaccidents

Alcohol, non-use of seat belts, speed, Alcohol, non-use of seat belts, speed, automobile design, roadway designautomobile design, roadway design

DiabetesDiabetes Obesity, dietObesity, diet

Cirrhosis of liverCirrhosis of liver AlcoholAlcohol 12Dr. Malik Muhammad Abdul Razzaq

“AT RISK GROUPS”

Biological situation:

- age: infants (low birth weight), toddlers, elderly

- sex: females in the reproductive age period - physiological state: pregnancy, cholesterol level, high

blood pressure- genetic factors : family history of genetic disorders- others: disease, physical functioning, unhealthy behavior

Physical situation:- rural, urban slums- living conditions, overcrowding- environment: water supply, proximity to industries 13 Dr. Malik Muhammad Abdul Razzaq

“AT RISK GROUPS”

Sociocultural situation:- social class- ethnic and cultural group- family disruption, education, housing- customs, habits and behaviour like

smoking, lack of exercise, over-eating, drug addicts)

- access to health services- lifestyles and attitudes


Disease ControlAn ongoing operation to reduce:

i. The incidence of diseaseii. The duration of disease

iii. The risk of transmission.iv. The effects of infection, including both the physical and psychosocial complicationsv. The financial burden to the community.

The disease “agent” is permitted to persist in thecommunity at a level where it ceases to be apublic health problem.


Disease EliminationBetween control and eradication.

Elimination is used to describe interruption of transmission of disease from large geographic regions or areas.


Disease Eradication

Termination of all transmission of infection by extermination of the infectious agent from the whole world.

Eradication is an absolute process.

It is all or none phenomenon.


MonitoringThe performance and analysis of routine measurements aimed at detecting changes in the environment or health status of population.The continuous oversight of activities to ensure that they are proceeding according to plan.


Surveillance

The continuous scrutiny of the The continuous scrutiny of the factors that determine the factors that determine the occurrence and distribution of occurrence and distribution of disease and other conditions of ill – disease and other conditions of ill – health. It includes the collection, health. It includes the collection, analysis, interpretation and analysis, interpretation and distribution of relevant data for distribution of relevant data for actionaction


Objectives

•To provide information about To provide information about new and changing h. problemsnew and changing h. problems•To provide feed-back which may To provide feed-back which may be expected to modify the policy be expected to modify the policy and redefine objectives.and redefine objectives.• Provide timely warning of public Provide timely warning of public health disasters so that health disasters so that interventions can be mobilizedinterventions can be mobilized


Iceberg of disease


LEVELS OF PREVENTION


1. Primordial Prevention

Prevention of emergence or development of risk factors in country or population groups in which they have not yet been appeared.

Discourage to adapt harmful lifestyle. THROUGH: Individual education

Mass education.


2. PRIMARY PREVENTIONAn action taken prior to the onset of

disease, which removes the possibility that disease will occur.

Intervention in the pre-pathogenesis phase of a disease or H. problem,

To promote general health To promote quality of lifeBy 1: adapting specific measures.

2: Elimination/modification of risk factors

STRATEGY: Population & High risk


3.SECONDARY PREVENTION

Action which halts the progress of a disease at its incipient stage and prevents complications.

Early Diagnosis &Adequate treatment.

To arrest the disease processRestore health by seeking unrecognized diseasePrompt treatment before irreversible changes

occurReverse communicabilty of infectious disease.


4. TERTIARY PREVENTIONAll measures available to reduce or limit

impairment and disabilities, minimize sufferings and promote patient’s adjustment to irremediable conditions.

intervention in late pathogenesisIntervention to limit disability


MODES OF INTERVENTION Any attempt to intervene or interrupt the

usual sequence in the development of disease in man.

1. Health promotion2. Specific protection3. Early diagnosis & prompt treatment4. Disability Limitation5. Rehabilitation.


1.HEALTH PROMOTION A process of enabling people to increase control over & to improve health.

Health educationEnvironmental modificationsNutritional interventionsLife style & behavioural changes


HEALTH PROMOTIONHealth educationGood standard of nutritionAttention to personality developmentProvision of good housing & recreationGood working conditionsMarriage counselingSex educationPeriodic selective examinationsGeneticsEnvironmental modifications


2.SPECIFIC PROTECTIONUSE OF SPECIFIC IMMUNIZATIONSUSE OF SPECIFIC NUTRIENTSCHEMOPROPHYLAXISPROTECTION AGAINST OCCUP.HAZARDSPROTECTION FROM CARCINOGENSAVOIDANCE OF ALLERGENSUSE OF ENVIRONMENTAL SANITATIONCONTROL OF QUALITY PRODUCTSPROTECTION FROM ACCIDENTSATTENTION TO PERSONAL HYGIENE


3.EARLY DIAGNOSIS & PROMPT TRAETMENT

To intercept the disease processTo cure and prevent disease processTo prevent secondary cases (spread)To prevent complications and sequelaeTo shorten period of disabilityTo reduce mortalityFor better prognosis (Critically important in chronic diseases)


3.EARLY DIAGNOSIS & PROMPT TRAETMENT

Case finding measuresScreening surveysSelective examinationsMass treatment approach

Total mass approachJuvenile mass treatmentselective mass treatment


Disability limitationTo prevent or halt the transition of the disease process from impairment to handicap.

Adequate treatment to arrest disease processTo prevent further complications/disabilityProvision of facilities to limit disability and to

prevent death.

Disease → Impairment → Disability → Handicap 33 Dr. Malik Muhammad Abdul Razzaq

IMPAIRMENT:

Any loss or abnormality of psychological, physiological or anatomical structure or function.e.g. Loss of foot

Defective visionMental retardation

IMPAIRMENTvisible or invisibleTemporary or permanentProgressive or regressive


DISABILITY Inability to carry out certain activities

“Any restriction or lack of ability to performan activity within the range considered

normal for a human being”.


HANDICAPA disadvantage for a given individual, resulting from an impairment or a disability, that

limits or prevents the fulfillment of a role that is normal for that individual (depending on age, sex, and social and cultural factors).


Concept of disabilityAccident DiseaseLoss of foot ImpairmentCannot walk DisabilityUnemployed Handicap


REHABILITATIONThe 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.


Rehabilitation

a. Medical rehabilitation – restoration of functionb. Vocational rehabilitation – restoration of the

capacity to earn a livelihood.c. Social rehabilitation – restoration of family and

social relationshipsd. Psychological rehabilitation – restoration of

personal dignity and confidence. “to live and work within the limits of disability but

to his capacity”.


RehabilitationEstablishing schools for blindProvision of aids for crippledReconstructive surgery Community facilities to retrain disabled to

use remaining capacitiesGraded exercisesChanges in professionModification of life & full employment as

possibleEducation of industry to utilize rehabilitatedUse of sheltered colony40 Dr. Malik Muhammad Abdul Razzaq

INFECTION

The entry and development or multiplication of an infectious agent in the body of man or animals. An infection does not always cause illness.Body responds as -immune response

-disease.


CONTAMINATION

The presence of an infectious agent on a body surface; also on or in clothes, beddings, toys, surgical instruments or dressings, or other inanimate articles or substances including water, milk and food.


POLLUTION

The presence of offensive material is called pollution. It is distinct from contamination.


INFESTATION

It is a state of having a parasite in or on the body which includes arthropods or animal parasites. The lodgement, development and reproduction of arthropods on the surface of the body of man or animal, in the clothings etc.


HOST

A person or animal that affords subsistence or lodgement of an infectious agent under natural conditions.

An obligate host: means the only host.An intermediate host: in which the parasite

is in a larval or asexual state. (Secondary))Definitive Host: in which the parasite

attains maturity or passes its sexual stage. (Primary)

A transport host: a carrier in which the organism remains alive but does not undergo development.


INFECTIOUS DISEASEA clinically manifest disease of man or animal that results from an infection.It is a state of disorder that results from an infection by bacteria or viruses.

e.g., cholera, Diphtheria, Tuberculosis, measles, Chickenpox.


CONTAGIOUS DISEASE

A disease that is transmitted through contact. e.g. scabies, trachoma, STD and leprosy.


COMMUNICABLE DISEASE

An illness due to a specific infectious agent or its toxic products capable of being transmitted directly or indirectly from man to man , animal to animal or from environment to man or animal.


EPIDEMIC

Unusual occurrence of a disease or health related problem and health related behaviour in a community or region clearly in excess of expected occurrence.

. Disease affecting a large number of

persons within a short space of time.


ENDEMIC

It refers to the constant presence of a disease or an infectious agent within a given geographic area or population group.

When the number of susceptible and immune persons are almost equal, the disease continues to smoulder in a community and is always present in the community.


HYPERENDEMIC It expresses that the disease is constantly present at a high incidence or prevalence and affects all age groups equally.


HOLOENDEMICIt is the high level of infection beginning in early life and affecting most of the child population.


SPORADIC

The cases occur irregularly, haphazardly from time to time and generally infrequently.

The cases are so few and separated that they show little or no connection with each other nor a common source of infection.


PANDEMIC

An epidemic usually affecting a large proportion of the population, occurring over a large geographic area such as nation, continent or the whole world.

A world wide epidemic is a pandemic. When the susceptibility of the whole

country or the world is increased for a particular organism e.g. influenza Pandemic of 1918-19.


EXOTIC

When a disease is not usually present in a locality but is introduced form abroad, it is called Exotic.


ZOONOSIS

An infection or infectious disease transmissible under normal conditions from vertebrate animals to man.e.g. rabies, plague, bovine tuberculosis,

Anthrax, brucellosis, endemic typhus etc.


EPIZOOTIC

An outbreak ( epidemic) of disease in an animal population.e.g. anthrax, brucellosis, rabies.


NOSOCOMIAL INFECTIONHospital acquiredAn infection originating in a patient while in

a hospital or health care facility.A disorder associated with being in a

hospital.It may be unrelated with the primary

condition.May appear after discharge.Infections to the staff of the facility.


OPPORTUNISTIC INFECTIONIt is an infection by an organism that takes

the opportunity provided by the defect in host defense to infect the host and cause disease.

Opportunistic infections are common in AIDS

E.g. Herpes, cytomegalovirus,toxoplasma


IATROGENIC DISEASEPhysician induced diseaseAn adverse consequence of a

preventive, diagnostic or therapeutic regimen or procedure that causes impairment, handicap, disability or death resulting from a physician’s professional activity.

Can prolong hospital stayRequires special treatmentThreaten life.


HOST

A person or animal that affords subsistence or lodgement of an infectious agent under natural conditions.

An obligate host: means the only host.An intermediate host: in which the parasite

is in a larval or asexual state. (Secondary))Definitive Host: in which the parasite

attains maturity or passes its sexual stage. (Primary)

A transport host: a carrier in which the organism remains alive but does not undergo development.


RESERVOIRAny person, animal, soil, arthropod, plant

or substance in which an infectious agent lives and multiplies, on which depends primarily for survival and can be transmitted to a susceptible host.

Reservoir is a natural habitat in which an organism metabolises and replicates.


SOURCEA PERSON, ANIMAL, OBJECT, OR SUBSTANCE FROM WHICH AN INFECTIOUS AGENT PASSES OR IS DESSIMINATED TO THE HOST.


HUMAN RESERVOIR

CASES: A person in the population or study

group identified as having the particular disease, health disorder or condition under investigation.

clinical, biochemical, laboratory tests Clinical cases Sub clinical cases Latent infection: host does not shed

infectious agent which lies dormant within the host without symptoms.


HUMAN RESERVOIRCARRIER:

An infected person or animal that harbours a specific infectious agent in the absence of discernible clinical disease and serves as a potential source of infection for others.

Carriers are less infectiousCarriers are more dangerous than cases.


CARRIERA Type

(a) Incubatory(b) Convalescent( c) Healthy

B Duration(a) Temporary(b) Chronic

C Portal of Exit(a) Urinary(b) Intestinal (c) Respiratory


MODES OF TRANSMISSION


DIRECT TRANSMISSION1. Direct Contact2. Droplet Infection3. Contact with soil4. Inoculation into skin or mucosa5. Transplacental (vertical)


INDIRECT TRANSMISSION

1. Vehicle-borne (water, food, milk, fruits)2. Vector-borne

a Mechanical Transmissionb Biological Transmission

i. Propagative ii. Cyclo – Propagativeiii. Cyclo Developmental


INDIRECT TRANSMISSION3. Air – Borne

a Droplet nucleib Dust

4. Fomite – borne5. Unclean hands and fingers


Incubation Period

The time interval between invasion by an infectious agent and appearance of the first sign or symptom of the disease.

Median Incubation Period:The time required for 50 per cent of the cases to occur following exposure..


USES OF INCUBATION PERIOD a. Tracing the source of infection and

contactsb. Period of Surveillancec. Immunizationd. Identification of point source or propagated epidemicse. Prognosis


بسم الله الرحمن الرحيم 1 dr. malik muhammad abdul razzaq

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malik muhammad abdul

lifestyle factors

genetic factors ethnicity

personal health

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disease process

community life

community wellbeing