1. Prevention & Control of Infectious Diseases
Dr. Anmar Aldewachi
Ass.Prof. Of Family Medicine
M.B.Ch.B MD
MPH
JHSFM

2. Definitions Infectious disease
A clinically manifested disease of human or animal resulting from infection.
Infected individual
A person or animal ,that harbors an infectious agent & who has either manifest disease or inapparent infection .
Infectivity :
The ability of the infectious agent to enter, survive & multiply in the host.

3. Definitions Infectiousness:
The relative ease with which an infectious agent is transmitted to other hosts.
Infection:
The entry & development or multiplication of an infectious agent in the body of persons or animals.
Inapparent infection
presence of infection in host without recognizable clinical signs or symptoms.

4. Definitions
Incubation period The time interval between initial contact with an infectious agent & the first appearance of symptoms associated with the infection . Period of communicability Is the time during which an infectious agent may be transmitted directly or indirectly from an infected person to another, from infected animal to humans, or from infected person to animals including arthropods.

5. Chain of infection Source or Susceptible Mode of reservoir host
transmission

6. Reservoir
Any person ,animal ,arthropod ,plant, soil ,or substance (or combination of these) in which an infectious agent normally lives & multiplies ,on which it depends primarily for survival, & where it reproduces itself in such manner that it can be transmitted to a susceptible host .
Reservoir is of three types
Human reservoir (cases, carriers)
Animal reservoir
Reservoir in non-living things

7. Carrier
A person or animal that harbors a specific infectious agent without clinical disease & serves as a potential source of infection.
As a rule carriers are less infectious than cases but more dangerous ,because they remain hidden and readily infect susceptible individual.

8. Carrier Elements of carrier state:
Disease agent is presents in the host
Absence of signs and symptoms
Shedding of disease agent in discharge and excretion and act as source of infection to others

9. Carriers are classified as below
Type
Incubatory,convalescent,healthy
Duration
Transient few weeks
Temporary months
Chronic more than year
Permanent for life
Portal of exit Respiratory,urinary,intestinal,others)

10. Mode of Transmission I. Direct Physical contact Droplet (projection)
Trans placental
II. Indirect
Vehicle (Water, Milk ,Blood, Eating utensils, Surgical instruments).
Insect
Air (droplet nuclei)
III. Both

11. Prevention and control of infectious diseases

12. Control of susciptable
Principles of control
Control of reservoir
Control of susciptable
host
Control of mode of
transmission

13. Control of reservoir Recognition Clinical signs& symptoms
Laboratory investigation
Notification.
Isolation (period of communicability)
Treatment
Disinfection
Quarantine

14. Control of mode of transmission :
Chlorination of water to control diseases like typhoid, hepatitis A, cholera…….etc
Control of breeding places of mosquito in case of malaria
Environmental control (proper sewage disposal)
Control of susciptible host:
Active immunization
Passive immunization
Chemoprophylaxis ( e.g meningitis, cholera)

15. Isolation
Applied to the patient , represent separation for a period of communicability of infected person, from others in such places & under such conditions as to prevent or limit the spread to those who are susceptible to the disease .
Disinfection
Killing of infectious agents outside the body by direct exposure to chemical or physical agents

16. Types Concurrent disinfection
Application of disinfection measures as soon as possible after discharge of infectious material from the body of an infected person or after soiling of articles with such infectious discharges.
Terminal disinfection
Application of disinfection measures after the patient has been removed by death or to the hospital or he has ceased to be a source of infection or after hospital isolation.

17. Quarantine
Restriction of activities of well person or animals who have been exposed to case of communicable disease during its period of communicability to prevent disease transmission during incubation period.

18. Types of quarantine Complete or absolute quarantine
The limitation of freedom of movement of those exposed to the communicable disease for period of time not longer than the longest incubation period of that disease ,in such manner as to prevent effective contact with those not exposed.
2. Modified quarantine
Partial limitation of freedom of movement of contact e.g. exclusion of children from school