INFECTION Basics on Transmission and Prevention 

1. INFECTION
Basics on Transmission and Prevention
Dr.T.V.Rao MD
Dr.T.V.Rao MD
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2. HOW TO CLASSIFY DISEASES
• Acute Diseases
– Acute diseases are those conditions in which the
peak severity of symptoms occurs within three
months (usually sooner), and recovery in those who
survive is usually complete
• Chronic Diseases
– Chronic diseases or conditions are those in which
symptoms continue longer than three months and in
some cases for the remainder of the person’s life.
Recovery is slow and sometimes incomplete.
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3. CLASSIFYING DISEASES (cont’d.)
• Communicable (Infectious) Diseases
– Diseases for which biological agents or their products are the cause and
which are transmissible from one individual to another
– The disease process begins when the causative agent is able to lodge and
grow or reproduce within the body
– The process of lodgment and growth of a microorganism or virus in the
host is termed infection
• Non-communicable (Noninfectious) Diseases/Illnessses
– Those diseases or illnesses that cannot be transmitted from an infected
person to a susceptible, healthy one
– Several, or even many, factors may contribute to the development of a
given non-communicable health condition
– The contributing factors may be genetic, environmental, or behavioral in
nature
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4. Classification of Diseases
Types of Diseases_____
Examples______________
• Acute Diseases
– Communicable
– Non-communicable
(e.g., (incl. trauma)
Common cold, pneumonia, mumps,
measles, pertussis, typhoid fever, flu
Appendicitis, poisoning, trauma
due to automobile accidence, fires,
etc.)
• Chronic Diseases
– Communicable
– Non-communicable
Lyme disease, tuberculosis, AIDS,
syphilis, rheumatic fever following
streptococcal infections, herpes
Diabetes, coronary heart disease,
osteoarthritis, cirrhosis of the liver dur
to alcoholism, hyptertension
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5. in·fec·tion
dictionary means
• a. Invasion by and multiplication of pathogenic
microorganisms in a bodily part or tissue, which
may produce subsequent tissue injury and
progress to overt disease through a variety of
cellular or toxic mechanisms.
• b. An instance of being infected.
• c. An agent or a contaminated substance
responsible for one's becoming infected.
• d. The pathological state resulting from having
been infected.
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6. Definitions
• Disease and Infectious Disease
–Disease
• Any deviation from a condition of
good health and well-being
–Infectious Disease
A disease condition caused by the
presence or growth of infectious
microorganisms or parasites
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7. Definitions
• Pathogenicity and Virulence
– Pathogenicity
• The ability of a microbe to cause disease
• This term is often used to describe or
compare species
– Virulence
• The degree of pathogenicity in a
microorganism
• This term is often used to describe or
compare strains within a species
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8. Infection means
• Infection is the invasion
of a host organism's
bodily tissues by diseasecausing organisms, their
multiplication, and the
reaction of host tissues to
these organisms and the
toxins they produce.
Infections are caused by
microorganisms such as
viruses, prions, bacteria,
and Viroids, and larger
organisms like parasites
and Dr.T.V.Rao MD
fungi.
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9. Spanish Flu (1918) changes the understanding of
Communicable Diseases with millions effected and
killing many
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10. COURSE OF INFECTIOUS DISEASEs
• Exposure/Invasion of Host
• Incubation -- period of time
between exposure and
onset of symptoms -- e.g.,
interval between HIV
infection and development
of AIDS can be as long as
10-15 years
• Host reaction
• Disease runs course -treatment, recovery/death
(most people don’t die from
infectious diseases)
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11. Causative Agents effecting humans
u Bacteria
u Viruses
u Fungi
u Protozoa
u Helminths
u Prions
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12. INCUBATION PERIOD
• Varies by disease
• Salmonella -- 12-72 hours after infection; symptoms usually resolve
in 5-7 days, unless infected person is in a very weakened health
status
• Measles (rubeola) -- approx. 10-12 days (prodomal -- i.e., interval
between the earliest symptoms and the appearance of the rash or
fever -- rash onset, on average, 14 days
• HIV -- 6 weeks upward to months; interval between HIV infection
and development of AIDS can be as long as 10-15 years
• 2-6 weeks after infection in many, but not all, diseases, most
people develop antibodies against reinfection
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13. MODES OF COMMUNICABLE DISEASE
TRANSMISSION
• Direct
Transmission
• Indirect
Transmission
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14. Definitions
• Acute infection vs. chronic infection
– Acute Infection
• An infection characterized by sudden onset, rapid
progression, and often with severe symptoms
– Chronic Infection
• An infection characterized by delayed onset and
slow progression
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15. Definitions
• Primary infection vs. secondary infection
– Primary Infection
• An infection that develops in an
otherwise healthy individual
– Secondary Infection
• An infection that develops in an
individual who is already infected with
a different pathogen
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16. Definitions
• Localized infection vs. systemic infection
– Localized Infection
• An infection that is restricted to a specific
location or region within the body of the
host
–Systemic Infection
• An infection that has spread to several
regions or areas in the body of the host
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17. Definitions
• Opportunistic infection
– An infection caused
by microorganisms
that are commonly
found in the host’s
environment This
term is often used to
refer to infections
caused by organisms
in the normal flora
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18. DIRECT TRANSMISSION
• Immediate transfer of the disease agent by
direct contact between the infected and the
susceptible individuals
• Occurs through such acts as touching, biting,
kissing, sexual intercourse, or by direct
projection (droplet spread) by coughing or
sneezing within a distance of one meter
• Examples of diseases for which transmission is
usually direct are AIDS, syphilis, gonorrhea,
and the common cold
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19. INDIRECT TRANSMISSION
• May be one of three types: air-borne, vehicle-borne, or
vector-borne
• Air-borne transmission -- transmission of microbial
aerosols to a suitable port of entry, usually the respiratory
tract
– Microbial aerosols are suspensions of dust or droplet
nuclei made up wholly or in part by microorganisms -may be suspended and infective for long periods of
time
– Examples of air-borne diseases include
tuberculosis, influenza, histoplasmosis, and
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20. INDIRECT TRANSMISSION (cont’d.)
• Vehicle-borne transmission -- contaminated materials or objects
(fomites) serve as vehicles, nonliving objects by which
communicable agents are transferred to a susceptible host
– The agent may or may not have multiplied or developed on the
vehicle
– Examples of vehicles include toys, handkerchiefs, soiled
clothes, bedding, food service utensils, and surgical instruments
– Also considered vehicles are water, milk, food (e.g., common
vehicles), or biological products such as
blood, serum, plasma, organs and tissues
– Almost any disease can be transmitted by vehicles, including
those for which the primary mode of transmission is direct, such
as dysentery and hepatitis
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21. INDIRECT TRANSMISSION (cont’d.)
• Vector-borne transmission -- disease transfer by a living
organism, such as a mosquito, fly, or tick
– Transmission may be mechanical, via the contaminated
mouth parts or feet of the vector, or biological, involving
multiplication or developmental changes of the agent in
the vector before transmission occurs
– In mechanical transmission, multiplication and
development of the disease do not usually occur -e.g., organisms that cause dysentery, polio, cholera, and
typhoid fever have been isolated from such insects as
cockroaches and house flies and could presumably be
deposited on food prepared for human consumption
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22. INDIRECT TRANSMISSION (cont’d.)
– In biological transmission , multiplication and/or
developmental changes of the disease agent occur in
the vector before transmission occurs
– Biological transmission is much more important than
mechanical transmission in terms of its impact on
public/community health
– Examples of biological vectors include mosquitoes,
fleas, ticks, lice, flies and other insects
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23. INDIRECT TRANSMISSION (cont’d.)
– Mosquitoes are extremely important vectors of
human diseases -- e.g., they transmit the viruses
that cause yellow fever and dengué fever as well as
200 other viruses -- they also transmit
malaria, which infects 100 million people in the
world each year (most in tropical areas), killing at
least 1 million of them each year
– Ticks are another important biological
vector, transmitting Rocky Mountain spotted
fever, relapsing fever, and Lyme disease
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24. Signs & Symptoms of Infection
•
•
•
•
•
•
Redness
Swelling
Tenderness
Warmth
Drainage
Red streaks
leading away
from wound
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25. DISEASE AND INJURY PREVENTION
AND CONTROL
• Prevention
– Includes individual, clinical, or personal health services such
as immunizations, screening for high blood pressure and
follow-up services, or the use of Pap smears to detect the
precursors to cancer of the cervix
• Protection
– Includes the activities of organizations, both public and
private, to reduce exposure to hazards such as polluted
water, contaminated food, traffic accidents, mosquitoes, or
use of electric saws without safety devices
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26. Beginning of infection control
Programmes
• Modern hospital
infection control
programs first began in
the 1950s in England,
where the primary
focus of these programs
was to prevent and
control hospitalacquired staphylococcal
outbreaks.
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27. PREVENTION OF COMMUNICABLE DISEASES
• Primary Prevention
– In the chain of infection model, primary prevention
strategies are evident at each link of the chain
– Successful application of each strategy can be seen as
weakening the link -- with the ultimate goal of interrupting
the disease transmission cycle
– Community measures -- e.g., chlorination of the
water supply, inspection of restaurants, immunization
programs that reach all citizens, maintenance of a wellfunctioning sewer system, proper disposal of solid
waste, and control of vectors and rodents
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28. PREVENTION OF COMMUNICABLE
DISEASES (cont’d.)
– Personal/Individual
actions -- hand
washing, proper
cooking of
foods, adequate
clothing and
housing, use of
condoms, obtaining all
of the available
immunizations against
specific diseases
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29. PREVENTION OF COMMUNICABLE
DISEASES (cont’d.)
• Secondary Prevention
– Community effort includes measures taken to control or
limit the extend of a disease outbreak/epidemic -- e.g.,
maintaining records of cases and compliance with
regulations requiring the reporting of notifiable diseases,
investigating cases and contacts, those who may have
become infected through contact with cases
– Individual effort includes either (1) self-diagnosis and
self-treatment with nonprescription medications or home
remedies, or (2) diagnosis and treatment with an antibiotic
or other physician-prescribed medicine
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30. PREVENTION OF COMMUNICABLE
DISEASES (cont’d.)
– Occasionally, secondary disease control measures may
include isolation or quarantine
– Isolation = separation, for the period of communicability,
of infected persons or animals from others so as to prevent
the direct or indirect transmission of the communicable
agent to a susceptible person/host
– Quarantine = limitation of the freedom of movement of
well persons or animals that have been exposed to a
communicable disease until the incubation period has
passed
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31. PREVENTION OF COMMUNICABLE
DISEASES (cont’d.)
– Further measures may
include disinfection -- the
killing of communicable
agents outside the the
host, and mass treatment
with antibiotics
– Public health education and
health promotion should also
be used as both primary and
secondary preventive
measures
– Timely laboratory
Diagnosis stop of many
Infections
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32. PREVENTION OF COMMUNICABLE DISEASES
(cont’d.)
• Tertiary Prevention
– Convalescence from infection, recovery to full or partial
health, and return to normal activity
– In some cases, such as paralytic polio, return to normal activity
may not be possible, even with extensive physical therapy
– At the community level, proper removal of infected items such as
clothing, disinfection, and burial of the dead, for example
– Tertiary prevention may also involve the reapplication of primary
and secondary measures to prevent further cases -- e.g., in Japan
and South Korea, people with colds or flu wear gauze masks in
public to reduce the spread of the disease
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33. An approach to infection control in
developing countries
Infection Control Team/ Infection Control Programme
Audit (process) & outcome Surveillance
Cost effective
Divert resources
Evidence
Wasteful
practices
Based Practice
Unsafe
practices
To reduce infection rate to
‘irreducible minimum’.
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34. Educating our Health Care
Workers
• Education programs for employees and volunteers are
one method to ensure competent infection control
practices. It is a unique challenge since employees
represent a wide range of expertise and educational
background. The ICP must become knowledgeable in
adult education principles and use educational tools and
techniques that will motivate and sustain behavioral
change. Much has been written about the education of
healthcare workers (HCWs). Some of the tools used to
educate HCWs successfully include newsletter, posters
and videos
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35. TOOLS AVAILABLE TO THE “STATE” FOR THE
CONTROL OF COMMUNICABLE DISEASE
• REPORTING -- Physicians and other health professionals
must report specified diseases to a designated authority,
usually to local or state health authority
• LABORATORY REPORTING -- In many states, licensed
laboratories must report positive results for certain diseases
to the health department, even though a diagnosis may not
have been established
• SURVEILLANCE -- The systematic measurement of health
status and risk factors
• MONITORING -- Involves the ongoing assessment of a
condition after intervention has been initiated
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36. TOOLS AVAILABLE TO THE “STATE” FOR THE
CONTROL OF COMMUNICABLE DISEASE
• LABORATORY ANALYSIS -- Involves public health
laboratories with authority for the study and
detection of infectious diseases
• CONTACT INVESTIGATION -- Once a case of a
particular disease has been diagnosed, personnel
from the health department are authorized to
interview the victim to establish a list of possible
contact. (A practice of considerable debate recently
because of AIDS.)
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37. TOOLS AVAILABLE TO THE “STATE” FOR THE
CONTROL OF COMMUNICABLE DISEASE
• TREATMENT -- Public health agencies are required to
provide treatment services for specified infectious diseases.
(In many cities, special hospitals were built for this purpose.)
Local health departments are also required to provide
services for people infected with sexually transmitted diseases
or tuberculosis. These services are not regarded as welfare
services but rather as tools to prevent the spread of
dangerous communicable diseases. It is important to note,
however, that the state cannot require treatment. The state
can only force treatment if it can prove that the victim is (1)
gravely disabled, and (2) a danger to self or others because of
the disability
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38. TOOLS AVAILABLE TO THE “STATE” FOR THE
CONTROL OF COMMUNICABLE DISEASE
• ISOLATION -- Means separation of infected people from
non-infected people during the period of communicability.
Follows the “least restrictive” principle
• IMMUNIZATION -- All states have requirements for the
immunization of children against certain infectious diseases
-- most common are diphtheria, pertussis (whooping
cough), tetanus, rubella (German measles), and polio. The
controlling agency is usually the school system, which is
required to prevent entry of any child who has not been
properly immunized
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39. TOOLS AVAILABLE TO THE “STATE” FOR THE
CONTROL OF COMMUNICABLE DISEASE
• INVESTIGATIONS -- In addition to the specific
authorities noted above, most health departments
are required to investigate unusual occurrences of
disease or injury. This includes the authority to
review medical records, to perform laboratory
investigations, to examine patients, and to interview
both patients and others who may have been
exposed to the disease or injury. (The public health
authorities may require court authorization to
undertake these investigations.)
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40. Our Vision to Future
• Infection control
programs must
maintain training
records of employees.
The minimum training
required is annual OSHA
blood borne pathogen,
tuberculosis prevention
and control and new
employee orientation.
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41. Impact of Infectious Diseases
• Economic
– Loss of revenue for the family
– Loss of productivity for the
employer
• Contagion
– Other children in child care
– Families
– Caregivers/teachers and their families
• Disruption
– Alternative caregivers
– Other colleagues filling in for
missing parent at work
• Health care
– Many office visits to get “sick
notes”
– Inappropriate use of antibiotics
– Added responsibility of
administering medication
in child care

42. Impact of Infectious Diseases
• All members of society are affected

43. Hand washing still continues to be best option
to prevent infections
Dr.T.V.Rao MD
10/15/2013
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44. HAND WASHING STIIL SAVES
MANY LIVES FROM INFECTIONS
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45. Visit me for more articles of interest on
infectious diseases ……
Dr.T.V.Rao MD
10/15/2013
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46. • Programme Created by Dr.T.V.Rao MD
for Medical and Health care workers in
the Developing World
• Email
• doctortvrao@gmail.com
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