INFECTION,TYPES OF IMMUNITY, ORGANS OF IMMUNITY, AGGRESSIVE FACTORS OF PATHOGENS, DISEASES

1. By.
OMPRAKASH KADAM
DIGAMBARRAOBINDUACS
COLLEGE,BHOKAR

2.  Infection, Immunity & immune response.???
Infection: Definition?
Types of infection?
Sources of Infection?
Modes of transmission?
Microbial pathogenicity?
Aggressive factors of pathogens?
Immunity: Definition & classification.

3.  Primary infection:
Initial infection caused by microorganisms in
host.
 Reinfection:
Subsequent infection caused by same organism
in a host (after recovery).
 Superinfection:
Infection by same organism in a host before
recovery.
 Secondary infection:
When a new m.o. set up an infection in a host
whose resistance is lowered by preexisting
infectious disease,

4.  Classification of infections
 Focal infection: It is a condition where due to
infection at localized sites like appendix and
tonsil, general effects are produced.
 Cross infection: When a patient suffering from
a disease and new infection it set up from
another host or external source.
 Nosocomial infection: Cross infection
occurring in hospital.
 Subclinical infection: It is one where clinical
affects are not apparent.

5.  Oppurtinic infection:-
 Vertical infection :- transplacently / prenatally : AIDS , rubella
 Systemic infection:- affects whole body
 Focal infection:- localised
 Cross infection;-
 Nosocomial infection:-
 Iatrogenic infection:-
 Exogenous infection:-
 Endogenous infection:-
 Latent infection:-
 Generalised infection:-
 Acute infection:-
 Chronic infection:-
 Pyogenic infection:-
 Terminal infection:-

6.  Sources of infection in Man
A) Endogenous &
B) B) Exogenous
Man himself is a common source of
infection from a patient or carrier. Healthy
carrier is a person harboring pathogenic
organism without causing any disease to him.
A convalescent carrier is one who has
recovered from disease but continues to
harbor the pathogen in his body.

7. HUMAN PATIENTS / HUMAN CARRIER:-
a.Healthy b. Incubatory. c. convelscent
d. temoprary e.chronic f. Contact
g. paradoxical carrier h. on the basis of
portal of entry :-
3) Animals: Infectious diseases transmitted from animals
to man are called zoonosis. Zoonosis may be bacterial, (e.g.
Plague from rat), rickettsial, (e.g. Murine typhus from
rodent), viral, (e.g. Rabies from dog), protozoal, (e.g.
Leishmaniasis from dogs), helminthic, (e.g. Hydatid cyst
from dogs) and fungal (zoophilic dermatophytes from cats
and dogs).

8.  Sources of infection in Man
4. Insects: The diseases caused by insects are
called arthropod borne disease. Insects like
mosquitoes, fleas, lice that transmit
infection are called vector. Transmission
may be mechanical (transmission of
Dysentery or typhoid bacilli by housefly) and
these are called mechanical vector. They
are called biological vector if pathogen
multiplies in the body of vector, e.g.
Anopheles mosquito in Malaria.

9.  Sources of infection in Man
Some vectors may acts as reservoir host, (e.g.
ticks in Relapsing fever and Spotted fever).
5) Soil: Spores of tetanus bacilli, Gas-gangrene
infection remain viable in soil for a long
time.

10.  Sources of infection in Man
6) Water: Vibrio cholerae, infective hepatitis
virus (Hepatitis A and Hepatitis E) may be
found water.
7) Food: Contaminated food may be source of
infection. Presence of pathogens in food may
be due to external contamination, (e.g. food
poisoning by Staphylococcus).

11.  Routes / Modes/ Methods Of
Transmission Of Infection/ Portals Of
Entry Of Pathogens
1)Contact
a) Direct:- person to person
b) Indirect contact:- fomites
2) Inhalation: aerosols , droplet nuclei, dust
born.
e.g. : influenza, tuberculosis, smallpox, measles,
mumps, etc.

12.  Methods of transmission of
infection
 Ingestion: cholera (water), food poisoning
(food) and dysentery (hand borne).
 Inoculation: tetanus (infection), rabies (dog),
arbovirus (insect) and serum hepatitis, i.e.
Hepatitis B (infection).
 Congenital: syphilis,rubella, toxoplasmosis,
cytomegaloviruses

13.  Methods of transmission of
infection
 Insects: they act as mechanical vector
(dysentery and typhoid by housefly) or
biological vector (malaria) of infectious
disease
 Iatrogenic and laboratory infections:
infection may be transmitted during
procedures

14.  Bacteria should be able to enter the body.
 Organism should be able to multiply in the
tissue.
 They should be able to damage the tissue.
 They must be capable to resist the host
defense.

15.  Pathogenicity is referred to the ability of
microbial species to produce disease.
 Virulence is referred to the degree /
intensity of microbial strains to produce
disease.

16.  Factors ofVirulence
 Adhesion: The initial event in the
pathogenesis of many infections is the
attachment of the bacteria to body surfaces.
This attachment is specific reaction between
surface receptors and adhesive structures on
the surface of bacteria (adhesins).
 Fimbriae, pilli, capsule, hemagglutinine, techoic acid,
fibronectin Ig A protease etc…

19.  Factors ofVirulence
Invasiveness ( aggresivness ) is the ability of
organism to spread in a host tissue after
establishing infection. Less invasive
organisms cause localized lesion. Highly
invasive organisms cause generalized
infection (septicemia).
 Toxigenicity. Bacteria produce two types of
toxins – exotoxins & endotoxins

21.  Immunity is the body's ability to fight off
harmful micro-organisms –PATHOGENS- that
invade it.
 The immune system produces antibodies or
cells that can deactivate pathogens.
 Fungi, protozoans, bacteria, and viruses are all
potential pathogens.

24.  All have a short life span and reproductive
time.
 So what?

25.  An infectious disease is one in which minute
organisms, invisible to the naked eye, invade
and multiply within the body.
 Many of these organisms are contagious, that
is they spread between people in close
contact.

26.  Endemic diseases are
those found normally in
a population.
 For example…….

27.  An epidemic disease is a disease that
many people acquire over a short
period of time.
 For example………

28.  A pandemic disease
is a world-wide
epidemic disease.
 For example……….
HIV -AIDS,
CORONA..

29. The Immune System –
includes all parts of the body that help in the
recognition and destruction of foreign materials.
White blood cells, phagocytes and lymphocytes,
bone marrow, lymph nodes, tonsils, thymus, and
your spleen are all part of the immune system.

30. The Immune System

31. 1) First-line Defenses /Innate Immunity/ Inborn
Immunity
 The body's first line of defense against pathogens
uses mostly physical and chemical barriers such as
 Skin – acts as a barrier to invasion
 Sweat – has chemicals which can kill different
pathogens.
 Tears - have lysozyme which has powerful digestive
abilities that render antigens harmless.
 Saliva – also has lysozyme.
 Mucus - can trap pathogens, which are then
sneezed, coughed, washed away, or destroyed by
chemicals.
 Stomach Acid – destroys pathogens

32. Second-Line Defenses –
If a pathogen is able to get past the body's first
line of defense, and an infection starts, the body
can rely on it's second line of defense. This will
result in what is called an……….

33.  Inflammatory response causes
 Redness - due to capillary dilation resulting in
increased blood flow
 Heat - due to capillary dilation resulting in
increased blood flow
 Swelling – due to passage of plasma from the
blood stream into the damaged tissue
 Pain – due mainly to tissue destruction and,
to a lesser extent, swelling.

35. 2) ADAPTIVE IMMUNITY / SPECIFIC IMMUNITY
Third-Line Defenses - Sometimes the second line of
defense is still not enough and the pathogen is then
heading for the body's last line of defense, the immune
system.
 The immune system recognizes, attacks, destroys, and
remembers each pathogen that enters the body. It
does this by making specialized cells
and antibodies that render the pathogens harmless.
 Unlike the first line and second line defense the
immune system differentiates among pathogens.
 For each type of pathogen, the immune system
produces cells that are specific for that particular
pathogen.

36.  An antibody is a protein produced in response to
an antigen.
 Antigens are macromolecules that elicit an
immune response in the body.The most common
antigens are proteins and polysaccharides.

37.  Antigens can enter the body from the environment. These
include
 inhaled macromolecules (e.g., proteins on cat hairs that
can trigger an attack of asthma in susceptible people)
 ingested macromolecules (e.g., shellfish proteins that
trigger an allergic response in susceptible people)
 molecules that are introduced beneath the skin (e.g., on a
splinter or in an injected vaccine)

38.  antigens can be generated within the cells of
the body. These include
 proteins encoded by the genes of viruses that
have infected a cell
 aberrant proteins that are encoded by
mutant genes; such as mutated genes in
cancer cells

39.  Lymph is a milky body fluid that contains a
type of white blood cells, called lymphocytes,
along with proteins and fats.
 Lymph seeps outside the blood vessels in
spaces of body tissues and is stored in the
lymphatic system to flow back into the
bloodstream.

40.  Through the flow of blood in and out of arteries, a
into the veins, lymph nodes, into the lymph, the
body is able to eliminate the products of cellular
breakdown and bacterial invasion.

41.  There are more than 100 tiny, oval structures
called lymph nodes.These are mainly in the
neck, groin and armpits, but are scattered all
along the lymph vessels.
 They act as barriers to infection by filtering
out and destroying toxins and germs.The
largest body of lymphoid tissue in the human
body is the spleen.

42. lymph nodes

43.  As the lymph flows through lymph vessels, it
passes through lymph nodes.
 White blood cells called macrophages trap
and engulf cell debris and pathogens. Other
white blood cells, called
 Lymphocytes - are a type of white blood cell
capable of producing a specific immune
response to unique antigens. They produce
antibodies which are chemicals that mark
pathogens for destruction.

44. The scanning electron micrograph above, shows a human
macrophage (gray) approaching a chain of Streptococcus pyogenes
(yellow). Riding atop the macrophage is a spherical lymphocyte.
Both macrophages and lymphocytes can be found near an infection,
and the interaction between these cells is important in eliminating
infection.

45.  Once a white cell has left the blood vessel and migrated to
the enemy, the next job is to EAT the microbe.
 The macrophage is a large phagocyte. A phagocyte is an
eating cell (phago = "eating", cyte = "cell") which engulfs
invaders.

46.  Immunity is the result of the action of two types lymphocytes,
the B lymphocytes and the T lymphocytes.
 B cells produce antibodies that are secreted into the blood
and lymph.
 T cells attack the cells that have antigens that they
recognize.

47.  Killer T Cells (lymphocytes) recognize surface
markers on other cells labeled for destruction. They,
Killer T Cells, help to keep virus-infected or malignant
cells in check.
Here, a smaller Killer T Cell (arrow) is attacking and
killing a much larger flu virus-infected target. The
sequence represents 30 minutes elapsed time.

48.  It has been estimated that during our lifetime, we will
encounter a million foreign antigens capable of causing
disease, and our bodies need the same amount of
lymphocytes to defend against them.
 There will always be a different type of lymphocyte for
each possible antigen.

49. •Active Immunity occurs when when one makes
his/her own antibodies. This type of immunity is
long term.
•Getting the disease : If you get an
infectious disease (like Chicken
Pox), often times, that stimulates the
production of MEMORY cells
which are then stored to prevent
the infection in the future.

50. Vaccination: A vaccination is an injection of a
weakened form of the actual antigen that causes the
disease. The injection is too weak to make you sick, but
your B lymphocytes will recognize the antigen and react
as if it were the "real thing". Thus, you produce
MEMORY cells for long term immunity.

51. Passive Immunity occurs when the antibodies
come from some other source. This type of
immunity is short term.
Breast milkMilk
from a mother's
breast contains
antibodies. The baby
is acquiring passive
immunity. These
antibodies will only
last several weeks.

52. Gamma Globulin: A Gamma Globulin shot is
purely an injection of antibodies to provide
temporary immunity. You might receive an
Gamma Globulin shot if you travel outside of
the country.