1. COMMUNICABLE DISEASES
EPIDEMIOLOGY,
CONTROL &
PREVENTION
CHP300

2. COMMUNICABLE DISEASE
Content
Sources & transmission of infection Host-parasite relationship Cycle of infection Outcome of infection Disease mechanism Spectrum of disease Levels of disease occurrence Control and prevention of disease Levels of Prevention Natural History of disease

3. Control DEFINITIONS COMMUNICABLE DISEASE : EPIDEMIOLOGY PREVENTION
COMMUNICABLE DISEASE : An illness due to a specific infectious agent or its toxic products. EPIDEMIOLOGY: Study of distribution and determinants of health-related states and events in specified populations and application of this study to control health problems. CONTROL : reducing occurrence of disease so that it is no longer a problem. PREVENTION : elimination of the probability that a disease will occur.

4. DEFINITIONS COMMUNICABLE DISEASE
An illness due to a specific infectious agent or its toxic products.
COMMUNICABLE DISEASE : An illness due to a specific infectious agent or its toxic products. EPIDEMIOLOGY: Study of distribution and determinants of health-related states and events in specified populations and application of this study to control health problems. CONTROL : reducing occurrence of disease so that it is no longer a problem. PREVENTION : elimination of the probability that a disease will occur.

5. DEFINITIONS EPIDEMIOLOGY
COMMUNICABLE DISEASE
DEFINITIONS
EPIDEMIOLOGY
Study of distribution and determinants of health-related states and events in specified populations and application of this study to control health problems.
COMMUNICABLE DISEASE : An illness due to a specific infectious agent or its toxic products. EPIDEMIOLOGY: Study of distribution and determinants of health-related states and events in specified populations and application of this study to control health problems. CONTROL : reducing occurrence of disease so that it is no longer a problem. PREVENTION : elimination of the probability that a disease will occur.

6. Control: Elimination : Eradication: Extinction: DEFINITIONS
COMMUNICABLE DISEASE
DEFINITIONS
Control:
Elimination :
Eradication:
Extinction:
Control: The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction. Example: diarrheal diseases. Elimination : Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent re-establishment of transmission are required. Example: measles, poliomyelitis. Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. Example: smallpox. Extinction: The specific infectious agent no longer exists in nature or in the laboratory. Example: none.

7. COMMUNICABLE DISEASE
DEFINITIONS
Control
The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction.
Control: The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction. Example: diarrheal diseases. Elimination : Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent re-establishment of transmission are required. Example: measles, poliomyelitis. Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. Example: smallpox. Extinction: The specific infectious agent no longer exists in nature or in the laboratory. Example: none.

8. Elimination DEFINITIONS
COMMUNICABLE DISEASE
DEFINITIONS
Elimination
Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent re-establishment of transmission are required.
Control: The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction. Example: diarrheal diseases. Elimination : Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent re-establishment of transmission are required. Example: measles, poliomyelitis. Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. Example: smallpox. Extinction: The specific infectious agent no longer exists in nature or in the laboratory. Example: none.

9. DEFINITIONS Eradication
COMMUNICABLE DISEASE
DEFINITIONS
Eradication
Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed..
Control: The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction. Example: diarrheal diseases. Elimination : Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent re-establishment of transmission are required. Example: measles, poliomyelitis. Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. Example: smallpox. Extinction: The specific infectious agent no longer exists in nature or in the laboratory. Example: none.

10. DEFINITIONS Extinction
COMMUNICABLE DISEASE
DEFINITIONS
Extinction
The specific infectious agent no longer exists in nature or in the laboratory.
Control: The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction. Example: diarrheal diseases. Elimination : Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent re-establishment of transmission are required. Example: measles, poliomyelitis. Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. Example: smallpox. Extinction: The specific infectious agent no longer exists in nature or in the laboratory. Example: none.

11. . Incubatory carrier . Convalescent carrier . Chronic carrier
COMMUNICABLE DISEASE
SOURCES OF INFECTIONS
CASE OF DISEASE : a patient
CARRIER :
. Incubatory carrier
. Convalescent carrier
. Chronic carrier
. In-apparent carrier
ANIMAL RESERVOIR (ZOONOSIS)
INANIMATE RESERVOIR (THE SOIL)
CARRIER: A person or animal without apparent disease who harbors a specific infectious agent and is capable of transmitting the agent to others.

12. COMMUNICABLE DISEASE
SOURCES OF INFECTIONS
CARRIER :
A person or animal without apparent disease who harbors a specific infectious agent and is capable of transmitting the agent to others.
CARRIER: A person or animal without apparent disease who harbors a specific infectious agent and is capable of transmitting the agent to others.

13. SOURCES OF INFECTIONS Reservoir:
COMMUNICABLE DISEASE
SOURCES OF INFECTIONS
Reservoir:
Any person, animal, arthropod, plant, soil or substance (or combination of these) in which an infectious agent lives and multiplies, on which it depends primarily for survival, and where it reproduces itself, in such a manner that it can be transmitted to a susceptible host
CARRIER: A person or animal without apparent disease who harbors a specific infectious agent and is capable of transmitting the agent to others.

14. Reservoir Zoonosis animal human SOURCES OF INFECTION
COMMUNICABLE DISEASE
SOURCES OF INFECTION
Reservoir
Zoonosis
animal
Reservoir: Any person, animal, arthropod, plant, soil or substance (or combination of these) in which an infectious agent lives and multiplies, on which it depends primarily for survival, and where it reproduces itself, in such a manner that it can be transmitted to a susceptible host
Zoonosis: An infectious disease that is transmissible under normal conditions from animal to human
animal
human

15. SOURCES OF INFECTION Examples: Salmonella typhi Neisseria gonorrhea
COMMUNICABLE DISEASE
SOURCES OF INFECTION
Examples:
Salmonella typhi
-Source = food/water
-Reservoir = humans
Neisseria gonorrhea
-Source = humans
-Reservoir = humans
Hepatitis C
-Source = transfusion,
blood products
-Reservoir = humans
Rabies virus
-Source = saliva of
the dog
-Reservoir = the dog

16. MODE OF TRANSMISSION OF INFECTION:
COMMUNICABLE DISEASE
MODE OF TRANSMISSION OF
INFECTION:
1- AIR-BORNE
2- FOOD AND DRINK-BORNE
3- ARTHROPOD-BORNE
4- CONTACT TRANSMISSION

17. TRANSMISSION OFINFECTION:
COMMUNICABLE DISEASE
TRANSMISSION OFINFECTION:
1. Water-washed dis (Dis. of skin, eye)
2. Fecal-oral disease (Viral, bact., parasitic)
3. Soil-mediated infections.(Tetanus, intestinal parasites)
4. Diseases of water contact. (Bilharzia, Guinea worm)
5. Food-borne dis (F.P., intestinal flukes)
6. Infectious skin rashes (Chickenpox, smallpox)
7. Respiratory infections (Viral, bacterial)
8. Dis. Transmitted via body fluids (STD)
9. Insect-borne (Viral, parasitic)
10. Zoonosis (Brucellosis, rabies)

18. COMMUNICABLE DISEASE
CHANNELS OF
TRANSMISSION OF
INFECTION:

19. CHANNELS OF TRANSMISSION OF INFECTION: 1- AIR-BORNE
COMMUNICABLE DISEASE
CHANNELS OF
TRANSMISSION OF
INFECTION:
1- AIR-BORNE
2- FOOD AND DRINK-BORNE
3- ARTHROPOD-BORNE
4- CONTACT TRANSMISSION

20. (indirect air-borne): TB, Diphtheria
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Droplet infection
(direct spread):
CSM, Whooping cough
Droplet nuclei
(direct air-borne):
Measles, Chickenpox
Infected dust
(indirect air-borne):
TB, Diphtheria

21. Caused by various strains of mycobacteria, usually Mycobacterium.
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Pulmonary Tuberculosis
Caused by various strains of mycobacteria, usually Mycobacterium.
Spread through the air
Most infections are asymptomatic and latent
active TB infection cough, sneeze, or otherwise transmit respiratory fluids through the ai.

22. caused by the influenza viruses RNA viruses
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Influenza
caused by the influenza viruses RNA viruses
The most common symptoms are chills, fever, runny nose, sore throat, muscle pains, headache (often severe), coughing, fatigue and general discomfort.

23. 1- AIR-BORNE Inhalation Infections: Pneumonia
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Pneumonia
Is an inflammatory condition of the lung
Caused by infection with viruses or bacteria and less commonly other microorganisms .
Typical symptoms include a cough, chest pain, fever, and difficulty breathing.

24. 1- AIR-BORNE Inhalation Infections: Sore-throat
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Sore-throat
Inflammation of the pharynx caused by a viruses& bacteria (group A streptococcus).
Discomfort, pain, or scratchiness in the throat. It often makes it painful to swallow.
pharyngitis

25. 1- AIR-BORNE Measles Inhalation Infections:
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Measles
an infection of the respiratory system and is highly contagious ,caused by a paramyxovirus
Symptoms include fever, cough, runny nose, red eyes and a generalized,confluent maculopapular, and erythematous rash.
Measles also known asmorbilli, English measles, or rubeola

26. Caused by the bacterium Bordetella pertussis
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Whooping cough:
Caused by the bacterium Bordetella pertussis
The first symptoms are similar to those of a common cold .
It's characterized by severe coughing spells.
It mainly affects infants younger than 6 months old before they're adequately protected by immunizations, and kids 11 to 18 years old whose immunity has started to fade.

27. 1- AIR-BORNE Diphtheria Caused by Corynebacterium diphtheriae,
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Diphtheria
Caused by Corynebacterium diphtheriae,
Spread by direct physical contact or breathing
Characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx.
consequences myocarditis and peripheral neuropathy.

28. COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Scarlet fever
caused by toxin , produced by the bacterium Streptococcus pyogenes (group A strep)
complications such as glomerulonephritis and endocarditis leading to heart valve disease,
most commonly affects 4-8 year old children.
Strawberry tongue seen in scarlet fever. Red cheeks and pale area around the mouth in scarlet fever.

29. caused by: varicella zoster virus (VZV).
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Chicken pox
caused by: varicella zoster virus (VZV).
Spread: coughing or sneezing or direct contact with secretions from the rash
Symptoms :vesicular skin rash also ulcers in the oral cavity and tonsil areas.
chickenpox is infectious one to two days before the rash appears.[2] They remain contagious until all lesions have crusted over (this takes approximately six days).[

30. 1- AIR-BORNE Inhalation Infections: Mumps Caused by: the mumps virus.
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Mumps
Caused by: the mumps virus.
Painful swelling of the salivary glands (the parotid gland) ,Painful testicular swelling (orchitis). Fever , headache , malaise and anorexia.
complications such as infertility or subfertility
• (epidemic parotitis), is the most typical presentation The disease is generally self-limiting, running its course before receding,

31. Caused by the rubella virus.
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Rubella :
Caused by the rubella virus.
Transmitted via airborne droplet (Acquired)or
if the mother is infected within the first 20 weeks of pregnancy, the child may be born with congenital rubella syndrome (trans placental )
also known as German measles. ). The virus may also be present in the urine, feces and on the skin. Infection of the mother by Rubella virus during pregnancy can be serious;

32. 1- AIR-BORNE Cerebrospinal fever
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Cerebrospinal fever
severe headaches, tenderness of the back of the neck, paralysis of the ocular muscles.
characterized by inflammation of the membranes of the brain and spinal cord,

33. 1- AIR-BORNE Inhalation Infections: Measles. Whooping cough Diphtheria
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
1- AIR-BORNE
Inhalation Infections:
Measles.
Whooping cough
Diphtheria
Scarlet fever
Chicken pox
Mumps
Rubella
Cerebrospinal fever
(Small Pox)

34. 2- FOOD AND DRINK-BORNE Categories: The enterica (salmonellae)
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
2- FOOD AND DRINK-BORNE
Categories:
The enterica (salmonellae)
The dysentery (shigellae ,Amoebic)
The rotaviruses (G.E.)
Hep A
Cholera
Food poisoning (staph).
Helminths.
Enterica is bacterial disease transmitted by the ingestion of food or which contain the bacterium Salmonella enterica , Dysentery is an inflammatory disorder of the intestine)( viral, bacterial, or parasitic)., Rotaviruses common cause of severe diarrhea among infants and young children caused by RNA virus in the family Reoviridae. Hepatitis A infection causes no clinical signs and symptoms in over 90% of infected children and since the infection confers lifelong immunity ,Hepatitis A is an acute infectious disease of the liver caused by the hepatitis A virus (HAV). Cholera is an infection in the small intestine caused by the bacterium Vibrio cholera. The main symptoms are watery diarrhea and vomiting . Foodborne illness usually arises from improper handling, preparation, or food storage. Goodhygiene practices before, during, and after food preparation can reduce the chances of contracting an illness. Parasitic worms, often referred to as helminths, Those that live inside the digestive tract are called intestinal parasites. They can live inside humans and other animals.

35. 2- FOOD AND Water-BORNE Musca domestica House fly
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
2- FOOD AND Water-BORNE
Methods of transmission:
The human hand
Flies
Musca domestica
House fly

36. 2- FOOD AND DRINK-BORNE Methods of transmission:
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
2- FOOD AND DRINK-BORNE
Methods of transmission:
Milk: Excellent medium
T.B.
F.P.
Diphtheria
Dirty udder
Dirty hands of milking man
Dirty bottle
Water: Very serious

37. 2- FOOD AND DRINK-BORNE Methods of transmission: Meat: Diseased animal
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
2- FOOD AND DRINK-BORNE
Methods of transmission:
Meat:
Diseased animal
Contaminated meat.
Fresh Vegetables and Fruits :
Poor medium.
Can be contaminated by:
Flies
Washing water
Dirty hands
Manure

38. 3- ARTHROPOD-BORNE Methods of transmission: Can be:
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
3- ARTHROPOD-BORNE
Methods of transmission:
Can be:
Biological transmission
Harborage transmission
Transovarial transmission
Mechanical transmission
Harborage transmission: a mode of infection transmission in which the organism does not undergo morphologic or physiologic changes in the vector.

39. 3- ARTHROPOD-BORNE Methods of transmission: Vector: Inoculation
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
3- ARTHROPOD-BORNE
Methods of transmission:
Vector:
Inoculation
Inoculation
Inoculation
Contamination (broken skin or mucous membranes)
By infectious feces.
Body fluids (when crushed)

40. 3- ARTHROPOD-BORNE Methods of transmission: Flies: Enteric fevers.
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
3- ARTHROPOD-BORNE
Methods of transmission:
Flies:
Enteric fevers.
Mucopurulent conjunctivitis.
Ascariasis.
Food poisoning.
Ascariasis caused by the parasitic roundworm Ascaris lumbricoides may cause malabsorption and anorexia which contribute to malnutrition.. Poliomyelitis often called polio or infantile paralysis, is an acute, viral, infectious disease. is highly contagious via the oral-oral (oropharyngeal source) and fecal-oral (intestinal source) routes. the virus enters the central nervous system, and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis.
Amoebic dysentery.
Poliomyelitis.

41. 3- ARTHROPOD-BORNE Methods of transmission:
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
3- ARTHROPOD-BORNE
Methods of transmission:
The louse (Pediculum humanus):
Epidemic typhus.
L.B. relapsing fever.
human body louse
L.B. relapsing fever is a vector-borne disease caused by infection with certain bacteria in the genus Rickettsia and Borrelia , which are transmitted through the bites of lice or soft-bodied ticks .
Human
Head
louse

42. 3- ARTHROPOD-BORNE Methods of transmission:
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
3- ARTHROPOD-BORNE
Methods of transmission:
The Flea (Xenopsylla cheopis;
rat flea) :
Bubonic plague
is a zoonotic disease, circulating mainly in fleas on small rodents, caused by Yersinia pestis. Swollen lymph nodes especially occur in the armpit and groin s, . Acral gangrene (i.e. of the fingers, toes, lips and nose), is another common symptom
Endemic typhus

43. 3- ARTHROPOD-BORNE Methods of transmission: The Mosquito (female of):
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
3- ARTHROPOD-BORNE
Methods of transmission:
The Mosquito (female of):
- Culex sp. (filariasis)
- Anopheles sp. (malaria)
- Aedes sp. (Dengue fever)
Filariasis caused by thread-like nematodes (roundworms). The most spectacular symptom of lymphatic filariasis is elephantiasis—edema with thickening of the skin and underlying tissues ,transmitted by mosquito bites.[3] Elephantiasis results when the parasites lodge in the lymphatic system.

44. - Cutaneous Leishmaniasis.
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
3- ARTHROPOD-BORNE
Methods of transmission:
The Sand Fly:
- Cutaneous Leishmaniasis.

45. 4- CONTACT Methods of transmission: Can be: Direct Indirect
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
4- CONTACT
Methods of transmission:
Can be:
Direct
Indirect
Disease which are easily transmitted by physical contact with the person suffering the disease, or by their secretions or objects they touched.
Diseases of Contact: Disease which are easily transmitted by physical contact with the person suffering the disease, or by their secretions or objects they touched.

46. 4- CONTACT Types: STD Hep.B Syphilis Herpes simplex Lymphogranuloma
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
4- CONTACT
Types:
STD
Hep.B
Syphilis
Herpes simplex
Lymphogranuloma
HIV
Herpes simplex caused by both Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2)Lymphogranuloma is a sexually transmitted disease caused by the invasive Chlamydia trachomatis .LGV is primarily an infection of lymphatics and lymph nodes.

47. - Tinea capitis (ring worm).
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
4- CONTACT
Types:
Fungal Infection of the skin
- Tinea capitis (ring worm).
Tinea pedis (athlete’s foot).
- Tinea cruris.
(crotch itch)

48. 4- CONTACT - Moniliasis - Mycetoma Madura foot Types: Mycosis
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
4- CONTACT
Types:
Mycosis
- Moniliasis
(Oral Thrush)
- Mycetoma
Madura foot

49. mite (Sarcoptes scabiei)
COMMUNICABLE DISEASE
CHANNELS OF TRANSMISSION OF INFECTION:
4- CONTACT
Types:
-Scabies:
mite (Sarcoptes scabiei)
-Trachoma and other
eye infections.

50. HOST-PARASITE RELATIONSHIP
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Epidemiologic Triangle
Agent
(Seed)
Environment
(Climate)
Host
(Soil)

51. HOST-PARASITE RELATIONSHIP Infectious Disease Model
COMMUNICABLE DISEASE
HOST-PARASITE
RELATIONSHIP
Infectious Disease Model
Host
Pathogen
Environment
disease

52. Disease Agents Biological Physical Chemical Mechanical Nutrient
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Disease Agents
Biological
Physical
Chemical
Mechanical
Nutrient

53. Biological Disease Agents
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Biological Disease Agents
Bacteria
Viruses
Parasites
Protozoa
Metazoa
Rickettsiae
Fungi

54. Microbes-humans Relationship
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Microbes-humans Relationship
Very few microbes are
always pathogenic
Many microbes are
potentially pathogenic
Most microbes are
never pathogenic

55. Microbes-humans Relationship (Symbiosis)
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Microbes-humans Relationship
(Symbiosis)
Mutualism
- Association in which both partners benefit
Commensalism
- Association in which one partner benefits and other is unharmed
Parasitism
- Association in which the microbe befits at expense of host
(Bacteria and synthesis of vitamins K and B)
(Flora living on skin)
(pathogenic infection)

56. - Ability to survive outside the host (milk, water, soil).
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Agent Factors
Intrinsic Properties of “Agent”
- Antigenic make-up.
- Growth requirements.
- Ability to survive outside the host
(milk, water, soil).
- Viability under varying conditions
(temp, humidity).
- Spectrum of hosts.
- Resistance to treatment.
- New genetic information.

57. Infectivity Pathogenicity Virulence Immunogenicity Agent Factors
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Agent Factors
Properties subject to interaction
Infectivity
Pathogenicity
Virulence
Immunogenicity
Colonization : presence of microorganisms without disease at that point, without actual tissue invasion. This term applies to surfaces only, i.e., the blood cannot be colonized, and host cells with intracellular infection are not colonized.
Infection: The entry and development or multiplication of an infectious agents in the body of person.
Infectivity: The proportion of persons exposed to a causative agent who become infected by an infectious disease
Pathogenicity: The proportion of persons infected after exposure to a causative agent, who then develops clinical disease
Virulence: The proportion of persons with clinical disease, who after becoming infected, become severely ill or die. (The degree of pathogenicity)
Immunogenicity: Is the ability of a particular substance to provoke an immune response

58. Agent Factors HOST-PARASITE RELATIONSHIP
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Agent Factors
Properties subject to interaction
Infectivity
Pathogenicity
Virulence
Immunogenicity
Dose
Source
Route
Duration before
reaching the host
Host characteristics
Age
Race
Nutritional Status

59. Exposure Susceptibility Response to the agent Host Factors
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Host Factors
( a HOST is a PERSON who can be
infected under normal conditions.)
Exposure
Susceptibility
Response to the agent

60. Host Factors Exposure Age Sex Race S.E.S ( occupation) Behavior
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Host Factors
Exposure
Age
Sex
Race
S.E.S ( occupation)
Behavior
Drug abuse
Sexual practice

61. Host Factors Age Pregnancy Malnutrition Immunity Other diseases
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Host Factors
Susceptibility and Response to the Agent
Age
Pregnancy
Malnutrition
Immunity
Other diseases
Medications

62. Climate Geography Water Housing Environmental Factors
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Environmental Factors
1- Physical Environment
Climate
Geography
Water
Housing

63. Man Microbes Insects Rodents Animals Environmental Factors
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Environmental Factors
2- Biological Environment
Man
Microbes
Insects
Rodents
Animals
Agents
Reservoirs
Intermediate hosts
Vectors

64. Education Occupation Beliefs Attitude Behavior Environmental Factors
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Environmental Factors
3- Psychosocial Environment
Education
Occupation
Beliefs
Attitude
Behavior

65. Reservoir of Infection Types :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Reservoir of Infection
Types :
1. Human to Human
Human
Human
Most viral and bact. RTIs
Most staph and strept.
Childhood exanthemata
STD
Reservoir: Any person, animal, arthropod, plant, soil or substance (or combination of these) in which an infectious agent lives and multiplies, on which it depends primarily for survival, and where it reproduces itself, in such a manner that it can be transmitted to a susceptible host
Zoonosis: An infectious disease that is transmissible under normal conditions from animal to human

66. Zoonosis animal human Reservoir of Infection Types :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Reservoir of Infection
Types :
2. Animal to Human
Zoonosis
animal
animal
human

67. - Malaria - Bilharzia - Tape worm Reservoir of Infection Types :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Reservoir of Infection
Types :
3. Complex cycles
- Malaria
- Bilharzia
- Tape worm

68. Some Concepts of Infection Phases of Infectious Disease :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Infectious Disease :
The Incubation Period :
Initial infection ( exposure )
Onset of clinical disease
( symptoms or signs)
Symptom = subjective complaint e.g.:
pain, loss of appetite, lethargy
Sign = observable or measurable change in body function eg : rash, fever

69. Some Concepts of Infection Phases of Infectious Disease :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Infectious Disease :
The Latent Period :
Initial infection Start of infectiousness
The Period of Communicability:
1. before onset early in disease course
The Period of Communicability: The Person is directly or indirectly infectious to other persons or animals.
2. After onset after recovery
- convalescence
- chronic

70. Some Concepts of Infection Phases of Disease Cycle :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Disease Cycle :
Incubation period:
-Variable length
-Prior to signs and symptoms
Prodromal stage:
- The period of early symptoms
- Indicates the start of disease before specific symptoms and signs occur.
- Often infectious/contagious
- Innate immune response starts
The innate immune system: The first line of defense, providing immediate defense against infection. It comprises the cells ( including: mast cells and phagocytes ) and mechanisms that defend the host from infection. It does not confer long-lasting or protective immunity to the host.

71. Some Concepts of Infection Phases of Disease Cycle
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Disease Cycle
Illness stage :
- Most severe phase
- Clear evidence of signs and symptoms
- Acquired immune responses begin
Decline stage:
- Alleviation of signs and symptoms
- Recovery/convalescence

72. Some Concepts of Infection Phases of Infectious Disease :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Infectious Disease :
Cycle of Infection
INFECTIOUS AGENT BACTERIA VIRUSES FUNGI PROTOZOA HELMINTH
SUSCEPTIBLE HOST NEONATES DIABETICS IMMUNOSUPPRESSED CARDIOPULMONARY DISEASE
RESERVOIR PEOPLE EQUIPMENT WATER
PORTAL OF ENTRY BROKEN SKIN MUCOUS MEMBRANES GIT/RESPIRATORY URINARY TRACT
PORTAL OF EXIT EXCRETIONS SECRETIONS DROPLETS SKIN
MODE OF TRANSMISSION AIRBOURNE INGESTION INNOCULATION CONTACT

73. Some Concepts of Infection Phases of Infectious Disease :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Infectious Disease :
Cycle of Infection

74. Some Concepts of Infection Phases of Infectious Disease :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Infectious Disease :
Cycle of Infection
PATHOGEN
RESERVOIR/ SOURCE
PORTAL of EXIT
MODE
of ENTRY
PORTAL
SUSCEPTIBLE
HOST

75. COLONIZATION C O V E R T O V E R T
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Infectious Disease :
Outcome of Infection P R A S I T E
H O S T
COLONIZATION
C O V E R T
disease
O V E R T
disease

76. Tissue invasion Toxin production Hypersensitivity
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Infectious Disease :
Disease Mechanism
Tissue invasion
Toxin production
Hypersensitivity

77. Some Concepts of Infection Phases of Infectious Disease :
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of Infection
Phases of Infectious Disease :
Spectrum of Disease
TB, Polio, Hep A f f f f f
Measles, Chickenpox f f f f f
Rabies, Amebic Encephalitis, Hemorrhagic Fever. f f f f f f f f f f
Inapparent
Mild
Moderate
Sever
Fatal

78. Occurs irregularly and only occasionally in a population .
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of
Communicable Disease :
Communicable Diseases Occurrence:
Sporadic Disease :
Occurs irregularly and only occasionally in a population .
e.g. Typhoid fever (Salmonella typhi)

79. COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Some Concepts of
Communicable Disease :
Communicable Diseases Occurrence
Endemic Disease :
Constant presence of an infectious disease within a given geographical area or population group.
the usual or
expected
frequency of disease

80. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Some Concepts of
Communicable Disease :
Communicable Diseases Occurrence
Hyperendemic Disease :
When occurrence frequency
rises,
but not to epidemic proportions.
e.g. - Common cold in the winter months
- high prevalence malaria

81. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Some Concepts of
Communicable Disease :
Communicable Diseases Occurrence
Epidemic :
The occurrence of cases of disease,
(( specific health related behavior, or other health related events ))
clearly more than expected
In a given area
or among a specific group of people
over a particular time.
? One example

82. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Some Concepts of
Communicable Disease :
Communicable Diseases Occurrence
Outbreak :
epidemic-like
increase in frequency,
but in a very limited (focal)
segment of the population;
Usually of shorter duration.
Example: Food poisoning,
URTI

83. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Some Concepts of
Communicable Disease :
Communicable Diseases Occurrence
Pandemic :
An epidemic occurring over a very wide area (several countries or continents) and usually affecting a large proportion of the population
? One example

84. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Some Concepts of
Communicable Disease :
Communicable Diseases Occurrence
Endemic Epidemic :
Number of Cases of a Disease
Endemic
Epidemic
Time

85. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Some Concepts of
Communicable Disease :
Communicable Diseases Occurrence
Endemic Epidemic :
Host Factors:
- Change in behavior ?
- Population movement
Immunity

86. Environmental Factors: - Adverse conditions: - War - Famine
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Communicable Diseases Occurrence
Endemic Epidemic :
Environmental Factors:
- Adverse conditions:
- War
- Famine
Vector:
- Mosquitos
- Flies

87. Environmental Factors:
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Communicable Diseases Occurrence
Endemic Epidemic :
Environmental Factors:
- New or Exposure
- Change in climate
- Irrigation scheme
- Control measures

88. Can be classified into:
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Control of Communicable Disease :
Can be classified into:
I Controlling the source of infection
II Blocking the channels of transmission
III Protecting the susceptible population

89. - Early diagnosis - Notification - Isolation - Treatment - Quarantine
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Controlling the source of infection
(CASES, CARRIERS AND ANIMAL RESERVOIR)
- Early diagnosis
- Notification
- Isolation
- Treatment
- Quarantine
- Surveillance
- Disinfection
ISOLOATION: Placement of patients in special rooms in hospital to prevent spread of infection to susceptible persons.
QUARANTINE: Restriction of freedom of movement, or detention of apparently well individuals who have been exposed to infectious disease, which is imposed for the maximal incubation period of the disease, to prevent disease from entering a country. This can involve vessels or vehicles coming from infected or suspected ports or places.
SURVEILLANCE: The systematic collection, analysis, interpretation, and dissemination of health data on an ongoing basis.
DISINFECTION: The process of destroying pathogenic organisms on patient's objects( or rendering them inert). It is applied to non-living objects.

90. - Effective ventilation - Good health habits - Air disinfection
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Blocking the channels of transmission
1.Air- borne:
- Bed-spacing
- Dust-control
- Effective ventilation
- Good health habits
- Air disinfection
- Use of masks
- Minimize over-crowding

91. 2.Food and Drink - borne: HOST-PARASITE RELATIONSHIP
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Blocking the channels of transmission cont.
2.Food and Drink - borne:
Provision of safe/sufficient water.
Pasteurization or boiling of milk.
Proper personal hygiene.
Sanitary sewage disposal.
Control of flies.
Washing fresh vegetables.
Meat and slaughter house control.
Refrigeration of unused food.
Control of food handlers and vendors.
Labs for food examination.

92. HOST-PARASITE RELATIONSHIP Blocking the channels of transmission cont.
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
Blocking the channels of transmission cont.
Food and Drink – borne:
BOTH FOOD and DRINK
FOOD
DRINK

93. Avoiding overcrowding. Dusting by insecticides.
COMMUNICABLE DISEASE
HOST-PARASITE RELATIONSHIP
3.Arthropod - borne:
Lice:
Personal cleanliness.
Avoiding overcrowding.
Dusting by insecticides.

94. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
II Blocking the channels of transmission :
Arthropod - borne:
Fleas:
Cleanliness of dwellings.
Avoid dust collection.
Spraying & dusting by insecticides.
Rodent control.

95. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
II Blocking the channels of transmission :
Arthropod - borne:
Mosquitos :
Vector control.
Personal protection.

96. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
II Blocking the channels of transmission :
Contact Diseases :
- Case finding and treatment.
- Tracing of contacts.
- Serological examination.
Control of sexual behaviour.
Personal cleanliness.

97. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
II Blocking the channels of transmission :
Contact Diseases :
- Avoid use of common articles:
- Comb.
- Hair brush.
- Towels.
- Underwear.
- Footwear ……. etc.

98. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
III Protecting the susceptible population :
- Primary Prevention:
- Health promotion.
- Specific protection.
- Secondary Prevention:
- Early diagnosis and
- Prompt treatment.
- Tertiary Prevention:
- Limitation of disability.
- Rehabilitation.

99. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
III Protecting the susceptible population :
- Primary Prevention:
- Health promotion.
- Adequate nutrition.
- Health education.
- Socio-economic development.
- Environmental sanitation.
- Personal hygiene.
(- Genetic counseling.)

100. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
III Protecting the susceptible population :
- Primary Prevention:
- Specific protection.
- Specific immunization.
- Protection against occupational hazards.
- Protection against accidents.
- Protection from carcinogens.
- Avoidance of allergens.
- Protection against occupational hazards.
- Protection against accidents.
- Protection from carcinogens.
- Avoidance of allergens.
- Protection against occupational hazards.
- Protection against accidents.
- Protection from carcinogens.
- Avoidance of allergens.

101. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
III Protecting the susceptible population :
- Secondary Prevention:
- Early diagnosis and
- Prompt treatment.
- Health education
Screening for sub-clinical disease.
- Case finding

102. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
III Protecting the susceptible population :
- Tertiary Prevention:
- Limitation of disability.
- Adequate treatment.
- Rehabilitation.
Psychological:
Restoration of personal confidence and independence.
- Medical:
- Physical restoration of function.

103. Communicable Disease :
HOST-PARASITE RELATIONSHIP
Control of
Communicable Disease :
III Protecting the susceptible population :
- Tertiary Prevention:
- Rehabilitation.
- Vocational:
- Restoration of capacity to earn. (Occupational)
- Social:
- Restoration of family and
community relationship.

104. Natural History of Disease
COMMUNICABLE DISEASE
Natural History of Disease
Recovery

105. Natural History of Disease
COMMUNICABLE DISEASE
Natural History of Disease
Recovery

106. Natural History of Disease
COMMUNICABLE DISEASE
Natural History of Disease
Recovery

107. Natural History of Disease
COMMUNICABLE DISEASE
Natural History of Disease
Recovery

108. Natural History of Disease
COMMUNICABLE DISEASE
Natural History of Disease
Recovery