epidemiology reservoir & incubation period

1. RESERVORESERVOIR & INCUBATION PERIOD
IR & INCUBATION PERIOD
EPIDEMIOLOGY
Prepared By:_
Aram Mustafa Ali
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2. CONTENT
1. Reservoir of infection
2. Chain Of infection
3. Types of reservoir
4. Stages of infectious disease
5. Chart Of Stage Of Infectious Disease
6. Human reservoir
7. Types of Human Reservoir
8. Animal Reservoir
9. Soil reservoir
10. Arthropod reservoir
11. Incubation period
12. The actual length of incubation period depends on
13. Types of incubation period
14. Advantages (Benefits) of the incubation period
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3. RESERVOIR OF INFECTION
 Any person, animal, arthropod, plant, soil, or substance, or a combination
of these, in which an infectious agent normally 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.
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4. CHAIN OF INFECTION
Reservoir & Incubation Period
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5. TYPES OF RESERVOIR:
1. Human reservoir
2. Animal reservoir
3. Arthropod reservoir
4. Soil reservoir
Reservoir & Incubation Period
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6. STAGES OF INFECTIOUS DISEASE
1. Incubation stage: period from the initial entrance of the organisms to the time when 1st
signs and symptoms appear 2-3 days (flu) wks-mths (Hep B) yrs (HIV)
2. Prodromal Stage: The initial appearance of symptoms, though they are usually vague.
They may include malaises, fatigue, anorexia, mild fever, myalgia, and headache. Flu like
symptoms.
3. Acute Stage: The maximum impact of the infectious process; there is rapid proliferation
and spread of the pathogen. The symptoms are more pronounced and specific.
4. Convalescent stage: Convalescent period;-Infection is contained and being
progressively eliminated; The damaged tissue is repaired. Symptoms are decreasing
5. Resolution: Total elimination of the pathogen; no residual signs and symptoms.
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7. STAGES OF INFECTIOUS DISEASE
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0
0.5
1
1.5
2
2.5
3
3.5
4
0 0.5 1 1.5 2 2.5 3 3.5
Chart Of Stage infectious Disease
IncubationPeriod
Periodofillness
Periodofdecline
Resolution
Time and Progression
PathogenPopulationorSymtomSeverity

8. HUMAN RESERVOIR:
 Certain biologic agent can multiply only in human, causing either clinical cases or
sub-clinical cases.
1- Acute clinical cases (symptomatic cases)
Acute clinical cases are people who are infected with the disease agent and become ill.
• Because they are ill, their contacts and activities may be limited.
• They are more likely to be diagnosed and treated than carriers.
2- Sub-clinical case (asymptomatic cases,) this mean individual may transmit the disease
to others without knowing that they are infected, these called carriers. 8

9. TYPES OF HUMAN RESERVOIR:
 1- Carriers:
A. Incubatory carrier: patient incubating the disease and may transmit before they
become symptomatic (chicken pox)
B. Convalescent carrier: patients who have recovered from an acute illness may
continue to shed the organisms. (Enteric infection).
C. Chronic carrier (more than one year): patients may develop chronic infection for
long period of time. (HBV, aids)
D. Healthy carrier: persons had the infection but never develop the diseases signs and
symptoms. (HAV)
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10. TYPES OF HUMAN RESERVOIR:
 2- Cases:
A. Typical cases (well-diagnosed)
B. Missed cases (not well recognized)
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11.  Disease can be transmitted under natural condition from animals to humans and these
called “Zoonosis“ For example:
2- ANIMAL RESERVOIR:
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(Animals) (Examples)
Cats Toxoplasmosis
Dogs Rabies and hydatid cysts
Cattle Malta fever, worms
Sheep Hydatid cysts, worms
Goats Brucellosis
Monkeys Aids, yellow fever
Rats Plague

12. 3- SOIL RESERVOIR:
 Tetanus
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13. 4- ARTHROPOD RESERVOIR:
1. Lices: relapsing fever
2. Mosquito: malaria
3. Sand fly: leishmaniasis
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14. INCUBATION PERIOD:
 The time interval between invasion by an infections agent and appearance of the first
sign and symptom of the disease.
 During the incubation period the infection agent under goes multiplication in the host,
when a sufficient density of the diseases is built up in the host, the health equilibrium
is disturbed and the diseases becomes overt.
 Median incubation period: - the time required for (50%) of cases to occur following
exposure.
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15. THE ACTUAL LENGTH OF INCUBATION PERIOD DEPENDS ON:
“There is an average incubation period for every communicable disease”.
 1. Resistance of the host
 2. Dosage and virulence of agent
 3. Type of agent
 4. Rout of infection inside body
 The short test incubation period is staphylococcal food poisoning (enterotoxin) in
food.
 The long incubation period is leprosy, TB, v hept. B C
 The longest incubation period is AIDS
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16. TYPES OF INCUBATION PERIOD:-
1. Internsic: - the period of the interaction between the agent and the host.
2. Externsic: - the period of the manifestation of the pathological and the clinical
feature.
3. Microgenic: - the period between the agent departure and its effect on the hosts.
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17. ADVANTAGES (BENEFITS) OF THE INCUBATION PERIOD:-
1. "Clinically"
diagnosis and treatment.
2. "Epidemiologically"
preventive and therapeutic measure.
3. "Administratively"
a- Budget b- planning c- implementation d- Evaluation.
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18. Thank You