epidemiology reservoir & incubation period

epidemiology reservoir & incubation period

1. Reservo Reservoir & Incubation Period ir & Incubation Period epidemiology Prepared By:_ Aram Mustafa Ali 1

2. Content Reservoir of infection Chain Of infection Types of reservoir Stages of infectious disease Chart Of Stage Of Infectious Disease Human reservoir Types of Human Reservoir Animal Reservoir Soil reservoir Arthropod reservoir Incubation period The actual length of incubation period depends on Types of incubation period Advantages (Benefits) of the incubation period 2

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. 3

4. Chain Of infection Reservoir & Incubation Period 4

5. Types of reservoir: 1 . Human reservoir 2. Animal reservoir 3. Arthropod reservoir 4. Soil reservoir Reservoir & Incubation Period 5

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. 6

7. Stages of infectious disease 7 Incubation Period Prodromal Period Period of illness Period of decline Period of Convalescent Resolution Time and Progression Pathogen Population or Symtom Severity

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: Incubatory carrier: patient incubating the disease and may transmit before they become symptomatic (chicken pox) Convalescent carrier: patients who have recovered from an acute illness may continue to shed the organisms. (Enteric infection). Chronic carrier (more than one year): patients may develop chronic infection for long period of time. (HBV, aids) Healthy carrier: persons had the infection but never develop the diseases signs and symptoms. (HAV) 9

10. Types of Human Reservoir: 2- Cases: Typical cases (well-diagnosed) Missed cases (not well recognized) 10

11. Disease can be transmitted under natural condition from animals to humans and these called “ Zoonosis“ For example : 2- Animal Reservoir : 11 (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 12

13. 4- Arthropod reservoir : Lices : relapsing fever Mosquito : malaria Sand fly: leishmaniasis 13

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. 14

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 15

16. Types of incubation period :- Internsic : - the period of the interaction between the agent and the host. Externsic : - the period of the manifestation of the pathological and the clinical feature. Microgenic : - the period between the agent departure and its effect on the hosts. 16

17. Advantages (Benefits) of the incubation period :- "Clinically " diagnosis and treatment. " Epidemiologically" preventive and therapeutic measure. " Administratively" a- Budget b- planning c- implementation d- Evaluation. 17

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