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Description
Flashcards by Ashutosh Kumar, updated more than 1 year ago
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Created by Ashutosh Kumar
almost 8 years ago
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| Question | Answer |
| Definition of a communicable disease: | Definition: An illness caused by a specific agent, or its toxic product that results from transmission of that agent, or its products from an infected source to a susceptible host. |
| Degrees of disease control and examples: | Degrees of disease control: Eradication: Smallpox. Elimination: Polio. Control: Diphtheria and mumps. |
| Epidemiological triangle: Apices: Linkages: | Epidemiological triangle: Apices: Host (descriptive epidemiology) Environment (environmental investigation) Agent (laboratory investigation) Linkages: Immunity: host and environment. Transmission: host and agent. Survival: environment and agent. All link via disease. |
| Epidemiological concepts: Incubation period: Generation time (serial interval): Epidemic curve: | Epidemiological concepts: Incubation period: Period in which host is infected before symptomatic/clinical disease. During this period there is a latent time and infectious period. Generation time (serial interval): Average number of days taken by an ill person to transmit the infection to another person. Epidemic curve: Illustrates the number of new cases per generation. |
| Terms: Reproduction number (R): Basic reproduction number (Ro): | Terms: Reproduction number (R): Measures the potential for an infection to spread in a community. Basic reproduction number (Ro): The average number of persons directly infected by an infected person during the entire infectious period, when they enter a totally susceptible population. |
| What determines (Ro): | What determines (Ro)= (Pi)x(K)x(D): The risk of transmission per contact (Pi). Number of contacts (K). Duration of infectious period (D). |
| Spread of infection likelihood based on (Ro): | Spread of infection likelihood based on (Ro): <1: Disease will not spread. =1: Disease will become endemic. >1: Disease will cause an epidemic. |
| Effect of immunization: | Effect of immunization: If proportion P have been immunized, P x Ro will escape infection. To prevent an epidemic: P>1-1/Ro |
| Herd immunity: | Herd immunity: The protection given when a large proportion of the population are protected against the spread of a disease. Can be calculated from Ro. H=(1-1/Ro)x100 |
| Why be concerned: | Why be concerned: Dynamic interaction between populations; dependency (source of new cases) Important health effects (mortality/DALYS and morbidity Understanding of an organism (immunity and novel organisms) Urgency for public health action (potential for control or elimination) |
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