Chapter 7 Learning Objectives: Communicable Diseases

describe the burden of disease caused by communiable diseases

communicable diseases were the leading cause of death and disability among all ages, especially the young and old; respite was due to medical efforts to treat infections, and public health efforts to prevent, eradicate, or control infections

koch’s postulates

organism must be shown to present in every case of the disease by isolation; the organism must not be found in cases of other disease; once isolated the organism must be capable of replicating the disease in an experimental animal; the organism must be recoverable from the animal

modern koch’s postulates

evidence of an epidemiological association between the presence of the organisms and the presence of a disease in human beings; isolation of the organism from most of those with the disease; transmissions to definitively establish that an organism is a contributory cause of the disease

chronic carriers

those without symptoms who have the ability to chronically transmit the disease

period of communicability

period during which the infection can be transmitted

transmission probability

probability of an infection being transmitted during contact

R-naught (R0)

a measure of the potential for transmission of a communicable disease; measures average number of infections produced by an infected individual; estimates the degree of communnicability of a disease and its potential to lead to an epidemic, and the proportion of the population which needs to be protected by vaccination to prevent epidemic

barrier protections

protects aginst sexually transmitted diseases

isolation

when individuals with symptoms are separated from those without

quarantine

when those suspected of having a disease but without current symptoms are separated from others

incubation period

expected time between contact and development of symptoms

vaccines/immunization

help to strengthen the immune system to fight off diseases

passive immunity

provides short term protection by injecting antibodies

inactivated/dead vaccines

injection of nonliving organisms/antigens to develop antibodies

live/attenuated vaccines

long term protection is provided by injecting altered living organisms to reduce the chances of developing/producing diseases

herd/population immunity

individual immunity through vaccination or natural infections by about 70%-90% of the population

cell-mediated immunity

protection thats produced by t-lymphocytes and other white blood cells that are all stimulated by live vaccines

screening

controls the spread of diseases by testing individuals who are suspected or have symptoms of a disease, that way they’re able to recieve treaatment faster

case findings

interviews those diagnosed with a disease to ask them about any recent close physical or sexual contacts, that way people are alerted if their chances of developing a disease has increased

contact treatment

reduces the risk of transmission and infectivity of diseases

epidemiological treatment

treatment of contacts with the disease, which controls the number of diseases

conditions for the eradication of a disease

\-no animal reservoir: doesn’t affect other species that can then infect additional humans

\-short persistence in environment: the virus cant persist for more than a brief time in the environment without a human host

\-absence of a long-term carrier state: once an individual recovers from the virus, they no longer carry it cant transmit it to others

\-the disease produces long-term immunity: recovering from the virus prevents a second infection

\-vaccination also establishes long-term immunity: live vaccines produces very successful long-term immunity

\-herd immunity protects those who are susceptible: at least 80% of the population needs to be vaccinated to interrupt the spread

\-easily identified disease: presentation of the virus is easy to identify by clinicians with experience observing the disease, making it easy to diagnose

\-effective postexposure vaccination: includes ring vaccination which involves identification of a case of a virus, vaccination of the individual’s household and close contacts, followed by vaccination of all those within a mile radius of the virus case

options for controlling the HIV/AIDS epidemic

anitviral creams, postcoital treatments, and early testing and case findings