Chapter 10: Infectious Disease and Outbreak Investigation

What is stage 1 of the epidemiologic transition?

infectious and parasitic diseases, accidents and animal attacks, "natural checks" on population

What is stage 2 of the epidemiologic transition?

receding pandemics, sanitation, nutrition, medicine lead to lower CDR

What is stage 3 of the epidemiologic transition?

Degenerative and man-made diseases, heart disease, cancer, diabetes, and obesity

What is stage 4 of the epidemiologic transition?

Delayed degenerative diseases, extended life expectancy due to medical advances

What is stage 5 of the epidemiologic transition?

potential resurgence of infectious diseases due to globalization

which two stages of the epidemiologic transition are characterized by infectious diseases?

1 and 2

which two stages of the epidemiologic transition are characterized by chronic diseases?

3 and 4

what is the epidemiological triangle?

agent, host, environment

a person or other organism providing subsistence/lodgment to an infectious agent in natural conditions

host

the domain in which disease-causing agents exist, survive, or originate. all that which is external to the individual human host

environment

a factor whose presence, excessive presence, or absence is essential for a disease to occur

agent

what are some examples of agents?

microorganism, chemical, radiation, mechanical, behavioral, social agent, process

entry and development or multiplication of an infectious agent in the body of persons or animals

infection

a disease due to an infectious agent (bacteria, viruses, etc.)

infectious disease

Illness due a specific infectious agent or its toxic products that arises through direct or indirect (a vector) transmission from an infected person, animal, reservoir to a susceptible host

communicable disease

a disease transmitted by direct/indirect contact with a host source of the pathogen

contagious disease

an infection caused by a parasite- an animal/vegetable/organism living on/in another and derives its nourishment therefrom

Parasitic disease

examples of infectious disease agents

microbial agents such as bacteria, rickettisa, viruses, fungi, parasites, and prions

infectious disease agents vary in their....

infectivity (capacity to enter and multiply in a susceptible host and thus produce infection or disease

severity of the disease produced

virulence

a toxic substance

a toxic substance made by living organisms

consequences of infectious disease agents

subclinical and clinically apparent infections, zoonotic illnesses, foodborne illnesses, infectious disease outbreaks associated with specific occupations, infectious disease linked with water pollution

_______ vary in their responses to disease agents

host

host's ability to resist infection by the presence of antibodies or cells having specific action on the microorganism concerned with a particular infectious disease or on its toxin. low risk

immunity

those at risk (capable) of acquiring an infection

susceptible hosts

host has developed as a result of a natural infection with a microbial agent, acquired from vaccine that contains an antigen (substance that stimulates antibody formation), usually of long duration and is measured in years

active immunity

immunity acquired from antibodies produced by another person or animal, newborn's natural immunity conferred transplacentally from its mother, artificial immunity conferred by injections of antibodies contained in immune serums from animals or humans, short duration lasting a few days to several months

passive immunity

Resistance (opposite of susceptibility) of an entire community to an infectious agent- Result of the immunity of a large proportion of individuals in that community to an agent- limit epidemics in the population even when not every member of the population has been vaccinated

herd immunity

Produces observable clinical signs and symptoms

clinically apparent disease

Time interval between entry of infectious agent and the maximal communicably of the host (not necessarily the same as incubation) applies to both inapparent and apparent cases of disease

generation time

time interval between the entry of the infectious agent and the appearance of the first sign/symptom

incubation period

does not show obvious clinical signs or symptoms

subclinical (inapparent) infection

person or animal, harbors a specific infectious agent, without discernible clinical disease, serves as a potential source of infection

carrier

when a carrier status is longstanding

chronic carrier

The first case of a disease to come to the attention of authorities, Aka patient zero ie. Mary Mallon - ie. For many years Gaetan Dugas was thought (falsely) to have been patient zero of HIV

index case

what are the four environment types for infectious diseases

physical, climatologic, biologic, social/economic

endemic

when an agent causing disease is habitually present in an environment (either geographic or population)

A place where infectious agents normally live and multiply (humans beings, animals, insects, soils, or plants)

reservoir

Infection transmissible under natural conditions from vertebrate animals to humans -ie. Rabies

zoonosis

direct and essentially immediate transfer of infectious agents to a receptive portal of entry (respiration, wound, bite) through which human or animal infection may take place

direct transmission

what are some examples of direct transmission?

direct contact; touching, kissing, biting, sexual intercourse or projection (droplet spread)

what are the three types of indirect transmission?

vehicle borne, vector borne, airborne

contaminated, nonmoving objects borne infections

vehicle

sars, through the air, could travel by plane

airborne

transmitted by fleas, ticks, mosquitoes, etc.

vector-borne

significant infectious diseases

STIs, foodborne illnesses, waterborne illnesses, bacterial conditions (cholera/typhoid), parasitic, vector-borne, vaccine-preventable diseases, emerging diseases, bioterrorism-related

Zoonotic Diseases

rabies, anthrax, avian flu, hantavirus, toxoplasmosis, tularemia

infectious disease newly appeared in a population or one that has been known for some time but is rapidly increasing in incidence or geographic range (ebola, e.coli, covid)

emerging infectious diseases

the deliberate release of viruses, bacteria, or other germs used to cause illness or death in people, animals, or plants

bioterrorism-related diseases

what are the steps for investigating an infectious disease outbreak?

define the problem --> appraise existing data--> formulate a hypothesis --> confirm the hypothesis -->draw conclusions and formulate practical applications

( ill/ (ill + well) ) x 100

attack rates (%)