Lecture16: Microbe-Human Interactions II

Reservoir

The primary habitat in the natural world where a potential pathogen makes its home

Living reservoir examples

Humans, arthropods, animals

Non-living reservoir examples

Soil, water, air

Carrier

An individual who inconspicuously shelters a pathogen and spreads it to others

Asymptomatic

Infected but no symptom

Incubating

Spread infection during incubation period

Convalescent

Spread infection during convalescent period

Chronic

Shelter an infectious agent for a long period because of latency or persistent infections

Passive

Healthcare workers who handle heavily contaminated patient materials and pass infectious agents to other patients

Zoonosis

An infectious agent usually present in animals spreads to humans

What kind of transmission does not occur?

Human-Human

Communicable

When an infected host can transmit the infectious agent to another host and establish infection

Contagious

When a disease is highly communicable

Noncommunicable

Infection and disease is not acquired through transmission of an infectious agent host-to-host

Types of horizontal transmission

Direct contact, indirect contact, vector-borne, foodborne, waterborne

Fomite

Inanimate object that harbors and transmits pathogens

Vehicle

A natural, nonliving material that can transmit infectious agents

Aerosols/droplets

Suspensions of dust or moisture in the air

Healthcare-associated (nosocomial) infections

Infectious diseases that are acquired or developed during a hospital or health care facility stay

Who are often immunocompromised and bring in infectious agents?

Patients

Etiologic agent

The precise, causative agent of disease

Koch’s postulates

Isolate hypothesized agent, inoculate naive population, and see the same disease

Epidemiology

The study of the frequency and distribution of disease and other health factors

Goal of Epidemiology

Help public health departments develop prevention and treatment programs

Who is Florence Nightingale?

Nurse, early epidemiologist, proved infection was killing soldiers at a high rate

Prevalence

The total number of existing cases in a given population

Incidence

The number of new cases over a certain time period

Mortality Rate

The total number of deaths in a population due to a certain disease

Morbidity Rate

The number of people afflicted with an infectious disease

Epidemiologic Curves

Tracking cases of infection can point us toward a source

Reproductive Rate

How many people will be infected from one sick person (in a unprotected population)

Endemic

An infectious disease that exhibits a relatively steady frequency over a long period of time (per geographical area)

Sporadic

Cases appear occasionally and at irregular intervals in random locales

Epidemic

When a disease exceeds the expected prevalence for an area or population

Pandemic

The spread of an epidemic across continents