Infection Disease & Covid-19 – Epidemiology

Infection Disease & Covid-19 – Epidemiology

This chapter is about Infection Disease & Covid-19 – Epidemiology

Select all the symptoms that may be caused by COVID-19



Runny or Stuffy Nos

Aches and Pains

Shortness of Breath




Sore Throat


Evidence shows that COVID-19 spreads through close personal contact – within about 6 feet or 2 meters.


Students that have COVID-19 symptoms should contact Holzer Health Center right away.


Where should you wear a facemask?

In public or shared spaces

Students will have to show up in a classroom in order to receive course materials.


Secondary infections

Caused by an opportunistic infection after a primary (predisposing) infection

Subclinical (inapparent) infection

No noticeable signs or symptoms (inapparent infection)

Predisposing Factor

Anything that makes the body more susceptible to disease

Incubation period

Time interval between the actual infection and first appearance of any signs or symptoms of disease

Prodromal period

The time following the incubation period when the first symptoms of illness appear

Period of Illness

Disease is more severe

Period of decline

Signs and symptoms decrease

Period of Convalescence

The recovery period

Reservoir of infection

A continual source of infection


People that harbor pathogens and transmit them to other


A disease that occurs primarily in animals but can be transmitted to humans

Contact transmission

Is the spread of an agent of disease by direct contact, indirect contact or droplet transmission

Direct contact transmission

Requires close association between infected and susceptible host

Indirect contact transmission

Spread by fomites. Occurs when the agent if disease is transmitted from its reservoir to a susceptible host by means of a nonliving object


A nonliving objects that can spread infections

Droplet transmission

Transmission via airborne droplets

Vehicle transmission

Transmission by a medium


An arthropods that carries disease causing organisms from one host to another

Mechanical transmission

Is the passive transport of the pathogens on the insect’s feet or other body parts

Biological transmission

Is an active process and is more complex that pathogens reproduces in vector

Composed host

A host whose resistance to infection is impaired

Emerging infectious disease (EIDs)

A new or changing disease that is in the past, present, and future


The study of where and when diseases occur

Descriptive epidemiology

Collection and analysis of data

Analytical epidemiology

A disease is analyzed to determine its cause

Experimental epidemelogy

The study of disease using controlled experiments

Case reporting

Health care workers are required to report specified disease to local, state, and national offices

Nationally notifiable disease

Physicians are required to report occurrence

Centers for Disease Control and Prevention (CDC)

A branch of the U.S. Public Health Services


Incidence of a specific notifiable disease


Deaths from notifiable diseases

Morbidity rate

Number of people affected in relation to the total population in a given time period

Mortality rate

Number of deaths from a disease in relation to the population in a given time

Notifiable infectious diseases

Are diseases that the U.S. physicians are required by law to report to the Public Health Services


disease-causing microorganism


Is the scientific study of disease


The study of cause of a disease


The development of a disease


Colonization of the body by pathogens


An abnormal state in which the body is not functioning normally


A disease causing microorganism

Normal Microbiota

Permanently colonize the host but do not cause disease

Transient Microbiota

May be prevented for days, weeks, or months than disappear


The living together of two different organisms or population


One of the organisms benefits, and the other is unaffected is the symbolic relationship

Microbial antagonism

The growth of some microbes prevents the growth of other

Competitive exclusion

Growth of some microbes prevents the growth of other microbes


Is a type of symbiosis that benefits both organisms


Are live microbial cultures applied to or ingested that are intended to exit a beneficial effect


One organism benefits by deriving nutrients at the expensive of the other


Chemicals to promote the growth of beneficial bacteria

Opportunistic Pathogens

A microorganism that does not ordinarily cause a disease but can become pathogens under certain circumstances

Koch’s postulates

Criteria used to determine the causative agent of infectious disease


The study of the cause of a disease


A change in body function that is felt by a patient as a result of disease


A change in a body that can be measured or observed as a result of disease


A specific group of signs and symptoms that accompany a particular disease

Communicable disease

A disease that is spread from one host to another

Contagious disease

A disease that is easily spread from one host to another

Noncommunicable disease

A disease that is not transmitted from one host to another


Fraction of a population that contracts a disease during a specific time period


Fraction of a population having a specific disease at a given time

Sporadic disease

Disease that occurs only occasionally in a population

Endemic disease

Disease constantly present in a population

Epidemic disease

Disease acquired by many people in a given area in a short time

Pandemic disease

Worldwide epidemic

Chronic disease

Disease develops slowly

Subacute disease

Disease with symptoms between acute and chronic

Latent disease

Disease with a period of no symptoms when the causative agent is inactive

Herd immunity

The presence of immunity in most of a population

Local infection

Pathogens are limited to a small area of the body

Systemic (generalized) infection

An infection throughout the body

Focal infection

Systematic infection that began as an infection in one place


Toxic inflammatory conditions arising from the spread of microbes (pathogens), especially bacteria or their toxins, from a focus of infection


(blood poising) growth of pathogens in the blood


Bacteria in the blood


Toxins in the blood


Viruses in the blood

Primary Infections

Acute infections that causes the initial illness