Chapter 11a: interactions between microbes and humans

A comprehensive set of vocabulary flashcards covering the interactions of microbes with humans, the mechanisms of disease, and epidemiology.

Colonization

Resident microbiota that colonize on or in the human body for the long term without causing disease.

Infection

When microbes breach host defenses, enter tissues, and multiply.

Disease

Deviation from health; pathological state that results when cumulative effects of infection damage or disrupt tissues and organs

Infectious disease

A pathogenic state caused directly by microorganisms or their products.

How do infectious agents cause diseases?

Agents follow a multi step process to become established and cause disease in humans

Step 1: entry to host- Portals of Entry, def

Routes microbes take to enter the body, initiating infection.

Exogenous Microbe

Microbe originating from outside the body, such as from the environment or another host like an animal.

Endogenous Microbe

Microbe that is already present in or on the body normal biota or a previously silent infection

Step 1: entry into the host- portal of entry, properties

Greatest number of pathogens enter body through realities system, if certain pathogens enter the wrong portal they will not cause infection, sometimes an infectious agent can enter more then one portal

Step 1:entry into the host -Infectious Dose (ID)

The minimum number of microbes needed to cause an infection., microorganism with smaller infectious diesel have greater virulence

Step 2: attaching to host cells- Adhesion, def

Process by which microbes gain a more stable foothold on host tissues a firm attachment is almost always a precursor for causing disease, b/c the body has so many mechanisms for flushing microbes from tissue

Microbial adherence structures

Pili, Fimbriae, Membrane and capsular materials, Specialized adhesion molecules on microbes cell surface

Step 3: surviving host defenses-Phagocytes, def

Cells that engulf and destroy host pathogens by means of enzymes and antimicrobial chemicals

Step 3 surviving host defenses- Antiphagocytic factor, def

Virulence factors used by some pathogens to avoid phagocytes (ex, extra cellular surface layer like slime or capsule make it hard for phagocyte to engulf the pathogens)

Phagocytes

Cells that engulf and destroy pathogens.

Step 4: causing disease- virulence factors, def

Are simply adaptations a microbe uses to establish itself a host

Step 4: causing disease- Virulence, def

The degree of pathogenicity or relative severity of disease caused by a microbe.

How is Virulence of a microbe determined

Its ability to establish itself in a host, cause damage

Step 4: causing disease- first way microbes can damage host

Directly through the action of enzymes or toxins(ex; mucinase(enzyme) digests the protective coating on mucous membranes, hepatotoxic (toxin) cause direct damage to liver

Step 4: causing disease-second way a microorganism causes damage to host

Indirectly by inducing the host defenses to respond excessively or inappropriately

Step 4 causing disease- Part of the second way a microorganism can damage host- Cytokine Storm

virus infections cause a sever immune reaction that results in the damage of vital organs

Step 5: vacating the host- Portal of Exit

Specific route through which pathogens exit the body through: secreation,extreation, discharge or sloughed tissue high number of microbes in the materials increases likelihood of the pathogen reaching other host, exit is usually same as portal of entry

Course of infection

many infections go through multiple stages in the human body

Incubation period

Time from initial infection contact with infections agent to appearance of symptoms, agent is multiplying at entry but has not caused damage to make symptoms, varies according to host, ranges from hours to years, majority of infections range from 2-30 days

Acute phase

infectious agent multiplies at high levels exhibiting greatest virulence becoming well established in its target tissue, marked by fever and other prominent and specific symptoms, extreme variable in length of this period

Prodromal stage

1-2 day period when earliest notable symptoms pf infection occur, phase characterized by vague feeling of discomfort symptoms( head and muscles aches, fatigue, upset stomach)

Convalescent period

Phase during which the patient begins to recover from infection,patient strength and Heal Grady return due to the healing nature of the immune response, many patients stop taking meds during this period leading to antibiotic resistance

Continuation phase

Only some infections have this phase , either the organism lingers for months, years, or indefinitely after the patient is well or the organism is gone but symptoms continue

Sequelae

Long-term or permanent damage to tissues or organs caused by infectious disease.

Reservoir

Primary habitat in natural world from where a pathogen originates, often a human or animal carrier also soil, water, and plants

Transmitter

Individual Person or object that spreads an infection

Animals as reservoirs

Majority of animals agents are arthropods such as fleas, mosquitoes, flies, and ticks. Larger animals can also spread infection like mammals and rabies

Zoonosis

Infection indigenous to animals but naturally transmissible to humans, spread is promoted by close associations between animals and humans they make up 70% of all new emerging diseases worldwide

Communicable disease

Disease that can be transmitted from one host to another.

Noncommunicable disease

Infectious disease not spread between hosts, compromised person is invited by their own microbiota, individual has accidental contact with microbe that exists in non living reservoir

Contagious disease

Highly communicable disease, easily spread through contact.

Horizontal transmission

Spread of disease through a population from one infected individual to others.

Vertical transmission

Transmission from parent to offspring via the ovum, sperm, placenta, or milk

Vector transmission

any agent which transmits an infectious pathogen into another living organism

Healthcare-Associated Infections (HAIs) or nosocomial infections

Infectious diseases acquired during healthcare facility stays.

Epidemiology

Study of disease frequency and distribution and other health related factors in defined populations.

Epidemiology involves?

Many disciplines: microbiology, anatomy, physiology, immunology, medicine, psychology, sociology, and statistics while considering all forms of diseases

Prevalence

Total number of existing cases in a population; snapshot

Incidence

Number of new cases during a specific time period.

Mortality rate

Total number of deaths due to a disease within a population.

Morbidity rate

Number of individuals afflicted by a disease.

Index case

May not be the first case but is the Initial case that brings an epidemic to attention.

Sporadic

Occasional cases reported at irregular intervals at random locales

Endemic

When stats indicate that the prevalence of an endemic or sporadic disease is increasing beyond what is expected for a population

Epidemic

Increase in prevalence of a disease beyond expected numbers.

Pandemic

Spread of epidemic over multiple continents.