mechanisms of infectious disease

Host supporting organism

Infection presence, multiplication and tissue injury from microorganisms

Pathogen: microorganisms capable of producing a disease

Opportunistic infection: cause disease in immunocompromised host

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Prions

o What are they? How do they affect the body (describe the pathos) They are

protein particles lacking a genome. Prions slowly progress in the degeneration of

nerves, create amyloid plaques in the brain and spread throughout the nervous

system, they are a mutant form of normal host proteins causing disease.

o What system is affected? Signs and symptoms? The nervous system is affected.

S/S include chronic wasting disease (mainly in animals), bovine spongiform

encephalopathy (mad cow disease which is uncommon), creutzfeld jacob disease

(humans), dementia, ataxia (lack of voluntary coordination of muscle movements)

there is no known treatment but most of these do not affect humans.

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VirusesThey

o Where do viruses thrive and replicate? Describe the life of a virus Viruses thrive

and replicate on the skin. Life: attachment, entry, uncoating/ secretion, replication,

maturation, release, spread

o Do they contain RNA or DNA? Yes they can but they cant have both

o How does the body get rid of viruses? Through innate immunity, adaptive

immunity, or memory cells

o How do viruses evade the host's immunity? They mutate and black immune

recognition (HIV)

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Bacteria

o Describe how bacteria are categorized. Which are harder to kill and why? Mainly

categorized by cell wall (gram negative: harder to get rid of and can cause sepsis.

This is because their outer membrane lacks many antibiotics. (stain pink) Gram

positive: easier to get rid of/ penetrate bacteria (stain purple), shape

(cocci/spherical, bacilli/rod-shaped, spirilla/spirochetes/sprial shaped), oxygen

(aerobic, anaerobic, facultative anaerobes) needs, spore formation, and special

features.

o Why is it important to know what bacteria are causing the infection? Target

treatment in order to know types of prevention and using the wrong drug.

Resistance concerns some bacteria are resistant to antibiotics. Severity of illness

because some are highly toxic and spread quickly. infection control.

o How do bacteria cause damage to cells? Direct cell invasion and destruction,

toxins (endo and exotoxins, trigger inflammation, nutrient theft.

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Fungio Who is most susceptible to fungal infections? Immunocompromised people, those

with chronic illnesses, infants and elders, hospitalized. Critically ill patients,

people living in certain environments.

o Where do most fungal infections grow and why? Most grow on the skin and

mucous membranes because

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Parasites

o What are they? Give some examples. They are members of the animal kingdom

that infect us such as ticks, mites, worms, lice, etc.

o What is a protozoal infection? Give an example Malaria

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How do infections overcome the immune system microbial adherence, encapsulation,

rapid replication, biofilm formation, mutation, etc.

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What are some signs and symptoms of infections? How are they diagnosed? Productive

cough (pneumonia), fever, malaise, increased WBC. They are diagnosed by culture +

sensitivity ( growth of microorganisms outside the body, gram stains, antibiotic

effectiveness) serology (measuring specific antibodies in serum) detection of antigen.

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Describe the course of an infectious disease. What should you expect with each stage?

Incubation period, prodromal stage, acute stage, convalescence. Atypical course:

fulminant (no prodrome) insidious (prolonged prodrome) subclinical/subacute (no

clinical s/s)