hosa microbiology ch 3
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Virology
the study of viruses, the most common infectious agent
Capsid
protein covering of the central core of a virus; protects the nucleic
acids and promotes attachment
Viruses are classified by
whether they contain DNA or RNA; DNA viruses cause the common cold, cold sores, warts, and mono, while RNA viruses cause
the flu, polio, AIDS, rabies, and encephalitis
Viruses cause disease via
cell lysis or takeover for replication, which can also make the host
more susceptible to other diseases
Natural active immunity
acquired from prior experience with a pathogen
Artificial immunity
acquired via immunization/deliberate exposure
Artificial passive immunity
acquired via the administration of pre-produced antibodies,
though does not last long
Latency
property of viruses to stay dormant
Viruses are generally only cultured for
research purposes, or by the CDC
Direct detection
includes isolation, electron microscopy, enzyme immunoassay to
detect viral antibodies/antigens, and PCR testing to detect viral
DNA/RNA
Multipathogen detection systems
help reduce antibiotic overuse by testing for multiple pathogens
at once; a sample is collected, viral RNA is turned into DNA and
amplified via PCR, tagged, and analyzed
Serodiagnosis
diagnosis via detection of viral antibodies in serum through tests
such as ELISA or EIA
Viral load
amount of virus circulating in the bloodstream
Antivirals
do not cure a disease, but lessen its severity or control it
Respiratory syncytial virus (RSV)
causes bronchiolitis, pneumonia, and/or acute respiratory disease
in children
acquired immunodeficiency syndrome (AIDS)
progressively fatal, caused by HIV; late-stage and diagnosed
when CD4 cells < 200
HIV is usually treated with
a combination of three antiretrovirals to prevent the development
of resistance
Hepatitis C Virus (HCV)
small enveloped RNA virus; asymptomatic and often becomes
chronic; can lead to liver cirrhosis and cancer and exists in 6
genotypes
Severe acute respiratory syndrome (SARS)
a highly contagious, potentially lethal viral respiratory illness characterized by a fever, cough, difficulty breathing, or hypoxia; similar
to MERS
Ebola virus
high mortality; s/s fever, sore throat, muscle + head pain, followed
by vomiting, diarrhea, rash, dehydration, kidney failure, etc
Parasitology
study of parasites and parasitism
Protozoa
unicellular and animal-like, one of the three categories of parasites
Helminths
wormlike animals, one of the three categories of parasites
Trophozoite
feeding and growing stage of protozoa; where parasites are motile
and in multiplying form
Cyst
dormant form of a parasite
Ova
eggs of a parasite; usually found in stool, urine, discharge, blood,
and skin
Larvae
immature form of the parasite
Adult
mature form of the parasite
Protozoa characteristics
require a human host for survival; infection is often caused by
ingestion of contaminated water via skin or bug bites
Giardia lamblia
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infection via ingestion of food/water contaminated by feces; tested
for using the stool; causes severe diarrhea
Entamoeba histolytica
infection via ingestion of contaminated food/water; tested for using
feces; causes amoebic dysentery
Plasmodium
malaria
Giardia
causes GI tract infections, can be asymptomatic or cause diarrhea, nausea, vomiting, gas, cramps, bloating, etc
Amoebiasis
caused by Entamoeba histolytica; can be asymptomatic or cause
diarrhea, abscesses, colitis, dysentery, etc
Malaria
caused by plasmodium; flulike s/s; sporozoite enters a liver cell,
produces daughter cells, invades RBCs, and causes lysis
Helminth characteristics
can survive without a host; separated into three groups, tapeworms, flukes, and roundworms (beef + pork tapeworm, sohistosoma mansoni, hookworms + pinworms)
Tapeworm
common in underdeveloped countries with poor sanitation; causes
digestive symptoms and sometimes blindness or seizure
Hookworm
common in tropical areas, contracted by walking barefoot in contaminated soil; infects the GI tract and causes nausea, vomiting,
diarrhea, pain, nutrient deficiencies, and anemia
Pinworm
largely affects children and the institutionalized; s/s anal itching
due to eggs; diagnosed by the tape test
Guinea worm disease
Dracunculus medinensis; infection via consumption of water; long
worm that bursts through the hands and feet
Ectoparasites
external parasites that thrive on the skin and have hard, segmented bodies; feed on blood and can transmit other diseases; include
lice, ticks, mosquitoes, bed bugs, etc
Mycology
study of fungi, which reproduce via spores, have rigid cell walls
(ergosterol), and have no chlorophyll
Antifungals target
ergosterol synthesis, as it is used in place of cholesterol in fungal
cell walls
Characteristics of fungal infections
contracted via inhalation, ingestion, or through wound entry; many
are opportunistic, and affect the skin; are identified via biochemical
tests and observation of spores
Yeasts
unicellular and thrive on organic matter; reproduce via budding
Candida
very common yeast, colonizes and/or infects the body; causes
thrush, esophagitis, vulvovaginitis, as well as infections of the
blood, bone, eye, etc
Dermatophytes
cause skin + nail infections by secreting keratinase to cause
scales, hair loss, and nail thickness; diagnosed based on observation
Cryptococcus neoformans
yeast that infects the brain and causes meningitis or infects the
lungs and causes pneumonia
Dimorphic
having two forms, eg yeast and mold
Histoplasmosis
caused by inhalation of histoplasma capsulatum spores from soil
where birds and bats roost
Coccidioidomycosis
Coccidioides immitis; common in the southwest US
Blastomycosis
blastomyces dermatiditis; common in various parts of the US;
causes inflammatory lesions and general invasion of the body
Molds
multicellular colonies of intertwined hyphae, capable of spreading
spores; require food, air, moisture, warmth, and darkness
Aspergillus
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found in soil; causes an allergic reaction in the host; the body
can wall off the fungus to create a ball in the lungs resembling
tuberculosis
Mucormycosis
opporunistic infection caused by saprophytic molds Rhizopus,
Mucor, and Rhizomucor; diabetes and blood cancer are risk factors; causes necrosis of nasal tissue
Creutzfeldt-Jakob disease (CJD)
formation of normal proteins into prions, causing dementia, disorientation, issues with memory, balance, walking, etc
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