Virology Flashcards
(40 cards)
Epizootic
A disease epidemic in an animal population
Zoonosis
Any infection transmitted to man from vertebrates
Arbovirus
Arthropod borne virus-mosquitoes, ticks etc.
Robovirus
Rodent-borne virus
Whats the difference between an intrinsic and extrinsic incubation period in the context of an arbovirus?
Extrinsic is when the arthropod vector (when is asymptomatic) is incubating the virus, and intrinsic is specific for the host infection.
How are natural hosts, arthropod vectors, and unnatural hosts affected by an arbovirus?
The natural host and arthropod are usually unaffected, whereas the dead end unnatural host manifests disease.
Humans are not dead end hosts for which arboviruses?
yellow fever and dengue
What are the important arboviruses found in the US, and among travelers?
US- Eastern equine encephalitis virus (EEE) Western equine encephalitis virus (WEE) California encephalitis virus (CEV) Colorado tick fever virus (CTFV) St. Louis encephalitis virus (SLEV) West Nile virus (WNV)
Travelers
Dengue
Yellow Fever
Chikungunya
What’s a brain abscess? What’s a common way to get it?
Rare focal intracerebral infection that starts as cerebritis and then develops into a collection of pus surrounded by a well vascularized capsule.
Hematogenous seeding from endocarditis-like those of Staph. Aureus
or direct spread from another infection
What’s the most common symptom of a brain abscess
headach or low fever or symptoms related to the legions location.
What’s a sequelae?
Pathologic condition resulting from a disease, injury, therapy, or other trauma.
What are some common etiologies of brain abscess in the immunocompromised? Immigrants?
Toxoplasma gondii
Crytococcus neo
Parasites
Taenia solium
Describe Cryptococcus neoformans and where its found; how is this different from cryptococcus gattii?
oval budding yeast with wide polysaccaride capsule.
found in soil contaminated with bird droppings (worldwide)
Usually disease of immunocompromised
Found in soil around eucalyptus trees (pacific NW)
Usually disease of the healthy
How is cryptococcus disease transmitted and spread through the body? What are its main virulence factors?
Transmission-respiration (get in macrophages)
Spread- hematogenous spread-lungs, skin (nodule guy), meninges–> abscess (rare)
Polysaccaride cap
Melanin (protects against oxidative killing)
How do you diagnose cryptococcus? How can you stain it?
test for capsule Ag using lateral flow assay
Also it stains with India ink
white mucoid colonies on Savouraud dextrose agar
lesions on MRI or CT
What’s a cestode? How are they structured?
Tapeworm
round head/scolex-hook for attachment to intestine
flat body with multiple segments/proglottids
Proglottids are hermaphroditic and those near the distal end of the worm contain eggs and are excreted in feces.
cestode life cycle?
humans eat tissue cysts from undercooked meat-pork
cestode hatches in intestines
mature
release eggs from proglottids in feces
eggs in feces ingested by animal reservoir and larae produce cysts
What’s the pork tapeworm called?
What disease caused by this cestode affects the brain? Who is the definitive and intermediate host?
Taenia solium
Cysticerosis-larvae develop in eyes, muscles (nodules) or brain (seizure, epilepsy, hydrocephalus, focal defects/lesions)
Definitive host=human
Intermediate hos=pigs
How does one diagnose treat and prevent taeniasis (adult tapeworms in the intestine)?
How does on diagnose cysticerosis?
diagnose-visualizing proglottid in stool
Treat with antiparasitic
Prevent-cook pork and limit access of pigs to human feces
Cysticerosis-Biopsy muscle, CT brain, or fundoscopic exam of the eye.
What’s the active and dormant form of a protozoan? How are they typically transmitted?
Trophozoite-active
Cyst-dormant, hearty
Arthropod vector or fecal oral route
Who is the definitive host for toxoplasma gondii and who are the intermediates?
Cats are definitive host
Humans and mammals are intermediate hosts (dead ends)
A patient of yours decides not to vaccinate her son, because of concern about the saftey of vaccines. Over the last two years though he’s been in cognitive decline and recently had a convulsion. When asked about the onset of his symptoms she admits he had a bad rash all over his body and was ill a few months before his personality started to change. What’s the likely disease and etiology?
Subacute sclerosing panencephalitis SSPE which is occasionally (though rarely) seen following measles infection.
A friend of yours who recently had major surgery for the removal of a benign tumor, has been complaining of some strange infections he’s been having due to all the immunosuppressive drugs he’s been on. He shares with you that he was just diagnosed with a rare fatal demyelinating disease of the brain from a viral reactivation. Which cells are primarily damaged in this disease, and how does the primary infection occur?
He has progressive multifocal leukoencephalophathy, from a JC virus. A small circular dsDNA, non-enveloped polyomavirus. The primary infection occurs in the tonsils and then the virus becomes latent in the kidney and bone marrow. When reactivated it is thought to cross the BBB with B-cells and infect oligodendrocytes which myelinate cells in the brain.
What are prions and how do they cause brain damage?
Prions are proteins that, when mis-folded, form aggregates that can cause neuronal cell death.
Prion disease is a group of progressive neurodegenerative disorders call Transmissible Spongiform Encephalophathy (TSE).
