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Flashcards in Viral BW Threats Deck (25)
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What are viral hemorrhagic fevers?

Group of illnesses caused by severe distinct families of viruses. Viral hemorrhagic fever is used to describe an overall vascular system damage with a loss of ability of the body to regulate itself. Symptoms often accompanied by hemorrhage


How do we transmit Arenavirus?

Transmission - Rodent excretions, inhalation of rodent urine or saliva, direct contact broken skin, ingest contaminated food. Human to human if contact with blood or bodily fluids.


Structure of Arenavirus?

Structure: Enveloped virions with grainy appearance due to ribosomes. 2 single strands of ambisense RNA (- and + strands). Helical shaped capsid.


What are the two types of Arenavirus?

Lassa Fever and LCMV (lymphocytic choriomeningitis virus → meningoencephalitis)


Who gets Arenavirus and when does it present?

Sx: Most severe in pregnant women (95% mortality in third trimester), less severe in children. Sx’s begin in 1 - 3 weeks post infection.


Symptoms of Arenavirus in adults and kids (Lassa fever, not the meningoencephalitis, which will be discussed in a future lecture apparently)

Fever, retrosternal pain, sore throat, back pain, cough, abdominal pain, vomiting, diarrhea, facial swelling → proteinuria and mucosal bleeding, hearing loss (1/3 of patients), encephalitis, tremors (lots of nonspecific stuff)

Children: Similar to adults. “Swollen baby syndrome” - Edema, abdominal distension, bleeding → poor prognosis


How do we treat Arenavirus?

Tx: Supportive care. Ribavirin provides 2-3 fold decrease in mortality in high risk patients if given early in illness. Low pH, detergents, heating, irradiation all inactivate it.


How do we treat Bunyavirus?

Transmission: Ticks or animal flesh right after slaughter (hantovirus subtypes), reservoir is deer mice and it is transmitted via rodent urine feces as well. However, typically, bunyaviruses are Arborviruses (arthropod transmission).


Discuss the structure of Bunyavirus

Structure: Circular, ambisense RNA (+ and - sense) in three parts (small, middle, large), enveloped (from the golgi body of host cells). Segmented virus (3 segments, circular). Arbovirus (from arthopods).


Symptoms of Bunyavirus

Sx: Pulmonary capillary leak in lungs. Capillary leak in kidneys leading to pre-renal azotemia and hypovolemic shock (fluid leaks out).High fatality (10-40%). Can progress to Crimeon-Congo Hemorrhagic fever.


The Aedes mosquito transmits a special type of Bunyavirus. Discuss what it leads to

Aedes Mosquito can transmit a Bunyavirus → California encephalitis and Rift Valley Fever. Presents as seizures and encephalitis.


What two strands of Filovirus are there?

Strains: Ebola and Marburg


Structure of Filoviruses

Structure: Many shapes (“pleomorphic”). Long, sometimes branched filaments, shorter filaments shaped like a “6”, a “U” or circles. Enveloped, single stranded, helical capsid, negative sense RNA


Discuss the history of Marburg virus

1967: Marburg: Contracted from lab workers in Germany handling tissue from green monkeys imported for polio vaccine prep. Developed hemorrhagic fever in Marburg, Germany.


Discuss the history and subtypes of Ebola filovirus

1976: Ebola: Named after river in the Zaire. Sudan strain (50% mortality) and Zaire strain (90% mortality)

Ebola Reston - Reston VA airborne between monkeys in research lab. Humans immune.

Bundibugyo and Ivory Coast, along with Zaire and Sudan, affect humans.


Ebola/Marburg reservoir?

Reservoir: Monkeys and fruit bats in Africa


Symptoms of any filovirus infection

Sx: Non-specific at first (red eyes, skin rash) → Fever, petechial rash → hemorrhagic fever, end-organ failure → hypovolemic shock → death in just a few days


How do we diagnose and treat filovirus?

Diagnosing: Early Days = ELISA, IgM ELISA, PCR, virus isolation.

Post-mortem = IHC, Virus isolation, PCR.

Tx: Supportive :(


Discuss the awesome structure of Poxvirus

Structure: Brick shaped particle with complex composition (neither icosahedral nor helical). Double stranded linear DNA. This is the only DNA virus that replicates solely in the cytoplasm (has everything it needs, even makes its own envelope and has a DNA dependent RNA polmerase)! Largest and most complex virus, resistant to inactivation. Dumbbell shaped core.


How do we transmit Poxvirus?

Transmissions: Secretions from mouth and nose and material from pocks (special lesions) or scabs


Discuss the symptoms of Poxvirus

Sx: Papule → vesicles (day 3) → Pustules, fever returns (day 5) → Drying and scab formation (day 10-14) → scarring (day 20). Denser on face, arms, hands, legs, and feet. Involves palms and soles


How can we distinguish chicken pox from small pox?

Distinguish from chicken pox by looking at blisters. Small pox changes all at once systemically, whereas the chickenpox rash will have a mix of healing blisters, new papules, etc.


Not discussed in lecture, but discused in Sketchy, is Molluscum Contagiosum. What's this guy all about? When do we see it?

Another pox-virus: Molluscum contagiosum, presents with flesh-colored, dome-shaped, umbilicated (little dimple in the middle) skin lesions in children on trunk , not in palms and soles. If adult, suspect HIV/immune suppression


How do we diagnose Poxvirus?

Dx: Smear from lesions = stained with gentian violet. Look for Guarnieri bodies (inclusions ONLY in the cytoplasm that are where the virus is replicating).

Electron microscopy of lesion to show brick virions and cytoplasmic inclusions, better for distinguishing smallpox from chickenpox.



Discuss the vaccine for small pox and how it came about

Vaccine: Uses a bifurcated needle. Treat adverse vaccine reactions with hVIG (human vaccinia immune globulin). Small pox vaccine made from cow-pox virus (from cow utters, causing blisters, but makes you immune to small pox).