Second Set of VIR Cards (Dz-specific) Flashcards

Question

Variant CJD

Answer 1

2. A spongiform encephalopathy of cows (“mad cow disease”) reached epidemic status in Great Britain as a result of using brains and bone marrow from cows and sheep in the manufacture of bovine food. 3. An outbreak of “atypical human Creuzfeld-Jacob disease” (vCJD) in Great Britain has been linked epidemiologically to eating beef from infected cows. Cows were infected by being fed dead cow brains in their feed. =/

Answer 2

Family = togaviridae (classified also as an arbovirus) Epidem = only in summer/when mosquitoes are alive; mostly children affected; swampy areas and wetlands are worst hit; also kills local horses; mostly kids \<10 y/o Trans = mosquito—\>bird\*—\>mosquit—\>horse/human (DEAD END HOSTS) \*the bird is usually unaffected Incubation = 1 week intrinsic incubation in host (2 week extrinsic incubation in vector) Pathogen w/ s/sx = direct viremia (delivered from mosquito's saliva to bloodstream); sudden onset severe headach, n/v, fever—\>mental status ∆s—\>seizures and nuchal rigidity—\>TWO OPTIONS: 1) if you survive: high %—\>severe neuro sequelae 2) if a severe case: paralysis—\>coma—\>death —EEE usually causes the worst dz w/ ~50% fatality rate Dx = isolate virus or incr titer Prevention = kill mosquitoes; wear repellent; monitor mosquito traps via PCRing ground up dead ones; killed vaccine for horses is available Tx = none

Answer 3

**Western Equine Encephalitis** Family = togavirus similar to EEE w/ higher incidence rate and lower death and permanent neuro sequelae rates; usually infants and adults \>50 y/o

Answer 4

**St. Louis Encephalitis** ## Footnote Family = flaviridae Epidem = indigenous to North America more common in urban areas; adults \>50y/o are most affected Trans = maintained by bird—\>mosq—\>bird cycles w/ humans as DEAD END hosts Incubation = again two: 1 week in humans two weeks in vector Pathogen w/ s/sx = most infections inapparent but does cause moderately severe encephalitis w/ 10% fatality; sequalae uncommon Dx = serologically Prevention = no vaccine Tx = no antiviral

Answer 5

Family = flaviviridae Epidem = urban and rural; causes the most cases of viral encephalitis per year in US now; usually in folks over 60 Trans = bird\<—\>mosquito—\> human DEAD END host (also 10% via blood transfusion) Incubation = same 2wks in vector 1wk in host Pathogen w/ s/sx = \<1% infected get symptomatic dz; Dx = isolate virus from: brain tissue, blood, CSF or detect Abs in CSF or blood; PCR also available Prevention = no vaccine; screen at bloodbanks Tx = no antiviral

Answer 6

Family = flavivirus Epidem = subtropics and tropics S.E. Asia and Caribbean Trans = Aedes aegypti—\>humans—\>A. aegypti (i.e. humans are NOT dead ends!) Incubation = 1 week in host Pathogen w/ s/sx = fever, severe retro-orbital headache, myalgia and arthralgia ("break-bone" fever") and rash —Dengue Hemmorrhagic fever in those native to endemic areas (likely b/c there are 4 cross-reacting antigenic types); severe/fatal: 2nd infection immune complexes form and then either a) activates complement cascade—\>incr vasc perm + thrombocytopenia OR b) virus penetrates monocytes and macrophages—\>release hella cytokines —point: hemorrhage—\>hematemesis—\>shock—death Dx = isolate—\>cell culture or IgM or 4X IgG at convalesecent vs. acute phase Prevention = no vaccine; insecticides, drain stagnant water, personal protection Tx = no antiviral

Answer 7

Family = flavivirus (w/in arbovirus grouping, too) Epidem = endemic to rural tropical Africa and South America; can cause import epidemics in U.S., etc. Trans = Aedes aegypti—\>humans—\>A. aegypti (i.e. humans are NOT dead end host) Incubation = 1 week in host, 2 weeks in vector Pathogen w/ s/sx = instant viremia due to direct injection by mosquito—\>multiplies in vasc endothelium—\>worsen viremia—\>liver, kidney, spleen—\>fever, jaundice, n/v w/ hematemesis —high mortality, occasional subclinical cases Dx = PCR of plasma specimen Prevention = 17-D vaccine is live-attenuated and gives great protection Tx = ?

Answer 8

Family = parvoviridae Epidem = super common; 50% adults are seropoz Trans = can go transplacentally Incubation = Pathogen w/ s/sx = RBC precursor tropism—\>inhibits RBC synth for ~1 week —usually just leads to ERYTHEMA INFECTIOSUM w/ sometimes a TRANSIENT ARTHRITIS —can lead to TRANSIENT APLASTIC CRISIS in pts with pre-existing erythrocytopenia (e.g. sickle); fatal w/o transfusion tx —HYDROPS FETALIS occurs when transplacental route occurs in 1st or 2nd trimester; still can cause fetal demise (just w/o the hydrops fetalis) in 3rd trimester; massive increase in CO b/c anemia leads to edema, etc. Dx = IgM (would not be present in immunocompromised pts so PCR from blood); fetal infection use PCR of amniotic fluid Prevention = none Tx = pool Ig for chronic/immunocomp. pts

Answer 9

**Rubella (a.k.a. "German Measles")** ## Footnote Family = togavirus (though NOT arbovirus) Epidem = less contagious than measles; near-universal vaccination in U.S.—\>last case 2005 Trans = resp drops (spread one week before and after rash!) Incubation = 18 days Pathogen w/ s/sx = resp epithel—\>viremia; 3 days of rash w/ fever and lymphadenopathy; even subclinical cases—\>lifelong immunity —TRANSPLACENTAL: cataracts, PDA, deafness, MR; less and less a risk as you move along in pregnancy Dx = ? Prevention = live-attenuated vaccine (in MMR); major purpose is to prevent congenital rubella Tx = ?

Answer 10

Family = Alphaherpesviruses (HHV-1 & HHV-2) Epidem = ubiquitous Trans = saliva, vaginal secretions and lesion fluids—\>eyes/breaks in the skin—\>axonal transport to achieve latency Incubation = ~7 days (CDC) Pathogen w/ s/sx = Cold sores, ocular infections, (HSV-1) genital sores (HSV-2) and encephalitis (deadly, caused by both 1&2) Dx = isolate and culture (causes CPE), ELISA, PCR of CSF, IgM/serology Prevention = no vaccine Tx = great drugs (nucleoside analogs) including: acyclovir, valacyclovir, famcilovir, pencilovir, adenosine arabinoside, iododeoxyuridine, trifluridine

Answer 11

Family = herpesviruses —\> alpha-herpesviruses —\> varicella zoster (HHV-3) Epidem = common in 4-10 y/o's in non-vacc countries Trans = aerosol or direct contact Incubation = 2-3 weeks Pathogen w/ s/sx = viremia —\> prodrome w/ fever & malaise —\> rash IN ADULTS: worse; tx w/ ACV; re-activation causes shingles—\> deratomal presentation VERY PAINFUL Dx = clinically Prevention = vaccines: pedi (oka strain = Varivax), adult (Zostavax = same strain, just 1/14 strength)) Tx = can try ACV in severe cases; usually just palliative

Answer 12

Family = Herpesvirus—\>betaherpesvirus (HHV-5) Epidem = ubiquitous Trans = blood, tissue, body secretions (URINE DIAPERS) Incubation = ?slow? (see Dx) Pathogen w/ s/sx = latency in leukocytes (powerful T-cell evasion strategy); usually subclinical, but also: _Most common cause of congenital abnormalities in U.S._; Pneumonia, retinitis, esp in immunocompromized (esp pre-HAART) Dx = have to PCR b/c grows very slowly Prevention = wash hands, warn pregnant women Tx = gancilovir, Vitravene (direct to retina)

Answer 13

Family = herpesviruses—\>gammaherpesviruses (HHV8) Epidem = ubiq. (\>90% U.S. adults positive) Trans = kissing/saliva Incubation = ~(2-?)4(-6? slides conflict) wks Pathogen w/ s/sx = infects oral epithel—\>blood—\>B-cells—\>immorts B-cells—\>T-cells clear things up which cause "mono" sx in teens/adults (mild/asymp in kids) —Mono sx: lymphadenopathy, hepatosplenomegaly *—in immunocomp: Burkitt's lymphoma and nasophar. carcinoma I.E. TUMOR VIRUS* Dx = Prevention = no vaccine Tx = no anti-virals

Answer 14

roseola infantum/ exanthem subitum. • Benign rash with high fever. Rarely encephalitis. • \>90% worldwide. • Approx 1% have HHV‐6 integration into germline Assoc'd with MS/CFS\*/epilepsy \*chronic fatigue synd

Answer 15

closely related to HHV‐6. • “No treatment for HHV‐7 infec4on exists, but no clinical situation where such treatment would be useful has yet been discovered.” "A virus that is looking for a dz."

Answer 16

**Kaposi's Sarcoma Herpes Virus (KSHV)** * tumor virus that causes opportunistic infection in HIV pts not on HAART * common in sexually-trans HIV * No vaccine * Tx w/ excision

Answer 17

zoonosis that sometimes infects zookeepers, etc. From Rhesus macaques Rare but serious encephalitis tx w/ acyclovir or immune serum

Answer 18

Family = Papillomaviridae Epidem = 1/3 of college-aged U.S. females have cervical infection of HPV Trans = sexual Incubation = ? Pathogen w/ s/sx = condyloma (6b and 11) or cervical carcinoma (16 & 18) Dx = Pap smear Prevention = vaccine Tx = ?

Answer 19

Family = Herpesviridae—\>Gammaherpesviridae—\>EBV (HHV-4) Epidem = common in "African children"; higher prev. in males Trans = Incubation = ? Pathogen w/ s/sx = ? Dx = ? Prevention = Tx =

Answer 20

Family = retroviruses Epidem = ? Trans = ? Incubation = ? Pathogen w/ s/sx = ? Dx = ? Prevention = ? Tx = ?