Viral infections: RNA viruses Flashcards

0
Q
  1. rhinovirus (some coronaviruses)
A

The common cold (coryza): acute, self-limiting
-rhinovirus likes cooler temperature (confined to upper aw)
-spread via infected secretions (indoor crowding)
-infects nasal respiratory epithelial cell (bradykinin)–> inc mucus and edema
-can lead to secondary inf: otitis media and bacterial sinusitis
Clinically: rhinorrhea, pharyngitis, cough, low-grade-fever

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1
Q

What are 5 RNA viruses (and the dz that they cause) that affect the respiratory tract?

A
  1. Rhino virus - common cold
  2. influenza virus A/B/C - influenza (flu)
  3. Parainfluenza virus - croup
  4. Respiratory Syncytial Virus (RSV) - bronchiolitis, pna
  5. Severe Acute Respiratory Sd assoc coronavirus (SAR-CoV)
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2
Q
  1. influenza virus
A

influenza: have vaccines, 75% effective bc viral ag’s change
-A is most common, infects upper and lower aw’s
-spread vis infected resp droplets, secretions
-has hemagglutinin (H) and neuramindase. H fuses with epithelial cells (via sialic acid residues) –> destroy mucociliary blanket –> lymphocytic inflmm infiltrate
-predisposes to bacterial pna (esp staph and strep)
-Clinically: rapid fever and chills, pharyngitis, nonproductive cough.
upper resp sx: tracheitis, bronchitis, pna
kills elderly, and ppl with cardiovascular probs

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3
Q
  1. parainfluenza virus
A

parainfluenza virus: acute upper and lower aw’s

  • **esp kids bronchiolitis and pneumonitis –> croup
  • SX: subglottis swelling, aw compression, resp distress, fever, hoarness, cough, CROUP (LARYNGOTRACHEOBRONCHITIS)
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4
Q
  1. RSV
A

cause bronchiolitis and pna in infants
-common day care centers, spread by resp secretions
-lymphocytic infiltrate, sometimes see multinucleated syncytial cells
-SX: wheezing, cough, resp distress, fever.
high mortality in sick kids.

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5
Q
  1. SARs-CoV
A

potential to reemerge
-host: bats
-incubation period: 2-7days
LUNGS - DIFFUSE ALV DAMAGE (multinucleated syn cells w/o viral inclusions
SX: fever, headache, then cough and SOB, diarrhea common, coryza rare
LABS: lymphopenia, inc aminotransferase, ARDS, mortality inc in elderly and resp pts, no tx (use glucocorticoids)

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6
Q

3 viral exanthems (dz and virus)

A
  1. measles = rubeola, sspe (subacute sclerosing panencephalitis)
  2. rubella
  3. mumps
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7
Q
  1. measles: have vaccines
A

rubeola = measles = highly contagious
-SX: upper resp sx, cough, fever, RASH (from T-cells on virally-inf vascular epithelium, VASCULITIS), conjunctivitis. may have secondary infections (otitis media, pna, cna invasion)
PATHOGNOMONIC:
1. warthink-finkelday giant cells - 100s nuclei with intracellular and intranuclear inclusion
2. mucosal and skin lesions such as KOPLIK spots (clustered white spots in buccal area (mouth))

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8
Q

measles - SSPE

A

subacute sclerosing panencephalitis

  • happens years after measles infection
  • slow chronic neurodegenerative disorder
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9
Q

rubella - have vaccine

A

infection in utero before 20weeks = congenital anomalies (death, premies, deafness, cateracts, glaucoma, heart defects, MR, eye, brain)
-spread via respiratory route, mild, self limiting systemic dz,
-infections resp epi –> LN–> blood –> RASH
SX: acute febrile, mild rhinorrhea, conjunctivitis, post auricular lymphadenopath.
path: causes mononuclear infiltrates (lymphocyte, macrophages, plasma cells)

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10
Q

Mumps - have vaccine

A

self limiting acute systemic illness
PATHOGNOMONIC: parotid swelling (salivary glands, from Tcell infiltrates and necrotic epithelium) + meingoencephalitis
-highly contagious via resp. can go to cns, pancreas, testes (epididymoorchitis)
-SX: fever, malaise, painful salivary gland swelling, if cna involved –> headache, vomiting, stiff neck, inc serum amylase (pancreas)
-also cause mononuclear infiltrates

prior to vaccine, most common cause of viral meningits and encephalitis in the US

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11
Q

2 intestinal viral infections

A
  1. rotavirus

2. Norwalk virus and other viral diarrheas

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12
Q
  1. rotavirus
A

rotavirus = DIARRHEA (could lead to dehydration and death)
most common cause of severe diarrhea worldwide, get from cruises.
DSRNA. INFECTS ENTEROCYTES of upper SI (Duodenum, jejunum). cant absorb –> inc osmotic load –> loose fluid –> diarrhea and dehydration
-spread by fecal-oral route (food, h20, surfaces).
-SX: vomiting (2-3d), fever, abd pain, watery diarrhea (5-8d)

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13
Q
  1. Norwalk virus
A

Norwalk = DIARRHEA

nonenveloped RNA virus that infects upper SI cells

  • self limiting vomiting and diarrhea
  • 1/3 of all diarrhea cases
  • causes gastroenteritis in children and adults
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14
Q

Viral hemorrhagic fevers (3)

A
  1. yellow fever = black vomit
  2. ebola hemorrhage fever
  3. West Nile virus
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15
Q

Yellow fever

A

yellow fever: BLACK VOMIT
Vector: mosquitoes (Aedes mosq)
tropism: HEPATOCYTES (councilman bodies)
-SX: sudden fever, chills, myalgias, N+V, 3-5d later –> liver failure –> jaundice, dec clotting factors –> bleeding –> die (10d)

pretty much restricted to S. Am, Af, jungle and urban
mortality inc to 30% with jaundice

16
Q

ebola hemorrhagic fever

A

usually caused by Ebola Zaire and ebola sudan strains
fatal african dz
reservoir: fruit bats
spread: bodily secretions, blood, needles, heathcare workers, funerary preps
MULTIPLIES MASSIVELY in endothelial cells, mononuclear phagocytes, HEPATOCYTES
RESULT: MOST WIDESPREAD DESTRUCTIVE TISSUE LESIONS = PETECHIAE ALL OVER of all viral hemorrhagic fever agents

17
Q
  1. West Nile virus
A

80% asx, 20% flulike SX. 1% severe neuroinvasive sx
vector: mosq, birds (mig –> spread)
incubation: 3-15d
SX: fever, rash, lymphadenopathy, polyarthropathy
if severe: ACUTE ASEPTIC MENINGITIS/ENCEPHALITIS –> convulsions and coma. highest mortality in elderly

labs: INC SED RATE, inc leukocytosis, CSF: clear, moderate pleocytosis (inc WBC) and inc protein. medulla can be involved, varying neuronal necrosis and neurodegeneration and neuronophagia

18
Q
DNA viruses: 
4 misc (1-4)
5 herpesviruses (5-9)
A
  1. adenovirus
  2. human parvovirus B19
  3. smallox (variola)
  4. monkeypox
  5. varicella - zoster virus (VZV): chicken pox and shingles
  6. herpes simplex virus
  7. epstein-barr virus (EBV)
  8. cytomegalovirus (CMV)
  9. human papilloma virus (HPV)
19
Q
  1. adenovirus - nonenveloped DNA virus
A
  • cause of chronic pul dz in infants and young kids
  • type 40/41: infects colon and SI epithelial cells –> DIARRHEA (in both healthy and IC pts)
  • type 35: causes UTI (AIDS pop MOST SUSCEPTIBLE)
    pathology: NECROTIZING BRONCHITIS and BRONCHIOLITIS, INTERSTITIAL PNEUMONITIS: consolidation and extensive necrosis, hemorrhage, mononuclear infl infiltrates
  • 2 types of intranuclear inclusions: 1. SMUDGE CELLS 2. COWDRY TYPE A INCLUSIONS
20
Q

human parvovirus B19 - ssDNA

A
  • benign self limited febrile in kids called ERYTHEMA INFECTIOSUM (mild exanthematous illness) can lead to TRANSIENT APLASTIC CRISIS (fatal anemia) if pt has chronic hemolytic anemia already
  • most likely infects resp tract first then infects RBCs to form giant pronormoblasts (enlarged nuclei, displaced chromatic by eosinophilic nuclear inclusion bodies)
  • SX: system: rash, arthralgias, interrupts RBC production in nonimmune adults. if fetus is infected–> cessation of erythropoieses –> severe anemia, hydrops fetalis, death in utero
21
Q

smallpox (variola)

A

fatal 30% if unvaccinated
-highly contagious EXANTHEMATOUS INFECTION caused by variola virus
-spread by aerosol of infected saliva
-SX: resp tract –> LN –> viremia –> malaise, fever vomit headaches
2-3d later: face rash, hands, forearm –> feet, trunk
macules –> papules –> pustular vesicles –> scabs –> depressed scar on healing

22
Q

monkeypox

A

-zoonatic dz, rare, mostly in central and west africa
-spread by bite of infected host/contact with bodily fluids
-human-human transmission is not common
SX: mild smallpox: illness lasts about 2 weeks

23
Q

5 herpesvirus: enveloped DNA viruses

many makes type A nuclear inclusion (acidophilic bodies surr by halo)

A
  1. VZV (chicken pox and shingles)
  2. HSV
  3. EBV
  4. CMV
  5. HPV
24
Q

VZV - vaccine

A

spread by resp, contact, highly contagious
-starts with resp epith –> LN and blood –> skin DESTROYS EPIDERMAL BASAL CELLS: upper dead layer separate and form vesicles

25
Q

chickenpox

A

varicella zoster virus: chickenpox
generalized and systemic skin eruptions:
fever, malaise, pruritic rash (starts in head) that starts as maculopapules –> vesicles–> pustules (PMNs)–> ulcerate and crust (nuclear homogenization, intranuclear inclusion sep by halo (cowdry type A), multinucleated giant cells
-goes away, establishes latent infection in DRG

years later –> shingles aka herpes zoster:
reactivated virus travels down from ganglion cells to a whole dermatome causing unilateral painful vesicular eruption.
RF: inc age, dec cell mediated immunity

skin eruptions are identical in chicken pox, shingles, and HSV

26
Q

HSV (also describe how skin is similar to chicken pox and shingles)

A

see previous slide
- primary infection: site of inoculation: oropharynx, genital mucosa, skin. virus destroys the basal cells –> vesicles –> cell necrosis –> infl (PMNs then lymphocytes) –> resolves –> latent (similar to VZV, sensory nerve endings in oral/genital mucosa)

stress -> reactivation (2ndary infection): with/without sx, sx = ulcerating vesicular lesions. viruses are shed

27
Q

HSV1+2

A

both HSV1 and 2 can cause disseminated dz in IC:
retrograde: herpes encephalitis
herpes hepatitis (in preggos, and ICs)

  • HSV1: oral and labial herpes (sx above waist)
  • HSV 2: genital herpes, can cause aseptic meningitis
  • both can cause cell necrosis, vigorous inflm response. freq painful ulcerating vesicular lesions (1-2 wks persists)
  • neonatal herpes (from mom)
  • AIDS POP: HERPES ESOPHAGITIS, superimposed candida infection, anal blisters
28
Q

EBV (3)

A
  1. infectious mononucleosis: fever, pharyngitis, lymphadenopathy, inc circulatory ATYPICAL lymphocytes. contagious, infected oral secretions. remains latent for life. some ppl shed virus intermittently
  2. African Burkitt lymphoma (IC): infected B cells transform into immature malignant lymphocytes
  3. nasopharyngeal carcinoma (IC): virus transforms the nasopharyngeal cells
29
Q

EBV: sx and spleen

A

SX: fever, malaise, lymphadenopathy (neck usually) - movable and tender, pharyngitis, splenomegaly, inc atypical lymphocytes and monocytes. resolves in 3-4weeks

  • histo of LN: big cells with polylobular nuclei (resemble Reed-Sternberg cell of hodgkin dz)
  • has heterophile antibody (called paul bunnel ab, will reaction with ag from another species (ex. sheep RBCs)

SPLEEN: large and soft bc red pulp hyperplasia –> may rupture
liver: atypical lymphocytes in sinusoids and portal tracts.

30
Q

cytomegalovirus (CMV) - congenital and OI

A

-most common congenital pathogen
-MOST VULN: fetus and IC pts
-spread via secretions/bodily fluids/crossing placenta to infect epithelial cells, lymphocytes, and monocytes (may create latency in WBCs for life)
children: saliva, urine ;;; adults: sex, transplants (severe systemic dz)
Sx: chorioretinitis (eyes), diarrhea, GI hemorrhage (colon ulceration), ENCEPHALITIS (AMS), PNUEMONITIS (SOB)

if congenital inf: brain, inner ears, eyes, liver, BM.
if severe: micro and hydrocephalus, CEREBRAL CALCIFICATIONS, hepatosplenomegaly, jaundice –> death
if survive: hearing and neurological defects (neurological detected later in life)

cytopathic: cytoplasmic and intranuclear inclusions, nucleus surr by clear zone

31
Q

human papillomavirus (HPV)

A

-spread by inoculation–> basal cells –> prolif of squamous epithelium: causes KOILOCYTOSIS (large cytoplasmic vacuoles and nuclei shrank), and epithelium thickening

COMMON SX: warts (VERRUCA VULGARIS), flat and plantar warts: firm, circumscribed, raised, rough surfaced lesions. surfaces to trauma (hands)
CONDYLOMA ACUMINATUM (ANOGENITAL WARTS) - soft, raised fleshy lesions on penis, vulva, vaginal wall, cervix, perianal region.
LARYNGEAL PAPILLOMATOSIS
some serotypes: squamous cell dysplasia --> SCC of genital tract

resolves spontaneously, persistent and sheds in IC.