Viral infections: RNA viruses

Question 0

1. rhinovirus (some coronaviruses)

Answer 0

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

Question 1

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

Answer 1

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)

Question 2

2. influenza virus

Answer 2

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

Question 3

3. parainfluenza virus

Answer 3

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)

Question 4

4. RSV

Answer 4

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.

Question 5

5. SARs-CoV

Answer 5

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)

Question 6

3 viral exanthems (dz and virus)

Answer 6

1. measles = rubeola, sspe (subacute sclerosing panencephalitis)
2. rubella
3. mumps

Question 7

1. measles: have vaccines

Answer 7

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))

Question 8

measles - SSPE

Answer 8

subacute sclerosing panencephalitis

• happens years after measles infection
• slow chronic neurodegenerative disorder

Question 9

rubella - have vaccine

Answer 9

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)

Question 10

Mumps - have vaccine

Answer 10

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

Question 11

2 intestinal viral infections

Answer 11

1. rotavirus

2. Norwalk virus and other viral diarrheas

Question 12

1. rotavirus

Answer 12

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)

Question 13

2. Norwalk virus

Answer 13

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

Question 14

Viral hemorrhagic fevers (3)

Answer 14

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

Question 15

Yellow fever

Answer 15

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

Question 16

ebola hemorrhagic fever

Answer 16

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

Question 17

3. West Nile virus

Answer 17

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

Question 18

DNA viruses: 
4 misc (1-4)
5 herpesviruses (5-9)

Answer 18

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)

Question 19

1. adenovirus - nonenveloped DNA virus

Answer 19

• 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

Question 20

human parvovirus B19 - ssDNA

Answer 20

• 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

Question 21

smallpox (variola)

Answer 21

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

Question 22

monkeypox

Answer 22

-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

Question 23

5 herpesvirus: enveloped DNA viruses

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

Answer 23

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

Question 24

VZV - vaccine

Answer 24

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

Question 25

chickenpox

Answer 25

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

Question 26

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

Answer 26

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

Question 27

HSV1+2

Answer 27

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

Question 28

EBV (3)

Answer 28

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

Question 29

EBV: sx and spleen

Answer 29

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.

Question 30

cytomegalovirus (CMV) - congenital and OI

Answer 30

-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

Question 31

human papillomavirus (HPV)

Answer 31

-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.