Viral Infections and Prions

Question 1

Common Cold

Answer 1

acute, self limited, UPPER respiratory
RNA viruses
spread person to person, winter (temperature), rainy (tropics)
caused by rhinovirus (40%), coronavirus (20%) and RSV (10%), infection confined to respiratory epithelium
infected cells secrete mediators (BRADYKININ) which caused symptoms
stasis–> secondary bacterial infections (sinusitis, otitis media)
symptoms - rhinorrhea, pharyngitis, cough, low grade fever, week long

Question 2

Influenza

Answer 2

acute, usually self limited, UPPER AND LOWER respiratory
enveloped, ssRNA
Types: A, B, C (A=most common and severe)
serotypes: hemagglutinin (H) and neuaminidase (N)
Herd immunity against one epidemic doesn’t protect against another
person to person, respiratory droplets and secretions
PATHOLOGY: H binds to sialic acid on epithelium and enters -> progeny -> cell death->no mucociliary clearance -> secondary bacterial infection (s. aureus + s. pneumoniae)
infection spreading to lungs ->necrosis/sloughing (hostologic appearance)
SYMPTOMS- rapid onset of fever, chills, myalgia, HA, weakness, nonproductive cough

Question 3

Parainfluenza

Answer 3

Associated with croup (stridor/barking) + young children
acute UPPER and LOWER respiratory
four serotypes, enveloped, ssRNA, paramyxovirus family
person to person, respiratory aerosols and secretions, highly contagious
second leading cause of hospitalization of 5 years and under for respiratory illness
PATHOLOGY: kill ciliated respiratory epithelium, inflamm response, in lower track in kids leads to bronchiolitis and pneumonitis, in children trachea is narrow and edema compresses upper airway and obstruct breathing (CROUP)
SYMPTOMS-fever, hoarseness and cough

Question 4

Respiratory Syncytial Virus

Answer 4

paramyxoviridae
person to person, respiratory aerosols and secretions (daycares, hospitals), contagious
most common cause of bronchiolitis and pneumonia in children under 1
PATHOLOGY: necrosis and sloughing of epithelium, lymphocytic infiltrate, multimucleated syncytial cells sometimes seen
CLINICAL FEATURES:wheezing, cough, respiratory distress, sometimes fever, self limited, mortality rises in hospitalized childrens with comorbidities

Question 5

Severe Acute Respiratory Syndrome

Answer 5

novel coronavirus (SARS-CoV)
from bats and civets in china, has not been eradicated
2-7 day incubation period
PATHOLOGY: diffuse alveolar damage, multinucleated syncytial cells without viral inclusions
CLINIAL FEATURES: fever and HA followed by cough and dyspnea, coryza absent, diarrhea present, some develop ARDS and have risk of complications and death
No Rx available, steroids may offer some benefit

Question 6

Measles (rubeola)

Answer 6

enveloped, ssRNA paramyxovirus
acute illness, UPPER respiratory tract, fever and rash
EPIDEMIOLOGY: person to person, respiratory aerosols and secretions, non-immunized children, severe in young, malnourished and immunocomprimised
PATHOPHYSIOLOGY: infection at mucous membranes through H and F glycoproteins attachment -> lymph nodes + bloodstream ->skin and lymphoid tissue involvement. RASH - T lymphocytes action on infected vascular endothelium
PATHOLOGY: necrosis, lymphocytic inflamm infiltrate, small blood vessel vasculitis, multinucleated giant cells with intracyto and intranuc inclusions (WARTHIN FINKELDEY GIANT CELLS)
CLINICAL FEATURES: fever, rhinorrhea, cough, conjunctivitis, mucosal (koplik spots) and skin lesions (face-> trunk->extremities), secondary bacterial infections (otitis media and pneumonia), CNS invasion, SSPE
VACCINE- live attenuated

Question 7

Rubella

Answer 7

enveloped, ssRNA
mild, self limited systemic disease with rash (German measles, in utero before 20 wks -> abnormalities
EPIDEMIOLOGY: person to person, respiratory, not contagious
VACCINE: live attenuate
PATHOPHYSIOLOGY: respiratory epithelium -> disseminates blood and lymphatics, rash -from immune response
PATHOLOGY: mild, acute febrile illness, rhinorrhea, conjunctivitis, postarticular lymphadenopathy, rash that resolves after 3 days, FETUS- heart (pul valve stenosis, pul artery hypoplasia, VSD, PDA), eye (cataracts, glaucoma, microphthalmia, retinal defcts), and brain (sensorineural deafness, microcephaly, MR) affected

Question 8

Mumps

Answer 8

paramyxovirus, enveloped, ssRNA
acute self limited systemic illness, parotid gland swelling,meningoencephalitis
EPIDEMIOLOGY: children, person to person, respiratory, contagious
VACCINE: live attenuated
PATHOPHYIOLOGY: respiratory tract epithelium ->blood and lymphatics -> salivary glands, CNS, pancreas, testes
PATHOLOGY: necrosis, lymphocytic inflammatory infiltrate, glands swell, testes swell to 3x their size and get infarcts, unilat orchitis
CLINICAL FEATURES: fever and malaise, gland swelling, meningeal (HA, stiff neck, vomiting), pancreatic involvement

Question 9

Rotavirus

Answer 9

5 species, dsRNA, reoviridae family, Type A - most common + children
EPIDEMIOLOGY: person to person, oral-fecal
PATHOPHYSIOLOGY: enterocytes of upper small intestine (decrease absorption of sugars, fats, ions) -> osmostic load->fluid loss into bowel-> diarrhea + dehydration; shedding of epithelium initally decreases absorptive capacity
PATHOLOGY: duodenum and jejunum, shortened villi, mild neutrophilic and lymphocytic infiltrate
CLINICAL FEATURES: vomiting, fever, abdominal pain, DIARRHEA, dehydration

Question 10

Norwalk family Virus

Answer 10

nonenveloped RNA
responsible for 1/3 of diarrheal disease
gastroenteritis in adults/children, self limited vomiting +diarrhea
infects upper small bowel and changes similar to rotovirus

Question 11

Yellow fever

Answer 11

acute hemorrhagic with hepatic necrosis and jaundice
insect borne flavivirus, enveloped ssRNA
EPIDEMIOLOGY: jungle and urban settings, aedes mosquitoes vector, human is resevoir
PATHOPHYSIOLOGY: inoculation -> multiplies in tissue ad vascular endothelium -> disseminated in blood -> hepatocellular destruction, vascular integrity loss, hemorrhages and shock
PATHOLOGY: coagulative necrosis of hepatocytes (lobules -> central veins and portal tracks), some necrosis and lose nuclei, dislodge and stain eosinophilic: COUNCILMAN BODIES
CLINICAL FEATURES: abruptonset of fever, chills, HA, myalgias, nausea, vomiting, after 3-5 days - hepatic failure, jaundice, decreased clotting factors, diffuse hemorrhages, black vomit (clotted blood) = severe disease, die within 10 days

Question 12

Ebola hemmorrhagic fever

Answer 12

RNA virus, filoviridae family, HIGH MORTALITY RATE
EPIDEMIOLOGY: africa, natural resevoir is fruit bats, transmitted from bodily secretions, blood, needles
ETIOLOGIC/PATHOLOGY: most widespread and destructive of hemorrhagic fever agents, replicates in endothelial cells, mononuc phagocytes, hepatoytes, necrosis in liver (necrosis+kupffer hyperplasia+ councilman bodies, microsteatosis), spleen, kidney, gonads, lymph nodes, lungs, petechial hemorrhages, can lead to shock
CLINICAL FEATURES: 2-21 day incubation, HA, weakness, fever, followed by diarrhea, nausea, vomiting, overt hemorrhage

Question 13

West nile virus

Answer 13

EPIDEMIOLOGY: flaviviridae family, africa, medit, US
PATHOLOGY: moderate pleocytosis, elevated CSF protein, mononuc meningocephalitis/encephalitis, can involce brain stem and cranial nerves
CLINICAL FEATURES: most subclinical, 3-15 incubation, fever, rash, lymphadenopathy, polyarthropathy, brain, organ infection

Question 14

Viral hemorrhagic fevers (vector and fever)

Answer 14

MOSQUITOES - yellow fever, rift valley fever, dengue, chikungunya
TICKS- omsk, crimean, kyasanur forest disease
RODENTS- lassa fever, bolivian, argentine, korean
FRUIT BATS - ebola virus

Question 15

Adenovirus

Answer 15

nonenveloped DNA
EPIDEMIOLOGY: causes acute respiratory and pneumonia in military, pulmonary disease in children, direct contact, fecal oral, water borne
PATHOLOGY: necrotizing bronchitis/bronchioloitis (sloughed epithelial cells), interstitial pneumonia (consolidation from necrosis, hemorrhage, infiltrates), intranuclear inclusions (COWDRY TYPE A and SMUDGE CELLS)
TYPES 40 and 41 - colonic and small intestinal epithelial cells, diarrhea
TYPE 35 - UTI in HIV patients
immunocomprimised - fulminant or disseminated disease

Question 16

Human parvovirus (erythrovirus) B19

Answer 16

ssDNA, benign self limited febrile illnessin children,
ETIOLOGIC FACTORS: person to person, respiratory route, infects tract and then erythroid precursors
PATHOLOGY: gains entry through P-erythrocte antigen, results in enlarged nuclei, peripheral chromatin, eosinophilic inclusion bodies (giant pronormoblasts)
CLINICAL FEATURES: ERYTHEMA INFECTIOSUM (fifth disease), if have hemolytic anemia, pause in erythrocyte production causes TRANSIENT APLASTIC CRISIS, fetal infection -> anemia, hydrops fetalis, death

Question 17

Smallpox (Variola)

Answer 17

poxviridae family, highly contagious exanthematous viral infection
EPIDEMIOLOGY: first successful vaccination using cowpox
ETIOLOGIC FACTORS: droplets or aerosol of infected saliva transmission, variola major (asia and africa) minor (africa, S. america europe)
PATHOLOGY: skin vesicles, cellular necrosis, GUARNIERI BODIES (not specific for smallpox), vesicles on palate, pharynx, trachea, esophagus, can have gastric or intestinal involvement
CLINICAL FEATURES: 12 day incubation, respiratory tract -> replicated in lymph nodes -> viremia. malaise, fever, vomiting, HA, rash (after 2-3 days), macules become papules to pustular vesicles to scars

Question 18

Monkeypox

Answer 18

rare viral disease in central and western africa, sudan,poxviridae family
EPIDEMIOLOGY: bite or contact with fluids of infected host, person to person uncommon
CLINICAL FEATURES: 12 day incubation, milder smallpox presentation, fever, HA, lymphadenopathy, malaise, muscle ache, backache, rash (after 1-3 days) papular to crust

Question 19

VZV

Answer 19

Chicken pox (acute systemic with generalized vesicular skin eruption) and herpes zoster (localized vesicular skin eruption)
ETIOLOGIC/EPIDEMIOLOGY: person to person, respiratory route, skin secretions, infects respiratory/conjunctiva epithelium -> blood + lymphatics -> cap endothelium -> epidermis -> basal cell destruction ->vesicles
LATENCY: perineuronal satellite cells of DRG, transcription continues during latency, when travel down nerve causes SHINGLES
PATHOLOGY: maculopapules-> vesicles fill with neutrophils (pustules)-> erode-> ulcers -> heal, nuclea homogenization, intranuc inclusions (COWDRY TYPE A), multinuc cells common
CLINICAL FEATURES: chicken pox - fever, malaise, pruritic rash head to trunk; shingles - unilat painful vesicular eruption, pain persists after healing

Question 20

HSV

Answer 20

HSV-1: oral secretion transmission, causes above the waist lesions
HSV-2: genital secretion transmission, causes genital ulcers and neonate infection during delivery
EPIDEMIOLOGY: person to person, direct contact with lesions
PATHOPHYSIOLOGY: primary HSV - site of inoculation, infects epithelial cells, destroys basal cells to form vesicles, resolves with humoral and cell mediated immunity, secondary HSV - ulcerating vesicular lesions or just shedding with no lesions, can become disseminated (encephalitis - retrograde travel/ hepatitis - immunocomprimised), aspectic meningitis without genital involvement is usually HSV-2
LATENCY: sensory neurons within corresponding ganglia
PATHOLOGY: necrosis with inflamm response, nuclear homogenization, Cowdry type A intranuc inclusions,multinuc giant cells
CLINICAL FEATURES: prodromal tingling, immunocomprimised prone to herpetic esophagitis and superimposed candida, neonates - 5-7 post delivery, irritable, lethargy, vesicular eruption, organ involvement, jaundice, bleeding, respiratory, seizures, coma
aciclovir can help but neonate carries high mortality rate

Question 21

EBV

Answer 21

causes infectious mononucleosis - fever, pharyngitis, lymphadenopathy, increased lymphocytes
CANCER ASSOCIATIONS - african burkitt lymphoma, b-cell lymphoma, nasopharyngeal carcinoma
EPIDEMIOLOGY: person to person, oral secretions,children - mono rare, adults - mono
PATHOPHYSIOLOGY: binds nasopharyngral cells then B lymphocytes ->generalized lymphoid tissue infection, polyclonal activator of B cells -.> killer and suppressor T cell proliferation -> infected B cell destruction + decrease Ig production from B cells respectively
PATHOLOGY: in lymph nodes and spleen, large movable nodes in neck, enlarged germinal centers with indistinct margins have large hyperchromatic cells that resemble Reed sternberg cells, spleen hyperplasia (red pulp) - can rupture, atypical (activated T cells with lobulated eccentric nuclei and vacuolated cytoplasm) lymphocytes in liver, HETEROPHILE ANTIBODY
CLINICAL FEATURES: fever, malaise, lymphadenopathy, pharyngitis, splenomegaly, leukocytosis, treatment is supportive

Question 22

CMV

Answer 22

congenital and opportunistic (fetus/immunocomprimised)
EPIDEMIOLOGY: person to person, secretions and bodily fluids, transplacental, saliva, sexual contact
ETIOLOGIC: infects epithelial, lymphocytes, monocytes, neonates/immunocomprimised - widespread necrosis and inflammation
LATENCY: WBC, can shed without lesions
PATHOLOGY: fetal - brain, inner ear, eyes, liver, bone marrow, cellular necrosis, cellular enlargement with inclusion (nuclear followed by cytoplasmic)
CLINICAL FEATURES: neonate infection- in utero death, adult subtle neurologic or hearing defects; immunocomprimised - wide range of presentations

Question 23

HPV

Answer 23

proliferative lesions of squamous epithelium
nonenveloped, dsDNA
HPV 1, 2, 4 common warts and plantar warts
HPV 6, 10, 11, 40-45 anogenital warts
HPV 16, 18, 31 squamous carcinomas of female genital tract
EPIDEMIOLOGY: person to person, direct and sexual contact
PATHOPHYSIOLOGY: viral inoculation in stratified squamous epithelium -> nuclei of basal cells -> induce proliferation -> lesions -? viral shedding -> resolve spon unless immunocomprimised
PATHOLOGY: varies, most show thickening of affected epithelium, KOILOCYTOSIS
CLINICAL FEATURES: common warts (verruca vulgaris), plantar warts, anogenital warts (condyloma acuminatum), flat warts can become malignant - HPV->CIN->SCC

Question 24

Kuru

Answer 24

progressive neurodegenerative disease
South Fore tribe in Papua New Guinea
cannibalism
disappeared after cannibalism eliminated

Question 25

sporadic, familial, iatrogenic Creutzfeldt-Jakob disease

Answer 25

rapidly progressive neurodegenerative disorder
myoclonus, behavior changes, dementia
sporadic most common
rarely results after transplantation
transmitted from hGH from cadaver pituitaries

Question 26

New variant Creuzfeldt-Jakob disease

Answer 26

mad cow disease
relentless terminal disease
genetic homozygosity - met-met at codon 129 of the gene PRNP
occurs in young adult (different from sfiCJD)
psychiatric signs and symptoms more predominant than sfiCJD

Question 27

Fatal familial insomnia

Answer 27

rare inherited prion
progressive course of insomnia
autonomic instability -> increased sympathetic tone
altered sensorium followed by motor system degeneration
spongiform changes seen later in disease course

Question 28

Gerstmann-Straussler-Scheinker syndrome

Answer 28

rare transmissible spongiform encephalopathy
usually familial, rare sporadic cases
variety of symptoms but mostly cerebellar degeneration
dementia seen later in disease course