Viruses

Question 1

basic unit from which capsids are built

Answer 1

structural unit

protomer

Question 2

surface structures seen by EM

Answer 2

morphological unit

capsomer

Question 3

protein shell surrounding the nucleic acid genome

Answer 3

capsid

coat

Question 4

lipid bilayer derived from host membrane carrying viral glycoprotein

Answer 4

envelop

viral membrane

Question 5

complete infectious virus particle

Answer 5

virion

Question 6

nucleic acid core (genome), core proteins, and capsid (protein coat)

Answer 6

nucleocapsid

Question 7

capsid type
assembly of nucleocapsid requires the presence of nucleic acid
each protomer interacts directly with nucleic acid
size of the nucleocapsid is limited by the amount of nucleic acid enclosed

Answer 7

helical capsids

Question 8

capsid type
nucleic acid is notneeded for capsid formation (empty capsid forms)
size of the capsid limits the amount of nucleic acid enclosed
multiple proteins are usually involved in forming the capsid

Answer 8

icosahedral capsid

Question 9

capsid type
poxviruses
DNA viruses carries machineries for cytoplasmic replication (replication enzymes)
virions are very sable (6 months) even when desiccated and at room temperature

Answer 9

complex virion

Question 10

viral genome directly translatable into protein, acts as mRNA

Answer 10

Positive sense RNA genome

Question 11

viral genome from which mRNA is made and translated into proteins

Answer 11

Negative sense RNA genome

Question 12

pattern of viral disease

infection and complete recovery

Answer 12

acute infection

Question 13

pattern of viral disease

final disease is different from initial disease

Answer 13

acute infection, rare late complication

Question 14

pattern of viral disease

second disease episode is the same as the first; no infectious virus between episodes

Answer 14

latent infection

Question 15

pattern of viral disease

following initial disease episode, virus is shed without overt disease

Answer 15

chronic infection

Question 16

pattern of viral disease

virus is produced and shed for long period before disease manifests

Answer 16

chronic infection, late disease

Question 17

amount of virus increases over time until sufficient level is reached to cause disease

Answer 17

slow infection

Question 18

virus family
10-12 segments in dsRNA genome
non-enveloped, icosahedral capsid
Coltivirus - Colorado Tick Fever
Rotavirus

Answer 18

Reoviruses

Question 19

most important cause of severe diarrhea in children under 5 worldwide (most common in 6-24 months)
outbreaks in child care centers, nosocomial infections in children’s hospitals
increased viral survival at higher humidity, peak incidence in cooler months
resists inactivation by concentration of chlorine used in treating sewage and drinking water

fever/vomiting for 2-3 days, progress to diarrhea for 4-8 days
watery profuse diarrhea, abdominal pain, severe volume depletion (dehydration)
seizures with aspiration of vomitus
chronic diarrhea in the immunocompromised

clinical diagnosis; ELISA, stool viral culture, stool EM, Latex agglutination, PCR

supportive care, no antivirals, hygiene, inactivation with 95% ethanol

RotaShield = oral, live attenuated vaccine, no longer available, causes intussusception
RotaTeq and Ratarix = oral, live attenutated vaccine, small risk of intussusception

non-enveloped, iscosahedral
11 dsRNA segments
triple layer structure: outercapsid (VP4, VP7), middle capsid (VP6, target of Ab), inner capsid (VP2, structure)
polymerase (VP1, transcription), guanyltransferase (VP3, RNA capping)
7 antigenic groups (Group A causes most human disease)

fecal-oral transmission; sloughing of enterocytes in stool results from receptor mediated endocytosis causing enterocyte infection and conversion to dual layer structure; viral replication produces new dual layer structures that obtain the third layer in the ER; progeny released by cell lysis

Answer 19

Rotavirus

Question 20

virus family
nonsegmented +ssRNA genome
non-enveloped, icosahedral
worldwide distribution, affects all ages
occurs year round but is more common in less humid months/winter
associated with epidemic outbreaks of waterborne, foodborne, and shellfish-associated gastroenteritis
Norovirus

Answer 20

Caliciviridae

Question 21

leading cause of food-borne disease outbreaks worldwide

Genetic mutation and recombination contribute to broad heterogeneity and emergence of new strains resulting in antigenic drift (especially genotype II)
Immunity is incomplete and temporary
Genotype GII.4 is responsible for 70-80% of outbreaks worldwide
VP1 is the major capsid protein; receptor binding region and major site of antigenic variation

Individual human susceptibility is related to the presence of specific histo-blood group antigens (secretor status); these are glycans on the surface of gut epithelial cells (polymorphic fucosyltransferase genes)
O negative individuals are resistant to infection

Frequently reported on ocean liners; transmission is linked to sewage contamination, poor water storage/ filtration/ chlorination, food handler carriage, food preparation/storage; also seen in hospitals, military camps, jails, and schools

rapid onset of symptoms and brief clinical course
Fever, anorexia, explosive watery diarrhea, forceful vomiting
Respiratory symptoms in 1/3 of children
Illness begins 12hr to 4 days after exposure and lasts 3-7 days
Diagnosis by clinical manifestations and PCR of stool, treatment is supportive

Answer 21

Norovirus

Norwalk virus

Question 22

virus family
linear ssRNA genome
icosahedral, non-enveloped
stable at pH 3-10 (survive stomach acid)
replicate in the GIT and pharynx
resistant to chloroform and alcohol
shed from GIT more than URT
cause minor and major viremia
Enteroviruses

Answer 22

Picornaviridae

Question 23

Enterovirus
Three serotypes; humans are the only natural host
life-long immunity, no cross-immunity with other serotypes
fecal-oral transmission

replication in the gut, dissemination to the RER via minor viremia, rare major viremia spread to other organs (muscle and brain)
biphasic

90-95% of infections are asymptomatic
abortive infection: fever, headache, sore throat, anorexia, indistinguishable from other viral infections
non-paralytic infection: aseptic meningitis similar to other enteroviruses, signs of meningeal irritation
paralytic infection: flaccid paralysis resulting from lower motor neuron damage; asymmetric, proximal muscles most affected, loss of reflexes but sensation intact; residual deficit in most
replication in the anterior horn cells of the spinal cord leads to spinal infection
involvement of the medulla and brain stem causes bulbar infection that leads to cranial nerve paralysis
involvement of the cortex causes encephalitic infection

Respiratory failure is responsible for most deaths (weakness of diaphragm and intercostals, involvement of respiratory center in brainstem, CN infection)

Post-infection syndrome is a late manifestation of acute paralytic infection in childhood; characterized by muscle pain and exacerbation of paralysis resulting from late attrition of oversized motor units that developed in the recovery process

Dx: viral isolation from throat, feces; serology

Occurred most often in the summer and fall in the US but can occur year round in tropic areas
Pre-industrial era: milder endemic form in infants protected by maternal antibodies
20th century: improved hygiene, epidemics in older children peaked in 1952; vaccine in 1955 resulted in sharp decline

Salk vaccine: (IPV) inactivated virus; mix of three types inactivated by formalin; currently used in most of Europe, US, and Canada
Sabin vaccine: (OPV) oral, leads to the additional development of mucosal immunity; used in developing countries; vaccine derived infection (if population is underimmunized, cVDPV)

Problems with eradication: subclinical cases, vaccine associated infections, changes in world populations/politics, long duration of eradication programs

Vaccine derived viruses can cause paralytic infection, potential for sustained circulation; can cause outbreaks in areas with low OPV coverage; OPV replaced with IPV in US; new cases in only 2 countries (Pakistan, Afghanistan)

Answer 23

Poliovirus

Question 24

Non-polio enterovirus
Acquired by ingestion of virus shed in feces or URT

Replication in lymphoid tissues of the ileum gives rise to transient minor viremia and RES involvement
Major viremia seeds other target organs (CNS [meningitis], heart [myocarditis], skin [viral exanthema])

Infants and young children have the highest rates of infection and disease

Most infections are asymptomatic but some develop nonspecific febrile illness (lethargy, poor feeding, vomiting, and diarrhea)
Exanthema = rash resembling measles and rubella;

herpangina, hand-foot-mouth disease, acute hemorrhage conjunctivitis

Diagnosis by viral isolation in cell culture and PCR; serology can be done but there is cross-reactivity

Infection is usually self-limited and do not require treatment; in severe infection, Ig therapy has been used

Answer 24

Coxsackie viruses A

Question 25

Non-polio enterovirus
Acquired by ingestion of virus shed in feces or URT

Replication in lymphoid tissues of the ileum gives rise to transient minor viremia and RES involvement
Major viremia seeds other target organs (CNS [meningitis], heart [myocarditis], skin [viral exanthema])

Infants and young children have the highest rates of infection and disease

Most infections are asymptomatic but some develop nonspecific febrile illness (lethargy, poor feeding, vomiting, and diarrhea)
Exanthema = rash resembling measles and rubella;

Aseptic meningitis, myocarditis and pleurodynia

Diagnosis by viral isolation in cell culture and PCR; serology can be done but there is cross-reactivity

Infection is usually self-limited and do not require treatment; in severe infection, Ig therapy has been used

Answer 25

Coxsackie virus B

Question 26

virus family
enveloped ssRNA genome
bud from cell surface with embedded surface proteins
attachment to cell surface glycoproteins via hemagglutinin-neuraminidase, hemagglutinin, or G proteins
F protein mediated fusion of virus to host cell

Parainfluenza, mumps, measles, respiratory syncytial virus, metaneumovirus

Answer 26

Paramyxovirus

Question 27

Morbillivirus; ssRNA virus
Hemagglutinin attaches to cell surface
predominantly a childhood illness, humans are the only hosts
seen worldwide, mostly in winter/spring
US cases largely due to importation
highly contagious, droplet spread by infected nasopharyngeal secretions

infects epithelial cells of respiratory tract, spread by viremia to RES, followed by secondary viremia
replication in conjunctiva, respiratory tract, GI, GU, lymphatics, blood vessels, and CNS
disease manifestations due to T-cell response to virus infected cells lining capillaries
multi-nucleated giant cells in skin, mucosa

Koplik’s spots = mucosal enenthem
maculopapular rash initially on face, spreads to trunk and limbs; confluent
complications: pneumonia, bacterial superinfection, encephaltits, subacute sclerosing panencephalitis

Dx: clinical appearance, serology, PCR
Tx: supportive, vitamin A
vaccine: MMR, two doses

Answer 27

Measles

Rubeola

Question 28

endemic worldwide
US outbreaks related to importation from UK
humans are the only host
transmitted by direct contact, droplets, fomites

prodromal low grade fever, malaise, headache (flu-like)
progresses to earache and tenderness with parotid palpation
bilateral parotid enlargement
post-pubertal epididymo-orhcitis, meningitis, encelphalitis are possible

vaccine preventable (MMR), some evidence of lost immunity with time

Answer 28

Mumps

Question 29

major cause of lower respiratory tract infection in young children; also seen in immunocompromised adults
primarily in winter and spring
outbreaks last up to 20 weeks
all children are infected in the first few years of life

inoculation through nose or eye (mouth is less effective)
Bronchiolitis (lymphocytic peribronchiolar infiltration): endothelial sloughing, mucus secretion, airflow obstruction
pneumonia with mononuclear cell infiltration

acute complications: apnes, increased risk of infant aspiration
chronic complications: recurrent wheezing, bronchiectasis
pneumonia in immunocompromised

tx: ribavirin, bronchodilators, corticosteroids
prevention: infection control, IVIG for high risk infants

Answer 29

Respiratory Syncytial Virus

RSV

Question 30

attaches via G protein, structure similar to RSV
infects all ages, most children are infected by age 5
infection mostly in winter

upper respiratory infection, bronchiolitis, pneumonia
co-infection with RSV and/or influenza possible

Answer 30

Metapneumovirus

MNV

Question 31

Togaviridae family; rubivirus
enveloped, +ssRNA, icosahedral, only one major antigenic type

moderately contagious, incidence is highest in spring
pre-vaccination period: minor epidemic every 6-9 years, major every 30 years; most common in 5-9 years
post-vaccination period: increasing frequency in older children, cases in recent immigrants

transmitted by respiratory droplets
most infectious when rash develops but virus is shed before and after rash
infants with congenital infection may shed virus for months
no viral shedding after vaccination

many infections are asymptomatic
fever, maculopapular rash (face>body), LAD (posterior auricular, posterior cervical), mild sore throat, coryza, cough, mild arthralgia
arthritis is more common in adolescent/young adult women

Answer 31

Rubella

German Measles

Question 32

most likely with viral infection of the pregnant woman in the 1st and 2nd trimesters

low birth weight, sensorineural deafness, blindness (congenital cataracts, glaucoma), congenital heart disease (patent ductus arteriosus), microcephaly, thrombocytopenic purpura, hepatomegaly, and severe cognitive impairment in the baby

preventable with maternal immunization

Dx: mild leukopenia with atypical lymphocytes, serology, PCR of amniotic fluid
Tx: supportive, Ig for susceptible pregnant woman after exposure

Answer 32

Congenital Rubella Syndrome

Question 33

family Orthomyxoviridae
enveloped, negative ssRNA genome in 8 segments (genetic reassortment)
hemagglutinin and neuraminidase surface projections (subtype Type A)

virus enters respiratory tract via small particle aerosols (talking, coughing, sneezing)
infection limited to superficial cells of URT and LRT; penetrates columnar epithelial cell causing cell death; inhibits protein synthesis inducing apoptosis
loss of ciliated and mucus secreting epithelial cells reduces bacterial clearance

abrupt onset of illness
fever, rigors, myalgias, headache, sore throat, dry cough, nasal obstrucion
may progress to viral pneumonia
secondary bacterial infection possible
may be followed by Guillain-Barre (bilateral ascending paralysis)

Dx: nasopharyngeal swab, rapid antigen testing, PCR, viral isolation

inactivated vaccine: chick embryo culture, trivalent/quadrivalent
inactivated vaccine high dose: for 18 years
recombinant vaccine: insect cell culture, >18 years
live attenuated vaccine: nasal, 2-49 years

epidemic = seasonal outbreak of subtype that already circulate in the community
pandemic = global outbreak of new subtype that emerges in human population
wild water fowl are reservoirs, all human viruses arise from avian viruses

Answer 33

Influenza

Question 34

highly pathogenic avian virus that spread form Asia to Europe and Africa
bird to human transmission with close contact, human to human transmission is rare
50% mortality, pandemic potential
cook poultry and eggs to internal temperature of 165 degrees

Answer 34

avian influenza

H5N1

Question 35

Non-enveloped DNA viruses, over 50 serotypes
Infection may be lytic, latent (chronic), or lead to oncogenic transformation

Primary infection occurs early on during the first years of life
Upper and lower respiratory tract infections, eye infections, or lower urinary tract infections in children
transplated organs often affected

Respiratory infections are often asymptomatic but can cause mild pharyngitis or tracheitis; cough, fever, sore throat and rhinorrhea are common; in infants, pneumonia and bronchiolitis
Pharyngoconjuntival fever, epidemic keratoconjunctivitis, hemorrhagic cyctitis
infantile diarrhea with fever, intussusception, CNS infections (encephalitis, meningoencephalitis)

Dx: clinical, tissue culture, EM, Ab detection, ELISA, immunofluorescence
Tx: supportive in immunocompetent, antivirals in immunocompromised

Answer 35

Adenoviruses

Question 36

important in transplant recipients, frequently involves transplanted organ

bilateral interstitial pneumonia, UTI, disseminated disease (lung, colon, CNS)
disseminated disease is more common in children and is associated with a high mortality rate

Answer 36

Adenovirus in immunocompromised host

Question 37

clinical syndrome caused by Adenovirus
occurs in outbreaks
pharyngitis, conjuntivitis, rhinitis, cervical adenopathy, fever
associated with contaminated swimming pools and ponds

Answer 37

Pharyngoconjuntival Fever

Question 38

clinical syndrome caused by Adenovirus
frequently bilateral, may last for 4 weeks
peri-auricular adenopathy
cornea involvement may last for months causing visual disturbances
contagious, spread to household contacts

Answer 38

Epidemic Keratoconjunctivitis

Question 39

clinical syndrome caused by Adenovirus
more common in boys
hematuris, dysuria, urinary frequency

Answer 39

Hemorrhagic cystitis

Question 40

small, non-enveloped DNA virus
only propagated in human erythroid progenitor cells
common in children by age 15
acquired via respiratory route

Children: erythema Infectiosum (Fifth Disease); self-limited syndrome with prodrome of fever, headache, nausea, and diarrhea followed by classic slapped cheek rash; second stage may follow with fain erythematous rash on trunk and limbs; manifestations are immune mediated

Adults: especially women; arthralgias or frank arthritis which is usually symmetrical and involves small joints; symptoms similar to acute rheumatoid arthritis

Underlying hematological disorders or iron deficiency anemia: transient aplastic crisis; dyspnea due to profound anemia, viremia

Underlying immunodeficiency: Pure red cell aplasia; chronic anemia, persistent viremia; lack or low parvovirus-specific antibody response

Dx: viremia detected with DNA hydribization in pure red cell aplastic crisis and transient aplastic hyperplasia; erythema infectiosum is not viremic, use ELISA; in immunocompromsed no Ab, use PCR

Tx: self-limiting, life-long immunity; in immunocompromised remove immunosuppression or give Ig

Answer 40

Parvovirus B19

Question 41

small, spherical RNA viruses
Flaviviridae, Togaviridae, Bunyaviridae, Reoviridae
require a biting arthropod to complete the life cycle
must produce a level of viremia in vertebrate host for arthropod to become infected during blood meal
most are zoonoses, humans are incidental hosts (except Dengue)

Answer 41

Arboviruses

Question 42

family Togaviridae
reservoir = primates
vector = mosquito (same species as Dengue)
Africa, Asia, Caribbean, South America, US

Biphasic illness
Initial presentation: 2-4 days incubation, resolves in 3 days
Fever, headache, back pain, myalgias, arthraglias, frank arthritis
Nonspecific maculopapular rash in 50%, facial edema

Chronic, debilitating polysrthralgias in a subset of patients: last for months to over a year
Affect peripheral joints, associated with teneosynovitis and Raynaud’s
Less common in children compared to adults

Death is rare but long recover results in morbidity and disability

Dx: PCR in early infection, IgM after 2 days of fever
Tx: no specific treatment

Answer 42

Chikungunya

Question 43

family Flaviviridae
reservoir = macaques and humans
vector = mosquito

Urban – mostly transmitted by mosquitoes in peri-domestic environment (breed in standing water)

Four serotypes, all can cause fatal disease. Infection with one serotype confers life-long immunity to that serotype but only temporary (6 month) protection against heterologous serotypes

Asymptomatic 20-50%
Undifferentiated fever (mild fever, usually in young children with first episode)
Fever Syndrome
Hemorrhagic Fever
Shock Syndrome

warning signs of progression:
abdominal pain/tenderness, persistent vomiting, lethargy/restlessness, fluid accumulation, mucosal bleeding, sudden increase in hematocrit with rapid decrease in platelet count
transfer to ICU for fluid management and management of shock

Dx: clinical (tourniquet test, RT-PCR in acute phase, serology
Tx: supportive; in hemorrhagic fever and shock syndrome, fluid replacement is key (when signs of convalescence appear watch for overload)

Answer 43

Dengue

Question 44

family Flaviviridae
reservoir = primates
vector = mosquito
endemic in sub-Saharan Africa and parts of South America

Biphasic illness, abrupt onset of illness 3-6 days after bite

Initial phase: extreme myalgias, headache, nausea, vomiting, conjunctival suffusion, Faget’s sign (relative bradycardia)
low WBC count, elevated liver enzymes
virus usually detectable in blood
3-4 days before resolution, followed by virus-specific IgG

Second phase: 15-20% recurrence after initial phase
Fever, hepatitis, jaundice, renal failure
Severe hemorrhage – hematemesis, melena, ecchymosis, bleeding from eyes, nose, bladder, rectum
25-50% mortality due to multisystem organ failure and shock
Life-long immunity in those who recover

Dx: IgM in initial phase, cross reactivity with other flaviviruses
Tx: supportive, no specific antiviral

Vaccination – live attenuated vaccine likely life-long immunity, required for travel to Africa and parts of South America

Answer 44

Yellow Fever

Question 45

family Flaviviridae 
reservoir = birds
vector = mosquito
also transmitted via blood transfusion, and transplacentally
infects humans and domestic animals

introduced to US in 1999 (migrating bird, illegal bird traffic, infected mosquito on airplane, infected traveler, or new viral strain)

most infections are asymptomatic
higher risk of disease in the elderly, immunocompromised, and with deletion in CCR5 gene which is protective against HIV

clinical manifestations: fever, neuroinvasive disease (meningitis, encephalitis, flaccid paralysis)

Dx: CSF IgM is more sensitive than PCR
Tx: supportive - fluids and respiratory support

Answer 45

West Nile Virus

Question 46

family Flaviviridae
arboviruses that infect the CNS
reservoir = birds and small mammals
vector = mosquito

asymptomatic infection (children)
flu-like syndrome
encephalitis-meningitis syndrome (adults)
acute flaccid paralysis/myelitis

prognosis worsens with age, those who recover have residual weakness

Dx: CSF IgM is more sensitive than PCR
Tx: supportive, no specific antiviral

Answer 46

North American Encephalitis Arboviruses

St. Louis Encephalitis

Question 47

clinical manifestation of West Nile Virus
Non-specific, influenza-like syndrome characterized by fever, headache fatigue, and myalgias
Neck pain and stiffness may be present but are not sue to meningitis – no elevated WBC on lumbar puncture
Rash in 25-50% - macropapular, present on trunk more than extremities
Usually recover within a week without permanent complication, fatigue may take longer to resolve
Rarely fatal although death due to cardiac arrhythmia or respiratory failure has been reported

Answer 47

West Nile Fever

Question 48

clinical manifestation of West Nile Virus

Meningitis
West Nile Fever symptoms plus severe headache, neck stiffness, photophobia
20% cranial nerve palsies
Mildly elevated WBC, paradoxical increase in neutrophils
CSF protein may be slightly elevated but CSF glucose is normal
Patients usually recover without permanent neurologic complications

Encephalitis
Approximately half of WNND
More likely in elderly and immunocompromised
Severe encephalitis resulting in hospitalization and permanent neurologic damage (movement disorders, tremors, weakness)
Fatality rate is 20% and death is often due to cardiac arrhythmias or respiratory failure

Flaccid paralysis
Least common manifestation, mimics poliomyelitis
Weakness is usually unilateral but can involve more than one limb
Half of cases also present with encephalitis
Permanent neurological damage is common
Prolonged period of recovery

Answer 48

West Nile Neuroinvasive Disease

Question 49

clinical manifestation of Dengue
Mainly in older children and adults
High fever plus two or more of the following: severe headache, retro-orbital pain, myalgias, arthralgias, diffuse erythematous maculopapular rash, mild hemorrhagic manifestations (petechiae, easy bruising, positive tourniquet sign
Plasma leakage from blood vessels and severe hemorrhage are usually absent
Patients usually recover without sequelae

Answer 49

Dengue Fever Syndrome

Question 50

clinical manifestation of Dengue

Dengue fever symptoms
hemorrhagic manifestations: petechiae, purpura, ecchymoses, gingival bleeding, nasal bleeding, GI bleeding, increased menstrual flow
thrombocytopenia
plasma leakage: hemoconcentration, pleural effusion, ascites, hypoproteinemia

mortality >20% if not recognized
development is due to pre-existing heterologous antibodies

Answer 50

Dengue Hemorrhagic Fever

Question 51

clinical manifestation of Dengue

Dengue Hemorrhagic Fever symptoms
circulatory failure: low BP, cold, clammy skin, narrow pulse pressure, hypoperfusion of organs

mortality >20% if not recognized

development is due to pre-existing heterologous antibodies

Answer 51

Dengue Shock Syndrome

Question 52

Emerging Coronavirus: enveloped, ssRNA virus

First case: China 2002; spread to 37 countries on 5 continents
Short lived epidemic, no new cases since 2003
Likely developed from horseshoe bat coronavirus, detected in a type of cat (civit) eaten in China

Virus binds angiotensin converting enzyme II on the surface of human cells

Transmission by respiratory droplet or fomites
Secondary transmission to healthcare workers was common and required quarantine

Early in infection (after 5 day incubation): fever, myalgias, chills, dry cough
CXR shows infiltrates in 60%
Recover or enter late stage infection

Late stage infection: persistent fever, worsening pneumonia, watery diarrhea
25% require ICU, intubation, assisted ventilation

Overall mortality 10% with worse outcomes in the elderly and those with comorbid conditions

Dx: Difficult to distinguish clinically from other viral pneumonias
RT-PCR on lower respiratory tract samples or stool
Tx: supportive, no specific antiviral
infection control is essential

Answer 52

Severe Acute Respiratory Syndrome (SARS)

Question 53

Emerging Coronavirus: enveloped, ssRNA virus

First case: Saudi Arabia 2012; spread throughout Arabian Peninsula, outbreak in S. Korea
Secondary transmission in healthcare workers
Source of virus remains, unclear but it may have come from camels or bats

Atypical pneumonia – fever, cough, dyspnea
GI symptoms; respiratory disease in those with comorbidities
45% mortality

Dx: RT-PCR to detect virus in nasopharyngeal aspirates, blood, feces
Tx: supportive

Answer 53

Middle East Respiratory Syndrome Coronavirus Infection (MERS-CoV)

Question 54

Emerging Filovirus; RNA virus
First described in 1976, outbreaks of hemorrhagic fever in Sudan and DRC
Zaire strain: Gabon, DRC, Congo-Brazzaville
Sudan strain: Sudan and Uganda
Suspected reservoir is the fruit bat
Transmission through direct contact with body fluids, entry through mucosal surfaces and breaks in the skin
Infectious at onset of fever, through late stages or immediate post-mortem period

Incubation 2-21 days, abrupt onset of fever, chills, malaise, and myalgias
Progresses to prostration, rash (maculopapular, desquamates in survivors), nausea/vomiting/diarrhea/abdominal pain, cough/SOB/chest pain, postural hypotension/edema, headache/confusion/coma
Hemorrhagic manifestations in

Answer 54

Ebola Virus

Question 55

Deltaretrovirus

infects T cells, endothelial cells, and fibroblasts

transmitted via cell associated virus - IVDU, contaminated blood products, sexual contact (more likely in women), breast milk

endemic in Japan and the Caribbean

associated with cellular transformation and oncogenesis
T cell lymphoma and myelopathy (tropical spastic paraparesis)

Answer 55

Human T Lymphocyte Virus 1

HTLV1

Question 56

virus family
large, enveloped dsDNA viruses

outer envelop, tegument, icosapentahedral nucleocapsid, internal core

viruses indistinguishable on EM, most do not exhibit homology

Answer 56

Herpesviridae

Question 57

HSV1, HSV2, VZV

site of latency = neuron

Answer 57

alpha herpesviruses

Question 58

CMV, HHV6, HHV7

site of latency = monocyte, lymphocyte

Answer 58

beta herpesviruses

Question 59

EBV, HHV8

site of latency = B lymphocytes

Answer 59

gamma herpesviruses

Question 60

fever, anorexia, malaise, headache, tender regional LAD, vesicular rash on genitalia
may have aseptic meningitis
inflammation of the sacral nerve may lead to urinary retention which is more commonly seen in females
lesions may take several weeks to heal and may be more severe in an immunocompromised host

Answer 60

HSV primary genital infection

Question 61

gingivostomatisis

generally seen in children

Answer 61

HSV primary oral infection

Question 62

no concurrent anti-HSV antibodies to HSV1 or HSV2

Answer 62

primary HSV

Question 63

evidence of prior exposure to the alternate type
HSV1 infection with HSV2 antibodies
HSV2 infection with HSV1 antibodies

Answer 63

non-primary HSV

Question 64

infection with the same type as seen in serum antibodies

Answer 64

recurrent HSV

Question 65

beginning of an HSV infection that does not fully develop due to preemptive or prophylactic treatment

Answer 65

Aborted lesions

Question 66

occurs more often with HSV2 infection

induced by stress, sunlight, local trauma, menstruation, fever

prodromal symptoms: pain, burnign, tingling, itching

stereotypes lesions
lesions are fewer in number, less severs with fewer systemic symptoms and more rapid healing

Answer 66

HSV recurrence

Question 67

most common with HSV1, except in infants (HSV2)

corneal scarring, frequent lid involvement, dendritic appearance
treated with topical antivirals

Answer 67

HSV Ketatitis/Conjunctivitis

Question 68

HSV infection with involvement of the nail bed , may resemble bacterial infection
HSV1 in medical personnel, HSV2 in the general population

fever, pain, axillary LAD, vesicular lesion at the nail margin

heals in 2-3 weeks but may be recurrent

Answer 68

Herpetic Whitlow

Question 69

more commonly seen with HSV2, also seen with HSV1

transmission from infected mother to baby at birth, especially when mother has active lesions, C-section is indicated

may cause seizures, blindness, psychomotor retardation, spasticity, developmental delay, and death

Answer 69

Neonatal HSV

Question 70

alpha-herpesvirus
childhood illness before vaccination
late winter/early spring, seen in temperate more than tropical climates
high household attack rate, person to person spread via respiratory route, may be transmitted days before rash

associated with some mortality, mostly in leukemic children and immunocompromised adults

fever, rash (begins on scalp or trunk and spreads to extremities)
superficial vesicles in different stages of development
“dew drop on a rose petal” appearance
vesicles on mucus membranes quickly become ulcers

diagnosis: clinical, Tzanck prep (multinucleated giant cells), tissue culture, direct immunofluorescence
complications: hepatitis, pneumonitis, encephalitis; super infection of cutaneous lesions (GAS, staph aureus), Reye’s syndrome (aspirin use), Guillan-Barre

Answer 70

Varicella-Zoster Virus

Question 71

incidence increases with age or immunosuppression
VZV latency in dorsal root ganglia
reemergence in dermatomal distribution (unilateral involving 1-3 dermatomes), 50% thoracic
prodromal pain

may have associated meningitis, dissemination to lung, liver, brain, post herpetic neuralgia

Answer 71

Herpes Zoster

Shingles

Question 72

gamma herpes virus
expression of specific viral proteins leads to cellular transformation

developing countries: childhood (early infection associated with Burkitt lymphoma)
developed countries: adolescence, early adulthood

intermittent virus excretion in oropharyngeal secretions in adults, especially immunocompromised

virus multiplies in pharyngeal lymphoid tissue and possibly oropharyngeal epithelial cells
dissemination throughout lymphoreticular system

causes tranformation of B cells, atypical CD8 T cells are seen

may be asymptomatic
infectious mononucleosis syndrome: sore throat, fever, tonsillar enlargement with exudate, palatal petechiae, cervical LAD, hepatomegaly, splenomegaly (caution - rutpure), rash to ampicillin

Diagnosis: atypical lymphocytosis, Thrombocytopenia, mild elevation of transaminase, monospot (heterophile Ab), specific virus Ab, PCR

complications: hemolytic anemia, thrombocytopenia, neurologic disease

no effective treatment, corticosteroids for hematologic and neurologic conditions

assoicated malignancies: Burkitt lymphoma, Hodgkin’s lymphoma, CNS lymphoma, lymphoproliferative syndromes, nasopharyngeal carcinoma

Answer 72

Epstein-Barr Virus

Question 73

beta herpesvirus
largest human virus, increases size of infected cells, prevents HLA1 molecules from reaching cell surface

transmitted by contact with saliva, urine, semen, contaminated blood products, vertical (intrapartum, at delivery, breast milk), day care setting

immunocompetent host: asymptomatic, mononucleosis, congenital

immunocompromised host: retinitis, pneumonitis, colitis, esophagitis, encephalitis, myelitis

diagnosis: cytoplasmic and nucler inclusions (owl eye inclusions = aggregates of CMV nucleoprotein cores), serology, PCR, culture

Answer 73

Cytomegalovirus

Question 74

primarily seen in HIV or transplant patients

necrotizing chorioretinitis (peripheral or central)
irregular sheathing of blood vessels, development of white granular lesions with hemorrhage
blurred vision, floaters

Answer 74

CMV retinitis

Question 75

most likely to occur with primary infection during pregnancy and intrapartum transmission

severe clinical manifestations involving multiple organ systems
jaundice, hepatosplenomegaly, petechial rash, microcephaly, motor disability, chorioretinitis, cerebral calcifications

Answer 75

Congenital CMV

Question 76

beta herpesvirus
infects multiple cell types (T cell, B cells, NK cells, epithelial cells, macrophages, glial cells
most people have been infected

more common in spring/fall, spread by contact with saliva

Roseola infantum, usually benign childhood illness
abrupt onset, high fever, suboccipital adenopathy, abrupt disappearance of fever and onset of macular rash
complications: usually self-limited and mild but can cause febrile seizures and rare encephalitis

mononucleosis-like illness in adults

diagnosis: serology
treatment is usually not indicated except in immunocompromised hosts

Answer 76

HHV6

Question 77

gamma herpesvirus
attaches to heparan sulfate and targets endothelial or spindle cells which may result in Kaposi’s sarcoma or B cells which may result in lymphoma

Kaposi’s sarcoma: vascular tumors usually associated with HIV
Castleman’s disease: focal or multicentric lymphoma

transmission via sexual contact

Answer 77

HHV8