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Compendium Microbiology > Virology > Flashcards

Virology Flashcards

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1
Q

How to identify viruses with viral culture method

A
  • morphology of cytopathic effect
  • types of cells demonstrating CPE
  • time from inoculation to detection of CPE
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2
Q

Shell vial technique

A
  • Shell vials contain a monolayer of cells on a circular cover slip at the base of a vial; specimen is inoculated into the vial and infection of the cells is enhanced by low speed centrifugation
  • <3 days the coverslip is removed and stained with antiviral antibody tagged with fluorescent dye
  • cytopathic effect is not used in diagnosis
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3
Q

non-culture methods for identifying viruses

A
  1. serology (detection of circulating Ab)
    • paired sera taken 7-10 days apart showing a 4x increase in IgG titer is considered diagnostic of infection
    • IgM means infection is current
  2. ELISA
  3. DFA
  4. Histology with IHC or EM
  5. Molecular
    • ISH for HPV in cervix, CMV in lung, HSV in skin, parvovirus B19 in marrow
    • quantitative PCR monitoring of HIV and HCV
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4
Q

HSV inclusions

A

Nuclear

Syncytia

molded nuclei
marginalized chromatin

cowdry type A bodes in multinucleated cells

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5
Q

Adenovirus inclusions

A

smudge cells (nuclear)

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6
Q

CMV inclusions

A

nuclear and cytoplasmic

owl eye, not multinucleated

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7
Q

Measles inclusions

A

Nuclear, cytoplasmic, syncytial

warthin-finkeldey giant cells

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8
Q

rabies inclusions

A

cytoplasmic

negri bodies

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9
Q

Enteroviruses

  • CPE
  • time to CPE
A
  • angular, tear shaped, focal swollen or glassy cells
  • 1-7 days
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10
Q

Rhinovirus

  • CPE
  • time to CPE
A
  • focal granular and swollen cells
  • 2-5 days
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11
Q

Influenza, mumps, and parainfluenza

  • CPE
  • time to CPE
A
  • none or focally enlarged and granular cells; parainfluenza may have focal multinucleated giant cells
  • if minimal to no CPE, confirm with hemadsorption/hemagglutination
  • 3-10 days
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12
Q

Adenovirus

  • CPE
  • time to CPE
A

grapelike clusters on Hep2 cells, which are derived from the upper respiratory tract

2-7 days

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13
Q

RSV

  • CPE
  • time to CPE
A
  • syncytia in Hep2 cells
  • 14 days
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14
Q

VZV

  • CPE
  • time to CPE
A
  • Focal shrunken or enlarged cells, advancing in a slow contiguous manner; grows poorly in culture
  • 14 days
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15
Q

CMV

  • CPE
  • time to CPE
A

slow, focal clusters of CPE (plaques) on HDF only

14 days

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16
Q

HSV 1 and 2

  • CPE
  • time to CPE
A

Shrunken or enlarged cells starting at edge of the cell sheet, sweeping CPE, occasional giant cells

rapid (1-3 days)

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17
Q

Nonenveloped single stranded DNA viruses

A

Parvoviridae

Bocavirus

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18
Q

Nonenveloped double stranded DNA

A

Adenoviridae

Papillomaviridae

Polyomaviridae

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19
Q

Nonenveloped single stranded RNA viruses

A

Picornaviridae (poliovirus, enterovirus, hepatitis A, rhinovirus)

Caliciviridae (norovirus)

Hepeviridae (hepatitis E)

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20
Q

Nonenveloped double stranded RNA viruses

A

Reoviridae: rotavirus

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21
Q

Enveloped double stranded DNA viruses

A

Herpesviridae

Hepadnaviridae (HBV)

Poxviridae

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22
Q

Enveloped single stranded RNA viruses

A
  1. Flaviviridae
    • HCV
    • yellow fever
    • dengue
    • WNV
    • St Louis and Japanese encephalitis
  2. Togaviridae
    • rubella
    • EEE
    • WEE
  3. Retroviridae
    • HIV
    • HTLV
  4. Orthomyxoviridae (influenza)
  5. Paramyxoviridae
    • RSV
    • hMPV
    • parainfluenza
    • mumps
    • measles
  6. Rhabdoviridae (rabies)
  7. Coronaviridae
  8. Arenaviridae
  9. Bunyaviridae
    • Hantavirus
    • California encephalitis
  10. Deltavirus (hepatitis D)
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23
Q

HSV type 1

  • clinical
  • transmission
  • dormant in
A
  • Gingivostomatitis, pharyngitis, keratoconjunctiviits, herpes labialis, skin infection (herpetic whitlow), and encephalitis
  • immunocompromised can get pneumonia, tracheobronchitis, hepatitis, herpetic esophagitis
  • Saliva (primary infection before puberty)
  • Latent in trigeminal ganglia
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24
Q

HSV type 2

  • clinical
  • dormancy
A
  • genital herpes, skin infections, herpes meningitis (not encephalitis), congenital herpes (less common than neonatal herpes), neonatal herpes
  • dormant in sacral ganglia
  • C/S recommended for pregnant women with active genital herpes
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25
Q

herpes diagnosis

A
  1. cell culture - CPE within 2-3 days
  2. PCR
  3. Tzanck smear: Giemsa stained direct smear of lesional material
  4. Histology
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26
Q

Clinical syndromes caused by EBV (primary or secondary?)

A
  1. Infectious mononucleolosis - primary
  2. X linked lymphoproliferative disease (Duncan disease) - primary (get B cell lymphoma, mono, aplastic anemia, infections, etc.)
  3. Burkitt lymphoma - latent (100% of endemic, 25% of sporadic and immunodeficiency forms)
  4. Hodgkin lymphoma - latent
  5. PEL - latent (also have HHV-8)
  6. Lymphomatoid granulomatosis - latent
  7. PTLD - latent
  8. Oral hairy leukoplakia - latent
  9. Nasopharyngeal carcinoma - latent (100% in Chinese and 75% in US)
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27
Q

Congenital VZV

  • diagnosis
  • incidence and severity depends on
A

Diagnosis

  • evidence of maternal infection during pregnancy
  • skin lesions on newborn in dermatomal distribution
  • serologic evidence of infection in the newborn (either IgM or persistent IgG beyond 7 months)
  • Insulin degrading enzyme is the receptor for VZV

Severity/Incidence

  • lowest when maternal infection occurs in the 1st trimester
  • higher in the 2nd and highest in the third trimester within days of delivery
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28
Q
A

neonatal VZV pneumonitis, showing multinucleated cells

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29
Q
A
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30
Q
A

a, b: CMV placentitis

c, d: CMV colitis (Cowdry type A inclusions)

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31
Q
A

HSV infection

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32
Q

Ramsey Hunt Syndrome

A

Reactivation of VZV from the geniculate ganglion of the facial nerve:

  • otalgia
  • unilateral facial paresis
  • vertigo
  • hearing loss
  • tinnitus
  • rash
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33
Q

HSV-1

  • latency
  • acute disease
  • reactivation disease
A

Latency

Dorsal root ganglia

Acute disease

  1. acute gingivostomatitis
  2. pharyngitis
  3. skin infection (herpetic whitlow)
  4. genital herpes (less common)

Reactivation

  1. herpes labialis
  2. herpes encephalitis
  3. less likely to cause recurrent genital herpes lesions than HSV2
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34
Q

HSV-2

  • latency
  • acute disease
  • reactivation disease
A

Latency:

Dorsal root ganglia

Acute disease:

  1. genital herpes
  2. herpetic whitlow
  3. acute gingivostomatitis

Reactivation

  1. genital herpes
  2. herpes meningitis
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35
Q

CMV

  • latency
  • acute disease
  • reactivation disease
A

Latency:

  1. Histiocytes
  2. Endothelial cells
  3. T cells

Acute disease

  1. Mono
  2. disseminated infection in neonates and immunocompromised

Reactivated disease: disseminated infection

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36
Q

VZV

  • latency
  • acute disease
  • reactivation disease
A

Latency:

Dorsal root ganglia

Acute disease: chicken pox

Reactivated disease: shingles

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37
Q

EBV

  • latency
  • diagnosis
  • acute disease
  • reactivation disease
A

Latency: B cells

Diagnosis:

  • not routinely cultured
  • serology used (like arboviruses)
  • similarly rota and rhabdoviruses are not cultured, but are diagnosed with antigen detection

Acute disease:

  1. infectious mono (primary)
  2. X linked lymphoproliferative disease (Duncan disease) (primary)

Reactivated disease:

  1. Burkitt lymphoma
  2. Hodgkin lymphoma
  3. PEL
  4. lymphomatoid granulomatosis
  5. PTLD
  6. Oral hairy leukoplakia
  7. Nasopharyngeal carcinoma
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38
Q

HHV-6

  • latency
  • acute disease
  • reactivation disease
A

Latent: T cells

Acute disease: roseola (exanthem subitum); childhood febrile seizures

Reactivated in immunocompromised hosts (1/2 of BMT and 1/3 solid organ recipients); highly neurotropic (viral encephalitis)

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39
Q

HHV-7

  • latency
  • acute disease
  • reactivation disease
A

Latency: lymphocytes

Acute disease: roseola

Reactivated disease in immunocompromised hosts

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40
Q

HHV-8

  • latency
  • acute disease
  • reactivation disease
A

Latency: B cells and endothelial cells

No known acute disease

Reactivation disease:

  1. Kaposi sarcoma
  2. Primary body cavity lymphoma
  3. PEL
  4. multicentric Castleman disease in HIV+ patients
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41
Q

Primary CMV infection

A
  • asymptomatic or mono
  • immunocompromised: pneumonia, hepatitis, retinitis, disseminated
  • neonatal CMV:
    1. microcephaly
    2. low birth weight
    3. intracerebral calcs
    4. HSM
    5. jaundice
    6. chorioretinitis
    7. thrombocytopenia
    8. petechial rash
    9. purpura
    10. sensorineural hearing loss
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42
Q

CMV colitis

A

Immunosuppressed patients

IBD exacerbation

43
Q

CMV diagnosis

A
  1. serology - positive IgM or 4x rise in IgG
  2. pp65 antigenemia on DFA of peripheral blood leukocytes
  3. PCR on any tissue
  4. histology
  5. culture - up to 2 weeks for CPE
44
Q

EBV

  • how does primary infection occur?
  • labs
  • how does EBV genome persist?
A
  • Primary infection occurs at pharyngeal or genital mucosa sites by infecting B cells via the C3d receptor (CD21)
  • CD8+ T cells proliferate and are responsible for the peripheral blood atypical lymphocytosis
  • LFTs often elevated
  • EBV genome persists in episomal form
45
Q

Duncan disease

A

X linked immunoproliferative disease

  • fulminant primary EBV infection that is often fatal
  • males
  • mechanism of death: hepatic necrosis, hemophagocytosis, agammaglobulinemia, B cell lymphoma
  • defect in the SH2D1A gene
  • uncontrolled activation of T/NK cells following EBV infection
46
Q

EBV serology

A

Heterophile antibodies:

  • positive in acute disease
  • monospot test detects antibody with affinity for beef RBC that is uninhibited by adsorption with guinea pig kidney antigen (the differential absorption test)
  • monospot is specific but insensitive (less positives in young children)

IgM anti VCA

  • positive in acute infection (1-2 months)

IgG anti EA

  • positive in acute, convalescent and remote infection

IgG anti VCAgG

  • positive in early acute through remote stages

Anti EBNA

  • positive in acute through remote

order of appearance:

IgM-VCA, heterophile and IgG VCA, EA, EBNA

47
Q

EBV stains

A
  • EBER ISH: RNA produced by EBV detected (HL RS cells)
  • ISH with BamHIW sequence of EBV DNA
  • IHC for LMP1

The above two perform almost as well as EBER

48
Q

Diagnosis of HHV-8

A
  • Molecular methods (FISH or PCR)
  • IHC (LANA1 expression in a speckled nuclear pattern)
  • Serology (IFA, ELISA, or Western blot)
49
Q

Adenovirus

  • clinical features
  • diagnosis
A

Clinical Features

  • respiratory infections caused by serotypes 1-14 and 21
  • Types 11 and 21 are associated with hemorrhagic cystitis
  • Types 40 and 41 are seen in childhood gastroenteritis

Diagnosis

  • Serology
  • Direct antigen detection
  • PCR
  • Culture: CPE in 1-7 days (grapelike clusters)
  • Histology (basophilic nuclear inclusions)
50
Q

Parvovirus B19 (genus erythrovirus)

A
  • P antigen is the target (associated with Donath-Landersteiner ab, PCH, neutralized pigeon egg and hydatid cyst fluid)
  • Erythema infectiosum (slapped cheek disease; fifth disease)
  • Aplastic anemia
    • primary maternal infection during gestation can lead to hydrops fetalis
    • infection in persons with chronic hemolytic anemia (e.g., sickle cell)
    • smudgy nuclear inclusions in bone marrow biopsies
    • IHC, FISH, or PCR
    • don’t culture this because it requires nucleated RBCs
51
Q

human bocavirus

A

respiratory virus that is detectable only by PCR

52
Q

JC and BK virus

  • virus category
  • latency
  • reactivation disease
A
  • papovaviridae
  • acquired in childhood
  • latent in epithelia of UG tract and lymphocytes
  • Reactivated in immunosuppressed:
    • JC virus
      • PML in oligodendroglia - demyelinating
      • AIDS patients
      • smudgy nuclear inclusions
    • BK virus
      • hemorrhagic cystitis and/or polyomavirus nephropathy
      • usually in transplant patients
      • smudgy nuclear inclusions in urothelial cells: decoy cells
53
Q

Merkel cell polyomavirus (MCPyV)

  • virus category
  • latency
A
  • papovaviridae
  • associated with Merkel cell carcinoma and CLL
  • clonally integrated and mutated MCPyV DNA in 80% of MCC
  • mutated in 15% of normal skin but not integrated
54
Q

HPV

  • virus type
  • latency
A
  • papovaviridae
  • episomal in benign lesions and integrated into host DNA in malignant lesions
  • viral E6 and E7 genes are needed for oncogenesis
55
Q

HPV lesions

A
  • Epidermodysplasia verruciformis - AR
    • first decade
    • lesions may undergo malignant transformation to SCC
    • similar syndrome in organ transplant patients
  • Recurrent respiratory papillomatosis (RRP)
    • 6 and 11
    • 2 types:
      • juvenile onset acquired through birth canal
      • adult form sexually transmitted
    • true vocal cords
    • 2-4 yo usually (can also present in adults)
  • Anogenital HPV
    • benign: 6 and 11
    • Bowenoid: 16 and 18
    • SCC: 16 and 18
    • Verrucous carcinoma (aka giant condyloma of Buschke and Lowenstein): 6 and 11
  • Head and neck SCC -
    • HPV positive gives good px especially in oropharynx
    • stain with p16 IHC
56
Q

HPV types associated with

  1. plantar wart
  2. common wart
  3. flat (juvenile) wart
  4. oral focal epithelial hyperplasia
  5. epidermodysplasia verruciformis
  6. HSIL
  7. cervical AIS
A
  1. 1, 2
  2. 2, 1, 4 (HPV 7 in fish and meat handlers)
  3. 3, 10
  4. 13, 32
  5. 2, 3, 10, 5, 8
  6. 16, 18, 31, 33, 35
  7. 18, 16, 45
57
Q

Poxviridae

list viruses and disease

A
  1. variola
    • smallpox
    • bioterrorism
  2. vaccinia
    • derived from variola used in small pox vaccine
  3. molluscum contagiosum
58
Q

Category A bioterrorism agents

A
  1. variola
  2. Hemorrhagic fever viruses
  3. B anthracis
  4. yersinia pestis
  5. C botulinum
  6. F tularensis
59
Q

Category B bioterrorism agents

A
  1. Encephalitis viruses
  2. Brucella
  3. Burkholderia mallei (glanders)
  4. C psittaci
  5. Burkholderia pseudomallei (meliodosis)
  6. Coxiella burnetii
  7. C perfringens
  8. Foodborne bacteria ( E coli, shigella, salmonella)
  9. waterborne bacteria (Vibrio, cryptosporidium, rickettsia prowazeckii (typhus), staph aureus enterotoxin B)
60
Q

Category C bioterrosim agents

A
  1. Influenza
  2. Nipah
  3. Hantavirus
  4. Rabies
  5. Yellow fever
  6. Drug resistant TB
  7. Rickettsia conorii
61
Q

Hepatitis A

  • virus type
  • transmission
  • disease
  • diagnosis
A
  • RNA picornavirus family
  • fecal oral
  • acute disease only: children
  • Relapse can occur within 5 months
  • Dx: IgM anti HAV
  • IgG persists for life
62
Q

HBV

  • virus family
  • important hep B markers
A
  • DNA virus; intact particle = Dane particle
  • Viral markers begin to emerge between 2-10 weeks after exposure
    • HBsAg - indicates active disease (acute infection or chronic carrier state)
    • HBeAg - chronic carriage with active viral replication
    • anti HBc - present in anyone who has been infected (IgM and IgG present in resolved HBV)
    • anti HBe - found when HBeAg becomes negative; does not imply resolved infection or immunity; indicates chronic carrier without active viral replication
    • HBsAb - resistance to infection (immunized or successfully cleared infection)
63
Q

Order of presentation of HBV markers

A

HBV DNA, HBs antigen, HBe antigen, IgM c antibody, anti-HBe, anti-HBs

(anti-HBc and anti-HBs occur with symptom onset)

(majority of patients clear infection heralded by anti HBs and anti HBe)

64
Q

Chronic HBV

  • define
  • occurs in what patients
  • associations
A
  • Definition: HBsAg > 6months; if this occurs without symptoms then the person is a “chronic carrier”
  • Chronicity occurs in
    • 5% of healthy adults
    • 10% of IC
    • 90% of neonates infected transplacentally
  • Chronic HBs antigenemia can be associated wtih PAN
65
Q

HBeAg negative chronic hepatitis B

A
  • tendency toward fulminant hepatitis with liver failure
  • mutations in the C or pre C region of the HBV genome impairing e synthesis
66
Q

Applications of molecular assays in HBV

A
  1. making initial diagnosis of HBV
  2. Replicative vs nonreplicative chronic HBV: (> 105 copies DNA/ ml) are replicative)
  3. response to therapy: undetectable HBV DNA is considered a virologic response
67
Q

HCV

  • clinical
  • chronicity
  • extrahepatic manifestations
  • diagnosis
  • monitoring
A

(Flavivirus family)

  • most common cause of transfusion associated viral hepatitis
  • 60% of those infected develop chronic HCV
  • 15% with chronic disease become cirrhotic
  • 5% of those with cirrhosis develop HCC
  • Extraheptic manifestations
    • mixed cryoglobulinemia
    • glomerulonephritis
    • aplastic anemia
  • Diagnosis
    • EIA
    • RNA - positive earlier than other methods; <3 months)
    • RIBA - recombinant immunoblot assay; positive in cleared infections
  • Sustained virologic response: undetectable RNA for 24 weeks after treatment ends
68
Q

HCV genotyping

A

Molecular or serologic assays

  • US: most common is genotype 1
  • Genotype 1 divided into 1a and 1b (mostly 1a)
  • 1a more likely to develop resistance to treatment
69
Q

HEV

A

RNA virus

fecal oral

chronic infection is rare

15-35 yo

more virulent in pregnant women with 30% mortality

70
Q

Hepatitis G virus

A

RNA virus in Flaviviridae family

parenteral transmission

chronic infection common

not shown to cause clinical hepatitis

71
Q

Viruses causing hepatitis (aside form HCV, HBV, HAV, HEV)

A
  1. EBV
  2. CMV
  3. HSV
  4. VZV
  5. yellow fever
72
Q

Orthomyxovirus

  • types
  • time of year
  • changes in virus
  • morbidity results from
A
  • influenza A more common than B and more serious
  • cold weather outbreaks
  • antigenic changes
    • Drift (minor): point mutations in H and N genes; produces annual outbreaks and epidemics
    • Shift (major): genetic reassortment betwen strains (q10-20 years pandemics)
  • morbidity
    • pneumonia
    • secondary bacterial pneumonia
    • Reye syndrome
    • myositis
    • myocarditis
    • Guillain-Barre syndrome
73
Q

Orthomyxovirus

  • surface antigens
A
  • H - binds sialic acid containing receptors on respiratory mucosa and becomes expressed on infected cells (basis for hemadsorption test)
  • Neuraminidase (N)
74
Q

Hemadsorption positive viruses

A

influenza A and B

parainfluenza

mumps

75
Q

Orthomyxovirus diagnosis

A
  • specimens: throat and nasopharyngeal swabs, BAL
  • Culture gold standard (being replaced by PCR) confirms dx by
    • CPE
    • hemadsorption
    • IF
    • EIA
  • Rapid antigen tests (e.g., DFA) is 50-80% sensitive, but very specific
  • Nucleic acid detection (NAT) - detects RNA by PCR
    • very S and S
    • allows for determination of subtype and strain
  • Serology - most common is hemagglutination inhibition; allows for determination of subtype and strain
76
Q

parainfluenza dx

A
  1. cell cultures (detection by hemabsorption/hemagglutination)
  2. antigen detection (IF)
  3. PCR
77
Q

Measles

  • rash
  • complications
  • atypical measles
  • incubation period of SSPE
A
  • descending rash starting on head
  • otitis media > pneumonia, myocarditis
  • atypical measles:
    • teenage patients who have gotten only 1 vaccine
  • SSPE - incubates for 7 years
78
Q

Mumps virus

  • clinical
  • dx
A
  • parotitis +/- meningoencephalitis, orchitis, myocarditis, or pancreatitis
  • DX: culture, NAT, serology
79
Q

RSV

  • clinical
  • attack rate
  • immunity
  • dx
A
  • most common cause of lower RTI (pneumonia and respiratory bronchiolitis) in infants and toddlers
  • outbreaks have 100% attack rate
  • immunity is short-lived and recurrence throughout childhood is the rule, but infections become less severe
  • DX: DFA, EIA, culture, PCR
80
Q

human metapneumovirus dx

A

PCR

81
Q

Enteroviruses

A
  1. poliovirus - destruction of spinal ventral horn motor neurons
  2. coxsackie A - herpangina, hand foot mouth disease (diagnose by seeing flaccid paralysis in suckling mice)
  3. coxsackie B - epidemic pleurodynia (the grippe), myocarditis, and pericarditis
  4. Enterovirus - most common cause of viral meningitis
82
Q

Rhinovirus

A

(picornavirus)

  • common cold
  • culture requires incubation at 32 degrees, but PCR preferred
83
Q

Bunyaviridae viruses

A
  1. hantavirus - aerosolized rodent excreta, pulmonary syndrome
  2. bunyavirus - e.g., California encephalitis
  3. nairovirus - e.g., Crimean Congo hemorrhagic fever
  4. phlebovirus - rift valley fever virus
84
Q

Togaviridae

A
  1. rubella
  2. alphavirus (equine encephalitis)
  3. flavivirus (HCV, dengue, yellow, St. Louis encephalitis, WNV)
85
Q

Rubella

  • transmission
  • clinical

infection according to trimester

A
  • person to person
  • febrile illness with rash
  • Fetal infections:
    • first trimester: most serious (sensorineural deafness, cataracts, glaucoma, microphthalmia, PDA, IUGR, microcephaly)
    • should test IgG titer in women before pregnancy
    • booster vaccination recommended in nonimmune women of childbearing age
86
Q

Flaviviruses

A
  1. HCV
  2. dengue fever (breakbone fever) and yellow fever - transmitted by Aedes mosquitos and cause fever, chills, backache, jaundice, hemorrhage
  3. yellow fever is viscerotropic for heart, kidney, GIT, liver (latter has midzonal necrosis, councilman bodies, microvesicular steatosis, no inflammation)
  4. St louis encephalitis
  5. WNV - bird - mosquito (culex) - bird cycle with humans as incidental host
87
Q

Rabies

  • how does it infect?
  • histologic findings
A
  • enters axon terminus of nerve cells at neuromuscular junction
  • transported via retrograde fast axonal transport to CNS
  • damages CNS and travels to periphery along autonomic and sensory neurons where it enters salivary gland, hair follicles
  • Negri bodies in Purkinje cells of cerebellum and hippocampus and Babes (microglial) nodules
88
Q

Family arenaviridae

A
  1. lassa fever virus
  2. machupo virus
  3. lymphocytic choriomeningitis (LCM) virus

Only LCM is in the US

virus particles contain host cell ribosomes, giving them a granular appearance

parasite of rodents that shed virus in their urine and feces - hamsters and house mice are hosts to LCM virus

89
Q

HTLV1

  • geography
  • transmission
  • dx
  • clinical diseases
A
  • Japan, Caribbean, southern Africa, Brazil
  • Transmission: parenteral (IV drugs, transfusion, sexual) and transplacental
  • Infects CD4 T cells
  • Dx similar to HIV: screening ELISA, confirmatory western blot or PCR
  • Acute infections usually asymptomatic
  • After incubation may have late sequelae:
    • Tropical spastic paraperesis (HTLV1 associated myelopathy)
      • women: men = 3:1
      • short incubation
      • demyelinating lesions within upper thoracic and lower cervical cord
    • Adult T cell leukemia/lymphoma
      • incubates 20-30 years
      • 5% risk in people infected before age 20
      • HSM, jaundice, weight loss
      • hypercalcemia
      • skin rash
      • increased IL-2 receptor
      • very thirsty
90
Q

Opt- out screening for HIV is offered to:

A
  1. 13-64 yo,
  2. new dx of TB, and
  3. seeking treatment for STD
91
Q

Repeat HIV screening offered annually to:

A
  1. IVDU and sexual partners of IVDU
  2. sex workers
  3. MSM
  4. heterosexual people who themselves or whose sex partners have had >1 sex partner since their most recent HIV test
92
Q

Diagnostic HIV testing offered to:

consent?

A
  1. patients with signs or symptoms of HIV
  2. when acute phase of infection is considered both HIV RNA test and HIV antibody test are offered
  3. patients with an opportunistic illness charactersistic of AIDs

written consent not required (but verbal consent is)

93
Q

HIV testing in pregnancy

A
  • CDC recommends screening all women prior to conception or early in pregnancy
  • CDC urges repeat testing in 3rd trimester for all pregnant women for following groups:
    • women in states with elevated incidence of HIV/AIDS if ages 15-45
    • women treated in facilities that identify at least 1 HIV infected pregnant woman per 1,000 women
    • women who are known to be at risk for HIV
    • women who have signs or symptoms of acute HIV
    • women who present in labor with unknown HIV status or deliver before status is known should undergo opt-out screening with a rapid HIV test (newborn should get rapid testing so that treatment can be started within 12 hours)
94
Q

HIV lab tests for diagnosis

A
  1. ELISA - test for anti HIV1/2 antibodies to recombinant antigens and peptides is principle screening method
    • detectable within 6-8 weeks of infection
    • p24 protein directly detectable by 2-3 weeks
  2. Western blot is used for confirmatory testing
  3. Detection of proviral DNA can confirm diagnosis - highly S and S (but low by HIV standards); cDNA integrated into host cell genome
95
Q

HIV western blot

  • how it works
  • define positive test
  • define negative test
  • define indeterminate test, what to do then
A
  • sample with known HIV proteins undergoes gel electrophoresis
  • gel is transferred onto nitrocellulose paper to which patient serum is added, then stained
  • Positive HIV1: presence of any 2 of the following bands:
    • p24
    • gp41
    • gp120/160
  • If no bands are present: negative
  • Indeterminate: if one or more bands present but not in combination that meets criteria for positivity; repeat test within 6 months
  • If repeated test within 6 months has another indeterminate test with no risk factors, then considered negative, otherwise do nucleic acid test
96
Q

CD4 count in HIV

A
  • undergoes diurnal variation
  • age dependent
  • counts monitored every 6 months
  • used in making treatment decisions
97
Q

quantification of HIV RNA (viral load)

A
  • correlation with 10 year outcome better than CD4 count, but inferior to 6 month outcome
  • expressed in log units
  • change of 0.5 log is considered significant
  • increase may occur transiently after immunization
  • primary variable used to determine response to HAART
  • 100% sensitivity, but false positives do occur
98
Q

recommended test for neonatal dx of HIV

A

PCR testing for HIV proviral DNA, but HIV RNA may be equally good

99
Q

Barnes HIV diagnosis (non-neonatal)

A

Screening:

4th generation assay detects IgM and IgG antibodies to HIV1/2 & p24 protein

Confirmation and differentiation:

2nd generation discriminatory test differentates HIV-1 from HIV-2 (Bio-Rad Multispot immunoassay)

100
Q
A

Negri body

101
Q
A
102
Q
A
103
Q
A

Compendium Microbiology (15 decks)

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