Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

DD & BL Unit III / Final Exam > Common Viral Pathogens > Flashcards

Common Viral Pathogens Flashcards

1
Q

4 ways to diagnose a viral infection

A
  1. Look for virus grown in tissue culture - distinctive patterns of CPE can be recognized
  2. Assay for viral antigens using enzymatic reactions or immunofluorescence (i.e. rapid flu test)
  3. PCR - amplifies a portion of viral genome in body tissues
  4. Look for host immune response to viral infection - i.e. ELISA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Herpes - Basics + 8 Types

A

Herpes are ds-DNA viruses that come in 8 varieites:

HHV-1: Herpes Simplex 1 (HSV1)
HHV-2: Herpes Simplex 2 (HSV2) 
HHV-3: Varicella Zoster Virus (VZV)
HHV-4: Epstein Barr Virus (EBV) 
HHV-5: Cytomegalovirus (CMV) 
HHV-6
HHV-7
HHV-8: Kaposi's Sarcoma Virus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

HSV-1 / HSV-2 Primary infection

A

HSV-1 primary infection often occurs durig childhood and is usually asymptomatic; HSV-2 primary infection usually occurs as a result of sexual contact and is often asymptomatic

If symptomatic, painful vesicles usually develop 1-3 days after inoculation and are contained to the area of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Manifestations of HSV Infection (4)

A

Gingivostomatitis - painful mouth ulcers of lips, gums, tongue; i.e. “Cold Sores”

Herpetic whitlow - inoculation of virus from oral secretions onto fingers

Herpes gladitorum - inoculation of virus from oral secretions onto skin

Herpes keratitis - infection of cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Encephalitis

A

HSV is the most common cause of encephalitis in the US; HSV infection in the brain has a predilecton for the temporal lobe, often presenting as psychiatric illness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Neonatal HSV

A

Primary infection of the infant transmitted perinatally via exposure to maternal secretions containing HSV (active lesions or asymptomatic viral shedding)

Often infects the skin, eye, and CNS; may become disseminated, causing hepatitis, DIC

HSV-associated encephalitis in a newborn is associated with 30% mortality; 75% of survivors will have intellectual disability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Prevention & Treatment of neonatal HSV

A

Pregnant women with HSV are treated prophylactically with anti-virals; if active genital lesions are present at the time of delivery C-section is recommended

Skin vesicles in a neonate < 1 month old are assumed HSV until proven otherwise; treated with acyclovir

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

HSV Latency & Reactivation

A

Latency occurs in the sensory ganglia of the areas affected by the primary infection - trigeminal (orofacial infection) and sacral ganglion (genital infection) are most common

Reactivation is provoked by a variety of stress stimuli and may include asymptomatic shedding or symptomatic reactivation infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

HSV Treatment

A

Oral antiviral therapy - patients with active outbreaks often prevent too late for therapeutic benefit but may be given extra refills to start taking at first sign of next outbreak

IV Acyclovir - for severe infections such as neonatal herpes, encephalitis, or active HSV in immunocompromised hosts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Chickenpox Vaccine

A

Live, attenuated vaccine, consists of a 2 dose series at 12-15 months and 4-6 years; not recommended for immunocompromised patients

Varizig - VZV immune globulin given within 4 days of exposure can reduce severity of varicella in high risk individuals (passive immunization); consists of pooled antibodies from donors with high VZV titers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Shingles vaccine

A

Zostavax - one dose recommended for healthy individuals 60+; boosts T-cell immune response to VZV, preventing reactivation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

VZV Primary Infection

A

Chickenpox; highly contagious with incubation period of 10-21 days; disease begins with fever, malaise, headache, and progresses to itchy vesicular rash described as “dew drops on a rose petal”; lesions appear in successive waves and typical course lasts 7 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

VZV Secondary Infection

A

Shingles; VZV remains dormant in the cranial, dorsal root, or trigeminal ganglia; reactivation is always symptomatic

Occurs as a result of declining T-cell mediated immunity vs. latent VZV with age

Begins as pain at the site where vesicles will erupt; lesions develop over a single dermatome and usually subside within 2 weeks

Post-herpetic neuralgia (PHN) is the most common complication; pain may last weeks to months after lesions resolve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

VZV Pathogenesis

A

Virus gains entry through the respiratory tract then spreads to the lymphatic system; primary viral replication takes place in regional lymph nodes and is followed by primary viremia; secondary replication occurs in the liver, spleen, and other organs and spreads through secondary viremia to the skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

VZV treatment

A

Chickenpox is usually self-limited and requires no treatment; immunocompromised patients should receive anti-viral treatment

Shingles may be treated with Acyclovir within 48-72 hours of symptoms to decrease number and duration of lesions as well as pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

EBV Primary Infection

A

Transmitted via saliva - 95% of individuals are infected by 40 years

Primary infection in young children is often asymptomatic; primary infection in teens/adults causes infectious mononucleiosis in 40% characterized by fever, sore throat, lymphadenopathy, fatigue, exudative tonsillitis, and splenomegaly; symptoms resolve in 4-8 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

EBV Pathophysiology

A

EBV infects the nasopharyngeal epithelium, resulting in cell lysis and viral spread to adjacent oropharyngeal lymphoid tissue; viremia occurs with distribution to the liver, spleen, and B lymphocytes

EBV remains latent in nasopharyngeal epithelium and B cells; may contribute to some B cell cancers (Burkitt’s and Hodgkin Lymphoma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

EBV Diagnosis

A

Many patients display >10% atypical lymphocytes in peripheral blood smear

Monospot/heterophile test - detects presence of antibodies that agglutinate horse/sheep/cattle RBCs via cross-reaction with EBV

EBV serology - presence of IgM indicates recent infection (4-6 weeks); IgG indicates past infection

19
Q

CMV Epidemiology

A

Transmitted via infected body fluids (saliva, breast milk, sexual contact, blood, tears, urine) or from mother to fetus (in utero, perinatal)

40-80% of people in the US infected by 40 years old

20
Q

CMV Primary Infection

A

CMV infects the epithelia of the salivary gland or genital tract; primary infection in healthy persons is almsot always asymptomatic but may be serious in immunocompromised patients and cause retinitis, colinitis, etc.

21
Q

CMV Secondary Infection

A

CMV remains latent in monocytes and lymphocytes; reactivation infection is asymptomatic in normal patients but virus is being shed in bodily secretions

Reactivation may be serious in immunocomrpomised patients; often non-focal viral syndrome or organ-specific infection (hepatitis, pneumonitis, etc.)

22
Q

Diagnosis of CMV

A

Serology:

IgM alone is seen in primary CMV infection

IgG alone is seen in previous CMV infection

IgM and IgG together are seen in recent reactivation infection

Tissue histology - infected cells have “owel’s eye” appearance (densely staining body surrounded by a halo) due to intranuclear inclusion bodies (viral proteins or particles)

23
Q

CMV treatment

A

Gancyclovir

Passive immunization for pregnant women positive for CMV - pooled CMV antibodies

24
Q

Risk of CMV transmission during pregnancy

A

CMV is the most common in-utero infection in the US; risk of transmission is 3-5% for a mother with primary CMV and <1% for a mother with reactivated CMV

10-15% of infected infants will have symptoms at birth

25
Q

Congenital CMV Syndrome

A 
Low birth weight
Microcephaly
Hearing loss - leading cause of congenital hearing loss in the US 
Mental Impairment
Hepatosplenomegaly
Skin rash (blueberry muffin spots) 
Jaundice

Treated with oral valganciclovir or gancyclovir

26
Q

RSV Pathogenesis

A

RSV is an enveloped virus with a ssRNA genome transmitted by contact with respiratory droplets at mucus membranes; localized infection of respiratory tract with cell-cell transfer of virus leads to spread from upper to lower respiratory tract

2 important surface proteins:
G protein mediates viral attachment to host cells; F (fusion) protein mediates fusion of infected cells to neighboring cells to form syncytia, multi-nucleated giant cells

27
Q

RSV Primary Infection

A

Usually symptomatic and causes acute respiratory disease in patients of all ages: most often bronchiolitis (children < 1), viral pneumonia (children and the elderly) and URI (children and adults)

Most common cause of bronchiolitis and viral pneumonia in young children; almost all children infected at least once by 2 years

Infection more commonly leads to severe respiratory disease in premature infants <32 weeks

28
Q

RSV Reinfection

A

Presents in older children and adults as a severe cold / URI

29
Q

RSV Diagnosis & Treatment

A

Diagnosis is usually clinical; rapid test exists but is not very sensitive (false negatives are common)

Treatment is mostly supportive - some children may benefit from a bronchodilator; Ribavirin can be used in high risk patients

30
Q

Rotavirus - Epidemiology

A

Leading single cause of severe diarrhea and gastroenteritis in infants and young children worldwide

31
Q

Rotavirus - Disease

A

Transmitted via the oral-fecal route with low infectious dose (10-100 particles)

Disease course lasts 3-8 days and is characterized by vomiting, watery diarrhea, fever, and abdominal pain

32
Q

Rotavirus Pathogenesis

A

dsRNA virus with a segmented genome; allows for reassortment and generation of multiple serotypes / strains

Rotavirus infects mature absorptive epithelial cells or enterocytes located at the tip of villi in the proximal 2/3 of the ileum; cell death leads to reduced absorptive surface area of small intestine, loss of enzymes that break down complex sugars, increased fluid and osmotic load in gut, and severe diarrhea

33
Q

Rotavirus - Prevention, Diagnosis, Treatment

A

2 oral, live-attenuated vaccines available for use in infants

Diagnosis - ELISA on stool sample

Treatment - supportive, with attention to fluids

34
Q

Influenza Structure

A

RNA virus with a segmented genome; made up of 8 different pieces of ss-RNA which encode different viral proteins; core is surrounded by a lipid envelope with a lining of matrix protein (M protein) on the inner side and cell surface proteins on the outside, including:

Hemagluttinin (H)
Neuraminidase (N)

35
Q

Type A Influenza

A

Infects horses, seals, swine, birds, humans; causes pandemics and epidemics of potentially severe illness

Nomenclature:
Virus Type / Geographic origin / Strain/ Year of Isolation / Virus Subtype

36
Q

Type B Influenza

A

Only infects humans, causing less severe disease; does not cause pandemics

From 1 of 2 lineages (Victoria or Yamagata); different strains exist

Nomenclature:
Virus Type / Geographic origin / Strain / Year of Isolation / Lineage

37
Q

Pathophysiology of Influenza

A

Transmitted by respiratory droplets and small particle aerosols that make contact with host mucous membranes; transmission may also occur via contact with infected fomites

Incubation period is 1-3 days

38
Q

Signs and Symptoms of influenza

A

Neonates: Lethargy, decreased eating, mottling, apnea

Infants and tolddlers: Nausea, vomiting, diarrhea, fever, anorexia, various respiratory syndromes (croup, bronchiolitis, etc.)

Older children and adults: Acute onset of fever, chills, myalgias, headache, and cough

39
Q

Matrix Protein Inhibitors

A

Effective for susceptible type A viruses

Ex: Amantadine, Rimantadine

40
Q

Neuraminidase Inhibitors

A

Effective for susceptible both type A and B viruses

Ex: Osteltamivir (Tamiflu), Zanamivir (Relenza)

41
Q

Pandemic H1N1

A

i.e. “Swine Flu,” or A/California/7/2009 (H1N1)-like virus; first detected human cases occurred in Mexico; rate of infection was highest among children and young adults 65, likely due to pre-existing immunity against an antigenically similar strain that circulated prior to 1957

42
Q

Inactivated Influenza Vaccine (TIIV)

A

Injectable, killed virus approved for all individuals 6 months and older, including pregnat and immunocompromised

Trivalent (2A and 1B strains) widely available

Available in standard dose and high dose (for adults >65)

Typically 50-70% effective among healthy persons <65 in well-matched years; 30-40% effective among elderly

43
Q

Live attenuated influenza vaccine (LAIV)

A

i.e. FluMist

Delivered intranasally via a fine mist applicator; approved for healthy persons 2 - 49 years old except for pregnant and/or immunocompromised

Quadrivalent (2A + 2B) formulation recently approved

DD & BL Unit III / Final Exam (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions