Common Viral Diseases Flashcards
What part of viruses are the complete infective particle and do not grow?
virons
WHat are small circular RNA molecules with a rod like secondary structure that possess no capsid or envelope?
Viroids
A virus particle, also known as a virion, is made of what?
2
nucleic acid (DNA or RNA) enclosed in a protein shell or coat.
How big are viruses?
15 - 25 nanometers in diameter
The type of genetic material found in a particular virus depends on the nature and function of the specific virus.
For example, double-stranded DNA viruses typically must enter the host cell’s what before it can replicate?
Where does RNA viruses replicate?
nucleus
host cell’s cytoplasm
What is a capsomere?
Whats the funciton of a capsid?
protein units that compose the capsid of a virus
Function to protect the viral genetic material from damage.
In addition to the protein coat, some viruses have specialized structures. What is special about the flu virus?
The flu virus has a membrane-like envelope around it’s capsid.
The envelope has both host cell and viral components and assists the virus in infecting its host
The basic process of viral infection and virus replication occurs in 6 main steps. What are these steps?
- Adsorption - virus binds to the host cell.
- Penetration - virus injects its genome into host cell.
- Viral Genome Replication - viral genome replicates using the host’s cellular machinery.
- Assembly - viral components and enzymes are produced and begin to assemble.
- Maturation - viral components assemble and viruses fully develop.
- Release - newly produced viruses are expelled from the host cell.
The key components of current classification systems are?
3
- Type of symmetry of the virus capsid (helical versus icosahedral)
- Presence or absence of a lipid envelope
- Type and structure of the viral nucleic acid and the strategy used in its replication
Why does the HA and NA make the flu virus so virulent?
These protein subunits can swap back and forth and become resistant to the vaccine that has been made
Class I viruses are what kind of viruses?
What are the viruses in this class?
4
- double stranded DNA
- Papovavirus
- Adenovirus
- Herpesvirus
- Poxvirus
What are 2 examples of papovaviruses?
Examples of adenoviruses?
Examples of the herpesvirus?4
Examples of the poxvirus?
- warts, cervical cancer
- respiratory diseases
- (cold sores, genital herpes, chicken pox, mononucleosis)
- (smallpox, cowpox)
Class II viruses are what kind of viruses?
What is the virus in this class?
single stranded DNA
Parvovirus
-easy to recognize by the body because we dont have them
Class III virsuses are what kind of viruses?
What are the viruses in this class? 4
- double stranded RNA Coronavirus Picornavirus Togavirus Hepatitis C virus
WHat are examples of picornavirus? 2
What are exampes of a togavirus? 2
- (polio, common cold)
2. (rubella, yellow fever)
Class IV viruses are what kind of viruses and what viruses are in this class?5
- positive single stranded RNA itself acting as mRNA
- Rhabdovirus
- Paramyxovirus
- Orthomyxovirus
- Bunyavirus
- Arenaviruses
GIve an example of a rabdovirus?
Give an example of a paramyxovirus? 2
Give an example of an orthomyxovirus?
Give an example of a bunyavirus?
(rabies)
(measles, mumps)
(influenza viruses)
(Korean hemorrhagic fever)
WHat kind of virus is a class V virus.
What kind of virus is in this category and what does it cause?
- negative single stranded RNA used as a template for mRNA synthesis
Reovirus (diarrhea)
What kind of viruses are class VI viruses and what virus is in this class?
GIve two examples?
What kind of viruses are class VII viruses and what virus is in this category?
- positive single stranded RNA with a DNA intermediate in replication
Retrovirus (leukemia, AIDS)
- double stranded DNA with an RNA intermediate in replication.
Hepatitis B virus
Viral exanthematous diseases?
7
- Chickenpox/Herpes zoster
- Infectious mononucleosis
- Roseola infantum (Sixth Disease or Erythema subitum)
- Fifth disease (Erythema infectiosum)
- Measles
- Rubella
- Enteroviral exanthems
Enteroviral exanthems examples? 2
Coxsackievirus
Echovirus
DDx of exanthematous eruptions?
7
- Rickettsial infections
- Mycoplasma pneumoniae
- Syphilis- palms and soles
- Typhoid fever-
- Bacterial toxins- staph - toxin shock syndrome
- Drug eruptions
- Live-virus vaccinations
What are the Human herpes viruses in order?
8
- HHV-1: Herpes Simplex Virus 1 (HSV1)
- HHV-2: Herpes Simplex Virus 2 (HSV2)
- HHV-3: Varicella-Zoster Virus (VZV)
- HHV-4: Epstein-Barr Virus (EBV)
- HHV-5: Cytomegalovirus (CMV)
- HHV-6: Exanthema (or Roseola) subitum (Roseola infantum or Sixth Disease)
- HHV-7: T-lymphotropic virus (could cause cancer)
- HHV-8: Virus associated with Kaposi’s sarcoma
What viruses have the blistering rash look?
HSV 1and 2 and chicken pox
How does herpes simplex infect infect the body?
2
- through mucosal membranes or abraded skin
- Latent infections harbored in neuronal cells
- -Trigeminal ganglia
- -Pre-sacral ganglia
How is the rash described for HSV?
What are the clinical manifestations for the oral facial lesions for the primary infection of HSV? 2
What demographic is it commonly seen in?
What are the other symtpoms? 6
How long does it last?
What does it reoccur as?
Dew-drop on rose petal
Gingivostomatitis (canker sores on gum) and pharyngitis most frequent
Commonly seen in children and young adults
- Fever,
- malaise,
- myalgias,
- inability to eat,
- irritability and
- cervical adenopathy lasts 3-14 days
Herpes labialis (“Cold Sores”)
HSV urogential lesion systemic symtpoms? 4
Local symtpoms?6
What will the pt experience in the prodromal phase?
- Headache,
- fever,
- malaise and
- myalgia
Vesicular lesions of external genitalia with
- pain,
- itching,
- dysuria (horrible pain peeing),
- vagina and urethral discharge,
- tender inguinal lymph adenopathy
patient will usually present early. makes area sore and tender first then you get the lesions
Moist ulcers will form in how many days with HSV?
How long will they last untreated?
What are recurrent infections of HSV caused by? 5
Vesicles form moist ulcers after several days and crust over in 1-2 weeks of left unaddressed
Are induced by stress, fever, infection, sunlight, chemo.
Complications of HSV?
4
- Ocular disease- herpetic kerokitis
- Neonatal and Congenital infections
- Bells Palsy (facial nerve paralysis)
- Encephalitis and recurrent Meningitis- you can treat it with your cyclovirs IV
If we see diseminated herpes what should we think about?
What is the most common cause of viral encepholopathy?
AIDS or some other kind of immunosuppression
Herpes
How do we diagnose HSV?
5
Usually clinically made
Lab tests:
- viral culture (only if its blistering)
- PCR
- Direct flouroscence antibody
- Tzanck prepartion
- Types specific serologic tests
What have emerged as a more sensitive method to confirm HSV infection in clinical specimens obtained from genital ulcers, mucocutaneous sites, and cerebrospinal fluid?
What test is particularly useful for the detection of asymptomatic HSV shedding?
real-time HSV PCR assays
PCR
What test is used to detect HSV in clinical specimens?This test is specific and reproducible.
Direct fluorescent antibody
What test helps us identify the cytopathic effect of the virus (multinucleate giant cells) and can be performed on lesions scrapings?
Why dont we use it more?
What test is the only test that can determine whether an infection is HSV1 or 2?
Tzanck smear
low sensitivity and specificity and is only helpful if positive.
viral culture
What are inclusion cells in HSV?
inclusion cells are the virus replicating in the cell
What is the management for Herpes simplex acute infections?
Antiviral agents only shorten duration of symptoms by 1-2 days
-Acyclovir
Cant do suppressive therapy too. Daily
Where does herpatic whitelow occur?
finger and nails
Occassionally toes
Two distinct clinical presentations for herpes zoster. What are they?
Primary infection: Chickenpox
Recurrent infections: Herpes zoster
Primary infection by Varicella Zoster is transmitted how?
Recurrent infection?
respiratory
VZV probably infects dorsal root ganglia during primary infection. Certain sitations will trigger it to come out
Incubation period of varicella zoster?
Infected persons are infectious for how long?
10-21 days (usually 14-17)
48 h before onset of vesicular rash, throughout vesicle formation (~4-5 d), and until all vesicles are crusted.
Clinical Presentation
Primary infection: Chickenpox?
3
- Rash, fever (100-103F) lasting 3-5 days, malaise
- Skin lesions are hallmark of disease:
Maculopapules, vesicles, and scabs in varying stages of development (“crops” of lesions) on an erythematous base of 5-10 mm - Distribution centripetal
(much more common on trunk)
Clinical presentation for varicella zoster recurrent infection or shingles?2
What are the most common dermatomes? 2
- Unilateral vesicular eruptions which develop within a single dermatome (T3 to L3 most common)
- Often associated with severe pain
Diagnostics for varicella zoster?
2
Usually clinically made
Tests can include
- Specialized complement fixation and virus neutralization in cell culture
- Fluorescent antibody test of smear of lesions
- Cell culture
- Flourescent antibody stain
Management of varicella zoster:
Primary infeciton prevention?
Primary disease?
Recurrent infection? 2
- Primary infection prevention: Vaccination
- Primary disease: Prevent secondary infections
- Recurrent infection: Zoster
A. Antivirals (high dose)
–Acyclovir
–Famcyclorvir
B. Analgesics
HOw is EBV transmitted and what does it infect in the body?
Incubation period?
Peak incidence occurrence?
(ages?)
How long can it be contagious/symtpomatic for?
B-cell lymphotropic virus primarily transmitted in saliva
4-8 weeks incubation period
Peak incidence occurrence
Ages 14-16 for girls
Ages 16-18 for boys
EBV shed from oropharynx for up to 18 months post-infection
Clinical presentation for EBV:
Childhood?
Adolescence/adult? 2
Subclinical or mild when infected during childhood
Infectious mononucleosis defined by transient appearance of heterophil Ab and clinical triad
- Fever/chills
- Lymphadenopathy
- Severe pharyngitis with exudates