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62 Cards in this Set
- Front
- Back
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What does "reoviridae" mean?
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Respiratory Enteric Orphan viruses
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What is unique about reoviridae's nucleic acid?
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Only dsRNA.
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What are the 4 reovirus genera that infect humans?
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1) Reovirus
2) Rotavirus 3) Orbivirus 4) Coltivirus |
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Diseases associated with Reovirus
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Although infection is common, hasn't conclusively been linked to any specific disease
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T/F Reoviridae are enveloped
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F.
This means they can't be destroyed with detergents. |
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Physical properties of Reoviridae
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Most are resistant to chloroform and other lipid solvents
Stable over a wide range of pH |
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Orbivirus and Coltivirus: How are they distinguished from other Reoviridae?
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Arthropod vectors
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Coltiviruses include one human pathogen: what is it?
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Colorado tick fever virus
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Colorado Tick Fever: causative agent
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Coltivirus, 12-segmented dsRNA virus
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Colorado Tick Fever: risk factors
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Exposure during camping, hiking, fishing, etc.; ticks may be carried home on clothing or equipment
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Colorado Tick Fever: signs, symptoms, and course
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Symptoms: sudden onset headache, myalgia, fever, chills, ocular pain, photophobia; absence of respiratory symptoms
Signs: acute prostration, elevated temperature; conjunctival and pharyngeal injection without exudate; rash present in <10% Course: fever and symptoms remit in 3-4 days; recurrence of symptoms after 1-3 days (50%) |
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Top 5 killers of children worldwide
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1) Pneumonia
2) Diarrhea 3) Measles 4) Tuberculosis 5) Malaria |
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Single most important agent of severe diarrheal illness in infants and children
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Rotaviruses
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4 major viral causes of gastroenteritis
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Astroviruses, Calci(noro) viruses, Enteric adenoviruses, Rotavirus
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What are the rotavirus antigens?
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VP6 – group and subgroup antigen (A-G)
VP4 – neutralization, hemagglutinin P (P serotype) VP7 – neutralization, (G serotype) |
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Most abundant rotavirus antigen?
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VP6 (51% of virion). Inner capsid.
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Rotavirus antigens located on inner capsid, make up 51% of the virion
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VP6
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Rotavirus Viral attachment protein, hemagglutinin. Sensitive to protease (P antigen)
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VP4
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Rotavirus glycoprotein (G antigen)
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Vp7
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Protein determining P serotype
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VP4
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Protein determining G serotype
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VP7
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Structure of rotavirus
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Double-layered outer shell around a central core of genetic material
Inner shell: VP6 Outer shell: VP4 and VP7 |
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Symptoms of Rotavirus Gastroenteritis
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Wide range from asymptomatic viral excretion to mild diarrhea to severe diarrhea with potentially fatal dehydration/electrolyte imbalance.
Generally, Vomiting, Fever, and Diarrhea (5-10/day) |
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T/F in Rotavirus infection, can usually find WBC and RBC in stool
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F
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Which population group generally has the most severe rotaviral disease?
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Infants.
Immunocompromised can also develop chronic disease |
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T/F most rotavirus infections occur in winter months in temperate climates
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T
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Distribution of rotavirus infections across the US
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Starts in the west around november and moves east to reach east coast around March/April
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Rotavirus treatment
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Supportive therapy
Replacement of fluid and electrolyte losses Orally or by nasogastric tube preferred IV if intractable vomiting Early feeding when vomiting subsides No antiviral therapy currently available |
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Rotavirus prevention
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Vaccines: live attenuated group A vaccines. New.
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Treatment of Colorado Tick Fever
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general supportive
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Rotavirus diagnosis
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Detection of viral antigen in stool is primary diagnostic test
ELISA and latex agglutination assays for detection of rotavirus group A antigen are commercially available and widely used |
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Noroviruses are members of family ____________
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Calciviridae
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Major cause of acute infectious diarrheal outbreaks on cruise ships or in aftermath of natural disasters
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Norovirus
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Characteristics of norovirus
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Non-enveloped, (+)ssRNA
Won't grow in cell culture. Lack definitive morphology on EM |
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Characteristics of a Norovirus outbreak (epidemiology, etc.)
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Outbreaks tend to occur in closed populations (eg., cruiseships) with high attack rate, often “explosive” onset.
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Norovirus infection: signs and symptoms
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Diarrhea, vomiting, frequently fever, headache, cramps, myalgias.
Lasts 1 day to 2 weeks. |
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Characteristics of astroviruses
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ssRNA. Can be grown in cell culture. Characteristic star-like (ASTRO - STAR) appearance on EM
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Shape of astrovirus on EM
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Star
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Second most common cause of severe diarrhea in hospital-based studies of children
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Enteric adenoviruses
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Seasonality of astrovirus
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winter months in temperate climates, rainy season in tropics (similar to rotavirus)
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Which serotypes of adenovirus associated with gastroenteritis?
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40 and 41
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How to diagnose the following:
1) Astrovirus 2) Adenovirus |
1) No commercially available tests
2) Antigen detection assays for 40 and 41 |
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Characteristics of parvovirus
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SMALL, nonenveloped, ssDNA virus.
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What does not having an envelope due to virus?
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Makes it relatively heat and solvent resistant
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What are the three Parvovirinae that infect humans?
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1) Dependovirus aka Adeno-associated virus (AAV)
2) Erythrovirus (includes human parvovirus B19) 3)Bocavirus (HBov) |
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Dependoviruses – also known as adeno-associated viruses (AAV)
require coinfection with what? |
an unrelated “helper” virus (e.g. adenovirus, CMV, etc.)
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Illnesses associated with dependoviruses/AAV infection
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none
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Illnesses associated with bocavirus
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Recently associated with acute wheezing in hospitalized children
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Illnesses associated with Erythrovirus/B19
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Identified as cause of erythema infectiosum (fifth disease); Arthropathy, fetal hydrops, chronic anemia, transient aplastic crisis (in sickle cell)
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Erythrovirus/B19: tropism
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Erythroid precursor cells
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cause of fifth disease
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Erythrovirus/B19
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When are patients with Erythrovirus/B19 infective?
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before rash
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Diagnosis of Erythrovirus/B19
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A) B19-specific IgM (acute); 4x rise in IgG on paired sera confirms infections
B) Use viral detection methods (PCR) on patients who can't mount immune response |
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Treatment of Erythrovirus/B19
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no specific antiviral therapy; May help to infuse with immunoglobulin
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Fifth disease is aka
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erythema infectiosum
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Symptoms of fifth disease/erythema infectiosum
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Fever, "slapped face" rash on cheeks
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Which population is most affected by B19/fifth disease?
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Infection rate is highest among school-aged children ages 5-15.
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Characteristics of Parvo B19 arthropathy
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Symmetric polyarthropathy primarly affecting peripheral joints
Frequent cause of acute arthritis in adults Joint symptoms reported in >60% of B19-infected adults Incidence in women>men Symptoms last 2 weeks to 2 months in general Chronicity is rare but some may persist for months to years |
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Transient Aplastic Crisis caused by Parvo B19: characteristics
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Classically occurs in patients with sickle cell disease but has been described in most conditions of accelerated hematopoiesis
Patients present with fever, lethargy, malaise – but not rash Signs and symptoms of severe anemia: pallor, tachypnea, tachycardia, etc. Patients are viremic at presentation Laboratory features: profound anemia, absolute reticulocytopenia |
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What will happen if Parvo B19 is contracted during pregnancy?
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Primary maternal infection in pregnancy can lead to miscarriage, nonimmune fetal hydrops, or stillbirth
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Transient Aplastic Crisis caused by Parvo B19: treatment and prevention
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Supportive measures – transfusion, oxygen, fluids, etc.
Respiratory droplet and contact isolation during hospitalization |
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Persistent anemia in immunocompromised patients caused by Parvo B19: treatment and prevention
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Respiratory droplet and contact isolation
Discontinue immunosuppressive therapy if feasible IVIG |
