Positive Sense (+)RNA Viruses Flashcards
What viruses are in the Picornaviridae family and classification?
(+) ssRNA Virus, naked
- Hep A
- Enteroviruses (Polio, Coxsackie, Echo)
- Rhino
Where would you most commonly get Hep A from in developed countries?
Uncooked Shellfish – contaminates water
- Patients traveling to endemic areas
- Virus is Acid-Stable
What are the clinical signs of Hep A infection?
Jaundice (no jaundice in children)
Tobacco Aversion
1 month duration
Where does Polio virus replicate in the GI tract? (Enterovirus)
Peyer’s Patches (2-3 weeks before symptoms)
What are complications of Polio infection?
– Attacks the anterior horn in the spinal column, can lead to Resp insufficiency (due to no motor) and aseptic meningitis
What are the pros and cons of polio viruses?
Live Virus (Sabin) -- IgA + IgG, but can cause the disease in compromised people and infants. Killed Virus (Salk) -- IgG only, not as effective and long lasting.
What are the major clinical syndromes of Coxsackie A virus?
Hand, Foot, Mouth Disease – red vessicular lesions everywhere including palsm and feet. Summer time.
If a patient is diagnosed with dilated cardiomyopathy, what might have been an infectious agent to cause it?
Coxsackie B Virus
–Can also cause Pleurodynia (Devil’s Grip) very intense sharp pain in the lower chest making it difficult to breath
What is the source of the common cold?
Rhinovirus – (+)RNA, naked
– from fomites, attaches to ICAM-1 on resp epithelium, grows best at lower temps, thus Upper Resp infections
What are characteristics of Togavirus family?
(+) ssRNA, enveloped – polypeptide precursor, rep in cytoplasm
- Arbovirus
- Rubella
What can cause encephalitis from a arthropod vector?
Arbovirus - from mosquitos
- Eastern/Western US
- Venezualan
What is the classic triade of congenital Rubella?
- Congenital Cataracts
- Deafness
- Patient Ductus Arteriosus
+ Blue berry rash, microcephaly
What are the features of childhood rubella?
- postauricular and occipital LAD (Key)
- Macular Rash, starts on face and moves outward
- Resp infection
What are the buzz words associated with adult rubella?
Immigrant from another country with LAD, fever, and arthalgias/arthritis
How to prevent Rubella (TORCH infection)?
Live Attenuated Vaccine before becoming pregnant, developed countries everyone is usually covered, thus the reason to be suspicious of immigrants
What kind of virus are you likely to find on cruiseships, buffets, and daycares – causing explosive diarrhea?
Norwalk / Calicivirus – (+)RNA, naked, produces long polypeptide in cytoplasm that needs to be cleaved.
– Norovirus = most common type
What do Dengue Fever, Yellow Fever, Hep C, and West Nile Virus all have in common?
(+) ssRNA, enveloped
– All apart of the Flavivirus Group
What causative agent is spread by Aedes Egypti mosquito and causes severe bone pain, thrombocytopenia, and hemorrhagic fever? (Usually around the equator)
Dengue Fever — affects bone marrow
- can lead to renal failure and shock
- usually only happens on the 2nd time being infected by a different strain than the first time.
What vector borne illness causes blood diarrhea, hematemesis with jaundice, typically from African region?
Yellow Fever – aedes mosquito, vaccine useful if travel to those regions
– Councilmen Bodies on Liver biopsy
How is Hep C classified as a virus?
(+)RNA, enveloped virus – antigenic variable envelope
What are the most common means of transmission of Hep C?
- blood exposure
- sharing needles
- sexual
- blood transfusion (pre-1990)
- placenta
Why does Hep C have a variable antigenic enveloped capsule?
RNA Polymerase, has no exonuclease 3->5 activity (unable to correct errors) leading to more errors and constantly changing antigens.
What are the clinical syndrome of Hep C infection?
Most will go become chronically infected
- jaundice/hepatitis
- fibrosis of the liver
- hepatocellular carcinoma
What is a unique attribute of diagnosing Hep C, what test can you perform?
Hep C cryoglobulins (antibodies) if lowered to a cool temperature percipitate (IgM)
