Micro 20 - DNA Virus Part 1 Flashcards
(45 cards)
What does HSV-1 cause?
Oral herpes labialis, “cold sore”. Can also cause gingivostomatitis, keratoconjunctivitis, temporal lobe encephalitis, genital herpes.
What nerve does HSV-1 usually lie dormant?
Trigeminal ganglia.
What does HSV-2 cause?
Affects genital regions (multiple painful vesicles). Causes latent infections.
Where does HSV-2 like to lie dormant?
Lies dormant in sacral nerve root ganglia.
What is another name for HHV-3? What does it cause?
It is VZV (Varicella-zoster virus). It depends; on primary infection it causes chickenpox (rarely encephalitis, pneumonia), while reactivation causes herpes zoster (shingles).
Where does VZV likes to lie dormant?
Dorsal ganglia after primary infection.
What are 2 characteristics of shingles?
Stays in a single dermatome and does not cross the midline.
How is VZV spread?
Respiratory route. On shingles it is by direct contact with active lesion unless the patient is immunocompromised and is shedding the virus everywhere (can spread by ventilation system).
When is the Tzank smear used? What are it’s weaknesses?
Used to detect HSV-1, HSV-2, or VZV but it cannot differentiate between them. It is positive when multinucleated giant cells are seen. Also has low specificity and low sensitivity. Better use a PCR test of the vesicular fluid for diagnosis.
What do we see in cells infected with HSV-1, HSV-2, or VZV?
Intranuclear eosinophilic inclusions called Type A Cowdry bodies or Type 1 Cowdry inclusions.
What is another name for HHV-4? What does it cause?
Epstein-Barr Virus, it causes mononucleosis.
How is EBV spread? Which type of cells does it like to infect?
Epstein-Barr virus is spread by oral secretion (“kissing disease”, affects 15-24 y.o. age group). Infects B cells.
What is the cause of the atypical lymphocytosis that is typical of EBV infection?
Because EBV likes to infect B cells. When system detects compromised B cells, it mounts a surge of cytotoxic T cells, producing atypical lymphocytosis. Produces Downey cells (atypical T cells that have a foamy-appearing basophilic cytoplasm).
What type of virus is the Herpesvirus?
DNA Virus.
What are the symptoms of infectious mononucleosis?
Fever, sore throat, lymphadenopathy (posterior cervial nodes), exudative pharyngitis.
EBV infection can be confused with strep throat and prescribed with amoxicillin. What happens to the patient?
Maculopapular rash that covers trunk and extremities.
What are the complications of mononucleosis?
Splenomegaly (can rupture), therefore no contact sports or splenic palpation.
How do we diagnose mononucleosis?
Monospot test: detects heterophile antibodies, antigens found in horse, sheep and beef RBCs (they are made in the body by unknown reason). Has high sensitivity and specificity. Can also test antbodies (IgM and IgG) specific for EBV.
What would a likely diagnostic conclusion of someone with mononucleosis symptoms but negative heterophile (Mono) test?
CMV infection, acute HIV, acute toxoplasmosis, viral hepatitis, strep throat.
What are six EBV-associated malignancies?
Hodgkin lymphoma, Burkitt lymphoma, Nasopharyngeal carcinoma, Diffuse large cell lymphoma, Oral hairy leukoplakia, Lymphoproliferative disorders.
What is another name for HHV-5? What cells does it infect?
Cytomegalovirus (CMV). It infects mononuclear cells and polymorphonuclear cells, causing nuclear inclusions called “Owl’s Eyes”.
What does CMV cause in bone marrow transplant patients?
Life-threatening pneumonia.
What does CMV cause in AIDS patients?
Retinitis, ulceration of the GI tract, Esophagitis.
What does HHV-6 cause?
Roseola in children “Sixth disease” or Exanthum subitum.
