13 virus 🦠 Flashcards
Herpes
simplex virus-1
Transmission….Respiratory secretions, saliva
Disease…..Gingivostomatitis, keratoconjunctivitis A ,herpes labialis B , herpetic whitlow on finger, temporal lobe encephalitis, esophagitis, erythema multiforme.
📝 ….Most commonly latent in trigeminal ganglia. Most common cause of sporadic encephalitis, can present as altered mental status, seizures, and/or aphasia.
Herpes
simplex virus-2
Transmission…..Sexual contact, perinatal
Disease……Herpes genitalis, neonatal herpes.
Note…..Most commonly latent in sacral
ganglia. Viral meningitis more common with HSV-2 than with HSV-1.
Varicella-
Zoster virus (HHV-3)
Transmission…..Respiratory secretions
Disease….Varicella-zoster (chickenpox D , shingles E ), encephalitis, pneumonia.Most common complication of shingles is post-herpetic neuralgia.
📝 Latent in dorsal root or trigeminal ganglia; CN V 1 branch involvement can cause herpes zoster ophthalmicus.
Epstein-Barr virus (HHV-4)
Is herpesvirus
Transmission….Respiratory secretions, saliva; aka “kissing disease,” (common in teens, young adults)
Disease….Mononucleosis—fever, hepatosplenomegaly F pharyngitis, and lymphadenopathy (especially posterior cervical nodes). Avoid contact sports until resolution due to risk of splenic rupture. Associated with lymphomas (eg, endemic Burkitt lymphoma), nasopharyngeal carcinoma (especially Asian adults), lymphoproliferative disease in transplant patients.
,
📝 Infects B cells through CD21. Atypical lymphocytes on peripheral blood smear G —not infected B cells but reactive cytotoxic T cells. ⊕ Monospot test—heterophile antibodies detected by agglutination of sheep or horse RBCs.
📝 Use of amoxicillin in mononucleosis can cause characteristic maculopapular rash.
Cytomegalovirus (HHV-5)
Transmission….Congenital transfusion, sexual contact, saliva, urine, transplant
Disease….Mononucleosis ( ⊝ Monospot) in immunocompetent patients; infection in immunocompromised, especially pneumonia in transplant patients; esophagitis; AIDS retinitis (“sightomegalovirus”): hemorrhage, cotton-wool exudates, vision loss.Congenital CMV
📝Infected cells have characteristic “owl eye” intranuclear inclusions H .
Latent in mononuclear cells.
Human
herpesviruses 6 and 7
Transmission…..Saliva
Disease…..Roseola infantum (exanthem subitum): high
fevers for several days that can cause seizures, followed by diffuse macular rash I .
📝Roseola: fever first, Rosy (rash) later. HHV-7—less common cause of roseola.
Human
herpesvirus 8
Transmission….Sexual contact
Disease…Kaposi sarcoma (neoplasm of endothelial cells). Seen in HIV/AIDS and transplant patients. Dark/violaceous plaques or nodules J representing vascular proliferations.
📝Can also affect GI tract and lungs.
Influenza viruses
😗Orthomyxoviruses. Enveloped, ⊝ ssRNA viruses with 8-segment genome.
😗Contain hemagglutinin (binds sialic acid and promotes viral entry) and neuraminidase (promotes progeny virion release) antigens.
😗Patients at risk for fatal bacterial superinfection, most commonly S aureus, S pneumoniae, and H influenzae.
😗Reformulated vaccine (“the flu shot”) contains viral strains most likely to appear during the flu season, due to the virus’ rapid genetic change. Killed viral vaccine is most frequently used. Live attenuated vaccine contains temperaturesensitive mutant that replicates in the nose but not in the lung; administered intranasally.
Rubella virus
🐽A togavirus. Causes rubella, once known as German (3-day) measles.
🐽Fever, postauricular and other lymphadenopathy, arthralgias, and fine, maculopapular rash that starts on face and spreads centrifugally to involve trunk and extremities A .
🐽Causes mild disease in children but serious congenital disease (a ToRCHeS infection). Congenital rubella findings include “blueberry muffin” appearance due to dermal extramedullary hematopoiesis.
Paramyxoviruses
😲Paramyxoviruses cause disease in children. They include those that cause parainfluenza (croup), mumps, measles, RSV, and human metapneumovirus, which causes respiratory tract infection (bronchiolitis, pneumonia) in infants.
😲All contain surface F (fusion) protein, which causes respiratory epithelial cells to fuse and form multinucleated cells.
😲Palivizumab (monoclonal antibody against F protein) prevents pneumonia caused by RSV infection in premature infants. Palivizumab for Paramyxovirus (RSV) Prophylaxis in Preemies.
Croup (acute laryngo-tracheobronchitis)
🌹Caused by parainfluenza viruses, which are paramyxoviruses.
🌹Virus membrane contains hemagglutinin (binds sialic acid and promotes viral entry) and neuraminidase (promotes progeny virion release) antigens.
🌹Results in a “seal-like” barking cough and inspiratory stridor
🌹. Narrowing of upper trachea and subglottis leads to characteristic steeple sign on x-ray A .
🌹Severe croup can result in pulsus paradoxus 2° to upper airway obstruction.
Measles (rubeola) virus
🤢A paramyxovirus that causes measles.
🤢 Usual presentation involves prodromal fever with ✨cough, ✨coryza, and ✨conjunctivitis, then eventually Koplik spots (bright red spots with blue-white center on buccal mucosa A ), followed 1–2 days later by a maculopapular rash B that starts at the head/neck and spreads downward.
🤢Lymphadenitis with Warthin-Finkeldey giant cells (fused lymphocytes) in a background of paracortical hyperplasia.
🦠Possible sequelae:
#SSPE (subacute sclerosing panencephalitis ,occurring years later) #Encephalitis (1:2000) Giant cell #pneumonia (rare except in immunosuppressed)
3 C’s of measles:
🌼Cough
🌹Coryza
🌺Conjunctivitis
📝Vitamin A supplementation can reduce morbidity and mortality from measles, particularly in malnourished children.
Mumps virus
A
🍒A paramyxovirus that causes mumps, uncommon due to effectiveness of MMR vaccine.
🍒Symptoms: Parotitis A , Orchitis (inflammation of testes), aseptic Meningitis, and Pancreatitis. Can cause sterility (especially after puberty).
Mumps makes your parotid glands and testes as big as POM-Poms.
Rabies virus
😵Bullet-shaped virus A . Negri bodies (cytoplasmic inclusions B ) commonly found in Purkinje cells of cerebellum and in hippocampal neurons.
😵Rabies has long incubation period (weeks to months) before symptom onset. Postexposure prophylaxis is wound cleaning plus immunization with killed vaccine and rabies immunoglobulin. Example of passive-active immunity.
😵Travels to the CNS by migrating in a retrograde fashion (via dynein motors) up nerve axons after binding to ACh receptors.
😵Progression of disease: fever, malaise agitation, photophobia, hydrophobia, hypersalivation paralysis, coma death.
😵Infection more commonly from bat, raccoon, and skunk bites than from dog bites in the United States; aerosol transmission (eg, bat caves) also possible.
