Viral Infections Associated With Skin Manifestations Flashcards
Some viruses cause changes in the skin indirectly and diffusely by
Examples
Appearance
D.x:
First causing derangements of internal organ function, including of cells of the immune system
Nonspecific viral exanthems- very common in children. No physical features reveal virus identity
Blanchable erythematous macules and papules, often on trunk or extremities (except meningitis is unblanchable)
Seasonal variation, winter often respiratory viruses like influenza adenovirus, RSV
Dx: drug reactions, contact dermatitis, other organisms
Some cause changes in the skin directly and locally, by
Examples
Replicating within the skin and damaging it
Measles, chicken pox, herpes simplex, rubella, roseola, erythema infectiosum
Scabies mites:
Dig tunnels in skin to lay eggs, often between fingers, at waistline, itchy allergic reaction common, easily spread, treat household, thorough laundering/vacuuming, permethrin lotion- neurotoxic to mites
Bedbugs bite:
Exposed skin at night (in contrast, fleas tend to bite ankles), see blood on sheets, exterminator
Lice
The louse attaches to hair, feed on blood, remove with nit comb/insecticidal shampoo
Ticks can:
Spread Lyme disease via bacterium Borrelia burgdorferi or Rocky Mountain spotted fever via bacterium Rickettsia ricekttsii, each associated with rashes
Kissing bugs (triatomine bugs) may spread the parasite:
Trypanosoma cruzi that causes Chaga’s disease (which can cause serious myocarditis)
Exanthem
Widespread symmetric rash (often feverish)- from microbe or drug or autoimmunity.
From a virus is an example of a febrile reaction, where events related to the infection lead to an elevation of hypothalamic set point (mechanisms of exogenous and endogenous pyrogens).
That elevation, in febrile reactions, commonly causes patients to feel cold/chills as their temperature is rising
In contrast, when a patient’s temperature is rising doe to a non-febrile hyperthermia (malignant hyperthermia), the patient commonly feels like they are burning up.
Enanthem
Rash of muscles membranes- like the mouth
Common maculopapular rashes
Pharmacological drug related- common in adults, including hospitalized. Also called a drug eruption, drug exanthem- ampicillin, NSAIDs, others. Can be morbilliform rash
Virus related- common cause in children worldwide- measles, reseola, rubella, various respiratory agents
Insect bites, food allergies- adults and children common
Maculopapular rash often arising in weeks following an HIV infection
HIV seroconversion exanthem
Kaposi sarcoma histology findings
Causative agent
Slit-like spaces filled with blood
Human herpes virus 8
Prevalence of tumor dropped massively with the introduction of highly active anti-retroviral (HAART) drug therapy for HIV infection
May present clinically with red patch that many be raised
Molluscum contagiousum histology
Causative agent
Virus accumulates in the skin in aggregations called molluscum bodies
Molluscum contagiosum virus
Very common cause of skin infection, especially anogenital regions, commonly spread by direct contact, in immune compromised (AIDs), more florid involvement includes face
No vaccine, treatments not very effective (include liquid nitrogen freezing)
Measles- “Red measles, Rubeola” causative agent
Transmission
Signs- early/first two week course
Measles virus (rubeola virus)
Transmitted by direct contact with respiratory secretions (droplets)
One of the most communicable diseases
In two weeks, virus first replicates in respiratory tract, then spreads to lymphatic tissue, then to blood (viremia), then to conjunctiva and skin (rash at 2 weeks)
Early signs- 3 C’s: cough, coryza (runny nose), conjunctivitis
Replication of measle’s virus occurs in both
Epithelial cells and leukocyte resulting in Warthin Finkeldey cells (multi-nucleated that also arise in lymph nodes)
