Insects, Bacteria, & Viral Flashcards
What type of parasite are lice?
- ectoparasite
What species of lice causes head lice?
- Pediculosis capitis
What species of lice causes body lice?
- Pediculosis corporis
What type of lice causes pubic lice?
- Pediculosis or Pthirus pubis
How is lice spread?
- person to person by close contact
- fomites
How is lice NOT spread?
- jumping
What is lice a vector for?
- typhus
- trench fever
- relapsing fever
Describe the lice ‘workup’
- distance of nits away from hair follicle
- cellulose tape
- UV light
What are the symptoms of lice?
- visible nits
- pruritis
What are the treatments for lice?
- topical pediculicidal agents
- oral antihelmintics
What are the lice treatments effective against?
- killing nymphs and mature lice
- not so much against eggs
What is the great clinical imitator?
- scabies
What are the symptoms of scabies?
- pruritis
What is the pathophysiology of scabies?
- female mite burrows into skin
- lays eggs
- move through layers and secrete proteases
- feed on tissue but not blood
scybala
- scabies feces
Why do humans react to scabies infestations?
- type IV hypersensitivity reaction to scybala
What are the treatments for scabies?
- scabicidal
- antipruritic
- antimicrobial if secondary infection
What is a characteristic of the brown recluse spider?
- dorsal violin shape
What is dermonecrotic arachnidisim?
- local skin/tissue injury resulting from envenomation
What is loxoscelism?
- systemic clinical syndrome caused bye envenomation from brown recluse spiders
How does a brown recluse spider bite present?
- edematous/ischemic bite site
- erythematous halo
Why does the margin enlarge peripherally in a brown recluse spider bite?
- 2nd to gravitational spread of the venom into the tissues
What happens 24-72h after a brown recluse spider bite?
- single clear or hemorrhagic vesicle at site
- later forms a dark eschar
What is the treatment for a brown recluse spider bite?
- wound management
- cool compress to hinder sphingomyelinase D activity
- dapsone
- hyperbaric oxygen
What causes latrodectism?
- latrotoxin, a neurotoxin
What is characteristic of the black widow spider?
- hourglass on its dorsum
What are the 3 phases of a black widow bite presentation?
- exacerbation
- dissipation
- residual
What is ominous in the residual phase?
- changes in heartbeat, breathing, or blood pressure
What is the treatment for a black widow spider bite?
- pain medication
- muscle relaxants
- antivenom
What is cellulitis?
- infection without formation of abscess and without purulent drainage or ulceration
When there is intact skin with cellulitis, what causes the majority of cases?
- Strep pyogenes
When the skin is not intact with cellulitis, what causes the majority of cases?
- Staph aureus
What is a ddx for cellulitis?
- erysipelas
How does cellulitis with a systemic infection present?
- violacious
- bullae
- lymphangitis
What causes facial cellulitis in children?
- H. influenza B
What comorbidities put a patient with cellulitis at risk?
- DM
- chronic edema
- splenectomy
- liver disease
- immunosuppression
- prosthetic implant
- arterial or venous disease
How is cellulitis with intact skin treated?
- beta-lactam abx (PCN)
How is cellulitis without intact skin treated?
- cefazlin
erysipelas
- bacterial infection of upper dermis extending into superficial cutaneous lymphatics
- not deep
What is the causative agent of erysipelas?
- Strep pyogenes (St. Anthony’s Fire)
How does erysipelas present?
- initially small erythematous patch progressing into a fiery-red indurated, tense, & shiny plaque with well demarcated borders
What is a ddx for erysipelas?
- SJS/TENS
What is the treatment for erysipelas?
- elevation
- saline wet dressings
- PCN
What are common complications of erysipelas?
- abscess
- gangrene
- thrombophlebitis
What are the two types of impetigo?
- nonbullous
- bullous
What causes impetigo?
- S. aureus
How does impetigo present?
- folliculitis
- superficial, yellow, crust
What are the treatments for nonbullous impetigo?
- topical mupirocin
- antihistamines
What are the treatments for bullous impetigo?
- systemic antibiotics
- antihistamines
What are the classic exanthems?
- 1st-6th disease
What are the other names for 1st disease?
- measles
- rubeola
- morbilli
What are the other names for 2nd disease?
- scarlet fever
What are the other names for 3rd disease?
- rubella (German measles)
What are the other names for 4th disease?
- Duke’s disease
- staph scalded skin
What are the other names for 5th disease?
- erythema infectiosum
What are the other names for 5th disease?
- erythema infectiosum
What are the other names for 6th disease?
- roseola infantum
- exanthem subitum
How does measles present?
- incubation period
- prodrome
- rash
What is the incubation period for measles?
- 10-12d
What is characteristic of the prodrome phase prior to measles?
- febrile
- cough
- coryza
- conjunctivitis
- Koplik spots
coryza
- heavy rhinorhea
Koplik spots
- tiny white dots on mucous membranes inthantum
What is the time frame for the rash of measles?
- 2-4d after prodrome, 14d after exposure
Describe the measles rash
- discrete maculopapular that becomes confluent
- begins on face and head goes to trunk and extremities
How long does the measles rash last?
- 5-6d
How does the measles rash disappear?
- fades in order of appearance
How does scarlet fever develop?
- within 24-48 hours of onset of symptoms in untreated group A strep infected children
What is characteristic of scarlet fever presentation?
- scarletina rash
- peeling of the skin
- ‘hot potato’