Infestations, bites, stings Flashcards
Scabies
1. Life cycle of mite
2. RF for crusted scabies
3. Ix for initial episode
4. Initial mgmt - key points
- top options
- systemic options
5. Steps to take if Rx fails
- Ectoparasite / mite
Female, burrows to stratum granulosum. Lays 2-3 eggs/day. Egg - hatches 3-4 days -> larva -> 3 molts through nymph to become adult. Repeat
Lives ~2/12 - Immunosuppression, neurological disorder, overcrowding, SOTR
- FBE. eos.
Scraping for microsocpy
FBE UEC LFT CRP
HTLV1. ANA. HIV, C3/4, T cell subsets
Swabs, BC, nail clippings - Isolation. Environmental measures. Treat close contacts. Assess secondary infection
- Top: permethrin 5%, benzyl benzoate 25%, precipitated sulphur 5-10%, crotamiton 10%
- Oral: ivermectin 200microg/kg, moxidectin - Check compliance, other sources / reservoir, search for alt Dx (Bx), alt Rx eg PO
Headlice
1. Organism
2. Life cycle
3. What you would tell parent
4. Treatment options
- Pediculus capitis
- Blood sucking wingless 6 legged insect. Egg laid -> hatch 1/52 -> goes through moults over ~2/52 -> mate, egg lay -> lives ~32 days
- Common, not serious health risk, direct contact. Can’t transmit disease. Not related to hygiene. Can’t live on animals
Notify school
Treat contacts
Fomites - Physical/occlusive:
- Conditioner and fine tooth comb, weekly
-Dimethicone 4% gel
- Benzyl alcohol 5% lotion
- Isopropyl myristate 50% liquid
Insecticides:
- Malathion 0.5%-1%
- Permethrin 1% lotion or cream
Oral ivermectin
Pubic lice
1. Organism
2. Treatments
Body louse
1. Organism
2. Risk factors
3. Disease transmission?
4. Mgmt
- Phthirus pubis
- Shave hair. Top permethrin 1% shampoo, 5% cream
Oral ivermectin - Pediculus humanis var corporis
- Overcrowding, poor hygiene, war, prisons, detention centres, poverty
- Rickettsiae (epidemic typhus), Bartonella
- Treat clothing - where they live. Discard, burn, hot wash, hot ison. Insecticides
Tungiasis
1. Organism
2. Life cycle/progression of infestatino
3. Mgmt
Myiasis
1. Approx life cycle
2. Types of myiasis
3. Mgmt
- Tunga penetrans - burrowing flea. Wingless flea. Lives warm dry soil
- Burrows to feet. Papule -> nodule, black crust. Lays eggs, fall out through opening. Dies within 2/52
- Manual removal. Suffocation. Topical insecticides. C+C, EDC, cryo
Myiasis
1. Pregnant fly lands, lays eggs on host -> hatch and burrow immediately. Over weeks larval stages -> emerges from hole and drops off
2. Furuncular myiasis, wound myiasis
3. Surgical. Occlusion. pO ivermectin
Sea bather’s eruption vs swimmer’s itch
1. Sea bather
- Cause
- Distribution
- mgmt
- Swimmer’s itch
- Cause
- Distribution
- Mgmt
- Nematocysts / stinging cells of small jellyfish. Get trapped under togs, pressed against skin when getting out
- Under bathers
- Dilute vinegar - neutralise toxin. TCS, NSAIDs for inflammation
- Endoparasite. Snails release cercariae (trematodes/larvae) -> penetrate skin ->pruritic papules. Allergic reaction. Resolves 7-10/7
- Exposed areas
- Avoid infested areas. Symptomatic
Insect repellants and bite prevention
- Broad categories and examples
(physical, chemical, biologic, genetic vector control)
Physical vector control:
Long sleeves
Light coloured clothes
Pyrethroid sprayed clothing
Removing large areas of debris that could be inhabited by arthropods
Using nets
Staying indoors
Chemical vector control:
Widespread insecticide spray
Applying topical insect repellant
Biologic prophylaxis:
Fish species and nonpathogenic bacteria in water reserves that consume mosquito larvae
Genetic vector control:
Genetically engineered male mosquitoes to pass fatal genes to offspring
Transferring infertility inducing bacterium to female counterparts - Wolbachia species
Bed bugs
1. Organism name
2. Life cycle
3. Risk factors
4. Tell pt how to look
5. mgmt
- Cimex lectularius
- Blood sucking wingless insect, nocturnal. Can feed off other hosts (bat, chicken, other domestic)
Can live 6/12
Adult -> lay egg, hatch 5-10/7 -> goes through moults -> adult ~3/52 - Shared accom, overcrowding, accom w high rates turnover
- ~Size apple seed. Hide in dark. Mattress seams, behind headboard, wall cracks. Indirect signs - faecal specks, blood spots, cast skin
- Symptomatic for skin
Environmental - integrated pest mgmt
Bird mites
1. 2 species
2. Approx life cycle
3. Mgmt
- Dermanyssus, Ornithonyssus
- Completed on birds. Can’t complete in humans. Nuisance bites. Die within 3/52 without bird meal
- Identify and remove bird nests. Prevent birds coming back. Top lyclear. Wash soap and water, antipruritics
Strongyloidiasis
1. Life cycle
2. Risk factors
3. Cutaneous features
- Can live in humans 30 years with min Sx…
Life cycle either in humans or in environment
Humans: contaminated soil -> enter lungs -> cough up -> intestines. ecome adult worms - Extremes of age, malnutrition, ATSI, immunosuppressed, immigrants from endemic
- Ground itch. Mild rash
Larva currens: Strongyloides autoinfection, recurrent rashes. Starts perianal, spreads and itches. Lasts hours then subsides
Periumbilical thumbprint ecchyomses
Filariasis
1. Pathogenesis
2. Acute Sx
3. Chronic Sx
4. Mgmt
- Mosquito bite -> larvae enter lymphatics -> when mature, mate in LN. Release microfilariae
- Ascending adenolymphangitis. Orchitis, epididymitis.
- Lymphoedema, elephantiasis, hydrocoeles, chyluria. Fissures, ulcers
- Lymphoedeema stuff
Diethylcarbamazine 6mg/kg/day 12 days
MUST exclude onchocerciasis first (Mazzotti reaction)
Onchocerciasis
1. Organism
2. Approx transmission and life cycle
3. Spectrum of clinical features
4. Ix:
- Ocular
- Skin
- M one
5. Treatment
What is mazzotti reaction
- Onchocerca volvulus
- Fly - abrades skin, makes blood - larvae transmitted via proboscis - enter, take 12/12 to mature. Nodules close to skin surface
- S/C nodules
Pruritic papular dermatitis
Hanging groin. Depigmentation. Lichenified onchodermatitis - Eyes - slit lamp. See microfilariae anterior chamber
Skin snips - superficial dermis. Place in saline. Visualise microfilariae as they emerge
- Mazzotti. 50mg DEC - get itchy within 15 mins - Ivermectin single dose 3-12/12ly
Mazzotti: Sx, after DEC. Microfilariae die. Cause urticaria, fevers, LN, hypotension, arthralgias, oedema, pain
Cutaneous larva migrans
1. Organism
2. What is it?
3. Mgmt
- Animal hookworm - ancyclostoma
- Accidental penetration animal hookworm, can’t complete life cycle
- Self limiting. Resolves 4-8/52
Cryo
Albendazole. Ivermectin
Leishmaniasis
1. Life cycle
2. Organisms Old vs New world
3. Organisms:
- Visceral DIC
- Cutaneous TMM
- Diffuse AA
- Mucocutaneous BP
4. Look at notes clinical pres: cutaneous, mucocutaneous, visceral (kala azar)
5. Rx
- Transmitted sandfly -> bite, injects promastigote -> phagocytosed by macrophage. (transformed to amastigote) -> multiply, infect other cells
Incubation:
weeks to 2/12 cutaneous
3-9/12 to years for visceral, mucocutaneous - Old - DAMIT.
New - B MAC - DIC - Donovani, Infantum, Chagasi
TMM - tropica, major, mexicana
AA - aethiopica, amazonensis
BP - braziliensis, peruviana - Will resolve in months depending on type
Prevention (review notes)
Sodium stibogluconate IL, IV, IM
Meglumine antimoniate
Miltefosine
Paromycin
Pentamidine
Amphotericin B
Cryo
PDT
