Ectoparasitic Disease • An ectoparasite is an organism that derives benefit or fulfills a life cycle requirement through interaction with the outer, or cutaneous, surface of the host.
Order Hemiptera (true bugs) Family Cimicidae Cimex lectularius (Human Bedbug) Temperate climates 5 to 7 mm adults, 1.5 mm nymphs Cimex hemipterus Tropical climates. Bed Bugs
Bed Bugs • They hide in cracks ad crevices with eggs hatching every 4 to 10 days. • Heavy infestations produce a pungent odor. • Usually bites at night on exposed areas of skin. • Attracted to warmth and CO2. • Has a complete blood meal in 5-10 minutes. • The bite is painless and anticoagulant is injected by the insect.
Bed Bugs • May have several bites in a row. • Breakfast, Lunch, and Dinner. • Usually appears as a wheal with a central hemorrhagic punctum. • Have not been found to be competent vectors for disease. • Management of bedbug infestations start with identification of the bug and thus the primary host followed by calling pest control.
The suborder Anoplura (Sucking Lice) 200 species Pediculosis Capitis Pediculus humanus var. capitis Pediculosis Corporis Pediculus humanus var. corporis Pediculosis Pubis Phthirus pubis Lice
Pediculosis Capitis • Female life span is 1 month and lays 7-10 eggs (nits) daily. • Eggs hatch in 8 days. • Can survive 55 hours without a host. • Lice do not jump, fly, or use pets as vectors. • Nits do fluoresce a pale blue under a woods lamp and are cemented securely to the hair shaft unlike dandruff. • Using a fine toothed nit comb is more efficient for detecting lice compared to visual inspection.
Finding nits without lice does not mean active infection and may persist for months after successful therapy. Many nits found ¼ inch from the scalp indicates active infection. Pediculosis Capitis
Pediculosis Capitis • Topical permethrin, pyrethrin, and malathion are all effective in more than 95% of cases. • Permethrin creams appear the least toxic to humans and are considered first line therapy despite emerging resistence. • CDC recommends a second treatment application in 7 to 10 days. • Lindane shampoo is not first line due to potential neurotoxicity and widespread resistance.
Pediculosis Capitis • Suffocating the Lice with oils or silicone based jellies, electrocuting them with electric combs, and high volume heated air blown on the scalp have been unproven treatments. • Household members should be examined and treated if infested with bunkmates treated prophylactically.
Pediculosis Corporis • Largely a problem of the homeless and is a reflection of personal hygiene. • Associated diseases • Louse-borne typhus • Rickettsia prowazekii • Trench fever • Bartonella quintana • Relapsing fever • Borrelia recurrentis
Pediculosis Corporis • Itching is the chief complaint. • The patient should be bathed thoroughly with infested clothing and bed linen heat washed and dry cleaned, or discarded. • Can live as long as 30 days away from the host. • May use topical insecticides if nits are found.
Pediculosis Pubis • Most crab lice infestations in young adults result from sexual contact. • Itching is the chief complaint, usually involving the pubic area or axillae but may involve body hair excluding the scalp. • In children the eyelashes (pediculosis ciliaris) may be involved. • Should screen for other STD’s
Pediculosis Pubis • Treatment • Permethrin 1% cream or Pyrethrins with piperonyl butoxide applied to affected areas and washed off after 10 minutes. • Malathion 0.5% lotion applied to affected areas and washed off after 8-12hours. • Ivermectin 250mcg/kg orally, repeat in 2 weeks. • Treat all contacts at the same time.
Mites • From the Order Acarina and class Arachnida. • Only Scabies and Demodex (Follicle mites) parasitize humans. • Mites that affect humans which do not burrow into human skin. • Chiggers • Animal Mites • Food, Grain, and Straw Mites • Follicle Mites
Chiggers • The harvest mite or red bug. • Family Trombiculidae • Lives on grass and shrubs and is prevent in the southern U.S. • The larva attaches itself to passing animals or humans, feeds then drops off. • Hours later an extremely pruritic, erythematous papule appears. • Chiggers are vectors for: • Scrub Typhus in southeastern Asia • Orientia tsutsugamushi
Follicle Mites • Demodex folliculorum • Demodex brevis • Mites which inhabit the pilosebaceous follicles, especially the face and eyelids of humans and some animals. • Usually considered harmless saphrophytes.
Scabies • Sarcoptes scabiei var. hominis • 300 million people affected worldwide. • Can occur in epidemics. • More common in temporate climates and in the winter. • Transmission of scabies is from direct contact. • Children get it from there mothers. • Adults usually get it through sexual contact. • The mites can survive off of there host for 24-36 hours but can survive much longer in colder conditions with relatively high humidity.
Scabies • Once fertilized the female burrows into the epidermis where it lays up to 10-25 eggs over a month before dying. • The eggs hatch in 3 to 4 days and molt three times before leaving the burrow. • Symptoms usually appear 3-4 weeks after the primary infection with itching and redness as a reaction to the eggs and feces.
Crusted Scabies or Norwegian Scabies • Occurs in patients with compromised cellular immunity such as AIDS, Leprosy, or Lymphoma. • Because of the lack of cellular immunity the skin becomes crusted with hundred of thousand of mites. Itching maybe minimal or absent.
Scabies • Confirmation of infection can sometime be done by finding the mite or eggs in scrapings from burrows or papules. • Treatment usually includes topical Permethrin or oral Ivermectin. • Treat all close contacts at the same time. • Would wash clothes and linens as well.
Ticks • 899 species in the world. • 90 species in the US • 80 ssp. in the Family Ixodidae “HardTicks” • 10 ssp. in the Family Argasidae “ Soft Ticks”
The Differences Between Hard Ticks And Soft Ticks? Feature Hard Tick Soft Tick Scutum (dorsal shield) present not present Capitulum (mouth parts) anterior ventral visible from above not visible from above Nymphal stages one several Adult feeding time several days 30-60 min. Female blood meals one several Egg laying events one several Total eggs laid 3,000-8,000 400-500 Ticks
The Lone Star Tick Southeastern and South-central U.S Hosts include ground-dwelling birds, small mammals, and large mammals such as deer, livestock, humans, and pets Diseases Tularemia Human Monocytic Ehrlichiosis Southern tick-associated rash illness (STARI) Borrelia lonestari Amblyomma americanum
The Gulf Coast Tick Diseases None (but bites aggressively) Ambylomma maculatum
The American Dog Tick Eastern U.S., in Colorado, and the Pacific Northwest Larvae and nymphs feed on small mammals, especially meadow mice. Adults feed on deer and other wild animals, livestock, pets, and humans. Diseases RMSF (Primary Vector) Tick paralysis Tularemia Anaplasmosis Dermacentor variabilis
The Black-legged Tick Eastern U.S. Larvae feed primarily on white-footed mice. Nymphs feed primarily on bird, lizards, small mammals, humans, and pets. Adults feed readily on deer. Diseases Lyme Disease (primary vector) Human Granulocytic Ehrlichiosis (Anaplasmosis) Babesiosis Ixodes scapularis Ixodes pacificus (Western Black-legged Tick) transmits Lyme disease on the west coast.
The Brown Dog Tick Southern U.S. Dogs are the primary host for larvae, nymphs, and adults. Diseases Possibly RMSF Rhipicephalus sanguineus
The Rocky Mountain Wood Tick Rocky Mountains and adjacent areas. Diseases RMSF Colorado Tick Fever Tularemia Tick Paralysis Demacentor andersoni
The Relapsing Fever Tick Western, Southwestern, and South Central U.S. Mainly feed on rodents. Disease Relapsing fever Ornithodoros hermsi and Ornithodoros turicata