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Questions and Answers
What is the primary vector responsible for transmitting volvulus to humans?
What is the primary vector responsible for transmitting volvulus to humans?
Which type of onchocerciasis skin disease is characterized by large areas of wrinkled, thin, dry inelastic skin?
Which type of onchocerciasis skin disease is characterized by large areas of wrinkled, thin, dry inelastic skin?
In chronic papular onchodermatitis, which areas of the body are most commonly affected?
In chronic papular onchodermatitis, which areas of the body are most commonly affected?
What distinguishes palpable onchocercal nodules (onchocercomas) in terms of their contents?
What distinguishes palpable onchocercal nodules (onchocercomas) in terms of their contents?
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What skin feature is associated with onchocercal depigmentation?
What skin feature is associated with onchocercal depigmentation?
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What causes pediculosis capitis?
What causes pediculosis capitis?
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Which method is NOT effective in treating pediculosis capitis?
Which method is NOT effective in treating pediculosis capitis?
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Where are nits most commonly found on the head?
Where are nits most commonly found on the head?
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What is the main risk factor for contracting jiggers?
What is the main risk factor for contracting jiggers?
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Which of the following treatments is NOT used for cutaneous larva migrans?
Which of the following treatments is NOT used for cutaneous larva migrans?
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Which population is particularly susceptible to pediculosis capitis?
Which population is particularly susceptible to pediculosis capitis?
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What symptom is commonly associated with jigger infestation?
What symptom is commonly associated with jigger infestation?
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How long should hair not be washed after applying certain treatments for pediculosis capitis?
How long should hair not be washed after applying certain treatments for pediculosis capitis?
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Which hookworm larvae is primarily associated with cutaneous larva migrans?
Which hookworm larvae is primarily associated with cutaneous larva migrans?
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What is a potential side effect of using Lindane for treating pediculosis capitis?
What is a potential side effect of using Lindane for treating pediculosis capitis?
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What is a common complication associated with jigger infestation?
What is a common complication associated with jigger infestation?
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What is the primary clinical feature of pediculosis capitis?
What is the primary clinical feature of pediculosis capitis?
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Which statement about nits in schools is true?
Which statement about nits in schools is true?
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What is a distinguishing feature of onchocerciasis?
What is a distinguishing feature of onchocerciasis?
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What method is suggested for preventing jigger infestation?
What method is suggested for preventing jigger infestation?
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Which of the following statements about cutaneous larva migrans is incorrect?
Which of the following statements about cutaneous larva migrans is incorrect?
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What is the primary living environment of Pediculus humanus corporis?
What is the primary living environment of Pediculus humanus corporis?
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Which clinical feature is commonly associated with pediculosis corporis?
Which clinical feature is commonly associated with pediculosis corporis?
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Which diagnostic approach differentiates pediculosis corporis from scabies?
Which diagnostic approach differentiates pediculosis corporis from scabies?
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What characterizes the blue-gray hemorrhagic macules in pediculosis pubis?
What characterizes the blue-gray hemorrhagic macules in pediculosis pubis?
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What is a recommended therapy for pediculosis pubis?
What is a recommended therapy for pediculosis pubis?
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Which statement about lice survival without a blood meal is correct?
Which statement about lice survival without a blood meal is correct?
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What is the main mode of transmission for pediculosis pubis?
What is the main mode of transmission for pediculosis pubis?
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What primary symptom do patients with pediculosis pubis usually identify?
What primary symptom do patients with pediculosis pubis usually identify?
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What is one of the early clinical presentations of onchocerciasis?
What is one of the early clinical presentations of onchocerciasis?
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Which symptom is associated with late-stage onchocerciasis?
Which symptom is associated with late-stage onchocerciasis?
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What is the significance of identifying microfilariae in skin snips?
What is the significance of identifying microfilariae in skin snips?
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Which complication may arise from onchocerciasis eye disease?
Which complication may arise from onchocerciasis eye disease?
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Which treatment is effective in killing microfilariae but not adult worms in onchocerciasis?
Which treatment is effective in killing microfilariae but not adult worms in onchocerciasis?
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Which prevention method is recommended to avoid onchocerciasis?
Which prevention method is recommended to avoid onchocerciasis?
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What describes the general outlook for onchocerciasis in some regions?
What describes the general outlook for onchocerciasis in some regions?
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Which statement about the treatment of onchocerciasis is correct?
Which statement about the treatment of onchocerciasis is correct?
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What is the primary reason papular urticaria is more common in children than adults?
What is the primary reason papular urticaria is more common in children than adults?
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Which of the following clinical features distinguishes papular urticaria?
Which of the following clinical features distinguishes papular urticaria?
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What histopathological finding is characteristic of papular urticaria?
What histopathological finding is characteristic of papular urticaria?
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What complication can arise from scratching lesions of papular urticaria?
What complication can arise from scratching lesions of papular urticaria?
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Which measure is NOT recommended to prevent papular urticaria?
Which measure is NOT recommended to prevent papular urticaria?
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What role do topical steroid creams play in the management of papular urticaria?
What role do topical steroid creams play in the management of papular urticaria?
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Which of the following statements about papular urticaria is incorrect?
Which of the following statements about papular urticaria is incorrect?
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Which group of individuals may experience papular urticaria when exposed to new environments?
Which group of individuals may experience papular urticaria when exposed to new environments?
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Study Notes
Parasitic Infestations
- Parasitic infestations include pediculosis, scabies, myiasis, tungiasis, cutaneous larva migrans, and onchocerciasis.
Pediculosis
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Pediculosis is an ectoparasitosis caused by blood-sucking, wingless insects (lice).
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Human infestations are caused by Pediculus humanus capitis (head lice), Pediculus humanus corporis (body lice), and Phthirus pubis (pubic lice).
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Pediculosis capitis is commonly found on the head and is also known as head lice.
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Pediculosis corporis affects the body or clothes.
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Pediculosis pubis is caused by Phthirus pubis and affects the pubic area.
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Pediculosis Capitis is common in children.
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It is spread by head-to-head contact and shared combs/hats.
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Often seen in epidemics among school-age children.
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Also common in homeless people.
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Lice live on the scalp and suck blood.
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They firmly attach their eggs (nits) to the hair shaft.
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The head louse is about 3-4 mm long.
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Clinical features in Pediculosis capitis include pruritic eruption on the back of the scalp and nape, excoriations, and secondary infections.
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Hairs may become matted from repeated scratching.
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Lice are sometimes identified when combing the hair.
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Nits are commonly found in the retro-auricular region.
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Look for nits on hair shafts and lice on the scalp to diagnose Pediculosis capitis.
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Effective treatments for Pediculosis capitis include pyrethrins and synthetic permethrin (1% and 5% cream).
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Malathion 0.5% lotion—an effective treatment but can irritate the eyes.
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Lindane, or gammabenzene hexachloride, is widely used but has a high potential neurotoxicity.
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Crotamiton (Eurax) is also a treatment option.
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Nits are a continuing problem to manage.
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Many schools ban children with nits.
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If present, retreatment is reasonable a week or so later.
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Combing with a fine-toothed comb aids in treatment.
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Pediculosis corporis: Same pediculicides as for Pediculus humanus capitis can be used.
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Lice can survive in clothing for a month without blood meals.
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Disinfect clothing and bedding (boiling, hot ironing).
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Pediculosis pubis: Found in the pubic region and hairy areas of the legs, abdomen, chest, axillae, and arms.
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Spreading is through close physical contact.
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Commonly transmitted through sexual contacts.
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Lice and nits are present in the hair, with symptoms similar to that of body lice.
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Patients often report moving lice in pubic hair often accompanying pruritus.
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Nits are typically found on pubic hair but may sometimes be found elsewhere on the body.
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Feeding sites on the body may become distinctive blue-gray hemorrhagic macules.
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These macules, often called maculae cerulenne, are commonly found on the sides of the trunk and inner thighs.
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Malathion lotion and permethrin cream/shampoo are the preferred treatment choices for Pediculosis pubis.
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Malathion sticks well to the hair to help prevent re-infection.
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Lindane lotion/shampoo is also effective.
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Treatment application should be repeated a week later.
Scabies
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Scabies is a highly pruritic skin infestation caused by Sarcoptes scabiei var hominis.
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It's a host-specific mite.
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Prevalence higher in children and active individuals.
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Spread occurs through direct contact with an infected person (not from inanimate objects).
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Mites can survive outside a host for up to 3 days.
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Mites burrow into the epidermis (top layer of skin) after prolonged contact with an infected individual.
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The S. scabiei female mite burrows through the stratum corneum at the rate of about 2 mm per day.
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The female lays 2 or 3 oval eggs daily and the life cycle of the mites lasts 30 days, all within the epidermis.
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The mites feed on dissolved skin tissue.
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The feces of the mites are left behind within the skin's layers and cause irritation.
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On initial infestation, a delayed type IV hypersensitivity reaction occurs over 4–6 weeks.
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Symptoms include intense pruritus or itching, sometimes worse at night.
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Lesions appear differently in adults and infants.
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Adults: Lesions typically appear on the wrists, interdigital web spaces of the hands, feet, axillae, elbows, waist, buttocks, and genitalia.
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Infants and children: Lesions may appear on the face, scalp, neck, palms, and soles.
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Primary lesions include small papules, vesicles, and burrows.
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Burrow are pathognomonic for S. scabiei and are linear, slightly raised.
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Treatment options include scabicidal agents, antipruritic medication(e.g. sedating antihistamine), and antimicrobial medication if a secondary infection is present.
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Topically applied scabicidal agents are usually repeated after 7 days.
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Permethrin 5% cream is often the preferred option for infants and children.
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Lindane 1% lotion or cream, sulfur 6% in petrolatum, and crotamiton (Eurax) 10% cream or lotion are also used.
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In some cases, an oral ivermectin treatment is given.
Myiasis
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Myiasis refers to infestation of body tissues by larvae (maggots).
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Different types of myiasis include the following,
- facultative/traumatic wound myiasis: Eggs of certain flies which have larvae in suppurating tissues.
- obligate cutaneous myiasis: Creeping eruptions and furuncular myiasis.
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Furuncular myiasis presents with boils or pustules that have a central punctum.
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A serosanguinous (blood tinged) discharge accompanies such sores.
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Rapid resolution occurs when larvae are removed.
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Signs or symptoms may include rapid resolution following extraction, lymphangitis.
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Creeping eruption presents as a line of red, slightly raised tortuous lines.
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It may resemble cutaneous larva migrans infection.
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Treatment of myiasis types depends on the specific form.
Tungiasis
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Tungiasis is a disease caused by the tunga penetrans flea.
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The flea penetrates into the skin, resulting in a small, round, painful, and itching swelling.
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Secondary bacterial infection is likely to happen if not carefully dealt with.
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Prevention can occur by maintaining house and environment cleanliness and by wearing shoes.
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Treatment includes mechanical removal of the flea with a pin, followed by antiseptic dressing.
Cutaneous Larva Migrans
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Cutaneous larva migrans (CLM) is a parasitic skin infection caused by hookworm larvae, most often in tropical and subtropical locations.
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It is characterized by a snake-like or linear track that follows the larva's movement.
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The track is often itchy and elevated.
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It is common in areas with warm environments (tropical, subtropical) and often found in those who are close to animals, like farmers and gardeners.
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The eruption arises where the larvae penetrate the skin.
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The bites usually cause mild to intense itching followed by a non-specific eruption.
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The rash is often snake-like stretching up to 3-4 cm from the penetrating site.
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Usually a self-limiting infection, where humans are not the definitive host.
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Thus, the larvae die in most cases, and lesions resolve within 4–8 weeks without treatment.
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Treatment is not necessary in most cases, but if treated, helminthics like tiabendazole, mebendazole, albendazole, and ivermectin can be used.
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Additional treatments include liquid nitrogen cryotherapy or carbon dioxide laser treatment, antihistamines, topical corticosteroids, and antibiotics if a secondary bacterial infection is present.
Onchocerciasis
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Onchocerciasis is a chronic, progressive skin, eye, and neurological disease.
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It's caused by the filarial nematode Onchocerca volvulus.
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Often called “river blindness.”
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Initial infestations often happen in childhood, with little to no apparent symptoms for a varying length of time.
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Neurologic manifestations are common in children.
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The disease is transmitted to humans through the bite of a female blackfly (Simulium spp).
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Characteristics of the skin disease include widespread, itchy, eczema-like rash that progresses into vesicles and pustules.
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Chronic papular onchodermatitis presents as itchy plaques.
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The characteristic presentations in Onchocerciasis include acute or chronic onchodermatitis (itchy, eczematous rash with macules and papules), subcutaneous nodules (oncocercoma), lymphadenopathy, and sowda (sever pruritus).
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Later symptoms may include lizard skin—dry, scaly skin resembling ichthyosis, hanging groin—a sac of atrophic skin, scarring, atrophy, elephantiasis, and leopard skin (depigmentation in the skin).
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Eye disease occurs when microfilariae in the cornea and back of the eye die, often resulting in inflammation and bleeding.
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Early symptoms include itching, redness, pain, and photophobia.
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Continued inflammation can cause keratitis, sclerosis, blurring of vision, night blindness, glaucoma, visual field loss, and eventually blindness.
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Diagnoses are aided by identifying microfilariae in skin snips, a chain reaction, and seeing adult worms in excised nodules.
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To confirm, blood or eye analysis can also be used.
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Preventative measures are key to fighting the transmission through the bite of black fly.
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Such measures include using insect repellents, wearing long-sleeved shirts, and pants.
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Ivermectin (oral) kills microfilariae, but not adult worms.
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It should be administered every three months.
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Other potential treatments for the disease include suramin and moxidectin.
Papular Urticaria
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Papular urticaria is a papulovesicular reaction to insect bites, more common in children.
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It's also known as persistent insect bite reaction.
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Children get it more often due to a lack of desensitization to insect bites.
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Adults can still get it, especially those traveling to new areas or environments.
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A reaction develops a few months to years after the initial bite.
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The initial bite is often unnoticed.
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Papules are itchy red bumps present, often in clusters.
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The bumps most often occur on the legs and other exposed areas like forearms and face.
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They can range from 0.2 to 2 cm in diameter and have small central punctuate marks.
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Crops of fluid-filled blisters are possible.
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New lesions and new bites can sometimes trigger itching in others.
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Complications can include infected insect bites leading to cellulitis and rarely bacteremia.
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Scratching can also lead to secondary infections like impetigo.
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Localised vasculitis is also a possible complication.
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Papular urticaria is typically diagnosed clinically.
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Biopsy results sometimes can help with the diagnosis.
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Histological presentations include mild dermal oedema, erythrocyte extravasation, and eosinophils.
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Vasculitic markers in tissue might occasionally be present.
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Preventative measures include protective clothing, and insect repellents.
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Insect repellents and avoiding insect bites is part of the treatment too.
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Symptoms can sometimes be alleviated by topical steroid creams.
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Antibiotic or antiseptic creams can also aid in treating the presence of secondary infections in the skin.
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Description
Test your knowledge on various parasitic diseases, their causes, symptoms, and treatments. This quiz covers topics like onchocerciasis, pediculosis capitis, and jiggers. Delve into the complexities of these infections and understand their effects on humans.
