SDL Helminth causes of fever and skin rash

Helminths causing fever and skin rash

Ascaris lumbricoides, Wuchereria bancrofti, Brugia malayi, Brugia timori, Onchocerca volvulus, Ancylostoma braziliense, Ancylostoma caninum, Strongyloides stercoralis, Trichinella spiralis, Trichuris trichiura, Schistosoma spp, Taenia spp, Echinococcus spp

Filarial fever causative agents

Wuchereria bancrofti, Brugia malayi, Brugia timori

Filarial fever transmission

Spread by mosquito bites carrying infective larvae

Filarial fever life cycle

Microfilariae ingested by mosquito, develop to L3 larvae, transmitted to humans, mature in lymphatics, adults live 5–7 years producing microfilariae

Filarial fever signs

High fever, rigors, tremors, lymphangitis, lymphadenitis, transient edema, conjunctival congestion, cough, headache, body ache

Elephantoid fever

Fever associated with elephantiasis in filarial infection

Filarial fever recurrence

Fever attacks recur for years, sometimes decades after leaving endemic area

Filarial fever complications

Lymphedema, elephantiasis, hydrocele, tropical pulmonary eosinophilia

Tropical pulmonary eosinophilia

Filarial complication with cough, wheezing, breathlessness, eosinophilia, high IgE

Filarial fever pathophysiology

Due to toxins/allergens from worms causing sterile lymphangitis, histamine release causing rigor, lymphatic obstruction causing edema

Elephantiasis pathophysiology

Repeated lymphangitis and obstruction leading to lymph stasis, fibrosis, non-pitting edema, thickened cracked skin, secondary infections

Filarial fever diagnosis

Blood smear for microfilariae (night collection), serology for antifilarial antibodies, antigen detection tests

Filarial fever treatment

Diethylcarbamazine (DEC) kills adult worms and microfilariae, ivermectin kills microfilariae, albendazole used in combination therapy

Filarial fever prevention

Avoid mosquito bites by nets, repellents, protective clothing, vector control

Cutaneous larva migrans etiology

Caused by dog and cat hookworms Ancylostoma braziliense and Ancylostoma caninum

Cutaneous larva migrans transmission

Larvae from contaminated soil penetrate human skin

Cutaneous larva migrans pathogenesis

Larvae migrate in epidermis but cannot penetrate basement membrane in humans, causing superficial serpiginous tracks

Cutaneous larva migrans clinical features

Pruritic erythematous papules, serpiginous creeping eruptions, secondary bacterial infection possible

Larva currens

Rapidly moving lesion caused by Strongyloides stercoralis

Other causes of creeping eruptions

Gnathostomiasis, sparganosis, Fasciola, Paragonimus, Hypoderma flies

Cutaneous larva migrans diagnosis

Clinical based, biopsy rarely shows larvae, eosinophilia rare unless Loeffler’s syndrome develops

Cutaneous larva migrans treatment

Albendazole 400 mg daily for 7 days, cryotherapy with ethyl chloride for localized lesions

Onchocerca volvulus disease

Onchocerciasis (river blindness)

Onchocerca volvulus transmission

Day-biting blackflies (Simulium spp) transmit infective larvae during blood meal

Onchocerca volvulus life cycle

Larvae penetrate skin, develop into adults in subcutaneous nodules, females produce microfilariae for years, microfilariae migrate to skin and eyes, ingested by blackflies

Onchocercomas

Subcutaneous nodules containing adult Onchocerca worms

Onchocerca volvulus pathology

Adult worms cause nodules, microfilariae cause dermatitis, lymphadenitis, eye damage

Onchocerciasis dermatitis types

Hyper-reactive (sowda) with intense pruritus, hypo-reactive with mild dermatitis

Onchocerciasis skin changes

Lichenification, thickened cracked skin, loss of elasticity, “lizard skin” appearance

Onchocerciasis eye complications

Keratitis, chorioretinitis, iridocyclitis, optic atrophy, blindness

Onchocerciasis pathophysiology

Inflammatory response to dead microfilariae and Wolbachia antigens, Th2 response kills larvae but releases antigens causing inflammation

Onchocerciasis social impact

Disfigurement, isolation, low self-esteem, blindness leading to socioeconomic burden

Onchocerciasis diagnosis

Skin snip microscopy for microfilariae, serology, PCR, nodules examination

Onchocerciasis treatment

Ivermectin kills microfilariae, doxycycline targets Wolbachia endosymbionts, DEC contraindicated due to severe reactions

Onchocerciasis prevention

Vector control of blackflies, mass drug administration with ivermectin

Helminth fever mechanism

Fever due to immune response, toxins, allergens, secondary bacterial infections, cytokine release

Helminth skin rash mechanism

Larval migration in skin, immune response to antigens, inflammatory reaction to dead larvae, Wolbachia release in filarial infections

Risk factors for helminth fever and rash

Living in endemic tropical areas, poor sanitation, barefoot walking, exposure to contaminated soil, mosquito or blackfly bites

Diagnosis of helminth infections

Blood smear, antigen detection, serology, eosinophilia, clinical features, biopsy in skin lesions

Management of helminth infections

Anthelmintics (DEC, albendazole, ivermectin), supportive care, antibiotics for secondary infections, surgical removal of nodules if needed

Prevention of helminth infections

Vector control, protective clothing, footwear, hygiene, mass drug administration, health education