parasitology 3

• Onchocera volvulus
• river blindness
• in Central/South America, Central Africa

subcutaneous human filariasis

• Simulium spp. 
• vector for Onchocera volvulus 
• (river blindness)
• lay eggs/live near running water

• bites near ankles in daytime
• picks up L1 microfilariae from the skin
• releases L3

• Wolbachia spp. bacteria
• live symbiotically with Onchocera volvulus microfilariae (L1)
• --> inflammation

• Onchocercomata
• adult Onchocera volvulus live here

apathogenic

• Onchocera volvulus microfilariae
• on slide from skin snip

-> diagnostic

• using skin snips
• Onchocera volvulus only lives in skin

• Papular dermatitis
• very itchy

due to Onchocerca volvulus

Skin: puritis, papular dermatitis, Lichenification (lizard skin), depigmentation, dermal atrophy, hanging groin

Eye: sclerosing keratitis --> blindness

• skin atrophy
• 2* to Onchocerca volvulus

loss of elasticity of skin

• hanging groin
• 2* to Onchocerca volvulus

loss of skin elasticity

• depigmentation
• 2* to Onchocerca volvulus

• sclerosing keratitis
• 2* to Onchocerca volvulus

--> progressive blindness

• Wolbachia bacteria
• cause of pathology in Onchocerca volvulus

live symbiotically with microfilariae (L1)

• Ivermectin --> kills microfiliariae
• Doxycycline --> kills Wolbachia

• vector control (DDT)
• Ivermectin (2x per year)
• - blocks transmission
• - adult Onchocerca volvulus lives for 16 years

vectors in Americas kill microfilariae upon feeding

• Wuchereria bancrofti
• lymphatic filariasis
• in South America, Africa, Eastern Asia

• L1 microfilariae picked up by mosquito vector (**culex)
• (nighttime feeding - microfilariae only found in blood at nighttime)

L3 transmitted to humans

• **in cook islands, Aedes mosquito feeds in daytime
• Wuchereria bancrofti has adapted

• adult migrates to lymph nodes
• damages lymphatics
• symbiotic relationship with Wolbachia bacteria

**not 2* to lymph obstruction

• Historically:
• thick blood film to find microfilariae at night

• Now: ICT (Immuno Chromographic Test)
• --> female antigen test

• Lymphatic filariasis
• 2* to Wuchereria bancrofti

--> lymphedema/elephantiasis

• Chyluria (lymph in urine) - early
• hydrocele
• lymphedema
• elephantiasis
• filarial fevers (acute inflammatory response)

• Chyluria
• 2* to Wuchereria bancrofti

can detect infection prior to end of PPP (13 months)

• DEC
• Ivermectin with Albendazole
• DEC with Albendazole
• --> clears microfilariae (stops transmission)

surgery (for hydrocele)

• hygiene against fungal infections
• leg elevation
• skin care
• exercise