Filariasis Mae Marcattilio-McCracken -An endemic in tropical regions of Asia, Africa, Central/South America and Pacific Island nations: more than 120 million people infected

Filariodea-Superfamily Group#1: Lympatic Filariasis -Worms occupy lymphatic system Caused by: Wuchereria bancrofti, Brugia malayi, Brugia timori **Chronic cases may lead to the disease Elephantiasis Group#2: Subcutaneous Filariasis -Worms occupy the subcutaneous layer of the skin; fat layer Caused by: Loa loa (African eye worm), Mansonella strepocerca, Onchocerca volvulus, Dracunculus medinensis (guinea worm) Group#3: Serous Cavity Filariasis -Worms occupy serous cavity of abdommen Caused by: Mansonella perstans, Mansonella ozzardi

Transmission-Vectors Disease Parasite Vector Onchocerciasis O volvulus Blackflies: Simulium species Bancroftian filariasis W bancrofti Mosquitos: Anopheles, Aedes, Culex, and Mansonia species Malayan filariasis B malayi and B timori Mosquitos: Anopheles, Aedes, Culex, and Mansonia species Loiasis L loa Red flies: Chrysops species Mansonelliasis M streptocerca Midges: Culicoides species Dirofilariasis Dirofilaria species Mosquitos: Culex species

Life Cycle-five stages 1) Female gives birth to live microfilariae by the thousands 2) Microfilariae are taken up by the vector insect (intermediate host) during a blood meal 3) In the intermediate host, the microfilariae molt and develop into 3rd stage (infective) larvae 4) Upon taking another meal the vector insect injects infectious larvae into the dermis layer of our skin 5) Approximately one year later the larvae will molt through 2 more stages, maturing into the adult worm

Vector for Loa loa, Chrysops, feeding on human skin. Microfilariae of Mansonella perstans in peripheral blood smear.

Clinical Signs Elephantiasis: edema with thickening of the skin of underlying tissues -affects lower extremities, while ears, mm, and amputation stumps are affected less frequently skin rashes, urticarial papules, arthritis, hyper-hypopigmentation mascules, “river blindness” , abdominal pain **Different species of worm affect different parts of the body**

Diagnosis 1) I.D microfilariae on a Giemsa stained thick blood film (blood MUST be drawn at night-nocturnal due to temperature induced activity) 2) Polymerase chain reaction (PCR) and antigenic assays 3) Lymph Node aspirate-Chylus fluid may yield microfilariae 4) Imaging- CT, MRI reveals them “dancing” in Chylus fluid 5) X ray- show calcified adult worms in lymphatics

Treatment Outside U.S tx: albendazole (broad spectrum anthelminic) combined with invermectin. **combination of diethylcarbamazine (DEC) and albendazole is also effective -June 2005, clinical trials done by the Liverpool School of Tropical Medicine reported that an 8 wk course of the common antibiotic doxycycline almost completely eliminated microfilaemia . **suggested for treating elephantiasis

Prevention -Studies have demonstrated that transmission of the infection can be broken by a single dose of combined oral medicines is consistently maintained annually for approx. 7 yrs -With consistent tx, reduction of microfilariae means the disease wont be transmitted, the adult worms dies, and cycle is broken -Mass distribution of meds that kill microfilariae will stop transmission of the parasite by mosquitoes in endemic communities -Efforts of the Global Programme to Eliminate LF are estimated to have already prevented 6.6 million new filariasis cases from developing in children, and have stopped the progression of the disease in another 9.5 million ppl who have already contracted it

Sources: http://emedicine.medscape.com/article/110 9642-overview http://en.wikipedia.org/wiki/Filariasis http://entomology.montana.edu/historybug/ filariasis.htm