| blood and tissue nematodes (round worms) | Wuchereria bancrofti | Brugia malayi [Malayan filariasis] | Loa Loa [African eye worm] | Onchocerea volvulus (convoluted microfilaria) | Dracunculosis ,Medina worm ,Guinea worm |
| habit | lymph vesels and glands of man | lymphatics above diaphragm | SC tissue (free migrating) , appear under conjunctiva | skin (encapsulated in fibrous nodules) in SC tissue | cutaneous and SC tissue of man and animals |
| microfilaria | *loose sheath *free from nuclei | *loose sheath e 2 distinct nuclei in tail | tight sheath ,full of nuclei | no sheath *tail free from nuclei | *adult worm e triangular mouth ,with 6 papillae around it *gravid female uterus show huge tube ,ovary packed e larva *** D.H >man ,dog ,monkey ,horse ,cattle *** I.H >cyclops ,infective stg :larva in cyclops |
| periodicity | nocturnal | non periodicity (nocturnal) | diurenal periodicity (in blood) | non periodicic (in skin & SC) | |
| vector | culex Aedes ,Anopheles | mansonioides ,Aedes ,Anopheles | chysops (horse fly) | ||
| pathogenicity | *due to adult worm (microfilariae may cause slight or no pathogenicity) >inf lesions ,cellular infilteration ,eosinophilia >fibrosis of lymphatics >varricose *** ELAPHANTIASIS : as result of continous infection affect legs & genitalia where marked growth of fibrous tissue around dead worms also marked hypertrophy of skin. | and migrate from place to place in SC under skin ,,(appear under conjunctiva ,it may go from one eye to another through bridge of nose) | *both adult worms & microfilaria are found in in skin but not in blood * sc tissue usu encapsulated in fibrous nodules in any part of body ,*in african :lesions in trunk things and arms *in american : :head and shoulders lesions are most seriuos and responsible for much blindness | when worm reach skin >liberate toxic substance >blister is fromed symptoms :allergic Rx due to rupture of blister (appear during operative removal of worms or when it broken during extn and larva escape to Sc tissue ** 2ry bacterial infection may result in abscess formatn | |
| diagnosis | 1-exam of blood (taken at night for microfilaria ) 2-serological test a-intradermal skin test using filarial ext as antigen b- ELISA 3-Hetrazan provocation give 100 mg (small dose) >micro fil appear in blood ein 45 m ,so facilitate diagnosis at any time of day 4-X ray examn for calcified adult worms in lymphatics | *microfilaria demonstratn in aspirate of nodules or skin snips and adult in excised nodule | 1-demonstratn adult worm under skin 2-X ray examinatn of dead calcified worms 3-demonstratn of larvae in blisters or in water after their discharge 4-I.D test using antigenic ext of worm 5-complement fixatn test 6-eosinophilia (10%) | ||
| distribution | topical & subtropical countries | far east | tropical africa | Egypt ,sudan ,india ,persia ,china ,Brazil ,west Africa | |
| ttt | 1-DEC (only ttt fro elephantiasis) given e antihistaminics or steroids 2-antibacterial drugs (for ttt of 2ry infections) | 1-surgical removal of adults seen under conjunctiva 2-DEC 2mg/kg 3 times daily for 2-3 weeks e antihistaminics | 1-surgical removel of nodule (under anaethesia) 2-DEC (hetrazan) active # microfil 3-suramin (germanin) active # adults | 1-rolling up the worm by stick , remove few cms every day (in severe inf occur if rupture of worm during operatnthus surgical removal by multible incisions after localizatn of worm by X ray) 2-Thiabendazole 3-DEC (hetrazan) and suramin | |
| life cycle | adult (lymph vessels) >microfilaria in blood >ingested by mosquito >develop till become infective larva in labium {infective stg} >bit healthy man >larva migrate to lymphatics where it develops to mature worm | in D.H >gravid female migrate in SC tissue at w it will be in contact e water (feet ,shoulder ,legs ,arms) >papule >vesicle >ulcer >in contact e water >larva discharge in water >ingested by cyclops (I.H) (water flea) inside its body cavity(metamorphose in body cavity into infective form )>ingestion of cyclops in well water >larvae release in intestine >migrate to retroperitoneal tissue where they mature | |||
| notes | larva migrans:migratn of larval nematodes in unsuitable host >larva is unable to complete normal development so distributed in tissues and remain alive for some weeks or even months >dieand destroyed by cells of host in man : 1)cutaneous larva misrans (creeping eruption) > from contact of larvae of dog and cat hookworms (Ankylostoma braziliense or A caninum) 2)Visceral larvae migrans :from contact e toxocara larvae ,that enter through intestinal tract | ||||