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What is River blindness is caused by? and explain in detail?
Ans. A. Onchocerca volvulus. (Ref. Harrison 18th/Table. E16-2).Tissue nematodes:Onchocerca volvulusFemale blackfly bileHyper pigmented skin and river blindness (black flies, black skin nodules, "black sight"); allergic reaction to microfilaria possibleIvermectin (ivermectin for river blindness)LoahaDeer fly, horse fly, mango flySwelling in skin, worm in conjunctivaDiethylcarbamazinewucnerena ooncrowFemale mosquitoBlocks lymphatic vessels: elephantiasis; takes 9 mo-1 yr after bite to become symptomaticDiethylcarbamazineTaxocara cantsFecal-oralVisceral larva migransAlbendazole or mebendazole ROUNDWORM INFECTIOUS Life-Cyde Hosts Diagnosis Geographic DistributionIntermediate (Transmission) Parasite StageBody Fluid or TissueSerologic Tests ParasiteDefinitiveOtterIntestinal RoundwormsEnterobius vermicularis (pinworm)Temperate and tropical zonesFecal-oralHumansOvaPerianal skin "Cellophane tape"Trichuris trichiura(whipworm)Temperate and tropical zonesSoil, fecal-oralHumansOvaFeces--Rectal prolapseAscoris lumbricoids (roundworm of humans)Temperate and tropical zonesSolfocaForaiHumansOvaFeces--Sx of pulmonary migrationAncylostoma duodenale (Old World hookworm)Eurasia, Africa, PacificSoil-SkinHumansOva/larvaeFeces--Sx of pulmonary migration, anemiaNecator americanus (New World hookworm)US, Africa. worldwideSoil-SkinHumansOva/larvaeFeces--Sx of pulmonary migration, anemiagration. anemiaStrangyloids stercoralis (strongyloidiasis)Moist tropics and subtropicsSoil-SkinHumansLarvaeFeces, sputum duodenal FluidEIADissemination in immunodeficiencyCapillaria philippinensisSoutheast Asia Taiwan. EgyptRaw fishBirds Ova, larvae, adultsFeces--Malabsorption/ autoinfection, biopsyTissue Roundworms Trichinella spiralis (trichinellosis)WorldwideSwine/ humansSwine/ humansLarvaeMuscleEIAMuscle biopsyWuchereris bancrafti (Filariasis)Coastal areas in tropics and subtropics MosquitoesHumansMicrofilariaeBlood lymph nodesEIA RAPIDNocturnal periodicityBrugia malayl (filariasis)Asia, Indian SubcontinentMosquitoesHumansMicrofilariaeBloodEIA RAPIDNocturnalLoa loa (African eye worm)West and Central AfricaMango flies (Chrysops)HumansMicrofilariaeBlood--May be visible in eye diurnalOnchocerca volvulus (river blindness)Africa, Mexico, Central and South AmericaBlackfliesHumansAdults/ larvaeSkin/eye--Examine nodules or skin snipsDracunculus medinensis (gulnea wormAfricaCyciopsHumansAdultys/ larvaeSkin--May be visible in lesionAnglostrongylus contonensisSoutheast asia, Pacific CaribbeanSnils/ slugs, shrimp/ fishRatsLarvaeCSF rarely found)--Eosinophilic meningitisLarva Migrans Syndromes Ancylostoma braziliense (creeping eruption}Tropical and temperate zonesSoil-SkinDcgs/ cats. humansLarvaeSkin--Dog and cat hookwormToxocara canis and cot) (Visceral larva migrans)Tropical and temperate zonesSoil, fecal-oralDogs/ cats, humanslarvaeViscera, CNS, eyeEIAAlso caused by roundworms of other speciesAlso know: ManifestationsCausative parasite1"Visceral larva migrans"Toxocara canis2"Larva currens" Strongyloides stercoralis3"Cutaneous larva migrans"- Strongyloides larva- Hookworm larvae (E.g. A. braziliense and A. caninum),- Spiruroid larva (Gnathostoma spinigerum), and- Migrating flying maggot, Gasterophilus.4Pruritus aniEnterobius vermicularis5Rectal prolaspseTrichuris trichura6MyocarditisTrichinella spiralis7Tropical Pulmonary eosinophiliaWuchereria bancrofti8Calabar swellingLoa-loa9River blindnessOnchocercus volvulus10Black water feverPlasmodium falciparum11Painless hematuriaSchistosoma japonicum12"Ground itch" (Ancylostome dermatitis)Ancylostoma duodenale