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Dirofilaria immitis. Zach mess May 2012. Background. Common name: Heartworm Definitive host: Canids Foxes, wolves, dogs, etc. Cats (less persistent) Other mammals Accidental host: Humans Transmission Mosquito bite. Geographic Distribution World wide
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Dirofilariaimmitis Zach mess May 2012
Background • Common name: • Heartworm • Definitive host: • Canids • Foxes, wolves, dogs, etc. • Cats (less persistent) • Other mammals • Accidental host: • Humans • Transmission • Mosquito bite • Geographic Distribution • World wide • More common in warm climates (mosquitoes)
Characteristics • Adults • Very long and thin • Thin alae • 3 caudal papillae • Can live 5-10 • Viviparous • Gives live birth • Males • 12-19cm long • Spiral or coiled tail • Females • 23-30cm long • Vagina just posterior to esophagus • Juveniles (microfilariae) • 200-300um • Long, pointed tails
Life Cycle Breakdown • 3rd stage filarial larvae enter body when mosquito bites • travels through blood stream • molts once to 4th stage larvae (L4) • molts again to adult • adults reside in pulmonary arteries • female worms produce microfilariae which reside in peripheral blood • mosquito bites and picks up microfilariae with blood-meal • migrate from mid-gut to Malpighian tubules (in abdomen) • microfilariaedevelpe to 1st stage larvae, then to L2 and L3 • L3 migrate to proboscis (mosquito pokey thing) • mosquito bites and deposit L3 to host • **microfilariae can be cross placental barrier to puppies but adult worms will not form, no intermediate host interaction**
Human Pathway **follows same pathway in humans** • Adults end up in smaller blood vessels in lungs • build up causing “coin-lesions”
Symptoms • Dogs / Cats • Pulmonary artery blockage • Coughing • Difficulty breathing • Coughing up blood • Exhaustion • Fainting • Weight loss • Heavy infection ~ 25 worms • Further infection can fill cavities of heart
Symptoms • Humans • Most are asymptomatic • Cough • coughing up blood • fever • chest pain • Pulmonary dirofilariasis • Dying worms produce granulomas in pulmonary arteries • Pleural effusion • Excess fluid between tissue lining lungs and chest cavity • Inflamation caused by dying adult worms • Coin lesions in pulmonary arteries
Diagnosis • Blood tests • Observe microfiliariae in blood • Parasitic antigen testin • Identification of coin lesions in lungs and pulmonary arteries • Lesions observed in chest Xray • Mostly found by accident since most are asymptomatic • Identification of nodules under skin • Examination of inflamed tissue
Treatment • Dogs / Cats • Immiticide® (Adulticide) • Anti-inflamatory drugs • Surgical removal (if necessary) • Humans • Surgical removal of lung granulomas and inflamed nodules under skin • Drugs aren’t usually needed
Prevention • Dogs / Cats • Anti heartworm medications • Flee, tick, and mosquito medications • Humans • Vector control • Bug spray
Work Cited http://www.cdc.gov/parasites/dirofilariasis/faqs.html http://www.bronchitissymptomsinadults.org/ http://www.heartwormsociety.org/UrgentAlert-8-9-11.pdf http://vetpda.ucdavis.edu/parasitolog/Parasite.cfm?ID=50 http://www.cvbd.org/en/mosquito-borne-diseases/heartworm-disease/pathogen/ http://www.heartwormsociety.org/pet-owner-resources/heartworm.html#signs