ZAC H MESSMAY 2012

Dirofilaria immitis

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

Adult Worms

Microfilariae

Life Cycle

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) microfilariae develpe 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 granulomasin 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.pdfhttp://vetpda.ucdavis.edu/parasitolog/Parasite

.cfm?ID=50http://www.cvbd.org/en/mosquito-borne-disea

ses/heartworm-disease/pathogen/http://www.heartwormsociety.org/pet-owner-

resources/heartworm.html#signs