Parasitology lab notes
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    Parasitology lab notes Parasitology lab notes Presentation Transcript

    • Introduction to Blood Parasites Dirofillaria immitis & Dipetalonema reconditum
    • Dirofilaria immitis: Canine Heartworm
      • Commonly known as canine heartworm but can infect cats & ferrets also
      • Dogs are definitive hosts
      • Adults normally reside in the right ventricle & pulmonary arteries ( occult infection : when infected with adults only!)
      • Offspring are called microfilariae
      • Many can wander – becoming aberrant – they get lost on the way to the heart & can be found in variety of extravascular sites including cystic spaces in subcutaneous sites, the brain, & anterior chamber of the eye
    • Dirofilaria immitis: Life Cycle
      • Prepatent period= 5-6 months
      • Life cycle requires intermediate host – Mosquito.
      • Sexual reproduction – both males & females
      • Microfilariae are released into bloodstream, where ingested by feeding mosquito
      • Microfilariae grow & milt inside mosquito until reach infective 3 rd stage larvae
      • Once they become infective, they migrate to the mouth parts of the mosquito. When mosquito bites new host, microfilariae are injected into new host’s bloodstream.
      • They migrate & molt until they reach the heart
    • Dirofilaria immitis: Signs & Symptoms
      • Can be asymptomatic
      • Coughing, weakness, lethargy, exercise intolerance, hypertension, liver & kidney failure, abdominal ascites, pulmonary edema & right sided congestive heart failure
      • Can be fatal!!!!
      • Caval syndrome: overload of worms in heart, right atrium & caudal vena cava. Needs surgical intervention or animal will quickly die
    • Dirofilaria immitis: Diagnosis
      • Commercial snap test (ELISA) – needs to have females present!
      • Other serologic tests
      • Modified Knott’s test – milipore filtration, concentration techniques (blood samples are centrifuged &/or filtered to concentrate microfilariae)
      • Blood smear
      • X-rays – to check for right sided heart enlargement
    • Dirofilaria immitis: Prevention & Treatment
      • Ivermectin (Heartguard), Milbemycin (Interceptor & Sentinel), Moxidectin (ProHeart)
      • Preventative drugs are HIGHLY effective. When administered properly will prevent over 99% of infections.
      • Preventatives are microfilaricides and will kill microfilariae that are present. Therefore testing is necessary before beginning preventatives
      • Treatment is difficult.
      • First, testing is done to determine how fit the animal is for treatment by doing bloodwork & x-rays.
      • Second step is administering adulticides like Immiticide. As adults die – they move with flow of blood toward lungs – can cause problems if allowed to exercise after adulticide treatment.
    • Dirofilaria immitis: Treatment (cont’d)
      • Dog MUST be kept quiet (crated) for several weeks after treatment while body reabsorbs dead adults.
      • After adults are treated, dog is administered microfilaricide (usually ivermectin) to clear the blood of any microfilariae.
      • Final part of treatment is testing with ELISA to confirm all heartworms have been cleared from the body.
      • Treatment is VERY STRESSFUL. This is why it is so important to stress to clients that it is easier to prevent heartworm than to treat it!
    • Dipetalonema reconditum: Subcutaneous filarial worm
      • Also produces microfilariae.
      • Often confused with Dirofilaria immitis
      • Nonpathogenic nematode resides in subcutaneous sites in dogs.
      • Intermediate host is FLEA!!!
      • Tests: modified Knott’s, milipore filtration, blood smear
      • Transmission: Infective flea bites, ingestion of fleas
    • Microfilariae in Blood Smears: Dirofilaria immitis vs. Dipetalonema reconditum
      • Dirofilaria immitis
      • Large numbers
      • Undulates in one place
      • Tapered head
      • Straight tail
      • 120-310mm – much larger!!!
      • Dipetalonema reconditum
      • Few in numbers
      • Moves across field
      • Blunted head
      • Button-hooked tail
      • 9-32mm – smaller!!!