Internal parasites Flashcards
What are two major groups of internal parasites?
Protozoans (giardia, coccidiosis [eimeria and isospora], toxoplasma, tritrichomonas, neospora, cryptosporidium) and Helminths (cestodes, nematodes, trematodes)
What are the most commonly seen cestodes? How are they diagnosed?
Dipylidium caninum, Taenia pisiformis in dogs, taenia taeniaformis in cats, Echinococcus spp.
Diagnosed by finding eggs on fecal float.
What are the most commonly seen groups of nematodes?
Roundworms (toxocara, ascaris suum, parascarus equorum), hookworms (ancylostoma, , whipworms (trichuris vulpis, trichuris suis, trichinella), Habronema, Pinworms (oxyuris equi), lungworms (dictyocaulus, Oslerus osleri, aelurostrongylus abstrusus, capillaria), strongyles (large vs small, trichostrongyles - ostertagia, haemonchus, trichostrongylus), heartworm (dirofiliaria immitis), heartworm lookalike (Acanthocheilonema [dipetalonema] reconditum), thelazia.
Diagnosed by eggs on fecal float or by finding larvae on a baermann assay for lungworms.
What are some commonly seen trematodes? How would they be diagnosed?
The fluke nanophyetus salmincola transmits neorickettsia helminotheca to dogs. The fluke however is non pathogenic.
What are the hosts, transmission, diagnostics and treatment for dipylidium caninum? What type of parasite is this?
Type: Cestode (helminth)
Host: dogs and cats - It may cause scooting or gastrointestinal signs.
Transmission: ingestion of flea or lice containing eggs
Diagnosis: segment identification around perianal area, visualization of proglottids in feces
Tx: praziquantel or epsiprantel
What are the main classes of antihelminthic drugs in the US?
- Benzimidazoles - disrupt cell division by binding tubule and block mitochrondrial function (fenbendazole, albendazole, etc)
- Macrocyclic lactones are glutamate gated chloride channel agonists
(2A) avermectins - ivermectin, selamectin, doramectin
(2B) milbemycins - milbemycin oxime, moxidectin - Cholinergic agonists
(3A). Imidazothiazoles - levamisole (3B). Tetrahydropyrimidines - pyrantel, morantel - Isoquinolones are NMJ and tegument distruptors that cause calcium influx (Praziquantel)
- Melarsomine Dihydrochloride (for hwt tx as IM injection in dogs only)
- Piperazine is a GABA agonist that treats toxocara
What is a benzimidazole, what is the MOA? what are some examples?
A benzimidazole can be viewed as a combo of a benzene ring and imidazole. MOA:disrupt cell division by binding tubule and block mitochrondrial function (fenbendazole, albendazole, etc) . Examples are fenbendazole, febantel, flubendazole, albendazole, thiabendazole and oxfendazole. They are used to treat nematode and trematode infections. They also have limited activity against cestodes. IE fenbendazole is labeled for rounds, hookwors, whipworm and tapeworm (taenia)
What is a macrocyclic lactone, what are some examples?
The macrocyclic lactones have a potent, broad antiparasitic spectrum at low dose levels. They are active against many immature nematodes (including hypobiotic larvae) and arthropods. MOA: selective agonist of glutamate-gated chlored channels in neurons and pharyngeal muscles of nematodes and arthropods. The two groups of macrocyclic lactones are avermectins and milbemycins. The avermectins in commercial use are ivermectin, abamectin, doramectin, eprinomectin, and selamectin. Commercially available milbemycins are milbemycin oxime and moxidectin.
What are the hosts, transmission, diagnostics and treatment for taenia pisiformis? What type of Helminth is this?
T pisiformis is a cestode (helmnith) found in dogs only. It may cause scooting or gastrointestinal impaction. It is transmitted by ingestion of an infected intermediate host (rabbits). Diagnosed via visualization of segment in feces or a fecal float with high specific gravity. Treated with praziquantel or fenbendazole.
What are the hosts, transmission, diagnostics and treatment for Echinococcus granulosus?
Echinococcus is a cestode found in dogs. Dogs are the definitive host and become infected when ingesting an intermediate host, usually a rodent. Diagnosis is by CELISA or PCR. It is difficult to distinguish the eggs from taenia under the microscope. It is treated with praziquantel.
Ancylostoma caninum aka the ____ is treated with ____. This parasite migrates from ___ to ___ and end up in the ____ where they cause ___. This is also the cause of ____ in humans.
Hookworm; treat with Ivermectin, fenbendazole, pyrantel, or butamisole. Can penetrate through the skin of young pups and migrate to the lungs where they are coughed up and swallowed and mature in the small intestine. There, the worms suck blood and cause bleeding ulcers; up to 0.1 ml of blood per worm can be lost per day. Aberrant migration under the skin of infected people results in cutaneous larva migrans.
Dirofilaria immitis
canine heartworm
Neorichettsia helminthoeca
“salmon poisoning” etiologic agent which is vectored by the intestinal fluke, Nanophyetus salmincola. Dog gets the disease by eating the salmonid fish infected with the cercaria of the fluke, which harbors rickettsia. Clinical signs along with finding fluke eggs int he feces of the dog is usually enough to make the diagnosis.
Treatment: tratracycline antibiotics
Taenia infection treatment
Proziquantel
Toxacara canis
Canine roundworm that is passed along to puppies transplacentally. The roundworm migrates from the small intestines through the liver and lungs, which is what causes the animal to cough. Beyond 6 months of age, the larvae distribute to the somatic tissue, where their development is arrested.
