Parasitology

Monday March 23, 2015 What is an endoparasite? Can you think of an example of an endoparasite? What is an ectoparasite? Can you think of an example of an ectoparasite?

Introduction Endoparasites Ectoparasites Nematodes Cestodes Trematodes Protozoa Ectoparasites Ticks, fleas, lice, mites, biting flies

Signs of parasites Diarrhea Vomiting Anemia Intestinal obstruction Malnutrition (hypoproteinemia) Lack of weight gain Milk production (itching)

Transmission Direct Transport hosts (intermediate host) Often fecal-oral route Transport hosts (intermediate host) Organism completes a development stage Short transitory period Definitive host (primary host) Lives, reaches maturity, reproduces

Endoparasite “families” Nematodes Cestodes Protozoa

Nematodes Roundworms Esophageal worms Stomach worms Ascarids Hookworms Intestinal threadworms Whipworms Pinworms Heartworms

Roundworm characteristics Live and move about in tissues Intestines, lungs, kidneys, urinary bladder, muscle, blood Eggs and larvae most commonly found in the feces Intestinal Ascarids Hookworms Whipworms

Nematodes - Ascarids Toxocara species (spp) Eggs Stages Toxocara canis, Toxocara cati Eggs Large, round – oval, dark colored, thick shell Stages Eggs are ingested Hatch in small intestine Larvae penetrate mucosa of intestine, migrate through tissues (liver/heart/lungs) Larvae are coughed up and swallowed and make way back to intestine

Adult Worm

Eggs under microscope

Prenatal/transplacental migration of T. canis Larvae leave the circulation and are stored in tissues/organs Dog becomes pregnant Larvae leave the tissues at 42-56 day of gestation Cross placenta and enter lungs of fetuses Puppies are born with the larvae in their lungs and cycle continues as the larvae mature and enter intestines T. canis and T. cati : some larvae migrate to mammary glands and are ingested by puppies and kittens when they nurse

Zoonosis of Toxocara Eggs are ingested by small child Larvae hatch and migrate through liver, lungs, eyes Called visceral larva migrans

Visceral Larva Migrans

Medication for ascarids/ roundworms Fenbendazole, milbemycin oxime, moxidectin, and pyrantel pamoate Pyrantel is available in a highly palatable liquid formulation that is readily administered to nursing animals and thus may be considered the preferred treatment for very young pups. To prevent environmental contamination, all pups should be routinely treated with pyrantel pamoate at 2, 4, 6, and 8 weeks of age and then placed on a monthly heartworm preventative with efficacy against Toxocara spp.

Roundworms and hookworms (pyrantel)

Symptoms of “Roundworms” Cough Shortness of breath Abdominal pain Pot bellied appearance Nausea and Diarrhea Blood in the stool Weight loss Dull coat Fatigue Presence of the worm in vomit or stool

- Hookworms Ancylostoma species or Uncinaria stenocephala Eggs Oval, thin shelled

Stages Eggs are passed into environment Develop and hatch in environment Larvae are ingested or penetrate skin Enter veins (circulatory system) into the lungs Coughed up and swallowed Enter small intestine and mature Transplacental and transmammary migration also

Nematodes - Hookworms

Zoonosis of Hookworms Cutaneous larva migrans

Nematodes - Whipworms Tricherus Vulpis Eggs Stages Thick brown yellow shell with a clear polar plug at each end Stages Eggs are ingested Larvae hatch into small intestines Penetrate mucosa, migrate and return to intestines Migrate to cecumand colon and bury their anterior ends into the mucosa and mature to adult stage

Whipworm Egg

Whipworms

Medications for Whipworms febantel , pyrantel pamoate and praziquantel Drontal fenbendazole Panacur® To achieve control, treatment can be administered once a month for 3 months. Milbemycin oxime (found in: interceptor, triflexis, sentinel)

Tuesday March 24, 2015 Name these three parasites… A._____________ B. ____________ C. ____________ Name these three parasites…

Nematodes - Heartworms Dirofilaria immitis Parasite of the circulatory system In dogs: right ventricle of heart and pulmonary arteries Dog is definitive host

Heartworm Adult is called dirofilaria immitis Larvae are called microfilaria Found in the bloodstream Migrate to the heart and lungs Intermediate host is mosquito

Heartworm Heartworm disease in dogs HARD in cats Heartworm associated respiratory disease Medication: Preventative - Ivermectin Treatment – melarsomine (Immiticide)

Cestodes Tapeworm spp Flea is intermediary host Dipyldium caninum Taenia taeniaeformis Flea is intermediary host Rodents, rabbits, deer = different species of tapeworms Primary host (canine or feline) ingest the intermediary host Eggs Thin shelled, when found under microscope may find “packets” Proglottids (tapeworm body segments) are filled with thousands of egg packets

Taenia or dipylidium

Tapeworms

Medication for tapeworms Praziquantel (Droncit) Epsiprantel, and Fenbendazole Preventative flea control!

Protozoa Single celled organism Giardhia Coccidia (have a nucleus so are eukaryotic) Giardhia dogs, cats, humans, beavers Coccidia Isospora Cryptosporidium Toxoplasma gondii (cat is definitive host)

Giardia Live in the intestines From contaminated items or environment Villi become damaged/ malabsoption occurs From contaminated items or environment Treated with metronidazole Prevention Cleanliness Water, ground surface, soil, undercooked foods Often fecal- oral transmission

Giardia - two forms Trophozites Feeding stage Found in the small intestine

Oocysts Thick walled spore that protects Cyst is ingested, wall is digested away, trophozite is released and immediate divides into two organisms Binary fusion

Coccidia Isospora Oocysts in the feces Sporulates (divide/ become infective) 2 sporocysts Each enclose four sporozoites Total of 8 infective forms per oocyst Walls are digested and sporozoites penetrate intestinal cells Grow, replicate, mature, “reproduce” After fertilization, oocyst is produced and cycle starts over Causes diarrhea Affects very young and immune compromised animals If severe infestation can mimic parvovirus and even be fatal

Toxoplasma and Cryptosporidium Intestinal Same type of life cycle as Isospora Toxoplasma causes birth defects in humans Cryptosporidium causes severe diarrhea

Isospora

isospora Toxoplasma Gondii cryptosporidium

Name the three parasites…

Roundworm and hookworm eggs

Answer whipworm Ascarid (roundworm)

Ectoparasites Fleas Ticks Mites

Flea Ctenocephalides felis Not host specific 65 - 80 ° Warm, humid Cat flea Not host specific 65 - 80 ° Warm, humid

Fleas…a vicious (life) cycle

Flea lifecycle stages: Egg - The flea egg hatches in 2-21 days, depending on environmental conditions. Three larval stages - The larval stages grow and undergo their moults over about 9-15 days. The pupal stage (cocoon) - The cocoon is the crux of flea infestation persistence in the house-hold. It generally hatches in 1-2 weeks, but can last up to a year. The adult flea - Adult fleas can live for some weeks (maximum of about 2 months if no host is present) in ideal conditions.

Flea disease Anemia Tapeworms Plague Catscratch fever (Yersinia pestis) Catscratch fever (Bartonella henselae infection)

Ticks – multiple host cycle

Tick life stages

Common species of ticks Two families of ticks –soft ticks and hard ticks Ixodid family (hard ticks) Brown dog tick Lone star tick Deer tick Diseases babesia, ehrlichia, rocky mountain spotted tick fever, lyme, tularemia, anaplasmosis

Brown dog tick

Tick and Fleas medications are aimed at killing different stages of the parasites Eggs Larvae Pupae (cocoons – fleas) Nymphs Adults

Neurotoxins Fipronil (Frontline) Imidaclopride (Advantix) Permethrin (common brands) Only kill adults Other ingredients work synergistically as IGRs (Insect Growth Regulators) Repellants Amitraz (for ticks) Cats- Use caution!!!

Mites Sarcoptic mites Sarcoptes scabiei Burrow into the epidermis Pruritic skin condition Rash Scaling, crusting, excoriation 4 stage life cycle spent on the host Eggs Larvae Nymph Adult (takes 12- 17 days to become adult) Contagious by direct contact Zoonotic but self limiting in people

Sarcoptic mange

Ear Mites Otodectes cynotis Reside within external ear canal 5 stage lifecycle lived on host Egg, larva, protonymph, deutonymph, adult Common cause of otitis externa in dogs, cats, ferrets Feed on dead cells on the ear canal / produce intense irritation Head shaking/ scratching ears Aural hematomas Sometimes can be seen with otoscope Prepared slide Brown exudate usually will have mites moving around

Ear mites

Demodex Demodex Mites Live in hair follicles and sebaceous glands Normal and nonpathogenic Host specific / not transmissible An increase of these mites is called demodicosis Immune system related May be localized to one area or generalized / all over

Demodex under the microscope

Cheyletiella Live on surface of skin – ingesting skin “debris” Host is dog, cat, rabbit “Walking dandruff” Diagnostics View moving “flakes” through magnifying glass Cellophane tape Flea comb Area: dorsal midline and head

Cheyletiella

Ringworm Not a “worm” Is a fungus Zoonotic Keratin seeking Dermatophyte Lesions are circular