Protozoan Parasites: Flagellates, Amoebae, Ciliates & Apicomplexans Spencer Greenwood BSc, MSc, PhD, DVM Dept. of Biomedical Sciences Office: 2332N AVC-North Annex Phone: 566-6002 Home: 892-4686 E-mail: sgreenwood@upei.ca
http://people.upei.ca/sgreenwood/html/teaching.html
Protozoa or Protists Single-celled eukaryotes Heterogeneous group Reproduction - asexual but some have sexual stages Locomotion - flagella, cilia, pseudopods or gliding Life style - free living & parasitic forms
Parasitic Protozoa All vertebrates & invertebrates are infected by protozoa Life cycles: Simple & complex Transmission: Direct Intermediate or paratenic hosts Resistant stages (cysts)
Parasitic Protozoa Taxonomy - major groups Flagellates Amoebae Ciliates Apicomplexa Microsporida/Myxozoa
Parasitic Protozoa Eimeria Isospora Cryptosporidium Giardia Toxoplasma
The Father of Protozoology
Giardiasis Zoonotic species - Beaver Fever Giardia duodenalis = intestinalis = lamblia Mammals - dogs, cats, cattle, sheep & humans...wildlife Not all assemblages are zoonotic... Host Adapted species G. muris rodents G. microti muskrats & voles G. ardeae & G. psittaci birds G. agilis amphibians
Giardia morphology - 2 life stages Axostyle Cyst Trophozoite The cyst is immediately infectious
Giardia - Site of infection http://www.stanford.edu/class/humbio103/parasites2003/g iardia/giardia2_files/image006.jpg http://www.snow.edu/~kevins/giardia.jpg http://www.deltagen.com/target/histologyatlas/atlas_files/digestive/duodenum_20x.jpg
http://www.cdfound.to.it/i mg/giardia-04-250x.jpg
http://www.cdfound.to.it/img/giardia-08-1000x.jpg
Giardia Life cycle simple & direct Fecal-oral Waterborne Cysts highly resistant 10 6 / gram of feces Cyst = infective stage Trophozoite = non-infectious Prepatent period 7-10 days
Transmission Cysts immediately infectious 10-100 cysts infectious dose Fecal- oral & water borne Environmentally resistant ~ 2 months (cool & moist) resistant to chlorination other disinfectants
Transmission
Prevalence Worldwide Most common in young animals Barnyards, kennels, catteries, shelters, puppy mills, daycares... Stress crowded, confinement poor hygiene/sanitation Dogs: > 1 year = 4% < 1 year = 36% Kittens 11% Livestock up to 100% in calves > 30 days Pet birds up to 60%
Pathogenesis Variable Severity dependent on dose of infection... Diffuse shortening of microvilli Villus atrophy Malabsorption Increase G.I. motility Intestinal wall permeability increased
Clinical Signs Gastro-intestinal signs: Most infections are sub-clinical Acute to chronic small bowel diarrhea Signs last ~ 1-2 weeks to months Watery explosive, Steatorrhea, pale foul smelling Abdominal discomfort -> pain Vomiting & anorexia http://www.petservice.com/libraries/pictures/coron_pict.html
Clinical Signs Extra-intestinal signs Allergic response urticaria, pruritus in dogs & humans Feather picking in birds www.geocities.com/.../ Bluffs/1958/pluck.html http://education.vetmed.vt.edu/curriculum/ VM9144/PRURITUS/pruritus.htm
Diagnosis most commonly mis -, under- & over- diagnosed parasite in veterinary practice Gold Standard: Centrifugal Fecal Flotation Zinc sulphate or sucrose with or without Lugol s iodine stain Scan microscope slide at 10X but confirm Dx by observation at 40X Osmotic artifact - causes trophozoites in cysts to collapse Often has a refractile edge which makes it easier to see cysts Intermittent shedding Perform 3 fecal exams in 5-7days Osmotic artifact Refractile edge
Diagnosis Direct Fecal Smear Fresh feces Saline smear Trophozoites falling leaf movement May also see cysts
Antigen Detection Fecal ELISA IDEXX SNAP Giardia coproantigen No test 100% Use combination flotation & antigen to increase accuracy Diagnosis
No licensed products Treatment & Control Fenbendazole, metronidazole extra-label & off label Azithromycin? Resistance is an emerging issue? Vaccination - Giardia Vax New Research (2016) VSP based vaccine the future?
Treatment & Control Good hygiene Cysts stick to fur... remember to bathe infected pets (daily?)... Disinfect fouled areas...long contact times Proper sanitation Reduce Stress
Hexamitosis Hexamita meleagridis Turkeys & game birds Hexamita columbae Pigeons
Morphology - Hexamita Trophozoite oval shaped, bilaterally symmetrical with 8 flagella binucleate with prominent nucleolus 6-12 µm long Cysts rarely formed Wood & Smith 2005, Avian Diseases
Life cycle Direct transmission fecal-oral, contamination of feeders & waterers Trophozoite is infectious stage Trophs colonize small intestine Young birds most susceptible 1-9 weeks Subclinical carriers (adults) Chickens may also be carriers
A problem in every commercial turkey producing area
Heavy losses reported in outbreaks of farmed ringnecked pheasants
Pathogenesis & Clinical signs Catarrhal enteritis & atony Swollen, bulbous, liquid filled small intestine Diarrhea Greenish-yellow watery & foamy Listless, inappetence, anorexia, dehydration Convulsions & coma Survivors stunted
Diagnosis History Mixing of young birds with adult subclinical carriers Clinical signs PM - scrapings from duodenum Trophs fluid Cysts - mucus/squash prep Stain both with Hemacolor Beware confounding flagellates in cecum
Treatment & Control Segregation Remove carriers, separate adults & poults All-in / All-out strategy Sanitation Remove litter with fecal matter Disinfect building, feeders & waterers Biosecurity Antibiotics for secondary infections? Food animals: chlortetracycline, tetracycline & oxytetracycline Pet birds: metronidazole & ronidazole
VPM-122 Midterm Exam # 3 Thursday, March 23, 2017 Lecture 286A N/286B N/286C N/287N 0830-0920H Covers my lectures (#17-22) Lecture 23 is a review (20/03/2017) Protozoan Parasites lecture notes pages, 1-54. Format Multiple choice, short answer & essay Point form is okay for answers...including the essay!!!!! Say no to drugs & no drug names on exam either! No prevalence numbers