Protozoan Parasites: Lecture 17 - Trichomonas & Histomonas

Pages 10-18

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/index.htm

Trichomonosis

• Bovine Trichomonosis – “Trich”

• Avian Trichomonosis – “Canker” or “Frounce”

• Feline Trichomonosis

• Non-pathogenic Trichs – Pigs, horses & dogs...

Bovine Trichomonosis

• Tritrichomonas foetus

• Infection of the reproductive tract

• Morphology

• Only a single life stage – Trophozoite is the infectious stage

– pyriform shaped

– 10-25 um long with 3 flagella & an undulating membrane with a posterior free flagellum

• Do not produce cysts

Life Cycle

• Direct – Transmitted by “natural

service”

• Bulls – Trophs in the prepuce, penis,

epididymis & vas deferens

• Cows/ heifers – Trophs in the vagina, cervix &

uterus

Transmission

• Cows/heifers – Trophs during copulation

– Infections persist for weeks- months

– Usually recover

• but can be re-infected

• Bulls – Trophs during copulation

– Bulls may be infected for life (carrier)

– Mature bulls > young bulls

• A.I. – Rare - contamination

Prevalence

• Bull infection rates 6-8% – BUT as high as 44%!!

• Reports increasing: – New Mexico

– Colorado

– Oklahoma

– Alberta...yes, Canada too!

Pathogenesis

• Invasion of the uterus – Leads to placentitis which results in detachment, death & abortion of

fetus

• Trophs may also invade the fetal tissues

Clinical signs

Cows/heifers • Typically minimal

– Mild mucopurulent discharge

• “Open cows” – Calf production decreases by 50-

80% in newly infected herd

• “Abortion” before 5 months gestation

• Vaginitis &/or pyometra

• Retained fetus & membranes – Leading to endometritus &

sterility

• Increased calving interval

Clinical signs

Bulls • No clinical signs of infection

Diagnosis

• Trophs – Preputial scrapings or

washings (smegma)

– Vaginal secretions, vaginal washings

– Absorbed fetuses

– Avoid contamination with gastrointestinal trichs (non-pathogenic confounders)

• Distinct "rolling" motion

• Diff-Quick/iodine stain

http://www.indiancountryextension.org/extension.php?=24

Diagnosis

• In Pouch TF - culture kit – Look for trophs under microscope

– Selective medium for Trichs

• Polymerase chain reaction (PCR)

• Immunofluorescent assay (IFA)

• Repeat sampling may be required to confirm infection status – 3 tests @ weekly intervals

Treatment

Cows/heifers: – No treatment available

• 4 months sexual rest to clear infection

• ~3% remain as ‘carrier cows’

• Normal term pregnancy expected

Treatment

• Bulls: – No approved drugs

– CULL ALL INFECTED BULLS

Control

• Bulls: – Cull infected bulls & use non-

infected or virgin bulls

– Pre-breeding exam

• Test all bulls for trich

• Use A.I.

• Younger bulls – Reduce transmission

– Replace every two years

Control

Cows: • Maintain a limited breeding

season

• ID & separate infected cows – Sexual rest of 4 months or cull

• Buy only confirmed pregnant replacements

• Vaccine: Trich Guard®

• Female herd only

• “partial” efficacy

• Annual re-vaccination

• No efficacy in Bulls

Avian Trichomonosis Trichomonas gallinae - Infection of the crop of birds

Trichomonas gallinae Infection of the crop of birds

• Disease known by many names:

– ‘Canker’

• pigeons, songbirds...

– ‘Frounce’

• Raptors

– ‘Roup’

• poultry & fowl

Morphology

• Trophozoite – Single life stage

– Pyriform shaped

– 5-9 um, with 4 flagella & an undulating membrane with embeded recurrent flagellum

• Trophozoite or Trich is the infectious stage

• No cysts

http://www.ucm.es/info/parasito/gallinae.jpg

Life cycle

• Transmission:

• Direct – Oral-oral, contaminated

waterers, bird baths, puddles... Moist bird feed!

– Trophs reproduce by binary fission

– T. gallinae & other Trichs are normal oral flora

• Avirulent & virulent strains

– STRESS

Transmission

Pathogenesis

• Rapid disease

– 10-14 days

• Trophs invade upper intestinal tract

– Oral cavity, sinuses, pharynx, esophagus & crop

Pathogenesis

• “Canker” - yellow, caseous nodules

Pathogenesis

• Liver may be invaded by trophs (rare)

– Lesions on surface, solid white-yellow & circular

Clinical signs

• Difficulty swallowing – Yellow-caseous mass,

– Drool, green- yellow mucus in oral cavity & dripping from beak

• Gape mouth

• Listless, ruffled & emaciated

Diagnosis

• Clinical signs & gross lesions (PM) – Restricted to the upper portion of the

digestive tract

• Direct smears - Definitive Dx – Trophs in oral fluids or lesions in the

mouth, crop or digestive tract

• Culture – In Pouch technique useful

• Medium selective for Trichs

• Confounding non-pathogenic Trichs

• PCR

Trich research in action

Control & Treatment

• Eliminate infected birds & suspected carriers

• Avoid feeding pigeons to raptors in rehab

• Proper sanitation – Source of fresh, clean food & water

– Prevent pigeons from contaminating water & food supply of domestic fowl

• Anti-flagellate drugs – Metronidazole, dimetronidazole & ronidazole

• REDUCE STRESS

Feline Trichomonosis

• “Discovered” in 1996

• Problem in young cats

– in multi-cat households, catteries & shelters

• Tritrichomonas foetus

– Morphology identical to bovine trichomonad

• 31% infection in 117 cats from 89 catteries @ International cat show

• First reports found that feral cats, same demographic - no trichs!

Transmission

• Trichomonads usually commensal organisms & cause no clinical signs

• Transmission route unknown – No cysts, so trich/troph is

infectious stage

• Direct “cat to cat” most likely – Mutual grooming

• Multi-cat litter box? – Trichs can survive ~6-24 hours in

feces (moist but firm)

Clinical Signs

• Chronic large bowel diarrhea – Waxing & waning

– Duration up to ~ 2 years

• May resolve spontaneously

– Cow-pie diarrhea

• w/wo blood & mucus

– Often with fecal incontinence

• P.E. – Anus edematous & painful

– Dribbling feces, rectal prolapse... http://www2.ncsu.edu/unity/lockers/project/cvmaprhome/gookin_file2.htm

Pathogenesis

• T. foetus colonizes mucosal surface of ileum, cecum & colon – Less frequently found in colonic crypts lumen

• Infiltration of lymphocytes & neutrophils, loss of goblet cells in intestinal mucosa

– mild to severe lymphoplasmacytic colitis

• Mechanism unknown

– likely involves disruption of normal flora, adherence to the epithelium & induction of host cytokines & enzymes

http://www2.ncsu.edu/unity/lockers/project/cvmaprhome/gookin_file2.htm

Diagnosis

• Direct fecal smear

• In pouch TF culture – Medium selective for Trichs

• Polymerase chain reaction (PCR) @ CVM-NC State University

• Confounding organisms – Other trichomonads, Giardia...

Treatment

• Sanitation & hygiene – Human infections?

• Reduce stress – Numbers of cats…

• No approved treatment – Ronidazole: 30 mg/Kg twice

daily for 2 weeks

– Resolves diarrhea & eradicates infection!

Transmission - Cross infection?

Histomonosis

• Histomonas meleagridis

• Blackhead disease or Infectious enterohepatitis

Histomonosis

• Site of infection

– Cecum & liver

• Morphology

– Pleomorphic

– Various trophozoites

• Flagellate & amoeba stages

• 5-30 um long

• No cysts?

“Artist’s rendering…not mine”

Transmission

• Fecal-oral

– Heterakis eggs

– Earthworm

– Mechanical vectors • Flies…

• Cloacal drinking

• Virulence/isolates?

Epidemiology

• Common in North America

• Histomonas remain viable within Heterakis eggs for 1-2 years

• Mainly affects young birds

– Turkeys 3-12 weeks old

• High mortality (50 - 100%)

– Chickens 4-6 weeks old

• High morbidity, low mortality

Pathogenesis

• Trophs penetrate – Cecum & invade liver via

the blood stream

• Cecal lesions – Edematous & lumen is

filled with yellow caseous smelly exudate

• Liver lesions – Circular depressed yellow-

green to grey areas of necrosis (1-2 cm)

– ~ 10 days post infection w3.ufsm.br/.../ histomonastrofozoitofigado2.jpg

Clinical signs

• 2-3 weeks post infection – Hunched appearance, droopy wings &

tail, ruffled feathers

– Anorexia & emaciation

– Black or cyanotic head (occasionally)

– Foul smelling, sulfur- coloured diarrhea

Diagnosis

• Clinical signs

– Brilliant yellow (sulfur) feces with cecal & liver lesions (PM)

• Histomonas on histo sections (liver & cecum)

• Cecal or liver scrapings

– Saline smear

• Beware confounding cecal flagellates – Normal flora?

http://www.vet.purdue.edu/courses/ai/vm550/Spring%202003/Bird/fig8.jpg

http://www.affrc.go.jp/AVEM/Japanese/atlas/protozoa/histomonas/histom1.jpg

Treatment & Control

• Good sanitation practices

• Turkeys & chickens must be raised separately

• Control Heterakis gallinarum in birds & limit access to eggs & earthworms

• Prophylactic & therapeutic treatment? – Antibiotic resistance emerging…

– Tiamulin 25 mg/kg for five days • (Birch et al. 2007 Vet Record)

Amoebae, Ciliates & Coccidia