Capillarids, Trichinella, Trichurids Flashcards
Classification
Order: Enoplida Superfamily: Trichinelloidea (Stichosome esophagus) - Trichuris (whipworm) - Capillarids (urinary,airway,GI) - Trichinella spiralis (intestines) Superfamily: Dioctophymatoidea - Dioctophyme renale (giant kidney worm)
Trichinelloidea - general characteristics
- all lay eggs with 2 polar plugs
- stichosome esophagus
- tube surrounded by stichocytes arranged single file down length of tube
Which Trichinelloidea spp is larviparous?
Trichinella spp
- females do not have polar plugs
Trichuris spp. PPP varies with ______
Species: swine, canids, ruminants, felids, humans
Trichuris spp - life cycle
Eggs passed in feces –> L1 develops in egg, does not hatch –> L1 in egg ingested –> hatches in SI –> migrates to mucosal glands of cecum –> L1, L2, L3, immature adult –> immature adults return to lumen of cecum –> adults attach to mucosa
Trichuris suis - pathogenesis and clinical sign
Adult trichurids - hematophagous
- diarreha
- dehydration
- anemia
- weight loss
- catarrhal enteritis
- mucosal necrosis
- hemorrhage
Trichuris spp. - clinical signs
Ruminants - usually subclinical - inappetence - bloody diarrhea Cats: rare and asymptomatic
Trichuris vulpis - life cycle
Unembryonated eggs pass in feces –> L1 devleops in egg, infective eggs remain viable for years –> DH ingests L1 in egg –> hatch in SI (2-10 days) –> migrate to cecum –> Li-L3 in cecum –> penetrate to mucosa –> mature to adults in lumen of cecum –> adults attach to mucosa –> female can produce 2000 eggs/day
Trichuris vulpis - clinical signs
- mild: asymptomatic, subclinical
- severe: hemorrhagic typhlitis or colitis, diarrhea with mucus and fresh blood
- rarely: bloody diarrhea, weight loss, dehydration, anemia, and death
Trichuris vulpis - pathology
Developing larvae
- mucosa of SI, no disease associated!!
Adults
- primarily in cecum, thread anterior ends thru superficial mucosa
- large posterior end extends into cecal lumen
- consume blood, tissue fluids, mucosal epithelium = bloody diarrhea, weight loss, dehydration
Trichuris spp. - diagnosis
- fecal float: eggs are double pored/plugged, must differentiate from capillarid egg
- adult: necropsy, whip like
Trichuris spp - treatment
Numerous approved anthelmintics!!
- fenbendazole
- milbemycin oxime
- febantel
- moxidectin
Trichuris spp. - control
Management
- maintain clean, dry environment
- kennels: remove feces daily, thoroughly clean all areas at least twice a month
Small animal capillarids
- Eucoleus aerophilus: epithelium of trachea, bronchioles (cats, dogs, carniovores)
- Eucoleus boehmi: muosa of nasal turbinates, or frontal/paranasal sinuses (canids)
- Aonchotheca putorii: stomach (cats, dogs)
- Pearsonema plica: urinary bladder mucosa (cat, dog)
- Pearsonema felis-cati: urinary bladder mucosa or free in bladder (cats)
Eucoleus aerophilus - hosts
DH: parasite of respiratory tract of fox
- reported from dog, cat, other carnivores
- foxes serve as reservoir for infections in domestic animals
- distribution: NA, SA, Europe
Eucoleus aerophilus - life cycle
Eggs in sputum or feces –> embryonate in 30-50 days –> L1 from ingested eggs hatch in SI –> penetrate mucosa –> adult inhabit bronchiole, bronchi, trachea, threaded thru epithelial surface –> tracheal mucus, saliva –> migrate by bloodstream to lungs –> L1 penetrate alveoli, migrate up air passages as they develop (L2-L4) –> adults inhabit epithelium of bronchioles, bronchi, trachea –> thin bodies threaded thru epithelial surface
Eucoleus aerophilus - clinical signs
Often light, inapparent infection
- slight cough, wheezing, nasal discharge
- secondary bacterial infections
- possibly severe in foxes: tracheitis, bronchitis, pneumonia
Eucoleus aerophilus - diagnosis
Fecal float for eggs
Eucoleus boehmi - clinical signs
Epithelium becomes hyperemic and hyperplastic
- sneezing, rhinitis
- nasal discharge +/- bloody
Eucoleus boehmi - diagnosis
- fecal float
- nasal discharge
- looking for eggs*
Eucoleus boehmi - life cycle
Direct
- adults threaded through nasal sinus mucosa
E. aerophilus, boehmi, and Trichuris vulpis egg comparison
- E. aerophilus: multicellular embryo fills egg, net-like pattern or ridges on surface
- E. boehmi: multicellular embryo does not fill egg, pitted surface
- T. vulpis: lemon-shaped, contains single cell when passed in feces
Aonchotheca putorii - clinical signs
- hyperplastic pyloric gastritis
- superficial mucosal fibrosis
- ulceration
- diagnosis via fecal float
Pearsonema plica - clinical signs
Usually subclinical
- hematuria
- dysuria
- cystitis
- diagnosis (eggs): urine sediment, flotation of urine, contaminated feces
Pearsonema spp - treatment
No approved treatments in dogs and cats
- off label: fenbendazole and ivermectin
- requires several doses to eliminate infection
Eucoleus spp - treatment
Both E. aerophilus and E. boehmi have been successfully treated with ivermectin or fenbendazole
Trichinella spp - hosts
DH: carnivores, omnivores
- has to be a meat eater!
- can cause human disease
Trichinella spiralis
Swine, carnivores, humans
- worldwide distribution
- adults in mucosa of small intestine
- direct life cycle
Which Trichinella spp are found in the US?
- T. nativa
- T. pseudospiralis
- T. murelli
Trichinellosis - life cycle
DH: adult nematodes in intestines (PPP: 5-6 days)
- female nematodes burrow into intestine –> produces larvae (L1) –> bloodstream –> L1 distributed in cysts (nurse cell) throughout muscle of host (especially tongue, diaphragm!!) –> infected muscle is ingested by DH
Trichinella spiralis sylvatic cycle
Predation
- wild carnivorous/omnivorous mammals and prey species
Trichinella spiralis domestic cycle
Meat scraps/cannibalism
- prey species (rats) ingested by pigs, dogs, or cats
Trichinella spiralis - human infections
Undercooked:
- pork
- pork products
- horse meat
- bear meat
- walrus meat
Trichinellosis
Ingestion of undercooked meat containing encysted larvae of Trichinella spp
Trichinellosis - pathogenesis
Exposure to gastric acid and pepsin:
- larvae released from the cysts
- invade small bowel mucosa
- develop into adults (females larger)
- live 4 weeks in the bowel
- after 1 week: females release larvae, larvae migrate to striated muscle
Trichinellosis - diagnosis
Based on clinical signs
- serology
- muscle biopsy
Trichinella spiralis - clinical signs
No signs in naturally infected swine!!
- adults in intestine: females burrowing = diarrhea, abdominal pain, fever
- larvae (L1) in muscles: slow down physically, difficulty breathing if invade diaphragm, neurologic signs if in CNS
T. spiralis - clinical signs in humans
- inapparent
- abdominal pain
- diarrhea
- fever
- myalgia
- malaise
- periorbital edema
- death
Trichinella spiralis - pathology
Larvae enter myocytes
- encapsulated by host derived membrane, takes 3 months
Cysts calcify over time
- larvae may remain alive for 2 years
Myocarditis
- no gross lesions, nurse cells with larvae histologically
Trichinella spiralis - diagnosis
Muscle biopsy/squash
- may be negative even in heavy infections
- larvae may be at early development
- inconspicuous
- identification of nurse cell parasite complex in muscle biopsy/squash
- squash uses 1-5g muscle pressed between 2 glass slides
- artificial digestion of muscle, then sedimentation to recover larvae
- detects 3 larvae/g of muscle!!
Trichinella spiralis - human diagnosis
Clinical signs, serology, biopsy
- look for antibodies (ELISA)
- PCR: detection of Trichinella-specific DNA
- sensitive/specific for detecting small numbers of larvae in muscle tissue
World Organization for Animal Health
- requirements for declaring country or parts free of trichinae in domestic swine
- guarantees the transparency of animal disease status worldwide
Trichinella spiralis - pre slaughter control
Reduce risks:
- exposure to infective rodents in wildlife
- prevent cannibalism in pig herds
- illegal to feed raw garbage
National Trichinella certification program
Farm audits performed by veterinarians!!
- certify farms as free from Trichinella spiralis infection
- purpose is to open up trade restrictions
Trichinella spp - zoonotic potential
Certain wild game have high zoonotic risk since we inspect meat from domestic swine
- some Trichinella are resistant to normal freezing processes (T. nativa, T. britovi)
Trichinella spp - post harvest methods for management
- slaughter testing: squash preps, muscle digestion
- processing techniques: traditional approach for US, heating, curing, freezing (not for T. nativa), irradiating
- consumer education: larval death in 6 min @ 55C, cook to internal temp of 77 C
Dioctophyme renale - hosts
DH: mustelids, carnivores, canids, felids (PPP 6 months)
IH: invertebrate (2-3 months) ingests L1-L3
PH: crustaceans, fish, amphibians (L3, infective stage, encyst)
Dioctophyme renale - incidental hosts
- other mammals
- herbivores
- humans: ingest undercooked PH, public health risk!
- larvae in subq tissue, sporadic distribution including NA
Diocotophyme renale adults are usually located in the -_______
Right kidney!
Dioctophyme renale infections
- patent infection: found in right kidney pelvis
- latent infection: free in abdominal cavity
- pathology: destroy/damage right kidney, enlarged left kidney, pressure necrosis
Dioctophyme renale - diagnosis
Nematodes in kidney, eggs in urine
- no specific management implications
- eggs: thick shelled, brown, barrel shaped, bipolar plugs, heavily pitted surface
Dioctophyme renale eggs are shed in ______
Urine (sediment)
- unlarvated eggs
- larvated eggs ingested by intermediate host
Dioctophyme renale - clinical signs
None in naturally infected hosts
- unilateral infections: compensation, dysruia, hematuria, lumbar pain, fatal if in both kidneys
Dioctophyme renale in humans
Not usual DH, does not usually present the way it would in natural DH
- often larvae wind up in subq nodules and do not develop further
Dioctophyme renale - treatment and control
Most infections are symptomatic
- treatment is not pursued
- surgical removal of adult nematodes along with affected kidney or from peritoneal cavity will eliminate infection
