KAI Trematodes & Protozoa Parasites
TREMATODES
· Aka Flukes
· Flat, leaf shaped worms
· Have 1 or 2 simple suckers
o Oral- to take in nutrients, excrete waste material (fluke puke)
o Ventral sucker – for attachment
· Always require intermediate hosts (sometimes more than one)
· More common in LA than SA
· Eggs usually have one operculum
· Diagnosis: fecal sedimentation vs floatation
· Larval forms:
o First stage = Miracidium (covered in cilia) (plural=miracidia)
o Second stage = Cercaria
o Metacercaria = encysted cercaria (not found in all flukes)
PARAGONIMUS KELLICOTTI
· Lung fluke- most common
· Final host – dogs, cats, other carnivores; humans
· Intermediate hosts:
o 1st – Snail
o 2nd – Crayfish
· Lifecycle:
o Ova in feces – contaminate a water source
o In water – develop into cercaria
o Eaten by snail
o Within snail - develop into miracidium (larval form)
o Crayfish ingests snail; inside, it develops into metacercaria
o Crayfish eaten by final host or paratenic host (mink, rat, etc.)
o Once ingested – young flukes penetrate intestinal tract
o Enter peritoneal cavity; migrate through diaphragm and into lungs
o Adults- live in cysts in lungs; 2/cyst
o Eggs excreted into bronchi, cough/swallow, excreted through feces
· Clinical signs:
o Coughing
o Respiratory issue with heavy load
· Diagnosis:
o Cysts visible on radiographs
o Look for eggs in feces (sedimentation) or sputum
· Control: prevent animals from eating crayfish or paratenic hosts
· Zoonotic Potential:
o Can live 20 years in a human
o Causes fever, cough, weight loss, sometimes misdiagnosed as tuberculosis
NANOPHYETUS SALMINCOLA
· Small intestine fluke
· Final host: dog, cat, racoon, other carnivores (skunk, foxes, etc.)
· Intermediate hosts:
o 1st – snail
o 2nd – salmon
· Adults live in SI
· Lifecycle
o Ova in water via feces; develops into miracidium
o Snail infected with miracidium; turns into cercaria
o Cercaria leaves snail, infects salmon
o Within salmon – becomes metacercaria
o Final host ingests salmon; adults develop in intestinal tract
· Fluke itself = nonpathogenic to final host
· Issue: fluke carries bacteria Neorickettsia helminthoeca
o Clinical signs: high fever, vomiting/diarrhea
o 90% mortality rate in dogs (“salmon poisoning”)
o Cooking/freezing salmon kills the bacteria
o Humans – mild diarrhea
PROTOZOAL PARASITES (EXAM 4)
PROTOZOAL PARASITES
· Belonging to subkingdom “Protozoa”
· Single-celled; microscopic
· Most nonpathogenic; come can parasitize, cause issues
o Youn; immunocompromised
· Can live in: blood, intestines, other areas
· Can produce sexually or asexually
· These parasites have more complex lifecycles – not into extreme detail now.
TERMINOLOGY
· Trophozoite: activated, feeding stage
· Cyst: incapably of movement, can enable protozoa to survive outside of the hosts body
· Oocyst: rigid-walled cyst stage of certain protozoal parasites
CYSTOISOSPORA SPP
· Microscopic, spore-forming single-celled parasite
· Previously referred to as “Isospora”
· Also called Coccidia
· Final host: dogs and cats
· Intermediate host: none
· Site of adults: small intestinal epithelium (cells lining in the SI)
· Usually more of an issue with puppies/kittens
· Lifecycle: Direct – Complex; involves both asexual and sexual reproduction
o Patient ingests infective coccidia oocyst
o Invade the small intestinal epithelium (lining)
o Go through multiple stages of asexual development
o Eventually go through a stage of sexual reproduction, creating a zygote
o Zygote develops to oocyst – released in the feces of the host
o Oocyst sporulates (develops) in the environment for 4 days – now infectious, ready for next host
· Prepatent period = anywhere from 1-3 weeks
· Clinical signs:
o Diarrhea (with or without blood)
o Dehydration
o Weight loss
o Poor hair coat
o Intensity of sign corresponding with concentration of protozoa
· Diagnosis
o Finding oocysts in feces (very tiny)
o Can have positive test for oocysts with no clinical signs
· Treatment: specific type of antibiotics
· Control
o Easily spread in confinement situations (shelters)
o Disinfect cage with ammonia (resistant to many cleaners)
· Zoonotic potential: none (humans have their own species that will infect them though)
CYSTOISOSPORA VS EIMERIA
· Eimeria can not reach adult in cats and dogs
· Get notes from Dani
TOXOPLASMA GONDII
· Final host: cat
· Intermediate hosts: several species, including humans
· Site of adults: varies, can encyst in respiratory, digestive, reproductive systems
· Estimated 45% of cats have been infected
· Oocysts passed into cats feces
o Infective in 1-5 days
· Cat sheds oocysts only after infected; shed for 10-14 days
· Oocysts remain infective in moist soil for months, possibly a year
· Lifecycle: Indirect
o Oocysts pass into feces of infected final host; sporulate (become infective) within 1-5 days
o Intermediate host ingests infective oocysts
o Oocysts develop into tachyzoite stage (active asexual reproductive stage) in intermediate host
o Tachyzoites move through intermediate host’s body via blood and lymph
§ Encyst in tissue – now called “bradyzoites” not moving, small
o Final host ingests intermediate host; bradyzoites released
o Parasites undergoes sexual reproduction; oocysts shed in final hosts feces
o Transplacental transmission possible
§ They do develop, but differently
· Tachyzoites are active reproduction
· Clinical signs:
o Usually see only in very young or immunocompromised
o Fever
o Listlessness
o Encephalitis – Brain Inflammation
o Pneumonia
o Eye issues
· Diagnosis:
o Immunoglobulin testing
o Fecal floatation for oocysts
o Microscopic evaluation of tissue lesions for tachyzoites
· Treatment: Antibiotics
· Control: Prevent predatory behavior in cats
· Zoonotic potential:
o Humans = intermediate hosts
§ Estimated 30-50% infected worldwide
o Dangerous for pregnant women, immunocompromised
o Acute form: tachyzoites circulating
§ Symptomatic to mild signs (fever, headache, general malaise)
o Chronic form: bradyzoites encysted in tissue – no clinical signs
o Pregnant women: danger to fetus
§ See early in child’s life or years later
§ Signs: jaundice, splenomegaly, anemia, convulsions, intellectual disabilities
§ Without treatment – infant mortality as high as 12%
o Immunocompromised individuals: cannot fight tachyzoites
§ Encephalitis, tissue damage
· Pregnant women do not have to give up their cats
o Shed for 10-14 days post initial infection
§ Parasite takes 24 hours to become infectious once it leaves the host
o Must come in contact with oocysts in feces
o Recommended that women do not scoop litter boxes while pregnant, especially with outdoor cats
GIARDIA SPP
· Final host: dogs, cats, birds, humans
· Intermediate host: none
· Site of adult parasite: small intestine
· Special developmental form = trophozoite
o Pyriform – pear shaped
o Twin nuclei
o Flagellated – they have flagella that helps them move
· Lifecycle: Direct – Fecal Oral transmission
o Infected hosts shed cyst in feces
§ Remain formant until ingested by new host
§ Can stay in environment for months (especially in cold water)
o Once inside new host, each cyst will produce 2 trophozoites
§ Trophozoites will swim to intestinal wall, adhere to epithelium
§ Reproduce via binary fission – form new trophozoites or cysts
o Cysts shed into feces – start lifecycle over
· Clinical signs:
o Vomiting diarrhea, dysentery (severe diarrhea with blood & mucus)
· Diagnosis:
o Find trophozoites on direct fecal smear or tracheal wash, duodenal aspiration (endoscopically)
o Finding cysts via fecal float (zinc sulfate solution)
o Fecal antigen testing
· Treatment: Antibiotic (Metronidazole); Fenbendazole
· Control: Proper sanitation
· Zoonotic potential: Yes; fecal oral route, contaminated food/water