Protozoa V: Apicomplexa Toxoplasma, Neospora Flashcards by Anika Eidson

Describe Toxoplasma gondii

Only species in the genus, but has many genotypes
Common
Can infect many vertebrates
Can cause multi-systemic disease, but can also be covert
Distributed worldwide

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What is the definitive host of Toxoplasma gondii?

Felidae (domestic and wild)

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What is the intermediate host of Toxoplasma gondii?

Almost all warm-blooded animals

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What is the Toxoplasma gondii life cycle?

Tissue cysts from intermediate host is ingested by cat
Unsporulated oocysts passed in feces
Sproulates in 1-2 days
Sporulated oocysts in feed, water, or soil are ingested by intermediate host and warm-blooded vertebrates (cycle starts over with cat)
Warm-blooded vertebrates ingest contaminated food and water or uncooked meat
Tachyzoites are transmitted through the placenta

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What parasites sporulate outside the host?

Toxoplasma gondii
Hammondia
Isospora
Eimeria
Neospora

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What parasites sporulate inside the host?

Sarcocystis

Cryptosporidium

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What are the routes of infection with Toxoplasma gondii?

Ingestion of tissue cysts in IH

INgestion of sporulated oocysts

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What are the Toxoplasma gondii protozoal stages in felids?

Sexual stages in intestine (gametogony): fertilization—unsporulated oocysts shed
Asexual stages are extra-intestinal (tachyzoites, bradyzoites)

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What is a prepatent period?

Time from infection until demonstration of oocysts in feces

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What is the PPP with ingestion of Toxoplasma gondii tissue cysts?

3-10 days (most efficient route)

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What is the PPP with infestion of Toxoplasma gondii sporulated oocysts?

About 20 days

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When is peak oocyst shedding of Toxoplasma gondii? How long does it last?

6-7 days post infection

Lasts about 10-14 day, then decreases rapidly

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What are the clinical signs of Toxoplasma gondii in Felids?

Usually subclinical
Feline toxoplasmosis
Cats with clinical disease are unlikely to be shedding oocysts

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What is Toxoplasma gondii a major cause of in adult sheep in the US?

Abortions

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What is the transmission of Toxoplasma gondii in sheep?

Vertical transmission: congenitally infected offspring

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What is Toxoplasma gondii associated with in goats?

Primarily abortions

Clinical toxoplasmosis

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What is the transmission of Toxoplasma gondii in goats?

Vertical transmission: congenitally infected offspring

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What is the transmission risk of Toxoplasma gondii between humans and goats?

Raw goat milk

Undercooked meat

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Describe Toxoplasma gondii in cattle

Cattle are resistant to infection
Seropositive, but not epidemiologically important
No reports of clinical toxoplasmosis
Tissue cysts typically undetectable

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Describe Toxoplasma gondii in chickens

Seropositive and have tissue cysts
Commercial flocks: clinical toxoplasmosis not documented
Backyard flocks: lesions and necrosis in brain

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Describe Toxoplasma gondii in swine

Domestic and feral populations are seropositive

Clinical toxoplasmosis is rare

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Describe Toxoplasma gondii in horses

Resistant: no reports of clinical cases

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Describe Toxoplasma gondii in dogs

Clinical toxoplasmosis is rare

Vertical transmission rare

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Describe Toxoplasma gondii in wildlife

Seroprevalence high in many wildlife populations
Clinical toxoplasmosis in multiple species including marsupials, non-human primates, etc.
Marine animals impacted from water run-off

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What is seen in IH infected with Toxoplasma gondii?

Behavioral changes

What are the methods of diagnosis of Toxoplasma gondii in Felid definitve host?

Fecal float (rarely detects oocysts Usually subclinical Serology

Describe serology for Toxoplasma gondii

Does not predict oocyst shedding IgM peaks early IgG develops 2 weeks post infection Active infection requires demonstrating rising titer

What are the methods of diagnosis of Toxoplasma gondii in the intermediate host?

``` Clinical signs Antibody titers PCR Immunohistochemistry Histology ```

What are methods of treatment for Toxoplasma gondii?

No vaccine | No approved drugs, but off-label options (Clindamycin hydrochloride)

What are methods of control for Toxoplasma gondii?

Remove feces daily Feed cats dry/canned/cooked meat only Prevent carnivorism/hunting

What are vulnerable populations that can be infected with Toxoplasma gondii?

Pregnant women | Immunosuppressed individuals

What are the primary sources of infection of Toxoplasma gondii?

``` Transplacental/transmammary Organ transplants/blood transfusions Meat sources Raw goat milk* Environmental contamination ```

What is the pathology for Toxoplasma gondii in immunocompetent patients?

No symptoms to flu-like symptoms for a few weeks

What is the pathology for Toxoplasma gondii in immunocomprised patients?

Most frequent neurological infections | Toxoplasma encephalitis

What is the pathology for Toxoplasma gondii in the transmission from pregnant mother to unborn fetus?

Stillbirths, abortion, hydrocephalus, microcephalus, blindness Congenital infections develop later in life

What life cycle does Neospora caninum?

Indirect life cycle only

How is Neospora caninum different from T. gondii?

DH: Canids ---Neuromuscular disease ---HIgh seroprevalence in strays and dogs around cattle IH: Cattle ---Primary cause of cattle abortion worldwide ---Antibody titers in a wide range of hosts

Describe the Neospora caninum life cycle

Definitive host: dog Dogs can get reinfected Sporulated oocysts in food, water, and soil are ingested by intermediate host Dog ingests infected tissue cyst (e.g. in aborted fetus or infected calf)

What is the PPP of Neospora caninum?

5-17 days Oocysts sporulate in environment in 24-72 hours When sporulated: 2 sporocysts/4 sporozoites each

What are the routes of infection for Neospora caninum?

IH: oocyst. transplacental DH: ingestion of tissue cyst, transplacental

What are the clinical signs and pathology of Neospora caninum in dogs (DH)?

Usually subclincial Clinical infection ---Congenitally infected puppies or immunocompromised dogs ---Signs are usually neuromuscular ---Lesions: focal necrosis to sever myositis in skeletal muscles Congenital infection---asymptomatic carriers

What are the neuromuscular signs associated with Neospora caninum?

Progressive hind limb paralysis Muscle atrophy Difficulty swallowing

What are the clinical signs and pathology of Neospora caninum in IH?

Cattle: Abortions (Abortion storms; stillbirths) Infected calves that survive are asymptomatic carriers or have clinical infection

What is the method of diagnosing Neospora caninum in DH?

Fecal flotation: unsporulated oocysts | Antibody titers in dogs vary widely

What is the method of diagnosing Neospora caninum in IH?

Cattle: antibody test using serum or milk (ELISA); multiple testing Aborted calves: brain, fetal fluid, placental tissue collected for histology Other hosts: histology

What are the methods of treatment of Neospora caninum?

No approved treatment | No vaccine available

What are methods of control of Neospora caninum?

Limited access of dogs to cattle Minimize fecal contamination, by dogs, of food and water Remove aborted cattle fetus/placenta/stilbirths Herd management: culling. testing

What must Hammondia be distinguished from? Why?

Toxoplasma and Neospora | Oocysts have similar appearance/size

What makes Hammondia different from Toxoplasma and Neospora?

It is non-pathogenic Has no extra-intestinal stage in DH Infects IH only via ingestion of oocysts Infects DH only via ingestion of tissue cysts

What is the DH of Hammondia heydorni?

Dogs, coyotes

What is the IH of Hammondia heydorni?

Herbivores

What is the DH of Hammondia hammondi?

Cat

What is the IH of Hammondia hammondi?

Mammals, birds

What is the site of infection in hosts with Hammondia?

DH: intestinal tract only IH: throughout entire body

Where does Hammondia sproulate?

Outside the host

What is the treatment for Hammondia?

None

What is the control for Hammondia?

Proper sanitation

What is the pathology for Hammondia?

None

What is the Hammondia oocyst like?

2 sporocysts with 4 sporozoites each

What is the PPP for Hammondia?

1 week

How long is Hammondia patent?

1-2 weeks

What is Neospora hughesi the less common cause of?

Equine Protozoal Myelitis

Describe the life cycle of Neospora hughesi

``` Poorly understood DH: unknown IH: horse ---Transplacental transmission ---Clinical signs and treatment similar to EPM ```