10: Ruminant Protozoa

Why are Eimeria spp. (coccidia) not zoonotic

Eimeria spp. are incredibly host, site, and cell specific

T/F: Eimeria spp. are likely to cause coccidiosis

F; many species are non or mildly pathogenic

CS associated with coccidiosis

Severe diarrhea ± blood, dehydration

Patient demographic for coccidiosis

Young, old, and stressed

Ruminant species that is more likely to die from coccidiosis

Goats

Why is “winter coccidiosis” a thing

Animals in closer contact to preserve warmth spread disease more easily

Coccidiosis syndrome more common in the NW US

“Nervous coccidiosis” causing neuro signs and occasionally death

Type of life cycle in Eimeria spp.

Direct LC

Where does Eimeria spp. set up shop

Various locations in the SI

Gross lesions associated with the more pathogenic species of Eimeria spp.

Nodules in the SI

How do DH get infected with Eimeria spp.

Ingestion of sporulated oocysts

How long does it take for an oocyst to undergo sporogony

24-48 hours in environment

How does Eimeria spp. (and any apicomplexan really) cause damage in the host

Asexual replication (schizogony/merogony) is incredibly damaging

Morphology of Eimeria spp. eggs

Small but variable egg with centrally located morula or spores (depending on development), may see a micropyle cap if you are lucky

Eimeria spp. that are different than normal and are larger and brown

Eimeria macusaniensis (camelids)

Goal of Eimeria spp. treatment

Manage clinical disease

Management techniques to decrease incidence of coccidiosis

• Reduce exposure to infective oocysts: clean feces, elevate feed

• Prophylactic treatment

When should prophylactic coccidiostats be given

Just before or just after a period of increased stress

How do prophylactic coccidiostats allow for adaptive immunity

Knocks down the level of internal Eimeria spp. but doesn’t wipe out the entire population

Eimeria spp. treatment that is toxic to horses

Ionophores

Coccidiostats used in goats

Decoquinate, monensin

ELDU that may be warranted but cannot be used for market animals

Diclazuril or toltrazuril

Cryptosporidium life cycle

Direct life cycle

Patient demographic for cryptosporidium

Young animals

Where does cryptosporidium set up shop

Superficially associated with gut cells

T/F: crypto is zoonotic

True

Key CS associated with cryptosporidium

BAD watery diarrhea

How do cattle get cryptosporidium

Ingestion of sporulated oocysts

When do cryptosporidium oocysts become sporulated

They are infectious when excreted

How does cryptosporidium cause autoinfection

Sporozoites can bust out of sporulated oocysts while inside the host and re-infect the GIT

Primary diagnostic for cryptosporidium

Centrifugal sugar float

Morphology of cryptosporidium eggs

SMALL (almost RBC sized) eggs

Parasiticide of choice for cryptosporidium

No approved treatment :(

Treatment of choice for cryptosporidium

Supportive care and management

Babesia species in cattle

Babesia bovis and Babesia bigemina

Small babesia

Babesia bovis

Large babesia

Babesia bigemina

T/F: Babesia is reportable in cattle

True

Vector for babesia

Tick

Common name for babesia

Redwater disease

CS associated with babesia

Severe anemia and hemoglobinuria

Diagnostic for babesia

Blood smear or PCR

Blood smear findings associated with small babesia

Signet ring inclusion

Blood smear findings associated with large babesia

Teardrop or pear shaped inclusion

Treatment for babesia

Cull

Life cycle type of babesia

Apicomplexan

DH of babesia

Tick

Apicomplexan stage that causes damage in ruminants

Merozoite

Why is it so hard to control tick transmission of babesia

Female ticks can pass babesia to offspring transovarially

Tick host for bovine theileria

Longhorn tick (Haemaphysalis longicornis)

Specific type of theileria that is more pathogenic and responsible for disease in cattle

Theileria orientalis ikeda

CS associated with Theileria orientalis ikeda

• Generic tick borne illness: anemia, fever

• Lethargy

• Abortion

• Death

Top alternative differential to Theileria orientalis ikeda

Anaplasma spp.

What happens to cattle that survive a theileria infection

Carriers for life

Diagnostics for theileria

Blood smear or PCR

Blood smear findings associated with Theileria orientalis ikeda

Signet ring inclusions

How do we differentiate small babesia (reportable) from theileria

Patient history and CS: does the patient have hemoglobinuria, can you find the babesia tick (one host tick)

Management for theileria

Limit contact with vectors, reservoir cattle, and fomites

How do apicomplexans damage ruminants when they are the IH

Cysts in tissue, commonly muscle and nervous

Common zoonotic protozoa that use ruminants as IH

Toxoplasma gondii and Neospora caninum

Toxoplasma gondii and Neospora caninum route of infection for ruminants

Ingestion of sporulated oocysts or transplacental transmission

T. gondii is a major cause of abortion in which species

Small ruminants

N. caninum is a major cause of abortion in which species

Cattle

Diagnostics to confirm Toxoplasma gondii and Neospora caninum as the cause of abortion

PCR and histopath

Treatment for Toxoplasma gondii and Neospora caninum

No drugs available for the tissue stages

Prevention for Toxoplasma gondii and Neospora caninum

Prevent DH (dogs and cats) from ingesting aborted tissues or contaminated raw meat

Flagellate reproductive parasite in cattle

Tritrichomonas foetus

Life cycle of Tritrichomonas foetus

Direct life cycle with one stage

Single stage of Tritrichomonas foetus

Trophozoite

Where does Tritrichomonas foetus set up shop

Repro tract of females and prepuce of bulls

How long does Tritrichomonas foetus last outside the host

Not very long, it’s not a hardy protozoa

Patient demographic for Tritrichomonas foetus infection

Beef cattle and older bulls

CS associated with Tritrichomonas foetus in heifers

• Mild vaginitis (often undiagnosed)

• Breeding failure

• Early abortion

CS associated with Tritrichomonas foetus in bulls

They are asymptomatic carriers

Why are beef cattle often more affected than dairy cattle

Dairy cattle are usually bred via AI

Presumptive signs of Tritrichomonas foetus infection in a herd

• Widespread breeding failure

• Long calving interval

• Bull-sharing

Diagnostic of choice for Tritrichomonas foetus

• Look at preputial wash under microscope

• Mucus sample form cervix or mucus

Why do you have to culture your sample if testing for Tritrichomonas foetus

It increases the sensitivity of your microscopic and PCR tests

Oklahoma regulatory definition for a negative designation for Tritrichomonas foetus

3 consecutive negative culture tests or 1 negative PCR test

Populations that should be tested for Tritrichomonas foetus

• Any bull >12 mos that is changing ownership

• Potentially exposed female cattle

• Any breeding bull entering OK

Parasiticide for Tritrichomonas foetus

No approved drugs

Treatment for Tritrichomonas foetus in cows

Reproductive rest for 3 most

Treatment for Tritrichomonas foetus in bulls

Cull

Purpose of Tritrichomonas foetus vaccine in cows

Minimizes disease and prevents shedding, but won’t prevent infection