Liver

Thomas M. Craig

Texas A&M University 12 July 2016 at Beni-Suef University

Cyst ingested and larvae cross into intestinal blood vessels and are carried to the liver where they migrate for 2 months then to bile ducts where they mature in bile ducts produce eggs

Acute disease: during migration in liver; anemia, bloody tracts and associated with reproductive problems in cattle

Clostridia toxins Cl. novyi , Cl. hemolyticum Chronic disease: biliary fibrosis, anemia, ill

thrift, jaundice

Fasciola

hepatica

Common

Liver fluke

Life cycle in snail and environment same as F. hepatica except the fluke eggs were produced in the liver of white-tailed deer

Migration through cattle tissues leaves black pigment which is pathognomonic for infection

Omentum, lymph nodes, fat may also contain pigment

Migrate in lungs, uterus, elsewhere in cattle Migration in small ruminants apparently never

stops until the host dies Treatment of cattle somewhat effective but will

not control

Fascioloides magna bovine

liver, omentum

Sheep other small ruminants Psocids (book lice) IH Adult tape worms in bile ducts, direct

migration from small intestine sometimes found in duodenum

No clinical signs but has been associated with fungal liver toxicity

Liver condemnation

common bile duct, small intestine

Cysticercus in the liver or abdominal cavity of ruminants

Canids DH Larvae migrates through liver may cause damage

enough to cause bacillary hemaglobinuria or black disease

Liver may be condemned Do not feed raw offal to dogs

Taenia hydatigena

cysticercus

Ruminants, macropods, swine and humans IH

Canids DH

Adult tapeworms very small 3-6 mm

Cyst can contain several liters in liver, lungs,

abdominal cavity

Thick walled cyst with thousands of protoscolices

No disease in ruminants but serous problem in

humans

Sheep dog cycle most often associated with human disease

Locally; swine/ dog, reindeer/ wolf, camel/ dog and in one

instance human/ dog cycles perpetuate disease

Treatment of humans surgery and anthelmintics

Control, treatment of dogs with praziquantel

Do not feed raw offal to canids

Control of wild and feral canine populations

North America

Organism not know to be in US at this time Eradicated by controlling DH tick Tick has been reintroduce on several occasions

from Mexico on cattle, or possibly other hosts i.e. horses, white-tailed deer, nilgai

Dipping and vacating pastures along with control of deer has been adequate but?

Treating cattle with oral pesticide in pastures may be a better approach

Babesia bovis

capillaries brain

Premunize: infect cattle at a young age with

viable organisms

Premunize: infect adult cattle and treat with drug

to prevent death

Infection from blood of chronic carriers: parasites

may be enumerated to give an adequate dose to

infect but not to kill

Selection of attenuated organisms

Vaccine developed in Australia then Brazil (may

help?)

Large Babesia of Equines: fever,

icterus, anemia, ataxia, paralysis

Transmitted by Dermacentor species

Present in US 1960’s has been

identified since that time but not

considered endemic

Small Babesia Natural transmission in Texas 2009 Several ticks transmit in laboratory and

associated with infection Amblyomma cajennense, Dermacentor variablis, D. nitens, Boophilus microplus

Fever, conjunctivitis, anemia, icterus, emaciation, hemoglobinuria

Piroplasms in erythrocytes and meronts in lymphocytes or other cells

Tick transmitted species of Theileria and geographic range of ticks variable

T. parva of East Africa kills 95% + susceptible cattle, carried by Cape Buffalo

T. cervi of US in white-tailed deer T. buffeli of cattle, common in East Texas but

seldom seen not virulent

Reproductive tract of cattle, nasal cavity of swine, intestine of cats (are they the same)?

Transmission via mucous membranes of reproductive tract or semen

Early abortion (first 4 months) of pregnancy fetus is not noticed

Apparently pregnant cow is in estrus Most cows will spontaneously clear of

infection and are resistant to further infection

Tritrichomonas

foetus

from

culture

Bulls become chronic carriers in the

mucous membranes of penis and prepuce

Some younger bulls may clear but not

older bulls

A few cows will not abort but retain fetus

which becomes mummified or pyometra

occurs

A few cows become chronic carriers

Testing bulls for trick a must in breeding soundness examinations

Easy to miss infected bulls but if there are several bulls positive in a herd consider all infected

Infected bulls can only be bred to previously infected females

Virgin bulls bred to virgin heifers May require two herds until infected

animals culled

Abortions and neonatal deaths in sheep and

goats

In cool moist climates a major causes of

abortion in small ruminants

Oocyst passed in the feces of felids ingested

by ruminant after sporulation

Tachyzoites in macrophages to all tissues

including placenta and mammary glands

Tachyzoites can be spread via saliva or semen

ACUTE PHASE

Recent infections when tachyzoites are

proliferating and are passed from body

via placenta, milk, saliva, semen

CHRONIC PHASE

Bradyzoites in tissues, host resistant to

reinfection

Toxoplasma gondii abortion

and neonatal death

Once ewe or doe is infected become chronic carrier with cysts (bradyzoites) in tissues

Only one abortion or transmission to young

Resistant to reinfection Vaccine has been produced used in UK,

New Zealand and Australia Large number of tachyzoites in placenta

of aborting animal, human health risk

Zoonotic potential

Undercooked mutton, lamb, cabrito, beef

from chronic infections

Unpasteurized milk from acute phase

infection

Handling placentas from acute phase

infections and not following good hygiene

Abortions and neonatal deaths in cattle Other ruminant species also infected Not known to occur in humans Life cycle similar to Toxoplasma gondii

but canids are DH Oocysts passed in feces of canid,

sporulates and is ingested by cow Sporozoites to tissues become tachyzoites

pass placenta to brain of fetus

Tachyzoites in muscle

Abortion mid gestation but variable

Calf born alive but dummies

Calf normal organism in tissues may be

passed to next generation

Usually only one abortion by individual

cow

Normal calves may have health problems

later in life; less responsive to therapy

Most commonly diagnosed abortions in dairy cows in California

In both beef and dairy cattle in Texas Recent outbreak up to 20 dairy cows aborted

/ day during a 2 week period Placenta may be primary source of infection

to canids Horizontal transmission appears to be more

important in causing disease than vertical

Larva Cysticercus bovis muscle of cattle

D H humans; typical predator prey relationship

Economic loss of carcasses or required freezing to kill possibly missed cysts in beef

Treat humans proper disposal of human excreta

Taenia saginata

cysticercus

Larva Cysticercus bovis muscle of cattle

D H humans; typical predator prey

relationship

Treat humans proper disposal of human

excreta

Cysts in muscle of ruminant Cysts may be macroscopic of

microscopic depending on species; surrounded by greenish eosinophilic granuloma

Bradyzoites in cysts ingested by predator: canid, felid, hominid: typical predator prey relationship

Sporulated sporocysts passed in feces each sporocyst contains 4 sporozoites

Sporocyst ingested by ruminant

IMAG0157.TIF

400X 100X

Sporozoites to endothelial cells meronts formed

With massive exposure disease may occur

Toxin, sarcocystin produced

Damage; endothelial cells, cardiac muscle,

abortions, weight loss, loss of hair,

lymphanopathy

Merozoites to muscle form cyst metrocytes

actively divide; later bradyzoites in cysts

Host resistant to new infections