2016-07-12 parasites of livestock ii
TRANSCRIPT
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Liver
Thomas M. Craig
Texas A&M University 12 July 2016 at Beni-Suef University
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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
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Fasciola
hepatica
Common
Liver fluke
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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
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Fascioloides magna bovine
liver, omentum
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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
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common bile duct, small intestine
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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
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Taenia hydatigena
cysticercus
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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
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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
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North America
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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
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Babesia bovis
capillaries brain
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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?)
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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
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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
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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
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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
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Tritrichomonas
foetus
from
culture
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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
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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
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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
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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
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Toxoplasma gondii abortion
and neonatal death
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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
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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
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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
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Tachyzoites in muscle
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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
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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
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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
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Taenia saginata
cysticercus
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Larva Cysticercus bovis muscle of cattle
D H humans; typical predator prey
relationship
Treat humans proper disposal of human
excreta
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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
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IMAG0157.TIF
400X 100X
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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