Lecture 14 4/8/24 Flashcards
What are the general characteristics of the subphylum Apicomplexa?
-obligate intracellular
-no locomotor organelles
-apical complex used to invade host cells
-produce sporozoites
What are the two groups of Apicomplexa of veterinary interest?
-Coccidia: intestinal sporozoa
-Hemosporidia: blood sporozoa
What are the general characteristics of Coccidia?
-live intracellularly in the GI tract
-highly species specific
-direct or indirect life cycles
-limited number of asexual generations: leads to self-limiting and ability to produce vx
What is schizogony?
life cycle stage in which asexual repro. occurs
What is gametogony?
life cycle stage in which transformation into male or female occurs
What is sporogony?
process of going through sporulation
What is a schizont/meront?
collection of dividing merozoites
Which stage of the life cycle leads to the most disease?
asexual/schizogony
What are the steps of the Eimeria/Isospora life cycle?
-unsporulated oocyst in environment sporulates after 48-72 hrs to become infectious
-sporulated oocyst is ingested and goes to small intestine
-bile salts break down oocyst and sporocyst to release sporozoites
-sporozoites invade small intestine epithelial cells
-sporozoite becomes merozoite and begins asexual repro.
-host epithelial cell bursts, spreading merozoites to new cells to form secondary schizonts
-after 5-15 asexual repro rounds, merozoite transforms in male or female gametocyte
-male and female enter epithelial cell, where male fertilizes female
-zygote forms with oocyst wall around it
-cell ruptures, releasing unsporulated oocysts to be shed in feces
How does Eimeria differ from Isospora?
-Eimeria sporocyst has 4 sporocysts with 2 sporozoites each
-Isospora sporocyst has 2 sporocysts with 4 sporozoites each
What are the general characteristics of Eimeria?
-DH includes herbivores, swine, birds, rodents, rabbits, fish
-oocyst is 10-50 x 10-35 um
-PPP of 1-3 weeks
-patent period of 1-4 weeks
-clinical disease often young animals in captivity
Which genus is a micropyle indicative of, if present?
Eimeria
Which Eimeria species are most pathogenic in cattle?
-Eimeria bovis
-Eimeria zuernii
Why are livestock and commercial poultry kept on Coccidia preventatives?
-once outbreak occurs it is too late to treat
-outbreaks can only be “treated” with supportive care and antibiotics to reduce secondary infections
What are the unusual forms of coccidiosis seen in cattle?
-winter coccidiosis
-nervous coccidiosis causing CNS signs
What are the characteristics of Eimeria macusaniensis?
-infects new world camelids
-PPP of 32-43 days; lots of asexual repro.
-around 100 um in length
-very pathogenic, esp. in young animals
-watermelon seed appearance of eggs
What are the clinical signs associated with E. macusaniensis?
-diarrhea
-wasting
-weakness
What are the characteristics of Eimeria leuckarti?
-only Eimeria spp. in horses in North America
seen infrequently in foals
-rarely associated with disease
Which anticoccidials are used in livestock and poultry?
-ionophores
-catalytic drugs
Why are ionophores not used in horses?
fatal even in small amounts
What is important about using Amprolium in ruminants to prevent Coccidia?
can lead to thiamin deficiency, so must supplement thiamin when using the drug
What is caused by Eimeria stiedae?
rabbit hepatic coccidia
Which lesions are seen in birds with Coccidia?
-cecal cores
-hemorrhage
-inflammation
-various Coccidia life stages in cells
What are the characteristics of Isospora spp.?
-DH includes carnivores, omnivores, birds
-PH is mice
-PPP of 1-2 weeks
