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40 Cards in this Set

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  • Back
What are some characterisitics of protozoan species?
- plasma membrane
- subpellicular microtubules that comprise their skeleton
- mitochondria for energy in most protozoans
- macronucleus (in ciliates) and micronucleus
- flagella or cilia
What are some drug targets of protozoans?
- ionophores target the membrane
- decoquinate targets the mitochondria
- BZD's target microtubules
- many agents target the nucleus
What are the types of reproduction protozoan spp. undergo? Also describe the stages that can possible cause infection.
- asexual binary fission and multiple fision known as schizogony
- male and female gametes fuse to form a diploid cell called a zygote which is sexual
- the zygote stage can become a cyst by secreting a resistant covering as the cyst wall
- the cysts are often the infectious stage
- if the spp of protozoan can't become a cyst or hasn't become one yet it's a trophozoite and can also be infectious or cause disease
What is the major Kingdom and the phylums we need to be concerned with?
Kingdom Protista --> Phylum Ciliophora + Phylum Sarcomastigophora + Phylum Apicomplexa
Describe the Phylum Ciliophora.
- Ciliates arent as clinically important as other protozoans and are often commensal parasites
- cyst and trophozoite stages are the infectious stage are found in contaminated food, water, or environment
- undergo transverse binary fission, have a macro and micronucleus
- Balantidium coli infect pigs, humans, primates in the intestine but is rarely pathogenic unless invasion of the gut occurs in certain strains
- there are also rumen and cecal ciliates
- Ichthyophthirius multifillis are found in fish developing under skin and can cause asphyxiation
Describe the phylum Sarcomastigophora.
- Includes intestinal amoeba that infect rodents and reptiles
- also includes Subphylum Sarcodina Amoeba that causes blood diarrhea, has a trophozoite and cyst stage that sometimes bear flagella
- also includes soil/water amoeba that are opportunistic
- also includes our Subphylum mastigophora that includes Giardia spp.
What species are included in Phylum Apicomplexa and some general characteristics?
- generally include coccida spp. including Toxoplasma gondii
- also include Cryptosporidium spp.
- coccidia is collective and refers to parasites that produce cysts in the feces called oocysts which are formed by the union of male and female gametes but coccidia also includes those parasites that can have two separate hosts for asexual and sexual stages
- infection occurs in many spp. and is often site specific within the intestine
What are and describe the two coccidia spp. we discussed that have a one host life cycle?
- Eimeria and Cystoisospora
- transmitted by fecal oral transmission due to oocysts
- extreme importance in poultry, swine, cattle where diarrhea, weight loss and death can occur
- Eimeria spp. infect ruminants, horses, rabbits, chickens
- Cystoisospora spp prefer dogs, cats, and humans but can have a paratenic host
Name and describe the two coccidia spp. we discussed that have a two host life cycle.
- Toxoplasma gondii sometimes has an intermediate host
- Sarcocystis spp MUST use an intermediate host
What are the host specific spp. of coccidia?
- Eimeria spp of chickens and cattle infect them only
- Eimeria and Cystoisospora of pigs infects them only
Describe the stages of coccidia multiplication in the host.
- asexual reproduction is schizogony and ultimately produces individuals parasites called merozites
- sexual stages are female macrogamonts and male microgamonts
- result is zygote that then becomes the oocyst
Describe the characteristics of the coccidia oocyst.
- environmentaly resistant to disinfectants and can live up to two years, they are excreted unsporulated and then sporulate in the environment
- the sporulated stage of the oocyst is used as an identifier of species, this stage contains sporocysts which protect the sporozites which are the infective stage
Describe the oocyst sporocyst features of the different spp. of coccidia we discussed and those that cause disease.
- Eimeria spp. have 4 sporocysts with 2 sporozites each for a total of 8 infective sporozites
- E. bovis and zuernii cause disease
- Cystoisospora spp have 2 sporocysts with 4 sporozites each for a total of 8 infective sporozites
- Cystoisospora type spp. cause disease in chickens, cows and small ruminant and include Toxoplasma gondii, Neospora caninum, Besnitia spp, and Sarcocystitis spp.
- Cystoisospora type spp. have definitive AND intermediate hosts!
What is the life cycle of E. bovis?
- oocyst is the infective stage, the prepatent period is around 15 days for E. bovis
- sporulated ooxyst ruptures and infectious part is the sporozite
- sporozites reproduce asexually within the small intestine to become mature schizont and then merozites
- merozite ruptures and releases schizonts into the large intestine
- after reaching the large intestine additional asexual reproduction occurs and mature merozites become micro or macrogamonts
- sexual reproduction occurs and result in a gamete
- within the large intestine another oocyst forms within the intestinal crypts causing damage and is excreted in feces often causing bloody diarrhea
What are some factors in the pathogenicity of coccidial infection?
- species of coccida present
- numbers of oocysts ingested
- age of the host, young animals tend to be infected most commonly
- environmental conditions
- the rupture of infected cells releasing the merozites causes tissue destruction and therefore malabsorption, villous atrophy, hemorrhage and diarrhea (can be bloody but not always).
What are some problems with coccidia found in food animals?
- in chickens, anticoccidial resistance is a problems resulting in decreased weight gains and feed conversion
- young cattle often contract coccida which causes blood diarrhea, weight loss, opportunistic pneumonia and death
- stress induced coccidosis often seen in feed lot cattle in the winter after travel to feedlot
- swine coccidia is caused by Cystoisospora suis which causes diarrhea in 8-14 day old piglets, highly contagious, and it's not economical to treat, but rather keeping the environment VERY clean
Describe the characteristics of dog and cat coccidiosis.
- unlike the other food animal spp.specific coccidia, the Cystoisospora rivolta, felis, canis species that infect dogs and cats can include mice (or other prey animals) as a paratenic host
- Causes severe diarrhea in young animals and is often found in the lymph nodes where it can come out and cause intestinal infection
- Spurious oocysts are ingested when dogs or cat eat their prey or the prey feces, these have a more elongated shape, with markings, wall can be thicker, inside may not necessarily be 2 celled, non pathogenic
Describe the characteristics of rabbit coccidiosis.
- infects the intestine AND liver
- within the intestine, Eimeria stiedai causes liver enlargement and bile duct hyperplasia
What are the general characteristics of Cryptosporidium?
- classified as a coccidia spp. because of the presence of an oocyst however no sporocysts, sporozites exists on their own
- develop in a host microvilli and when excreted are fully sporulated
- Anti-coccidial drugs DON'T work with crypto
- not all species are zoonotic, C. parvum is a truly zoonotic spp found mostly in dairy calves resulting in non-bloody diarrhea at 5-6 days of age
- C. parvum is transmitted in diarrhea
- Crypto is found along the intestinal absorptive border
What are the specific Cryptospridium spp. of concern?
- C. hominis is human to human and is generally associated with water-borne outbreaks, oocysts not killed by chemicals in water and can make it past water filters
- C. parvum is calf - human
- Causes severe water diarrhea but especially problematic in AIDS patients
- No effective treatments, can be fatal in birds
How can oocysts of cryptosporidium be found?
Sugar float, acid-fast, direct, ELISA
What are some Piroplasms or tick borne Apicomplexas spp. we discussed in class? Where are these problematic?
- important disease of cattle in tropics
- asexual stages of Babesia in RBC's or Theileria and Cytauxzoon spp. are found in lymphoid cells + RBC's
- sexual stages occur in ticks
- cause hemolytic anemia, anorexia, fever, jaundice, hemoglobinuria
What are the species specific Babesia piroplasms? What ticks transmit these?
- Babesia bigeminia is also known as Texas cattle fever and is transmitted by Rhipicephalus anulatus
- Babesia gibsoni and canus is found in dogs and is transmitted by Rhipicephalus sanguineus
- often occurs as a carrier state and can become problematic when dogs especially require transfusion and receive infected blood
Describe the deadly cat specific piroplasm and the tick spp. that transmits this pathogen.
- Cytauxzoon felis is rapidly fatal
- undergoes life cycle stages in macrophages that line vessels and RBC's
- causes fever, anorexia, icterus, dyspnea, and splenomegaly
- transmitted by the Dermacentor variabilis tick
Describe the Hepatozoon americanum pathogen and the tick that transmits it.
- causes muscle stiffness, lameness, reluctance to move, weight loss, muscle atrophy, fever, depression, limb edema, periosteal bone proliferation and eventually death
- affects the WBC's
- transmitted by the Amblyomma maculatum tick which is a gulf coast tick
Describe the subphylum Mastigophora and what spp are included?
- bear flagella for all or part of their life cycles
- divide by longitudinal binary fission
- mucosal flagellates live in mucosa or lumen
- some spp live in the blood or tissues
- includes trichomonads (mucosoflagellates) that infects many spp., trypanosoma (hemoflagellates), and diplomonads which include giardia
Describe the general characteristics of trichomonads we discussed in class and some examples.
- usually nonpathogenic
- luminal parasites with no true cyst stage, require direct contact or fecal oral transmission
- most are commensal parasites that will be found in diarrhea BUT aren't the cause of diarrhea
- bear an undulating membrane and flagella
- Tritrichomonas foetus infects reproductive organs of cattle (STD in cattle), infects the large intestines of dogs, cats, pigs
- can cause abortions but it's not common around these parts
- Trichomonas gallinae in wild birds is an emerging disease
Describe the tritrichomonas foetus parasite, problems that it causes, diagnostic methods, possible treatment in cattle.
- STD of cattle, bulls are asymptomatic carriers
- causes infertility, early embryonic death, abortion of various aged gestation calves, pyometra
- bulls must be sampled after resting for 1-2 weeks using the in-pouch method, collect sample from preputial scrape
- cows can be sampled but it must be from anterior vagina or cervical os
- possible vaccine that isn't great
- use AI and cull infected bulls, replace with negative younger bulls
- cull open cows or rest for 4 months, use virgin or pregnant replacements
- treatments aren't effective
Describe the t.foetus infection in cats, diagnostic methods, and treatment.
- chronic, waxing and waning large bowel diarrhea
- cow pie consistency, malodorous, sometimes contains mucous or fresh blood
- causes involuntary fecal dribbling and inflammation
- trophozoites must be found in fresh feces using a fecal smear or in pouch method for positive diagnosis, can also send off PCR testing which detect live and dead trophozoites
- ronidazole treatment may actually worsen diarrhea, and in both treated and non-treated cats diarrhea will resolve in 2 years
- cat strains can infect cattle but it's much less pathogenic than cattle strains
- cattle strains can infect cats
Describe t. gallinae in birds.
- infects the crop, oronasal cavities, and esophagus
- problem in pigeons and song birds
Describe the general characteristics giardia duodenalis and problems associated with infection.
- giardia duodenalis for our purposes = g. intestinalis and lamlia
- most frequent agent identified in water borne outbreaks of disease, in humans, dogs and cats aren't considered the source of infection
- transmitted by cysts from feces, trophozoites rupture from cysts and develop in small intestine
- causes malabsorption problems with fat especially, causes diarrhea that is "fatty" looking
- diarrhea is often intermittent but signs develop about 1 week after infection
How is giardia diagnosed? What veterinary spp do we tend to have problems with giardia infection?
- generally dogs and cats are infected, not so much our large animals
- trophozoites (less likely) and cysts in smears or cysts in fecal floats are useful for diagnosis, but cysts are shed intermittently so you must take multiple samples over 1 week
- Zn sulfate and iodine stain are the best fecal float methods, can use stained smears
- IDEXX snap for giardia requires a single test and is a pretty good diagnostic tool
What are the assemblages for giardia?
- Assemblage A infects humans, dogs (less common), livestock
- B infects humans, dogs (less common)
- C and D infects dogs
- E infects livestock
- F infects cats
- G infects rats
- NO reports ever of C, D, or F in humans
What are the treatments for giardia?
- there is a vaccine but it's not very good
- bathing your animals regularly works really well especially when they're having diarrhea
- BZD's such as metronidazole, fenbendazole, febantel, and albendazole work really well as microtubule inhibitor
What are some examples of blood and tissue flagellates we discussed in class and how are they transmitted?
- Trypanosoma cruzi is transmitted by triatomid bugs
- Leishmainia infantum causes canine visceral leishmaniasis in the US and is transmitted by a sand fly or maternal transmission
- bugs are infected when they feed on infected blood or tissue
- Dogs suffer clinical disease and serve as a major reservoir of infection for humans
What order are the blood and tissue flagellates in and what are the characteristics of the life cycle?
- Order Kinetoplastida
- Promastigote stages are transmitted by the vector only for Leishmania
- Epimastigotes are stages that occur with in the insect vector for T.cruzi
- Amastigotes are pathogenic stages that occur in the host tissue cells for both T.cruzi and Leishmania
- Trypomastigotes are found in the blood and insect vector for T. cruzi
What are some characteristics of T.cruzi and problems that it causes?
- Pathogen that causes Chaga's disease
- transmitted by the Triatomid bugs, has been diagnosed in dogs in Virginia, but more common in wild dogs, raccoons, opossums
- Major cause of chronic heart disease in Latin America, cardiac disease includes arrhthmias or myocarditis
- trypomastigotes transferred from bugs by feces or dog eats the bug, the pathogen can enter a variety of cells including the heart and brain and multiply as amastigotes
- amastigotes rupture causing cell damage and release more trypomastigotes
- after rupture, additional tissues are invaded
How is T. cruzi diagnosed? What is the treatment
- any dog with signs of heart disease especially in Texas or if they traveled there may have T. cruzi
- blood smears will reveal trypomastigotes
- could also use ELISA and dipstick method, some cross reactivity with leishmania
- treatments are dangerous, rarely used
- supportive care
What are the general characteristics of leshmaniasis and how is it transmitted?
- visceral, cutaneous, and mucocutaneous forms of the disease transmitted by the sand fly
- dogs are a major reservoir host for visceral form, foxhounds especially common, blood transfusion induced infections due to amastigotes in the blood
- some dogs are asymptomatic
- pathogen lives in macrophages as promastigotes where they mature to become amastigotes inducing cell rupture and is maintained in the US because it's maternally transmitted
What are the clinical signs of leishmaniasis and how is it diagnosed, treated?
- causes lymphadenopathy, skin lesions, weight loss, ocular lesions, nose bleeds, lamness, anemia, renal failure, and diarrhea
- Dipstick test, presence of amstigotes in lymph node or bone marrow
- allopurinol, pentavalent antimonal drugs can be used to treat but relapses are common
- dog populations are controlled and monitored in countries where dogs are a major reservoir for human disease