More Flagellated Protozoans Flashcards
Describe the appearance of the Giardia duodenalis parasite
Rounded anteriorly and pointed posteriorly. Have adhesive disks (adhesive microtubules) on ventral side to stick to host cells and 2 prominent nuclei. Have 8 flagella in 4 pairs . Dorsal is convex, ventral is concave
Describe the flagella of the Giardia parasite
1st pair anchors in kinetosome at anterior. Posterior pair runs through more of the cytoplasm and exist near the posterior portion. Caudal flagella run entirely through flagella and run through cytoplasm and come through point at the end of the trophozoite. Ventral flagella come out of the ventral side.
Describe the Giardia cyst. What stage of the life cycle is this?
HAve a thick wall, 4 nuclei. IS the desiccation-resistant transmissible stage
Most Giardia infection occurs in the _____
Duodenum
How does a Giardia infection build up?
They divide through binary fission so populations can build up rapidly to the point where trophozoites can infect almost every cell in the small intestine.
At what point to Giardia form cysts?
When stools dry out in the colon, cysts form.
How do Giardia produce symptoms?
They may cause watery diarrhea, loss of weight, fatty stools, interference with fat/nutrient absorption (ex. Vitamin B or A) - this may be because of large number of parasites on intestinal epithelium
Are symptoms always present with Giardia infection?
Asymptomatic infections do exist, but they are still transmissible. This varies by strain of parasite/host immunity. The disease can also go in stages, with intermittent symptomatic and asymptomatic stages
A Giardia infection is referred to as ____
Giardiasis
In what areas are Giardia infections common?
Areas with poor water filtration, near beaver ponds, downstream from livestock operations
How is Giardiasis treated?
With metronidazole, nitroimidazoles, quinacrine
The parasite Spironucleus meleagridis affects many turkeys. Describe how it is similar to Giardia. How is it controlled?
Morphology is similar except it has no median bodies, no sucking disk, different flagella arrangement. This parasite is controlled by separation of young birds from parasitized survivors.
What is the most important feature of the Trichomonadida
Do not produce a cystic stage - must be transferred via direct contact of fluid
Briefly describe the basic structure of Trichomonadida trophozoites
Have a complex flagellar system consisting of a undulating flagellum/membrane over 1/2 of body. They have a very small cytostome. The Costa is a bar running along the base of the undulating membrane. They have axostyles (median rods) running through the middle of the body
Where does Trichomonas tenax live? Why is this important?
In gaps between gums and teeth in the mouth. It is harmless and feeds on bacteria. They cannot infect you as they do not form cysts and will not survive your stomach. They are passed by kissing.
Where does Trichomonas vaginalis live?
In reproductive tracts of both sexes
What symptoms does T. vaginalis infection cause?
Increased blood flow to vagina, cheesy-smelling yellowish “exudate”
What does T. vaginalis look like?
LArger than T. tenax, produced pseudopodia
How can T. vaginalis be transferred, outside of sexual contact?
Via moist towels that are shared
Does T. vaginalis have a 100% infection rate?
No, the natural acidic pH of the vagina should be hostile to it, but feminine hygiene products may affect pH enough to make infection easier
How is T. vaginalis infection diagnosed?
Microscopic identification of flagellates in scrapings/from discharge
How is T. vaginalis infection treated?
With Flagyl, but there is some resistance documented
What does Histomonas meleagridis attack and what does it cause?
Attacks birds such as domestic turkeys. Causes “black head”, infectious enterohepatitis. Black pigments accumulate in the head. Causes liver/metabolic dysfunction.
What does Histomonas meleagridis look like?
Reduced flagella, have no cysts but the trophozoites have many possible forms, They are amoeboid and reproduce by binary fission
How is Histomonas meleagridis transmitted?
Via nematode eggs (Histomonas survives in nematode gut, infects egg, and nematode eggs act as a cyst wall)
How does Histomonas meleagridis infection occur?
Cause lesions in caecum and liver of birds.