Pathogenic Protozoa I Flashcards
Includes Giardia and Trichomonas and their distant relatives Trypanosoma and Leishmania
Flagellates
Amoeboid at one stage of its life cycle and flagellated at another, may be more closely related to flagellates than to other amoeboid organisms
Naegleria
Includes Entamoeba (the cause of ‘amoebic dysentery’), Acanthamoeba, and Hartmanella
Amoebozoa
What are the three types of alveolates?
-named for their cortical alveoli and flattened membrane-bound sacs
Apicomplexa, Cilliates, and Dinoflagellates
Apicomplexa includes one of the most significant pathogens worldwide, the cause of malaria, which is called
Plasmodium
Human apicomplexa pathogens are members of the class Sporozoa and most of the subclass Coccidia, so are sometimes called
Sporozoans or coccidia
Includes the intestinal pathogen Balantidium and the familiar non-pathogen Paramecium
Ciliates
Flagellated photosynthetic >algae=; cause >red tides= that kill marine organisms
Dinoflagellates
Not known to cause human infections but secrete toxins which cause human illness either from direct exposure or from consumption of fish or shellfish which have fed on them
Dinoflagellates
Tiny intracellular parasites which lack mitochondria
Microsporidia
What are three other major groups of eukaryotes?
- ) Green algae, red algae, and plants
- ) Rhizaria or cercozoa
- ) Heterokonts
Amoeboid organisms, many with elaborate shells
Rhizaria or cercozoa
Made up of brown algae, diatoms, and their relatives, who, like Dinoflagellates, became photosynthetic via symbiosis not with bacteria but with eukaryotic algae
Heterokonts
Organism used by another as a source of nutrition and protection
Host
Organism that uses another as a source of nutrition and protection, with harm to the host
Parasite
Organism that uses another as a source of nutrition and protection, without harm to the host
Commensal
Organism in which a parasite replicates in nature, from which it is transmitted to humans
Reservoir
Organism which transmits a parasite to humans; it may or may not be a host
Vector
Host in which parasite undergoes sexual cycle (meiosis + fertilization)
Definitive host
Host in which parasite multiplies asexually
Intermediate host
Growing/multiplying form of a parasitic protozoan
Trophozoite
Non-growing form, specialized for resistance to unfavorable environments and dispersal
Cyst
Cells of a single species may take on different morphology at different stages of the life cycle. Some protozoa reproduce in an obligate cycle between two
Host species
In this situation, forms produced by growth in the first host are
Infectious for the second
Microscopic examination is often the key to diagnosis of
Protozoa infection
To check stool for protozoa, we perform an
O and P workup (Ova and parasites)
Unfixed “wet mounts” (unstained and stained with iodine) of fresh material to visualize live organisms
O and P workup
Called the “backpackers” diarrhea
Giardia lamblia
Infections acquired by consuming contaminated water
Giardia
Giardia multiplies in the lumen of the intestine; cells and cysts are shed in
Feces
Cells have two nuclei (giving them the appearance of a ‘face’ under the microscope) and a large ventral ‘sucker disk’ with which they adhere to the intestinal mucosa
Giardia
Acute or (in AIDS) chronic diarrhea. Organisms adhere to brush border
Giardia infection
The diarrhea seen in a giardia infection is from
Maladsorption
Sexually transmitted infection that multiplies on GU mucosal membranes
Trichomonas Vaginalis
Cells have a tuft of flagella at one end and an ‘undulating membrane’ which extends part-way down the cell
Trichomonas Vaginalis
In women, trichomonas vaginalis infection is typically limited to the
External genitalia, vagina, and cervix
Symptoms are itching or burning and a pale yellow, watery discharge; many infections asymptomatic
Trichomonas Vaginalis infection
Transmitted by insect vectors; multiply in both vector and host
Hemoflagellates
Produces bloodstream infections and multiply outside cells
Trypanosoma
Produce tissue infections and multiply intracellularly
Leishmania