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Protozoas
Question | Answer |
---|---|
Describe the group of organisms we know as Protozoa. | Eukaryotic; Unicellular; No cell wall |
Protozoa are usually grouped according to their means of locomotion. Name and describe these groups. | Pseudopods—false feet; Flagella—long; Cilia—short; No means of motility |
In what two life stages or forms can we find Protozoa? | “Troph” stage and Cyst stage |
How do we get infected with Entamoeba histolytica? | Ingesting cysts in contaminated food or water |
What condition does Entamoeba histolytica cause? | Amoebic dysentery |
What symptoms might we see in someone infected with Entamoeba? | Ulcers in intestinal wall, abscesses in liver |
What is dysentery? | Bloody diarrhea that can result in severe dehydration |
How do we diagnose disease caused by Entamoeba histolytica? | By its cyst stage—four nuclei with karysome in each, cigar-shaped chromatin body, perfectly spherical shape |
How do we get infected with Naegleria fowleri? | Found in sandy bottoms of warm waters; Gets stirred up when people jump in water; Ingested through nose |
Describe the disease process and consequences of being infected with Naegleria fowleri. | The organism is very invasive and when it gets high into the nasal passages, it can pass into the brain where it sets up a fatal infection called PAM (primary amoebic meningoencephalitis); Similar to bacterial meningitis symptoms; could lead to death |
Who would most likely get infected with Acanthamoeba? | People who wear contact lenses |
What kinds of symptoms are associated with infection by Acanthamoeba? | Eye infections |
How can infection of Acanthamoeba be prevented? | Storing and handling contact lenses appropriately |
What is the “common” name for the condition caused by Trichomonas vaginalis? | “ping-pong vaginitis” |
Why is Trichomonas vaginalis only transmitted by intimate contact? | Because it has no cyst stage and cannot survive outside its host for very long |
What is the “common” name for Giardia lamblia? | “backpacker’s parasite” |
How do we become infected with Giardia lamblia? | Drinking water without purifying it |
How can you prevent infection of Giardia lamblia? | Boiling water for 5-10 minutes or filtering water |
What are the common symptoms of infection with Giardia lamblia? | Deep, sulphur tasting burps; Abdominal discomfort, severe diarrhea, malabsorption, milk intolerance, and weight loss |
How does Giardia lamblia attach to your intestinal mucosa? | An ovoid, concave sucking disc occupies about three-fourths of the flat ventral surface—used to attach to intestinal mucosa |
Trypanosoma species need a vector for transmission. What are the vectors for African Sleeping Sickness and Chagas Disease? | African Sleep Sickness—tsetse fly; Chagas Disease—reduviid bug (“kissing bug”) |
What are the general symptoms for the systemic diseases African Sleeping Sickness and Chagas Disease? | Fever, headache, nausea, vomiting, and central nervous system involvement leading to coma and death |
What is the vector for Leishmania? | Sand fly |
What three types of Leishmaniasis do we find in humans? | Cutaneous; Mucocutaneous; Visceral form |
What “common” name do we give cases of Leishmaniasis that are seen in patients coming back from Iraq? | “Baghdad boil” |
How do we get infected with Balantidium coli? | Fecal-oral route—consuming contaminated food and/or water |
In what groups of people would Balantidium coli be most prevalent? | People in U.S. mental hospitals, nursing homes, prisons; places of crowding and lack of good hygiene |
Definitive host | host where we find the adult organism/host where sexual reproduction occurs |
Intermediate host | hosts where asexual reproduction occurs and where we find developing forms of the parasite |
What disease is caused by the parasite Plasmodium? | Malaria |
What is the genus of the vector that transmits Plasmodium? | Anopheles |
Name the definitive and intermediate hosts for Plasmodium. | Definitive—mosquito; Intermediate—human |
What does Plasmodium do in the human host once it is injected by the bite of the mosquito? | Invade the liver and undergo asexual multiplication; Then invade red blood cells; Blood stream phase of infection |
What causes the disease symptoms observed in Plasmodium infection? | Lysis of the red cells liberates products of metabolism of the parasites and the red cells—toxic materials cause symptoms |
What animal is the definitive host for Toxoplasma? | Cat |
How do cats get infected with Toxoplasma? | By eating an infected mouse or rat |
How do man, sheep, dogs, cows, and other animals get infected with Toxoplasma? | Ingestion of undercooked meat of infected animal, contact with dried feces of cats (such as when cleaning litter boxes) |
Why are pregnant women cautioned about cat litter boxes? | The fetus can develop severe congenital defects from exposure to Toxoplasma such as retinochoroiditis, mental retardation, convulsions, blindness, and death |
How do man and animals get infected with Cryptosporidium? | Fecal-oral route |
For whom is Cryptosporidium particularly dangerous? | Immunocompromised people; people with AIDS |
How must we control Cryptosporidium in our water supply? | Subject water to microfiltration using filters with pores no larger than 0.2 micrometers |
What stain is used to detect the oocysts of Cryptosporidium and Cyclospora in fecal samples? | Acid-fast stain |
What are the symptoms of Cryptosporidium infection? | Profuse, watery diarrhea; abdominal cramping, nausea, low-grade fever, and headache |