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57 Cards in this Set
- Front
- Back
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Phylum Apicomplexa |
All parasitic No obvious motility structures characterized by apical complex, rhoptries, micronemes, and micropores |
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apical complex |
set of structures that are considered distinguishing characteristic of Apicomplexa consists of: - 1 or two polar rings immediately beneath cell membrane - coniod - truncated cone of spirally arranged fibrillar structures within polar rings - subpellicular microtubules - radiate from rings and run posteriorly, parallel to body axis |
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Function of apical complex |
locomotion, structure |
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rhoptries and micronemes in apicomplexa |
- rhoptries (2 to several) extend to cell membrane within polar rings - help with adhesion to and penetration of host cell
- micronemes - smaller, more convoluted bodies that also extend posteriorly from apical complex Contents of these two organelles are enzymes that are released upon entry into the host cell |
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micropores |
aid in food ingestion within host cell |
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Class Sporozoea |
Subclass Coccidia Family Sarcocystidae Toxoplasma gondii Sarcocystis spp. Cryptosporidium sp. Cyclospora cayentanensis Pneumocystis carinii (actually in Fungi Kingdom kind of?) |
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Toxoplasma gondii causes _____ , which is asymptomatic in adult humans but causes major birth defects in fetuses. |
toxoplasmosis |
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Toxoplasma gondii prevalence |
parasite of many mammal species intracellular in many tissues |
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Life cycle of T. gondii: cat's infection from rat -> merozoites/gamonts |
- cats become infected by ingesting bradyzoites (within zooitocysts) in muscles of another host (ex rodent) - released in intestine - penetrate epithelial cells (enteroepithelial cycle) - others can penetrate mucosa and infect other organs (extraintestinal) - in epithelial cells, trophozoites divide asexually (merogeny/schizogany) - merozoites escape cell, initiate merogeny in other cells OR transform into gamonts and perform gametogony (separate note card) |
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Life Cycle of T. gondii: gametogenesis |
- after merozoites escape from a host cell, they can continue to initiate merogeny in other host cells OR transform into gamonts - Fertilization leads to formation of oocyst -immature oocyst passes with feces - sporulates when exposed to O2 contains 2 sporocysts (4 sporocysts each) *next step on other card |
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Life Cycle of T. gondii: when mammal ingests oocyst |
-when another mammal ingests oocyst
- sporozoites escape in small intestine - enters host cells - asexual reproduction occurs- produces tachyzoites that reproduce rapidly - host immune reaction slows divison and tachyzoites become bradyzoites - host forms wall around infected cell - zoitocyst - remains viable in host for a long time |
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Humans can become infected by T. gondii by ingesting ____ or _____ in uncooked meat |
oocyst or zoitocyst |
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Pathogenicity of T. gondii |
usually asymptomatic in immunocompetent many people have antibody virulence and susceptibility varies |
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Acute T. gondii |
mainly intestinal involvment flu-like symptoms, swelling of lymph nodes more likely in immunosuppressed |
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Chronic T. gondii |
kept in check by immune system |
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If immunosuppressed individual gets T. gondii or if a T. gondii cyst breaks |
bradyzoites released, immune reaction occurs and can cause extensive tissue damage in NS, can lead to blindness and brain/heart damage |
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Congenital toxoplasmosis |
when a mother contracts T. gondii near conception or during pregnancy |
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T. gondii crosses placental barrier in ___% of mothers nfected and causes congenital toxoplasmosis.
____% of those infected will be asymptomatic _____ % may be lethal ____ % severe pathogenesis - causes either hydrocephaly, brain damage/retardation, etc |
45% 60% 9% 30% |
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Sexual/asexual reproduction of T. gondii |
sexual reproduction occurs only in cats - in intestinal epithelial cells (asexual reproduction occurs in cats as well. in intestinal and other tissues) In other mammal hosts, asexual reproduction ONLY |
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Diagnosis of T. gondii |
- parasite in tissue biopsy - infection of mice with infected tissue - ELISA - enzyme/antibody/color identification test |
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Treatment of T. gondii |
- pyrimethamine and sulfonomides |
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____ % of the world pop. infected with T. gondii ___ million in US alone In 1976, ____ cases of congenital toxoplasmosis. In 1999, at least ______ cases. |
13 % of world pop 60 million in US 3500 cases in 1976 400 cases in 1999 |
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Pregnant women should not clean litter boxes, children's sandboxes should be covered. Why? |
Oocysts passing in cat feces (only occurs for a few days after infection of cat) |
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Major source of infection of T. gondii (besides cat feces) among humans is _____. |
undercooked meat Safe frozen ( -14 C) |
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Sarcocystis spp. intermediate host |
herbivorous mammals |
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Sarcocystis spp. definitive host |
carnivorous mammals |
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Life cycle of Sarcocystis spp. |
- Int. host ingests sporocysts (sometimes in oocyst) - sporozoites penetrate intestinal epithelium - go to various body tissues - invade endothelial cells of blood vessels - merogeny (may be several generations) - zoitocysts (also known as sarcocysts/Meischer's tubules) then form in skeletal and cardiac muscle and occasionally in the brain *separate notecard for these |
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zoitocysts of Sarcocystis spp. |
- each cyst has 2 distinct regions:
peripheral region is occupied by globular metrocytes. after several divisions the metrocytes give rise to more elongated bradyzoites. |
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only _________ are infective to definitive host of Sarcocystis spp. |
bradyzoites |
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(Sarcocystis spp Life Cycle) What occurs when a definitive host (carnivorous mammal) ingests a zoitocyst? |
- its wall is digested away - bradyzoites penetrate the lamina propria of the small intestine - there they undergo gamogony without intervening merogenic generation male gametes penetrate female gametes - resulting oocysts sporulate in the lamina propria. -oocyst walls are thin and usually break open during passage through intestine, therefore sporocysts are usually passed in feces. |
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Sporocysts of Sarcocystis spp. can infect ______ hosts but not _______ hosts. |
(first blank) intermediate (second blank) definitive |
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Are humans definitive hosts of Sarcocystis spp? |
Only in a couple species.
often asymptomatic |
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Cryptosporidium spp. |
- 6 valid species - very small, 2-6 um |
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Cryptosporidium parvum |
can be parasitic to humans, but not very host specific |
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Life cycle of Cryptosporidium sp. |
-live in brush borders of intestines - intracellular/extracytoplasmic - oocysts in feces ingested - excyst of sporozoites when exposed to bile salts, acidity, and temperature of digestive system - sporozoites invade cells and become trophozoites - merogeny -produces trophs and gametes -fertilization -> zygote -> sporogony -> 4 sporozoites -> oocyst |
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Life Cycle of Cryptosporidium sp. - live in brush borders of intestines - intracellular/extracytoplasmic - _______ in feces ingested - excyst of _______ when exposed to bile salts, acidity, and temperature of digestive system - sporozoites invade cells and become ________ - ______ occurs and produces trophs and gametes -fertilization -> ______ -> sporogony -> 4_______ -> oocyst |
- live in brush borders of intestines
- intracellular/extracytoplasmic - oocysts in feces ingested - excyst of sporozoites when exposed to bile salts, acidity, and temperature of digestive system - sporozoites invade cells and become trophozoites - merogeny occurs and produces trophs and gametes -fertilization -> zygote -> sporogony -> 4 sporozoites -> oocyst |
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Two types of cysts in Cryptosporidium life cycle |
Thick walled - passes out with feces Thin walled - excyst and can cause autoinfection (remains in host and can cause reinfection) |
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Symptoms of Cryptosporidum infection |
diarrhea, abdominal pain, nausea & vomiting, fatigue, fever major cause of persistant diarrhea in developing countries |
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Cryptosporidium identified as a human pathogen in _____ (year) |
1976 |
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Treatment of Cryptosporidium |
As of now, none. Nitazoxinide may be effective. self limiting in most (1-10 days) very dangerous in immunosuppressed |
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Immunosuppressed people with Cryptosporidium |
symptoms much more severe often fatal 6-25 profuse watery stools/day |
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Oocysts of Cryptosporidium not resistant to _______ but remain viable in ______ for a long time. They are highly resistant to chlorine. |
desiccation, water |
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1993 Milwaukee outbreak of Cryptosporidium |
largest outbreak of water born illness ever in US 403,000 people ill 4,400 people hospitalized took 2 weeks to ID cause. |
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_______ reservoir. This reservoir may be important source of infection of Cryptosporidium in humans (zoonosis). may be very common cause of short term diarrhea in general population, and persistent diarrhea in developing countries. |
cattle |
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1998 Texas outbreak of Cryptosporidium |
Brushy Creek, near Austin. lightning struck sewage station 170,000 galloons spilled, ran into wells of water system. |
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Cyclospora cayentanensis first isolated ? |
-relatively new parasite -first isolated in Peru in 1979 |
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C. cayentanensis first outbreak in US |
Chicago 1990, several cases reported since. |
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Symptoms of Cylospora cayentanensis similar to ________________. |
Cryptosporidiosis |
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Oocyst of C. cayentanensis is similar to Cryptosporidium sp but __________ . |
larger - 8 - 10 um. (Cryptosporidium oocyst is 2-6 um) |
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Pneumocystis carinii taxonomic status? |
Not agreed upon. Some place it in fungi, some in apicomplexa. |
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P. carinii |
very common parasite of mammalian lungs - usually harmless |
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P. carinii causes ______ in immunosuppressed |
pneumonia |
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_________ leading cause of death in individuals with AIDS. (60 % of patients infected) |
Pneumocystis carinii |
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Biology of P. carinii: 3 stages in lung |
- Trophozoite - Pre-cyst - Cyst surrounded by membrane enter air spaces may pass out in aerosol droplets or direct contact |
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Pathogenesis of P. carinii in immunosuppressed |
- damage to lung epithelium - alveoli fills with foamy exudate (full of parasites) - death by asphyxiation - mortality near 100% |
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Symptoms of P. carinii |
fever, cough, difficulty breathing, cyanosis |
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Diagnosis of P. carinii and treatment |
diagnosis: sputum sample or biopsy treatment (usually not effective because immune system is not functioning): Combination Trimethoprim-sulfamethoxazole or inhaled pentamidine isethionate |
