Term
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Definition
Stages: Tropososite (feeding stage),
Cyst (protective resistant stage)
Motility: Pseudopod (mobility & feeding),
Flagella present in some
Characteristic: Karyosome=Dx ring around nucleus
Clinical signs:
aymptomatic carriers,
intestine: abdominal pain, cramping, dysentery, perforated colon.
hepatic disease: abdominal pain, fever, weakness, weightloss
can move to brain
dignostic test: karyosome fecal smear
vector/transmission: contaminated water/food, ingestion of cyst |
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Term
Asexual reproduction strategies for Protozoas |
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Definition
- longitudinal binary fission
- transverse binary fission
- budding
- multiple fission
- endodyogeny
- endopolyogeny
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Term
Types of sexual reproduction for protozoas |
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Definition
- conjugation
- syngamy
- anisogamy
- isogamy
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Term
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Definition
the stage of parasitic protozoa that actively feed and multiply |
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Term
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Definition
stages with a protective membrane or thickended wall. protozoan cysts that must survive outside the host usually have more resistant wall than cysts that form in tissues. |
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Term
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Definition
- unicellular eukaryotes
- possesses organelles that often function similarly to organs and systems of multicellular organisms
- parasistic forms with holozoic nutrition (ingest complex organic material)
- basic forms of locomotion: flagella, cilia, pseudopodia, and gliding
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Term
important disease causing phlya for protozoans |
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Definition
Sacromastigophora
and
Apicomplexa |
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Term
longitudinal binary fission |
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Definition
equal division of organism into 2 across longitudinal axis
ex. lumen dwelling flagellates |
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Term
transverse binary fission |
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Definition
equal division of a ciliate into 2 across transvese axis |
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Term
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Definition
fragmentation into 2 or more unequal fragments |
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Term
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Definition
merogony: schizogony; multiple karyokinesis followed by multiple cytokinesis
Ex. malaria |
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Term
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Definition
2 daughter cells arising from internal budding of parents; many parental membranes and organelles utilized. |
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Term
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Definition
more than 2 daughter cells resulting from internal budding of parent |
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Term
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Definition
in ciliates, pairing and temporary plasma membrane fusion for genetic exchange |
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Term
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Definition
fusion of gametes
ex. Malaria |
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Term
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Definition
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Term
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Definition
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Term
protozoa of the intestin and urogenital tract |
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Definition
entamoeba histolytica
giardia lamblia duodenalis
trichomonas vaginalis
balantidium coli
isospora sp.
cryptosporidium parvum
cyclospora sp.
microsporidia |
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Term
Giardia lamblia doudenalis |
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Definition
“Once Smelled Never Forgotten”
Classification: Protozoa, Flagellate
Structure: Giardia has endoplasmic reticula and two separate nuclei, but lack mitochondria. Kite shaped with 2 nuclei giving it appearance of “monkey face.” Flagella for motility.
Life Cycle: Has two stages, a trophozoite (feeding stage) which is the only form found in tissues and the cyst form, which is the infectious stage (contains 4 nuclei).
Basic concepts of infection and Pathology: Cyst form is ingested, and matures to trophozoite. It adheres to intestinal wall and limits fats absorption. That’s causes fat in stool, which causes horrific odor and floating feces. Diagnosed by cysts in fecal smear.
Mode of locomotion: Rodents, deer, cattle, cats, dogs may act as Zoonosis for humans
Sites of Infection: Adheres to and coats intestinal wall.
Medicine: Metronidazole. |
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Term
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Definition
Classification: Protozoa, Flagellate
Structure: No mitochondria, has flagella for motility.
Mode of reproduction: Binary Fision. No cyst stage.
Basic concepts of infection and Pathology: Parasites invade vagina and urethra and cause infection, irritation and profuse discharge of leukocytes. Diagnosis is made of smear of urine, semen or discharge with flagellated parasites.
Mode of locomotion: Sexual contact
Sites of Infection: In vagina in females and urethra in males. Labia will be red.
Treatment: Metrondazole
Key Facts: Sexually transmitted disease 7 million cases annually in US, 180 million worldwide. Discharge gives off bad odor. |
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Term
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Definition
Classification: Protozoa. Ciliate.
Structure: Ciliated (only infectious ciliatd protozoa). Very large. Cyst form lacks cilia.
Mode of reproduction: Binary Fision of trophozoite. Conjugation may occur.
Basic concepts of infection and Pathology: Cyst enters mouth and goes though excystation in small intestines becoming trophozoite in large intestines. Then goes through encystations to produce infected cyst which is passed with feces.
Mode of locomotion: Fecal-Oral. Spread thru H2O and food through reservoirs, monkeys, rats, guinea pigs, dogs and pigs.
Sites of Infection: In large intestines and colon. Causes chronic diarrhea and ulcers in intestines.
Treatment: tetracycline, iodoquinol or metronidazole
Key Facts: known as Balantidiosis, balantidiasis, or balatidial dysentery. Prevention of contamination more useful than treatment. Verify is parasite is absent in stool after 1 month. |
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Term
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Definition
Classification: Protozoa, Apicomplexa
Life Cycle: Excreted as oocyst containing sporoblast. Sporoblast divides into 2. Sporoblasts secrete cyst wall becoming sporocysts. They divide twice producing 4 sporozoites each.
Mode of reproduction: Both asexual and sexual development in new epithelial cells.
Basic concepts of infection and Pathology: A sporocyst is eaten, and excysts in S.Intestines releasing sporozoite. It initiates schizogony and the schizonts rupture, releasing marozoites. Invade epi and do asexual multiplication. Trophozoites develop schizonts with contain merozoites. Sexual development of male and female gametes occur. Fertilization à oocysts
Mode of locomotion: Fecal-oral.
Sites of Infection: Small intestines causing diarrhea.
Treatment: Trimethoprim-sulfamethoxazole
Key Facts: Diagnosis by identigication of oocysts in feces using concentration techniques. Eosinphilia. |
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Term
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Definition
Cyclospora – “Tourist Diarrhea”
Classification: Protozoa, Apicomplexa
Life Cycle: Oocysts.
Basic Concepts of infection and pathology: Cyst form is eaten. Causes prolonged diarrhea (4-10 water stools a day). Non-inflammatory reaction (No WBCs). Causes anorexia, fatigue, weight loss.
Locations: Napal and S. America.
Mode of locomotion: Oocysts from stool contaminate fruits (most strawberries and raspberries) and vegetables.
Diagnosis: Fast Acid fecal stain or UV light.
Treatment: Trimethoprim/Sulfamethoxazole.
Key Facts: Should be considered diagnosis in the differential if prolonged diarrhea especially in pts with Hx of travel. Cause of endemic diarrhea in Peru. Also, share common epidemiology with cryptosporidium, and in fecal smear oocysts have to be measured to distinguish the two.
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Term
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Definition
Classification: Protozoa, Apicomplexa
Structure: Each oocysts contain 4 sporozoites.
Life Cycle: Oocysts sporolates in hosts with infective agent (4 sporozoites). Life cycle occurs within infected epi cells.
Mode of reproduction: Both asexual and sexual cycle.
Basic concepts of infection and Pathology: Water
Mode of locomotion: Fecal-oral. Found in drinking water, auto-infection cycle is possible
Sites of Infection: Small intestines causing diarrhea, vomiting and abdominal pain. Crypto develops in the microvilli border.
Diagnosis: Fecal smear with acid fast red stain. Oocysts are ~4-5um in diameter.
Treatment: Nothing good, supportive therapy, nitazoxinide, spiramycin and paromomycin in severe cases.
Key Facts: Risks factor: Exposure to untreated or inadequately treated water.Oocysts extremely resistence to breakdown |
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Term
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Definition
Classification: NOW fungus!
Structure: Unicellular spore, 1-2 nuclei, extrustion apparatus (polar caps, polar tube). Resistant spore is infective form. No mitochondria.
Life Cycle: Spore and microspore.
Sites of Infection: Small intestines causing diarrhea
Mode of Reproduction: Binary or multiple Fission.
Basic Concepts of infection and pathology: Spore extrudes polar tubule and infects host cell. Once inside cell, sporoplasm multiples extensively. The microsporidia develop by sporogony to mature spores. A thick wall forms around spores for protection. Spores keep multiply until cell bursts, and sports infect new cells.
Sites of Infection: Intestines lung and liver depending on the species.
Key Facts: Obligatory intracellular parasites. |
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Term
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Definition
Whipworm(Trichurius Trichura)
Classification: Nematode, Geohelminth
Clinical: Chronic diarrhea often with frank blood, Anemia, Growth retardation.
Life Cycle: Infected egg in swallowed. Larva hatch in small intestines and mature as an adult in cecum.
Diagnosis: Detection of characteristic football shaped eggs with bipolar plugs. May require more than 1 sample.
Treatment: Mebendazole, Albendazole
Key Fact:Ice Man's rectum infected with whipworm. People are often co-infected with Ascaris because they have similar distribution. World prevalence 900 million, U.S. prevalence about 1%. Infection in population, food preparation and toilet facilities in same area. Albendazole does not work. |
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Term
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Definition
Paragonimus westermani (Lung Fluke)
Classification: Trematode, Helminth
Mode of Locomotion: Found in carnivores, pigs, rodents and man but is acquired by eating uncooked crab.
Location: Mostly seen in Southern and Eastern Asia.
Pathogenesis: Adult worms live in fibrotic capsules in lungs. Eggs are trapped within the lung tissue.
Clinical Signs: Hemoptysis (spiting blood sputum), chronic cough, Seconary bacterial infection.
Diagnosis: Eggs in sputum or feces, radiolocal changes like white cloud in lung.
Life Cycle: Eggs hatch releasing miracidium, which infects first intermediate host (snail). Parasite reproduces asexually and cercariae are produced. They infect secondary intermediate host (crab). Cercariae encyst in host, forming matacercarie which is ingested by definitive host. Metacercaria “excysts” in the small intestines and immature worms penetrate gut wall to lungs. Adult parasites reside in lungs |
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Term
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Definition
Schistosoma (Blood Fluke)
Classification: Trematode, Helminth
Structure: Have sharp pointers that help pierce intestines to get into venous system. Cercicaria have forked tail and can penetrate human skin in water. NO METACERCARIAL STAGE
Mode of Locomotion: Fecal contaminated water, human water contant, human feces used as fertilizer.
Life Cycle: Egg hatches in fresh water. Larva infect snail, cercaraie leave snail and are now infectious to humans. In the water then penetrate through skin and travel to hepatic vein. Here the male and females mature and mate. Then, they go to either the small intestines or the bladder to lay their eggs ensuring the eggs will be released from the body.
Key Fact: Can practice molecular mimicry, by incorporating host antigens on surface to fool immune system into thinking its “self”. Eosinophilia. 200 million people infected w/ 1million deaths/year. Adult worms, separate sexes,permanent copulation
3 Species: S. Mansoni, S. Japonicum, S. Haematobium. |
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Term
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Definition
Pinworm (Enterobius Vermicularis)
Classification: Nematode, Helminth
Structure: Male worm is much smaller than female.
Life Cycle: Egg is ingested, mature worms live in large intestines. Larva is passed in feces.
Mode of Transmission: Self-infection/auto-infection may occur.
Site of Infection: Adults in the cecum, appendix, colon
Clinical: Pruritus and anal irritation, especially at night.
Diagnosis: Scotch tape on anal.
Treatment: Pyrantel, Albendazole or Mebendazole
Key Facts: Clean house to remove eggs
Heat bedclothes in hot dryer. |
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Term
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Definition
Hymenolepis nana
Classification: Cestode, Helminth
Structure: Small tapeworm (4 cm)
Life Cycle: Insect intermediate host
Mode of locomotion: Accidental ingestion in food, Tribolium beetle in cereal
Site of infection: Autoinfection possible with metacestode forming in intestine
Clinical: Heavy infection cause diarrhea, abdominal pain
Diagnosis: Identification of egg
Treatment: Praziquantel
Most common in children and institutionalized |
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Term
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Definition
Diphyllobothrium Latum
Classification: Cestode, Helminth
Structure: No spines on scolex.
Key Fact: Infection, presents a variable range of pathology, but is not commonly the cause of serious disease in man.
Clinical: abdominal pain and loss of weight, and are often similar to the symptoms displayed during infection with adult Taenia. However D. latum differs from Taenia in absorbing much more vitamin B12, (between ten and fifty times more) than other tapeworms. Infection may result in a macrocytic hypochromic anemia in some cases, vitamin B12 having an important role in formation of blood cells.
Location: Baltic region, particularly in Finland.
Life Cycle: Egg hatches and is eaten by copepod as 1st intermediate. Procercoid develops, and copepod is eaten by fish (2nd intermediate). Plerocercoid develops in fish muscle, and is eaten by human and matures to worm. |
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Term
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Definition
Taenia solium
Classifaction: Cestode, Helminth
Mode of Locomotion: Eggs passed in gravid segments from host. Intermediate host ingests eggs.
Life Cycle: Egg is feces is eaten by animal. Matures to bladder worm and attaches to muscle. Infect occurs by eating cysticerci larvae in un/undercooked meat. T. saginata is beef tapeworm, T. solium is pork. Bladder worm attach to intestines and segments.
Clinical Sign: Diarrhea, Indigestion.
Diagnosis: Identification of eggs or segments.
Treatment: Praziquantel and niclosamide.
Epidemiology: Found worldwide, but Seen primarily in Latin America (common public health problem in Mexico), Middle East, Asia, Africa T. Solium is seen mostly in travels and immigrants.
Key Facts: Humans can also act as intermediate host
Causes “Cysticercosis” in eye, brain and muscle. Death of cysticerci in NS often precipitates disease. |
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Term
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Definition
Ascaris lumbricoides
Classifaction: Nematode, Helminth
Mode of Locomotion: Eggs passed in gravid segments from host. Intermediate host ingests eggs. Passed in comtaminated water or pigs.
Life Cycle: Ingested eggs hatch, and larva migrate to liver and lung. Coughed up, swallowed and after 60 days, matures to worm in S.I.
Clinical Sign: Bloating, vomiting, abdominal pain, asthma like reachtion in lunch, obstruction of bile duct and bowel.
Diagnosis: Identification of eggs or adult worm in feces.
Treatment: Albendazole, mebendazole or pyrantel. |
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Term
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Definition
Toxoplasma gondii
Classification: Apicomplexa, Protozoa
Structure: Infection oocyst and trophozoites.
Mode of locomotion: Parasite is found in animal feces (inhalation, direct contant) or undercooked meat. Oocysts are shed in a cat's stool and can survive in kitty litter and for up to 18 months in the soil. From mother to fetus through placenta usually results in still born. Blood transfusion.
Mode of reproduction: Oocysts are only produces in cell lining of the intestine of cats.
Basic Concepts of infection and pathology: Sporozoites emerge from oocyst, leave gut and begin rapid division in cells called tachyzoites. ivision slows and bradyzoite (cyst) is formed.
Key Facts: Severe illness generally develops only in fetuses and people with a weakened immune system (HIV/AIDS). Also seen with hydrocephalus.
Diagnosis: blood smear.
Treatment: Clindamycin. |
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Term
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Definition
Babesiosis
Classification: Protozoa, Apicomplexa
Structure: 4 buds from 1 blood cell. Resemble Cross.
Mode of locomotion: Transmitted by same deer tick that transmits Lyme Disease or blood transfusion.
Mode of reproduction: Undergoes asexual replication by budding in RBC. Multiplication in blood causes clinical manifestations of the diease.
Basic Concepts of infection and pathology: Sporozoites from tick cause infection. Then matures into trophozoites and infects the red blood cells. Resembles malaria, high fever, jaundice, dark urine, kidney failure.
Key Facts: In people whose spleen has been removed, the risk of sever disease and death is high. Also, easy to confuse with malaria. Immunocompetent usually asymptomatic.
Diagnosis: Positive blood smear.
Treatment: Quinine and clindamycin. |
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Term
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Definition
Cutaneous Leishmania (Leishmania Tropica)
Classification: Protozoa, flagellate parasite
Life Cycle: Promastigote – flagellated in fly. Amastigote – intracellular and nonflagellated in phagocytic cells (macrophage)
Mode of locomotion: Through Sandfly vector.
Basic Concepts of infection and pathology: Promastigote enters skin. Phagocytized by macrophages, where transform and multiple to Amastigote. Stays in skin becase lower temp than viscera. Lesion begins as papule at bite site, and grows into ulcer as WBCs destroy skin tissue.
Sites of Infection: Ulcers on skin at site of bite.
Key Facts: Multiple lesions on ears in L.America. Often designated as New and Old World Forms. US military sites.
Diagnosis: Blood smear, biopsy of skin lesion.
Treatment: Stibugluconate, Amphotericin B
Also known as: Oriental Sore, Baghdad or Dehli Boil.
Location: 90% of cases in Middle East and South America. |
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Term
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Definition
Malaria (Plasmodium)
Classification: Apicomplexa Protozoa
Life Cycle: Sporozoites, Merozoites, Trophozoites, Gametocytes.
Mode of locomotion: Through mosquito vector. Found in warm tropical areas: S. America, Africa, South Asia and Middle East.
Mode of Reproduction: Sexual reproduction in vector and asexual reproduction in human. Can pass to fetus.
Basic Concepts of infection and pathology: Mosquito transfers sporozoites to human. They travel to liver and multiply asexually in hepatocytes. Hepatocyte ruptures (6-16days) and merozoites enter blood to become trophozoites.
Sites of Infection: Liver and blood (RBC) infection.
Key Facts: 4 types. P. Falciparum (most serious), P vivax, P. ovale, P. malaria. Falciparum 24hr fever. Vivax and Ovale 48 hr fever. Malaria 72 hr fever.Cyclic symptoms: cold, hot, sweating.
Clinical Signs: Flu-like, headache, vomiting, anemia, myalgia.
Diagnosis: Blood smear and dipstick technique.
Treatment: Quinine and clindamycin. |
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Term
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Definition
Trypanosoma cruzi (American Trypanosomiasis)
Chagas Disease
Classification: Trypanosoma Protozoa
Life Cycle: Trypomastigote, Amistogote and Epimastigote.
Mode of locomotion: Triatomine Bug (Kissing Bug, Reduviid Bug) or contaminated blood transfusion. Found in rodent, opossums and armadillos are reservoirs.
Basic Concepts of infection and pathology: Kissing bug defecates on skin. Trypomastigotes in feces tunnel into skin.
Clinical Signs: Healthy person is asymptomatic, hepato- and spleenomegaly, acute inflammation at bite site (Romanas Sign), mostly seen in children.
Sites of Infection: Bite is usually eye or lip but trypomastigote is found in circulation.
Location: Mostly S. American. Transmission by blood transfusion has become very important in some areas;Up to 50% of blood infected in some blood banks.
Diagnosis: Xenodiagnosis (Kissing Bug feeds on patient, then its intestines are examined for parasite) or blood smear. |
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Term
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Definition
Visceral leishmaniasis (kala azar)
Classification: Protozoa, flagellate parasite
Modes of transmission: Sandfly vector.
Sites for infection: Parasites not restricted to skin. Usually seen is reticuloendothelial cells (fixed phagocytic cells in spleen and lymph nodes).
Key Facts: Most serious form of leishmaniasis. STRONG relationship between AIDS and visercel leishmaniasis.
Clinical Signs: Hepatomegaly, low grade fever, progressive anemia.
Diagnosis: Microscopy of blood and bone marrow samples.PCR antigen test.
Treatment: Stiboguconate. |
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Term
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Definition
Dipylidium Caninus
Classification: Cestode, Helminth
Modes of transmission: Most common in dogs or cats, because flea is intermediate host.
Sites for infection: Children occasionally become infected with adult tapeworm.
Key Facts:. Juveniles in flea and louse.
Diagnosis: Two genital pores and reproductive system in each proglottid.
Treatment: Praziquantel |
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Term
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Definition
Clonorchis sinensis (Chinese liver Fluke)
Classification: Helminths, Trematodes.
Structures: Oral sucker, intestine, uterus, yolk gland, testes, ovary, Perculum and seminal receptacle.
Living Cycle: Cercaria infects fish. Fish is eaten raw and metacercaria in fish tissue is ingested.
Clinical Signs: Cirrhosis of liver, Diarrhea, Edema, abdominal Pain, biliary fibrosis and obstruction, hepatitis and hepatomegaly
Diagnosis: Detection of eggs in fecal samples, may require repeated samples.
Pathogenesis: Light infections asymptotic. Heavy infections up to 21,000 worms (can completely block bile passages.
Treatment: Several drugs used |
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Term
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Definition
Fasciolopsis buski (intestinal Fluke)
Classification: Helminth, Trematode
Diagnosis: Hemorrhage and abscesses of small intestines.
Affects: 10 million people (man and pig).
Life Cycle: Egg hatches producing miracidium. Infects intermediate host, a snail. Parasite reproduces asexually making cercariae. The cercarie encyst on edible vegetable into metacercariae. Then, once ingested by pig or human (definitive host) it excysts in the small intestines. The sexual mature adult resides on small intestines. |
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Term
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Definition
Fascioloa hepatica (Sheep Liver Fluke)
Classification: Helminths, Trematodes
Mode of locomotion: Eat vegetation with contaminated metacercaria. Usually raw water plant.
Life Cycle: Egg in water becomes meracidium and goes in snail. Matures to sporocyst and further to Redia. Leaves snail as cercaria and becomes metacarcia where it is eaten on plants.
Pathogenesis: Migratory phase is to ectopic locations. Juveniles in liver, causing liver damage and anemia. |
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Term
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Definition
Mucocutaneous Leishmanaisi (Leishmania Braziliensis)
Classification: Protozoa, flagellate parasite
Mode of transmission: Sandfly vector or carried zoonotically in rodents, dogs and foxes.
Clinical Signs: Lesion that spreads through skin to mucosal area (Nasal, Pharyngeal, Buccal mucosa).
Key Facts: Much less common that cutaneous form.
Random fact: Initial cutaneous ulcer heals, and months to years later ulcers in mucous membrane arise. |
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Term
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Definition
1. Schistosoma mansoni
Common in African, Middle East, S. America and Caribbean.
Infection site: Inferior Mesenteric Veins
Repoduction: Females release ~200 eggs a day.
2. Schistosoma hematobium
Common in African, Middle East, India and Portugal
Egg morphology: conspicuous terminal spine.
Pathology: Mostly in urinary tract, eggs passed by urine.
Infection siteL Venous plexus surrounding urinary bladder.
Clinical: Leads to calcification of bladder wall à Hydronephrosis,
Which leads to Squamous Cell Carcinoma.
3. Schistosomajaponicum
Common in Asia.
Structure – Inconspicuous lateral spine.
Infection site – Superior Mesenteric Veins
Pathology – Worse, due to a higher egg production
Repoduction – females release ~2000 eggs a day. |
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Term
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Definition
Classification: Trypanosoma Protozoa
Mode of locomotion: Tsetse Fly bite (vector) and contaminated blood transfusion. (NO AMASTIGOTE STAGE)
Life Cycle: Trypomastigote is flagellated in extracellular form. Trypomastigote and epimastigote are found in vector.
Mode of Reproduction: Binary fission in human and fly stages.
Basic Concepts of infection and pathology: Tsetse fly deposits trypomastigote when feeding. It divides and lives in circulation.
Key Facts: 2 Stages- 1. Acute Stage and 2. Neurologic Stage. Neurologic stage is “sleeping sickness” when parasite enters CNS. People eventually slip into coma and die.
Clinical Signs: 1.) fever, joint pain, headache //2.) confusion, seizures sensory disturbances, coma.
Diagnosis: Trypomastigotes in blood, CSF and LN.
Treatment: Suramin (doesn’t penetrate CNS), Melarsoprol.
Interesting: Can change antigen sequence as defense to immune
Flat, usually pretty big as adults
Segmented
All are parasites of the intestinal tract as adults
Life cycles involve 1 intermediate host
General term for the larval stage is a “metacestode”
Different kinds of metacestodes:
1. Cysticercus--invaginated scolex in fluid filled bladder
2. Cysticercoid--scolex without fluid filled bladder
3. Hydatid--like cysticercus only bladder can generate many scoleces with potential for large size
Scolex: Attachment organ with suckers, some also
have hooks
Neck: Right behind the scolex, gives rise to segments
Segments: Each segment a separate reproductive unit.
Most posterior segments are most mature.
Once egg development is complete the segment is called “gravid” |
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Term
Echinococcus multilocularis |
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Definition
Echinococcus multilocularis
Classification: Helminth, Cestode.
Key: Multilocular Hydatid cyst, More serious disease because difficult to remove surgically.
Life Cycle: Sheeps eat eggs on vegetation. Dogs eat entrails of sheep, and then human comes in contact with infected dogs feces. Egg becomes oncosphere, matures to hydatid cyst, then protoscolex, and finally a scolex to adult.
Clinical: Protoscolicies, Hydatid Sand and laminated cyst wall.
Site of Infection: Hydatid cyst in lungs and liver. Adult worm in small intestines.
Location: Europe, Asia, Alaska, Canada, northern U.S.
Possibly expanding south in U.S. |
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Term
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Definition
Echinococcus granulosus
Classification: Helminth, Cestode.
Structure: only 3 proglottids; Scolex/immature, Mature, Gravid
Size: Very small adults
Mode of Locomotion: Zoonotic, Canine definitive host. Humans and sheep both intermediate hosts.
Mode of Reproduction: Metacestode and cysts undergoes asexual
Key: Unilocular Hydatid cyst (cysticercus)- many protoscolices.
Life Cycle: Sheeps eat eggs on vegetation. Dogs eat entrails of sheep, and then human comes in contact with infected dogs feces. Egg becomes oncosphere, matures to hydatid cyst, then protoscolex, and finally a scolex to adult.
Clinical: Protoscolicies, Hydatid Sand and laminated cyst wall.
Site of Infection: Hydatid cyst in lungs and liver. Adult worm in small intestines.
Location: Worldwide, but commonly seen in Utah. |
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Term
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Definition
Hookworm(Ancylostoma duodenale)
Classification: Geohelminth, Nematode
Structure: Hookworms have mouths used to bite in intestinal wall and suck blood.
Mode of Locomotion: Egg is excreted, turns into larva, then worm which penetrates skin and goes to Blood, then heart, then coughed up, swallowed and the worm stays in intestines. Other routes are:Ingestion, Transmammary, and Meat.
Clinical: Anemia (bloodsucking parasites), diarrhea with melena, Vomiting, Weakness, Edema and pallor, “Ground itch”--papular rash and pruritus from sensitization to skin penetration of larvae, Stunted growth.
Diagnosis: Detectiong of eggs in fecal sample.
Treatment: Albendazole, mebendazole, pyrantel. Treatment will not remove arrested larvae
Key Facts: Seen mostly in Europe, N.Africa, China, SE Asia, India.
Total daily blood loss would exsanguinate 1.5mill. Important cause of anemia in developing countries. Higher in females. |
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Term
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Definition
Baylisascaris procyonis
Classication: Helminth, Nematode.
Life Cycle: These eggs can survive for months to years in the environment. The parasite is transmitted when the eggs are ingested by another animal. Humans generally become infected from accidentally ingesting eggs from soil, water, hands, or other objects which are contaminated with raccoon feces.
Site of Infection: Eggs hatch into larvae which then cause disease by migrating through the central nervous system, eyes, and other organs.
Characteristic diagnostic features: prominent lateral alae and excretory columns
Clinical: nausea, lethargy, liver enlargement, incoordination, loss of muscle control, coma, and blindness.
Treatment: There are no consistently effective treatment regimens available at this time.
At greater risk: Hunters, trappers, taxidermists, and wildlife rehabilitators are also at increased risk if they handle raccoons or items contaminated with raccoon feces. |
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Term
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Definition
Trichinella spiralis
Classification: Helminth, Nematode.
Site of Infection: Larvae encyst in muscles of humans and other mammals
Mode of transmission: Ingesting larvae in undercooked meat
“cycle of carnivorism” among hogs and rats.
Life Cycle: humans ingest encysted larvae in infected, undercooked pork. Larvae exist in stomach and burrow into small intestinal mucosa. Adult males and female reemerge and produce larvae which penetrate intestine and circulate in bloodstream. Larvae enter skeletal muscle cells and encyst
Treatment: Mebendazole to kill adults worms |
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Term
Strongyloides stercoralis |
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Definition
Strongyloides stercoralis
Classification: Helminth, Nematode.
Mode of Infection: Autoinfection; Infective larvae in gut must penetrate mucosa and go though migration to lungs and be coughed up and swallowed.
Clinical: Pneumonitis from migrating larvae, diarrhea, vomiting, epigastric pain, hyperinfection syndrome(in GI tract and Lungs).
Diagnosis: Detection of larvae in feces. May be difficult to find, repeated sampling required
Treatment: Ivermectin.
Key Facts: Of greatest concern in immunocompromised patients because no immunity to control larval production. Uncommon infection in dogs, but unclear how easily humans infected with canine strains. |
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Entamoeba histolytica
Karyosome
fecal smear |
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Isospora sp.
oocyst with sporoblasts |
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Cyrptospordium parvum
acid fast stain |
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a person or other living organism that can be infected by an infectious agent under natural conditions and sometimes exerimental conditions |
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A factor, such as a microoganism, chemical substance, or form of radiation, whose presence, excessive presence, or relative absence (deficiency diseases) is essential for the occurence of a disease |
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An extrinsic factor (geology, climate, insects, sanitation, health services, etc.) which affects the agent and the opportunity for exposure. |
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transmission of infection |
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any mode or mechanism by which an infectious agent is spread through the environment or to another person. |
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The locus is the specific site in or on the body where an infection orginates |
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- infect cells in one of these surfaces (the skin, respiratory mucosa, the alimentary tract, genital tract, and the conjuctiva)
- otherwise breach the surface (by trauma, the bite of an arthropod or animal, or injection, transfusion or transplantation)
- be transmitted congenitally.
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Transmission of an infection from one person to another of the same generation in the same population. |
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transmission of a disease from mother to child either during pregnancy, childbirth, or by breastfeeding |
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exposure to a source of an infection, or a person so exposed |
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the immediate transfer of an agent from a reservoir to a susceptible host by direct contact or droplet spread. |
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the transmission of an agent carried from a reservoir to a suceptible host by suspended air particles or by animate (vector) or inaminate (vehicle) intermediaries. |
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The direct transmission of an infectious agent from a reservoir to a susceptible host by spray with relativitely large, short-ranged aerosols produced by sneezing, coughing, or talking. |
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The residue of dried droplets that may remain suspended in the air for long periods, may be blown over great distances,, and are easily inhaled into the lungs and exhaled. |
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an animate intermediary in the indirect transmission of an agent that carries the agent from a reservoir to a susceptible host. |
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Parenteral refers to a route of administration that involves piercing the skin or mucous membrane. |
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infectious agent that is shed by the infected host in feces and acquired by the susceptible host through ingestion of contaminated food or other materials. |
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airborned transmission occurs when bacteria, viruses, or other pathogens travel on dust particles or on small respiratory droplets that may become aerosolized when people sneeze, cough, laugh, or exhale. they hang in the air much like invisible smoke. they can travel on air currents over considerable distances. these droplets are loaded with infectious particles. |
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a person or animal without apparent disease who harbors a specific infectious agent and is capable of transmitting the agent to others. |
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iatrogenesis and iatrogenic artifact refers to adverse effects or complications caused by or resulting from medical treatment or advice. |
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the proportion of persons exposed to a causative agent who become infected by an infectious disease. |
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an infectious disease that is transmissible under normal conditions from animals to humans. |
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endemic disease referrers to the constant presence of a disease or infectious agent within a given geographic area or population group; may also refer to the usual prevalence of a given disease within such area or group. |
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The occurrence of more cases of disease than expected in a given area or among a specific group of people ove a particular period of time. |
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a histogram that shows that course of a disease outbreak or epidemic by plotting the number of cases by time of onset. |
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a time period when the number of cases of disease reported is greater than expected. |
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an epidemic occuring over a very wide area (several countries or continents) and usually affecting a large proportion of the population. |
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1. contact
-direct
-indirect
-droplet
2 vechicle
-water borne
-airborne
-foodborne
3 vector
-mechanical
-biological
4 fecal-oral
5 iatrogenic |
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where one member, the parasite, lives in or on another organism, the host, at the expense of that organism. |
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phoresis
commensalism
mutualism
predation
parasitism |
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means traveling together a smaller organism, termed the phoront, is carried mechanically by the host. for instance, bacteria, fungus, mites, or leech carried on your skin. |
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is when one symbiont, the commensal, benefits and the other animal is neither helped nor harmed. |
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each member, a mutualist, depends upon the other; obligatory or facultative. many examples in nature like termites and flagellates. |
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is where one member, the predator, benifits and a smaller organism, the prey, is harmed; usually eaten. |
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is the study of the relationship between a parasite and its host. |
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ectoparasite, endoparasite, and hyperparasite. |
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live on surface of the host. animals are infested not infected. |
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live within the host. animals are infected. |
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are parasite within a parasite |
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are organisms which transmit parasites |
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are nonliving transmitters of parasite stages |
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is the host which parasite reaches sexual maturity and reproduces |
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are involved with some development but the parasite does not reach sexual maturty; ofent asexual stages or larval stages. |
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are hosts where the parasite continues to live and is infective to next host but no parasite development takes place. |
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reservoir hosts are non-human animals that serve as sources of infectin to humans. |
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high reproductive potential |
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- multiple fission
- hermaphrodism
- parthenogenesis
- strobilation
- high ova/larval output
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unique morphological or physiological specialization of parasites |
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- loss of digestive tract
- loss of wings
- loss of many sensory structures
- tegument
- special holdfasts organs
- anti-coagulants
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How parasites evade host's immune system |
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- antigenic variation
- tough tegument
- intracellular habitat
- antigen acquisition/mimicry
- suppression eosinophil or neutrophil
- encystment
- ability to cleave antibodies
- trigger immune response
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Pathology due to Parasite infection |
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- physical trauma
- nutritional diversion
- toxins/excretory products/immune complexes
- blood loss
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typical ways parasites are transmitted |
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- ingestion
- vectors
- direct penetration
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traditional methods for diagnosing parasites and parasitic infections |
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- fecal specimen collection
- collection of material other than fecal
- blood films/smears
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three major methods of molecular testing |
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- biochemical (first generation)
- immunological (antibodies)
- nucleic acid
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isoenzymes: perform same functions but diferent
movement on gels.
genetically controlled: parasites with different gel patterns genetically distanct.
enzymes separated by size: SDS-PAGE |
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advantages:
- rapid easy field-based test
- both individual & mass population screening
- Ig subclases-to improve specificity & sensitivity
disadvantages:
- cannot distinguish past/present infections
- cannot distinguish morphologically similar parasites
- expensive to develop-signifcant research prior to commercialization
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DNA Based Molecular Diagnosis |
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- ribosomal DNA/RNA
- specific sequences of genomic DNA
- random primer amplification (RADP) PCR
advantages:
- genomic DNA constant-parasite & hosts unique DNA sequences.
- very sensitive-small biopsy
- probes can be designed with flexibility: specific-detect single species, less specific-detect group
Disadvantages:
- expensive
- radioactivity needed
- PCR can fail
- DNA probes do not distinguish between dead & living parasites
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Coccidia from the phylum apicomplexa we need to know |
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Definition
- cryptosporidium
- isospora
- cyclospora
- toxosplasma
- plasmodium
- babesia
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small blood meals-many hosts
short period on host
characteristics:
-capillary location
-specialization mouthparts
-anti-coagulants
anaesthetic
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hard ticks
Ixodid ticks
-contains most of the common ticks
soft ticks
-much less common, not important in U.S. |
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Tick transmitted diseases |
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rocky mt. spotted fever
lyme disease
babesia |
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ascending flaccid paralysis
caused by attachment of female tick, usually near spinal cord, and release of toxins
reversed by removal of ticks |
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invaginated scolex in fluild filled bladder |
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scolex without fluid filled bladder |
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like cysticercus only bladder can generate many scoleces with potential for large size |
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attachment organ with suckers, some also have hooks |
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right behind the scolex, gives rise to segments |
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each segment a seperate reproductive unit. most posterior segments are most mature. once egg development is complete the segment ic called "gravid" |
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