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154 Cards in this Set
- Front
- Back
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Amoeba Pylum
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Sarcomastigophora
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Entamoeba taxonomy
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Phylum: Sarcomastigophora
Subphylum: Sarcodina Class: Lobosea Order: Amoebida Suborder: Tubulina |
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Orders that human parasites are in:
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Amoebida
Schizopyrenida |
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Use pseudopods for locomotion
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Sarcodina
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Entamoeba histolytica
(general features) |
- usually anerobic (and this is what drugs target) facultative
- mobile form is associated with disease - nucleolus is central - has a host cell - 25/12 um |
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Entamoeba Coli
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- eccentric nucleolus
- tend to have bacteria in them - no host cell - 8 nuclei |
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Entamoeba hartmanni
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- 12/6 um
- no host cell |
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Iodamoeba buctschlii
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- 10/10 um
- glycogen vacuole in cyst - found in pigs and primates |
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Entamoeba gingivalis
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- found in the mouth (poor hygiene)
- no cyst stage - 15um - will find more bacteria in the sample |
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Entamoeba histolytica (amebiasis)
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- ingest cysts
- colonizes large intestine - excystation then trophozoite - can transform back into cysts - start to lyse epithelial cells in the intestine - can then get into the bloodstream |
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Entamoeba histolytica (epidemiology)
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- 10% of worlds population is infected
- morbidity: 100,000/yr - worldwide, but more pathogenic in tropics - Daycare centers, male homosexuals, travelers, institutionalized population - 44% of young in schools in Bangladesh - water; fecal-oral route; food-borne - Luminal ameobiasis (carrier state) |
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Flask shaped lesions in the intestine are a characteristic of:
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amoeba histolytica
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Amebic Colitis (Symptoms)
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- gastrointestinal pain
- lysis of intestinal mucosal epithelium - thickening of mucosa (hyperplasia) - flask shaped lesions |
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Extra intestinal Disease
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- less than 1% of cases
- amebic liver abscess: induced by trophozoite - Hue-Vietnam: 21 of 100,000 cases have amebic liver abscess - Pulmonary amebiasis - Brain abscess - Genitourinary amebiasis |
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Mechanism of pahthogenesis (ameobiasis)
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- parasite motility is a prerequisite
- tissue inflammatory respons - ultimately leads to neutrophil mediated intestinal destruction |
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Amoebapores
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mediate cytolytic and apoptoic effects on neutrophils and epithelial cells
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Acid phosphates
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mediators - SAP & MAP
targe host phospho-proteins |
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How do ameoba resist complement attack and oxidative stress?
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Gal/GalNac lectin
lytic factors reducing enzymes |
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How to diagnose ameobiasis
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- multiple stool specimens
- cysts in stool - anti-amoebic antibodies - not present in E. disbar - antigen detection in feces - PCR of fece samples |
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Prevention/Treatment of Ameobiasis
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- eradicate fecal contamination - cysts can be killed by boiling - can also use chlorine tablets
- avoid fecal-oral route - drugs: metronidazole |
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Free-Living Amoebas (names)
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Acanthamoeba
-order: amoebida - suborder: Acanthopodina - genus: ananthamoeba Naegleria - order: schizopyrenida - genus: Naegleria |
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Free-Living Amoebas (characteristics of Naegleria)
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- amoeboid & flagellated forms
- no cyst stage in humans - plugged cysts - nose is primary mode of entry - thermophilic 45°C |
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Free-Living Amoebas (characterisics of Acanthamoeba)
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- ingest other bacteria
- trophozoites have poined pseudopodia 0 they get in through the skin - cysts are angular - only live in tissues - Legionalla live inside them (Hartmanella) |
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Naegleria foweri
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Order: Schizopyrenida
- Causes Primary Amebic Meningoencephalitis - Distributed worldwide - young adults have a prevalence of the antibody in their system due to high exposure - infection not dependent on immune system status - cysts not found in humans - amebostomes: nibble away at tissue cultures |
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Acanthamoeba
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Order; Amoebida
- Found in soil and water - have pointed pseudopodia - angular cysts - contaminated contact lens solution - trophozoites and cysts in the tissues of humans - immunocompromised: granulomatous disease |
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Acanthamoeba pathogenesis
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- Granulomatous amebic Encephalits: Skin and brain lesions
- Acanthamoeba Keratitis: corneal infection - Diagnosis is made through microscopy or biopsy |
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Ciliates
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Phylum: ciliophora
*Balantidium Coli - BIG, 50-150um - sexual reproduction by conjugation - contractile and food vacuoles - cysts have cilia - colonize large intestine |
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Balantidium Coli (epidemiology/pathogenesis)
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- primarily in the tropics
- malnourished are more susceptible - Reservoirs: pigs & monkeys - acquired by ingesting cysts - usually hosts are asymptomatic - rarely extraintestinal - diagnose by: cysts and trophozoites in stool |
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Flatworms
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trematodes, cestodes
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Roundworms
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nematodes
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Free-Living Amoebas (names)
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Acanthamoeba
-order: amoebida - suborder: Acanthopodina - genus: ananthamoeba Naegleria - order: schizopyrenida - genus: Naegleria |
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Free-Living Amoebas (characteristics of Naegleria)
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- amoeboid & flagellated forms
- no cyst stage in humans - plugged cysts - nose is primary mode of entry - thermophilic 45°C |
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Free-Living Amoebas (characterisics of Acanthamoeba)
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- ingest other bacteria
- trophozoites have poined pseudopodia 0 they get in through the skin - cysts are angular - only live in tissues - Legionalla live inside them (Hartmanella) |
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Naegleria foweri
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Order: Schizopyrenida
- Causes Primary Amebic Meningoencephalitis - Distributed worldwide - young adults have a prevalence of the antibody in their system due to high exposure - infection not dependent on immune system status - cysts not found in humans - amebostomes: nibble away at tissue cultures |
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Acanthamoeba
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Order; Amoebida
- Found in soil and water - have pointed pseudopodia - angular cysts - contaminated contact lens solution - trophozoites and cysts in the tissues of humans - immunocompromised: granulomatous disease |
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Acanthamoeba pathogenesis
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- Granulomatous amebic Encephalits: Skin and brain lesions
- Acanthamoeba Keratitis: corneal infection - Diagnosis is made through microscopy or biopsy |
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Ciliates
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Phylum: ciliophora
*Balantidium Coli - BIG, 50-150um - sexual reproduction by conjugation - contractile and food vacuoles - cysts have cilia - colonize large intestine |
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Balantidium Coli (epidemiology/pathogenesis)
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- primarily in the tropics
- malnourished are more susceptible - Reservoirs: pigs & monkeys - acquired by ingesting cysts - usually hosts are asymptomatic - rarely extraintestinal - diagnose by: cysts and trophozoites in stool |
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Flatworms
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trematodes, cestodes
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Roundworms
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nematodes
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Protozoa size range
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1-150um
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Phylum Sarcodina
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no pseudopodia
Entamoeba, Naegleria |
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Phylum Mastigophora
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use flagella for locomotion
Examples: Leishmania, Giardia, Trichomonas |
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Phylum Ciliophora
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have cilia and two types of nuclei
Balantidium Coli |
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Phylum Apicomplexa
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apical complex
Plasmodium, Toxoplasma |
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Examples of protozoa that are often found in HIV patients:
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cryptosporidium, toxoplasma,
sarcocystis |
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Mastigophora major diseases
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- visceral (leishmania)
- cutaneous lesions - sleeping sickness (trypanosoma) - Chagas disease - Diarrhea (giardia) - Vaginitis (trichomonas) |
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Sarcodina major diseases
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- dysentery (entamoeba)
- Liver abscess - Colitis (Dientabmoeba) - CNS symptoms (naegleria) - Corneal Ulcers (acanthamoeba) |
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Ciliophora major diseases
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- Dysentery (balantidium coli)
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Apicomplexa major diseases
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- Malaria (plasmodium)
- Diarrhea (isospora) - Diarrhea (sarcocystis) - Diarrhea (cryptosporidium) - Toxoplamsmosis (toxoplasma) |
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Four types of pseudopodia
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1. Filopoda
2. Lobopodia 3. Rhisopodia 4. Axopodia |
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Flagellum characteristic of eukaryotes
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9 + 2 organization
two microtubules in center and nine doublets on periphery |
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Dynein arms:
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important in generating energy needed for locomotion
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recurrent flagellum
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tries to follow body
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undulating flagellum
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attaches to body
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flagella pocket
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point where the flagella originates
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Vesicular nuclei (one of two nuclei in eukaryotes)
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scattered chromatin, nucleoli-like body called karyosome –lacks DNA in parasitic amoebas but contains DNA in apicomplexans
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Compact nuclei (one of two nuclei in eukaryotes)
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densely packed chromatin
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Ciliates nuclei
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have a macronucleus (trophic activities) and a micronucleus (reproductive activities)
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Fission
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Division follows a sequence: organelles then nucleus and then the cytoplasm
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Endodyogeny
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a form of endopolyogeny where two daughters are formed.
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Schizogony
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• Rapid organelle and nuclear divisions occur at the cell periphery.
• Cytoplasmic segmentation to form separate organisms called merozoites. • The multinucleated cell is called the schizont or segmenter. |
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Intestinal and Urogenictal Flagellates: taxonomy
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Phylum: sarcomastigophora
Subphylum: matigophora Class: Zoomastigophorea |
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Two known pathogens of the intestinal and urogenital group
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Giardia and trichomonas
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Giardia lamblia = giardia duodenalis - giardia intestinalis
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- trophozoite
- has adhesive disc (play an important role in pathogenesis) - microtubules and microfilaments - two nuclei, central - 4 pairs of flagella - parabasal body - Division is longitudinal binary fission |
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Giardia epidemiology
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• most prevalent intestinal parasite.
• world wide distribution. • Common in children 6-10 years of age. Daycare centers • prevalent in homosexual males. • travelers or visitors to endemic areas • Primary immuno-deficiency (IgA deficiency) • Recent increase in infection among wilderness campers – Backpacker’s disease (may be acquired from contaminated water) • Wild animals: Beavers; Dogs; sheep are also infected |
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Giardia pathogenesis
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- incubation is 1-2 weeks, may take longer for cysts to appear in stool
- 10-100 cysts to acquire infection - prolonged diarrhea - attachment of Giardia leads to shortening of villi in sm. intestine, inflammation and lesions - weight loss - malabsorption of fats (B12) - stools fatty, smelly |
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Mediators of giardia pathogenesis
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• Mechanical disruption of brush border
• Giardia produce an IgA protease • Antigenic variation of Variable Surface Protein (VSP) of Giardia. Response to immune pressure or intestinal secretions? |
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Diagnosis and prevention of Giardia
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Parasites in stool samples
• Cysts are seldom found in diarrheic stools. Cysts are passed intermittently, may require several stools • Immunity to infection may be acquired. • Detection of parasite antigens • Prevention: Limit exposure to contaminated water or food. |
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Chilomastix mesnili
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• Order Retortomonadida
• World wide distribution. • Inhabit cecal region of large intestine. • Morphological distinctions: asymmetric, 4flagellar, Spiral groove • - Single nucleus - cytostome. • Cyst stage (infective stage) is lemon shaped, single nucleus. |
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Retortomonas intestinalis
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• Non-pathogenic with world wide distribution
• Trophozoite stage: two flagellar, single nucleus, 4 to 9um in length and 3-4um wide. • Cysts: pear shaped, single nucleus. • Resides in large intestine |
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Enteromonas hominis
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• Nonpathogenic
• Trophozoite: 4 flagellar, no cytostome. • Cysts are ovoid and binucleate (sometimes 4 nuclei) • Reside in cecal area of large intestine. |
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Dientamoeba fragilis
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• World wide distribution.
• Only the amoeboid form of this parasite is known. • Measure 6-12um • Usually binucleate with karyosome consisting of four distinct granules. • lives in cecum and upper colon. • Is believed to cause irritation of the mucosa • Not invasive • May be transmitted with the egg of the nematode Enterobius vermicularis |
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Genus Trichomonas
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• Pear shaped
• 3 to 5 free flagellar, an extra flagellum or recurrent flagellum that runs on the side of the parasite forming an undulating membrane. • Have a costa that extends along the base of the undulating membrane. • A single nucleus. • Genome size -170 Mb; ~60,000 protein coding genes • They have a characteristic organelle called a hydogenosome, arranged in a row associated with the costa and or axostyle. • They have no known cysts • Are anatomical site specific |
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Hydrogenosome
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a doubled membraned organelle that has analogous function of mitochondria (production of ATP but proton acceptor is molecular hydrogen)
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Genus Trichomonas (more)
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• T. vaginalis
• Larger of the 3 • Shorter undulating membrane • Prefers an environment with pH ~6 • Trophozoites are very active, motile |
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Epidemiology of T. vaginalis
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• World wide distribution
• 3 million American women acquire infection each year • Men are asymptomatic carriers • Incidence highest in women with multiple sex partners • Individuals with other sexually transmitted diseases • Infection less in women using oral contraceptives • T vaginalis acquired by venereal contact • Parasites can survive in moist environments (high prevalence in institutionalized) • Incubation period 5-28 days • Symptoms may begin or be exacerbated during menstrual period |
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Pathogenesis of T. vaginalis
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• Infected vaginal discharge can contain 105protozoa/ml.
• damages epithelial cells upon contact,resulting in microulcerations. • activates complement therefore attracts neutrophils. • Vaginal discharge, vulvovaginal soreness or irritation. Vaginal odor may be result of coexisting bacterial infection • elevation of vaginal pH from 4.5 to 5.0 • Parasite can infect urethra causing dysuria. Swelling of prostrate gland in males. • In extreme cases, can result in gestational trichomoniasis and vaginal emphysematosa (gas filled blebs in vaginal walls) |
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Diagnosis and Treatment of T. vaginalis
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• Very active parasites in vaginal smear (wet mount [lots of white blood cells]) or urine
• Yellowish discharge; persistent itching and burning Prevention • Treatment: Restoration of vaginal pH to 4.5. Drug of choice - Metronidazole |
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Metronidazole
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• Mechanism of action
– Entry of drug in cell – Reactive group activated by reduction by ferrodoxinlike and flavodoxin like proteins (low redox potential electron transport proteins) – Intermediate formed is toxic, damages DNA and other macromolecules – Reduction of drug maintains gradient that drives drug uptake |
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Metronidazole treats (which protozoans)
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Entamoeba hystolitica, Giardia lamblia and Trichomonas
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Trichomonas tenax
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• 4 free flagellar
• 5-16um by 2-15um • found in mouth and nasopharyngeal region • Mostly nonpathogenic. May cause respiratory tract infection in patients with underlying pulmonary disease. • Transmitted through kissing or sharing of contaminated utensils. • Prevention: Practice proper hygiene |
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Pentatrichomonas hominis
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• 5 free flagellar
• resides in large intestine • Pathogenicity status unknown, parasite observed in patients with symptomatic bowel disease. • Transmission through fecal-oral route • Diagnosis: Identification of parasite in feces |
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Rickettsia:
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gram negative bacteria
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Two-winged flies, Order:
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Diptera
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Families in Diptera
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- Culicidae (mosquitoes)
- Simuliidae (black flies) - Psychodidae (sand flies) - Tabanidae (horse flies) - Muscidae ( house fly, tsetse fly) - Calliphoridae (blow flies) |
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Calliphoridae
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blow flies
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Muscidae
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house fly, tsetse fly
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Tabanidae
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horse fly
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Psychodidae
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sand fly
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Simuliidae
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black flies
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Culicidae
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mosquitoes
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Bugs: Order? Family?
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Order: hemiptera
Family: reduviidae (assassin bugs) |
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Fleas: Order? Family?
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Order: siphonaptera
Family: pulicidae |
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Sucking Lice: Order? Family?
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Order: Anoplura
Family: Pediculidae (body lice) Family: Pthiridae (pubic lice) |
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Spiders, scorpions, ticks, mites,
CLASS?? |
Arachnida
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Ticks and mites: Order?
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Acarina
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hard tick family?
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Ixodidae
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soft tick: family?
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Argasidae
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mites: family?
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trombiculidae
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Phagocytosis
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a process performed y specialized cells for the internalization of particles greater than 0.5um
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Functions of the cytoskeleton
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- structure and support
- intracellular transport - contractility and motility - spacial organization |
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innate immune system
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• Components of innate immunity:
– outer surface of body (skin) – Linings of internal tracts – secretions – Phagocytic cells (macrophages, neutrophils) and natural killer cells. – Soluble blood proteins: Complement |
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MHC class I
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binds to peptides from molecules that are synthesized by the cell or found in the cell cytoplasm.
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MHC Class II
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binds peptides from molecules that are internalized by cell.
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Mechanical Transmission
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- arthropod carrier
- no reproduction - no development - example: entamoeba histolytica, surra, anaplasmosis, diarrheic diseases |
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Biological Transmission
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- arthropod vector
- reproduction - development |
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Biological Transmission - Propagative
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- reproduction only
- plague bacillus (flea) - yellow fever (mosquito) - multiplication in disease agent |
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Biological Transmission - Cylcopropagative
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- reproduction
- development - both processes occur in the vector - Plasmodium, T. Brucei |
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Biological Transmission - Cyclodevelopmental
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- development only
- filaroid worms - causes river blindness |
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Biologica Transmission - Transovarial
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- trans generational
- from parasite in egg to host - RMSF - Scrub typhus |
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SIMPLE metamorphosis
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- 3 life stages - EGG NYMPH ADULT
- food and habitat, everything is in the same place - cockroach |
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COMPLETE Metamorphosis
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- 4 life stages - EGG LARVA PUPA ADULT
- wings are internal - pupa are non-feeding - mosquito - habitat is not in the same place as food |
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Crushing/Chewing mouthparts
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- cockroach
- no blood - solid food - vegetarian/carnivore/omnivore |
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Sponging mouthparts
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- Blow Fly
- liquid food - salivate/defecate/regurgitate/aspirate - no blood |
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Cutting/Sponging mouthparts
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TELMOPHAGIC
- horse fly - lacerate skin - blood spools to surface - suck up with labella |
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Piercing/Sucking mouthparts 1
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SOLENOPHAGIC
- Mosquito - insert stylus - probe for capillary |
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Piercing/Sucking mouthparts 2
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TELMOPHAGIC
- tsetse fly - rigid labium - lacerate skin - suck up pooled blood |
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Order Diptera
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- two winged fly
- complete metamorphosis - one pair of functional wings |
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Culcidae
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- mosquitoes
- piercing/sucking MP 1 - transmit protozoa/filarial worms/viruses - males feed on plant juices - Aedes, Anopheles, Culex |
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Mosquitoes - Culicidae - Anopheles
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- lay eggs in permanent impoundment (swamp)
- eggs have floating device - HUMAN MALARIA VECTORS |
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Mosquitoes - Culicidae - Aedes
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- water containers, treeholes, areas subject to periodic flooding
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Mosquitoes - Culicidae - Culex
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semipermanent impoundments, polluted water
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Human Filariasis
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• Wuchereria and Brugia
• 120 million cases worldwide • multiple mosquito vectors involved • mosq biting cycles match presence of microfilariae in peripheral blood • Culex, Anopheles: bite during twilight and dark • Aedes, Mansonia, Psorophora: bite during day |
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Yellow Fever
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• hundreds to thousands of cases annually
• maintained in sylvatic cycle • bridge vector(s) to urban cycle • Aedes aegypti principal urban vector • vaccine available • vector control can be effective |
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Dengue and dengue hemorrhagic fevers
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• four serotypes of dengue virus
• single infection causes dengue fever • multiple serotype infections result in hemorrhagic (DHF) form • no vaccine • recent epidemics Cuba, Brazil • Ae. aegypti, Ae. albopictus vectors |
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West Nile Virus
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• discovered Uganda 1937
• epidemics Europe, Israel 1960-70s • infect humans, equines, cats, dogs, bats, chipmunks, skunks, squirrels, domestic rabbits • primary vector: Culex spp. • avian reservoir; 110 bird species infected - no human vaccine |
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Black Flies
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• telmophagic (females only)
• Onchocerca volvulus • Africa, Central and South America • Simulium spp. • eggs, larvae, pupae in running water • avermectins as oral systemic treatment for humans |
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Sand Flies
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• solenophagic (females only)
• sand fly fever (virus) • Bartonella spp. (bacterium) • Leishmania spp. (protozoa) • Phlebotomus spp. old world flies • Lutzomyia spp. new world flies • weak flyers; stay low to ground • bite head, face,neck, shoulders |
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Tabanid Flies
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• telmophagic (females only)
• strong flyers, aggressive biters • Tabanus spp. and Chrysops spp. important genera • mechanical transmission of anthrax, tularemia, surra, anaplasmosis • cyclodevelopmental transmission of Loa loa to humans by Chrysops spp. |
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Tsetse flies
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• piercing-sucking2 mouthparts (both sexes)
• larviparous, "milk glands" (female) • pupation in soil • adult emerge in 3-4 weeks • 24 Glossina spp.; tropical Africa • weak flyers; aggressive biters • Glossina palpalis - Trypanosoma brucei gambiense (riverine, WASS) • Glossina morsitans - Trypanosoma brucei rhodesiense (savanna, EASS) |
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Glossina palpalis - Trypanosoma brucei gambiense
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riverine
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Glossina morsitans - Trypanosoma brucei rhodesiense
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savanna
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Non-biting Diptera
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- larvae have ‘oral hooks
- blow flies, flesh flies, - mechanical transmission: typhoid fever, bacillary dysentery, trachoma, conjunctivitis, cholera, and yaws |
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Reduviidae - assassin bugs
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• new world only
• simple metamorphosis • piercing-sucking mouthparts • insectivorous • crawl rather than fly • feed at night • Chagas disease |
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Cimicidae
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Bed Bug
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Pulicidae
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- fleas
- piercing/sucking mouthparts - host specific - Yersinia pestis: sylvatic plague - complete metamorphosis - tapeworm is intm host |
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Lice - Order Mallophaga - chewing lice
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- wingless
- simple metamorphosis - intm host is tapeworm |
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Pubic Lice - Order Anoplura - sucking lice
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Phthiris pubis
- relapsing fever, epidemic typhus, trench fever |
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body/head louse
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Pediculus humanus ssp.
- relapsing fever, epidemic typhus, trench fever |
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Relapsing Fever
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- Borrelia recurrentis
- lives in insect hemocoel - spirochete - |
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Louse-borne typhus
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- infection with Rickettsia prowazeki
- replicate in insect midgut - can be inhaled or gain entry through skin breaks, mucous membranes |
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Trench fever
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- infection with Rochalimaea quintana
- replicate in louse midgut - can be inhaled or gain entry through skin breaks, mucous membranes - rarely fatal |
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Acarine
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•cephalothorax
•abdomen •wingless •larva with 6 legs •nymph, adult with 8 legs •body appears unsegmented |
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Acarine mouthparts
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- piercing-tearing
- hypostome - chelicerae - pedipalps |
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Hard ticks
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Family Ixodidae
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Soft Ticks-
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Family Argasidae
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Mites
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Family Trombiculidae
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Ixodid ticks
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• mouthparts project forward
• hard scutum dorsally • ‘ambushers’ (await host) • attach and feed for days • mate on the host • engorge, detach, drop • female lays eggs then dies |
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Dermacentor spp.
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• ixodidae
• Rickettsia rickettsia causes Rocky Mountain Spotted Fever • rickettsiae pass to host via tick saliva • transovarial transmission • RMSF is a zoonosis • many wild animals reservoirs • can be fatal |
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Ixodes spp.
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- Lyme disease
- not fatal - vaccine 70% effective |
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Argasid ticks
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• Argasidae
•mouthparts ventral •soft, leather-like integument •seek host (hunters) •attach and feed 20-30 min •mate off the host •attach, engorge, depart •female produces dozens to hundreds eggs, re-feed •nighttime feeders |
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Ornithodorus spp.
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• Argasidae - soft tick
• zoonotic • tropics, subtropics |
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Trombiculid mites
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- Trombiculidae
- 1st stage of life is infectious stage - transovarial transmission - zoonotic disease |
