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Foundations 7 > Parasitology 1 > Flashcards

Parasitology 1 Flashcards

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1
Q

Parasite lifestyle factors

A 
Host 
Establish productive infection
Evade host mechs
Maintain host viablity and potential spread
Successful transmission
Not all stages are infective for humans
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2
Q

Productive infection establishment

A

Needs to get to right tissue
Non-productive infection can cause serious pathology
May be within host or move to another host

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3
Q

How do parasites circumvent various host physical response

A

Cross skin via vectors and direct penetration
Adhere to GI tract to prevent peristalsis
Sequester to venous/arterial circulation to avoid blood flow

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4
Q

Parasite and immune interactio

A

2 way street…parasite adapts based on immune response

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5
Q

Parasitic dzs nomrally

A

Long term chronic

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6
Q

Parasitic dz not always evident…when does it become evident

A

Change in host status or reactivation due to changes in pathogen

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7
Q

Acute dz outcomes

A

Pathogen or host induced pathology leads to resolution

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8
Q

Sub clinical outcomes

A

Immune response leads to potential pathology leads to sterile resolution
Chronic infection…change in immune status leads to symptomatic dz

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9
Q

Actue dz with mild and non-specific dz outcomes

A

Immune response leads to chronic infection…change in immune status and symptoms

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10
Q

Protozoa

A

Single celled eukaryotes

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11
Q

Metazoa

A

Made up of helminths (worms), arthropods (everything else but snails) and molluscs (snails)

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12
Q

Main function of arthropods

A

Act as vectors and reservoirs for dz

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13
Q

Amoebae
Flagellates
Sporozoa
Ciliates

A

Crawling motion on a substrate
Use of one of more whip like flagella (includes Kinetoplastids)
Gliding motility
Hair like cilia

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14
Q

Helminth classifications

A

Nematoda (roundworms)
Cestoda (tapeworms)
Trematoda (tissue and blood flukes)
All endoparasites

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15
Q

Host

A

Animal where a parasite can establish an infection

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16
Q

Definitive vs intermediate host

A

Def - adult phase (metazoa) or sexual reproductive phase (proto)
Int - Larval (metazoa) or asexual (protozoa)…obligatory for completion of life cycle

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17
Q

Accidental host

A

Host that is a dead end for a given parasite…still leads to pathology and dz

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18
Q

Transmission to def host allows

A

Sexual recombination and diversity

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19
Q

Transmission to IM host allows

A

Higher levels of parasite in the population

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20
Q

Environmental cyts

A

Mechanism to surive in envrionment in absence of a host

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21
Q

Dormant state within host

A

Permits transmission…often a cyst

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22
Q

How are parasites transferred from vertebrae to vertebra

A

Carniverous
Close contact with animals
Infected waste
Sexual activity or handling of tissues

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23
Q

Life cycle stages reflect

A

Adaptations to environments

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24
Q

Helminth development

A

Egg to larval to mature to mating back to egg

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25
Incubation period
Time from acquisition to appearance of symptoms - hours to years
26
Prepatent period
Time from acquisition to detection - days to years | Can be shorter than incubation...often detect cyst form in feces
27
Patent period
Time in course of parasitic dz during which parasitic organisms can be demonstrated in the body...don't need symptoms
28
Most parasitic dz have
Acute and chronic infection
29
Most common parasitic dz
Intestinal roundworms
30
Amoebae protozoa
Entamoeba histolyyica | Acanthamoeba
31
Amoebae/giardia/trichomonas common themes
``` Evolutionarily among earliest Facultative anaerobes using carb metab Lack mitochondria EC parasite adhere to epithelium (don't invade) Cause contact dependent cytotoxicity Divide like bacteria (binary fission) Killed by metronidazole ```
32
Cyst forms of protozoa
Designed for transmission Non-replicative Survive in environment Typically infectious form
33
Trophic forms of protozoa
Actively replicating, active growhti nthe host, not involved in transmission ALL protozoa have trophic, not all have environmental cyst
34
Entamoeba histolytica life cycle
Infection with cysts Cyst wall disrupted in GI tract and release 4 nuclei amoeba Trophozoites form after division Trophozoites divide in intestine and differentiate back into cysts Cysts deposited in feces
35
EH trophozoites can move
To portal vein where they can establish liver infection (extraintestinal) Also can get to lungs, diaphragm, and brain
36
Intestinal amebiasis characteristics
Bloody and mucoid diarrhea Blood in the stool with lack of leukocytes Look for cysts or trophozoites Trophozoites may be laden with erythrocytes
37
Acute symptoms of intestinal amebiasis
Ab pain, bloody mucoid diarrhea, flatulence and ab tenderness May last 2-21 days
38
Chronic symptoms of intestinal amebiasis
Occassional bloody diarrhea, weight loss, fatigue
39
Most people with intestinal amebiasis are
Asymptomatic and shed cysts
40
Extraintestinal symptoms of amebiasis via EH
Pain in upper right quadrant..tender and enlarged liver with abscess, fever, weight loss
41
EH effect on liver
Amebic hepatitis...lysis and digestion of hepatocytes
42
Other sites of EH
Lungs, skin, brain...cysts never outside of intestine
43
GI tract Entamoeba species
E dispar...oftne confused with EH
44
DIagnosis of EH
Trophozoites with RBCs in the stool or 4 nucleus containing cysts in the stool Tenderness in upperright quadrant (use Xray and CAT scan to confimr) Trophozoites in sputum (lung) CAT scan/MRI for brain
45
2 other pathogenic amoebae besides EH
Acanthamoeda castellani Naegleria fowleri Free living envrionemtal organisms Cause severe dz in both healthy and immunocompromised individuals Acquired swimming in warm lakes
46
Acanthamoeba castellani eye infection
Conjunctivits, keratitis, and uveitis...contact lens wearers Diagnose by culturing Keep contacts clean and avoid swimming in wamr lakes
47
Acanthamoeba castellani CNS involvement
Invades CNS through olfactory bulb Causes GAE - seizures, brain disturbs, headaches, death Cannot be detected in the CSF
48
Tx of GAE and ocular infection by acanthamoeba
Ketoconazole and surgical excision | Topical azole and cessation of contact lens use
49
Naegleria Fowleri...including tx and diagnosis
Infects healthy young people (often water sports) Causes PAME with trophozoites but NO cysts Death in days (1-3 day incubation) Can see them in CSF Amphtericin B to treat Try to diagnosie with culture
50
important flagellate to remember
Giardia lamblia
51
Giardia lamblia life cycle
Flagellated diplomonades with 2 nuclei (look like eyes) ingest cysts, replicate by binary fission and attach to intest epithelium...upper and small intestine are preferred Cysts have 4 nuclei Trophozoites have 2
52
Beaver fever symptoms
Severe cramps Non-bloody foul smelling diarrhea with greasy stool due to malabsorption of fat Asymptomatic will shed cysts for years Incubation = 3-21 days
53
Giardia cysts
Resitant to chlorination but not to filtration | Infects many different animals, not just humans
54
Giardiasis is most prevlanet
Cause of non-bacteiral diarrhea in the US
55
Risk factors for giardiasis
Unfiltered or unboiled water while hiking (Beaver fever) Fecal oral Immune suppresssion
56
Patholgy of giardia
Attach to intestinal epithelium and efface the villi
57
Sporozoa we need to know
Plasmodium (malaria) | Toxoplasma gondii
58
Anopheles mosquito
Used to spread malaria Only females will spread Obtaining bloodmeal is essential for eggs Lay 4-5 clutches per lifetime Where plasmodia undergo completion of their sexual cyce
59
Malaria life cycle
Passed to humans...goes to liver as asymptomatic...invades erythrocytes Completes cycle in mosquito
60
Plasmodium falciparum
Majority of malrial deaths 6-12 PP period May not have defined fever periodicity
61
PLasmodium vivax
Most common cause Benign tertian malaria 10-17 PPP
62
Plasmodium ovale
Similar to vivax | 14 PPP
63
Plasmodium malariae
Mildest dz but longest | 28-35 PPP
64
Time of infection of malaria
Bite to when the erythrocytic cycle commences and symptoms are present...also defines how long it takes to detect
65
Symptoms of malaria
During erythrocytic stage...high dever with defined periodicity Tertian - day 1 and 3 (vivax) Quartan - fever on day 4 (seen in plasmodium malarium)
66
Cerebral malaria
Infected erythrocytes have knobs that make them sticky to linings and RBCs...this causes blockages which leads to multiple strokes Renal and pregnancy complications can result from P falciparum
67
AIDS associated opportunistic
Toxoplasmosis
68
Opportunistic pathogens
Don't normally cuase symptoms in healthy, but will in immunocomporomised
69
Life cycle of toxoplasmosis gondii
Cat is the definitive host...bradyzoite becomes oocyst...oocyst leaves in the feces and goes to another anuimal...shifts between bradyzoite (chronic) and tachyzoite (actue)...bradyzoite can be transmitted to humans via undercooked meats Then can transfer tachyzoite to child
70
Clinical spectrum of toxo
Congenital Cerebral toxoplasmosis (from AIDS) ocular
71
Most severe toxo complicaton
Toxoplasmic encephalitis...tissue cysts form in brain and muscle
72
Toxoplamsosis encephalitis
Cerebral abscess leads to multifacotiral neurological symtpoms...lethal if untreated Txs do not target dormant so you need lifelong tx
73
COngintal toxo
if mother has no ABs, then still at risk but no infection at time If IgG, then no risk If IgM, then potential risk to fetus
74
Conginetal toxo exposures and when symptoms occur
If 3rd trimester, generally no effect Can occur in under 26 weeks Mild dz to spontaneous abortion Chorioretinitis is typically the first to show...could include failure to thrive, and a bunch of other things Most (75%) are subclinical
75
Toxoplasmic hydrocephaly symtpoms
Hydrocephalus Retinochorditis intracerebral calcifcation Psycho/motor retardation
76
Ocular toxoplasmosis
Consequence of congintally acquired Could occur in 10-20 years after birth Untreated could lead to blindness
77
Cryptosporidium
Diarrheal dz in immunocompromised patients Does NOT penetrate into cells Sexual cycle occurs in GI tract and not restircted to single host species
78
Life cycle of cryptosporidum
Oocyst ingested contained 4 sporozoites...oocysts attach...8 new merozoites form from schizogony...differnetiate into male and female gametocytes that then begin process of oocyst formation
79
Symptoms of crypto
Ab pain, dirrhea for 3-10 days Often mistaken for food poisoning Life-threatening in AIDS patients - persistant dirrhea, malabsorption with severe weight loss
80
Risk factors for crypto
Both animal and human feces Contam water sources (can be filtered) Conditions of crowding Contact with animal waste
81
Diagnosis and tx of crypto
Oocysts in the feces and PCR approaches | No effective tx...just rehydrate and control

Foundations 7 (19 decks)

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