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MD1 SF3 - EXAM 2 > Introduction à la parasitologie médicale > Flashcards

Introduction à la parasitologie médicale Flashcards

1
Q

What is parasitology?

A

The study of infections directly or indirectly caused by parasites

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2
Q

What is a parasite?

A

organism that feeds exclusively at the expense of a host organism of a different species, either permanently or during a phase of its life cycle

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3
Q

What is parasitosis?

A

infestation with or disease caused by parasites.

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4
Q

What are the three different kinds of hosts?

A

Hôte définitif: parasite à l’état adulte

Hôte intermédiaire: parasite à l’état de larve

Hôte accidentel: parasitosis usually found in another species

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5
Q

What is a reservoir?

A

Organism in which parasites multiply between transmissions and infections

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6
Q

How are parasites a problem globally?

A

Omnipresent on our planet —> found in all climates

Important cause of morbidity and mortality

Affect extremely high number of people

ex: Geohelminths —> 1.5 billion people infected, 24% of global population

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7
Q

How are parasites acquired in Canada? (3 main causes of parasitosis)

A

Locally acquired

Immigrants from endemic locations

Travellers and tourism

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8
Q

What are the three main ways in which parasites can be transmitted?

A
  1. Fecal-oral (digestive)
  2. Direct and indirect contact including transcutaneous
  3. Vectors (ex: ticks, mosquitos, etc.)
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9
Q

How is intestinal parasitosis dx in a lab?

A

Microscopie —> méthode de référence

Feces is the specimen of choice (need 2-3 specimens for dx)

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10
Q

Why do you study selles fraiches?

A

Fast dx, evaluate “charge parasitaire”, evaluate motility of protozoa, detect mobile larvae

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11
Q

Why do you study selles fixées?

A

SAF-fixatives can be used (formol d’acétate de sodium) which allows for permanent colouration that helps with better visualization of Trophozoïtes and Kystes

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12
Q

How is cutaneous parasitosis dx?

A

Microscope and colourations

Clinic?

  • Aspect of lesions and anatomical localization
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13
Q

How is “parasitose profond” dx?

A

Specimen for microscopy if possible… if not:

  1. Medical imagery
  2. Serology
  3. Antigen detection
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14
Q

Eosinophils and parasitosis:

A

Type of WBC

Increased in blood during allergic rxns and certain parisitoses

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15
Q

When are eosinophils associated with parasitosis?

A

Severe infections

Infections plus profondes

Dissemination and migration of parasites

IN CUTANEOUS AND INTESTINAL PARASITOSIS —> NO EOSINOPHILS

The absence of eosinophils does not mean an absence of parasites

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16
Q

What are the two classification groups of parasites?

A
  1. Ectoparasites
  2. Endoparasites
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17
Q

What are ectoparasites?

A

Live on the surface of the body (skin, hair, nails, etc.)

Either insects and arachnids

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18
Q

What are the different kinds of insects (4) and arachnids (2) that are considered ectoparasites?

A
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19
Q

What are Sarcoptes scabei? —> SCABIES

A

Mite (human skin)

Omnipresent globally

300M new cases annually

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20
Q

Who is the most vulnerable? (scabies)

A

Lower socioeconomic classes

People living in overcrowded living conditions

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21
Q

How is it transmitted? (scabies)

A

Person to person contact (direct)

VERY CONTAGIOUS (outbreaks in hospitals very very possible)

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22
Q

How do they reproduce? (scabies)

A

Creusent des sillons sous la peau

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23
Q

What sites are affected by scabies?

A
  1. Wrists
  2. Interdigital grooves
  3. Navel
  4. Lower back
  5. Buttocks and genitals
  6. Underarms and breasts
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24
Q

What is the incubation period of scabies?

A

Around 2 months but shorter if been exposed before

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25
Q

Sx associated with scabies:

A

Prurit cutané

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26
Q

Dx of scabies:

A

Microscopie sur raclures de peau

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27
Q

Tx of scabies:

A

Permethrin 5% (topical cream) or Ivermectin

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28
Q

What are endoparasites?

A

Parasites that live inside organism

Deep tissues and organs (ex: lungs, intestines, brain, etc.)

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29
Q

What are the 4 main categories of endoparasites?

A
  1. Protozoa
  2. Helminthes (worms)
  3. Chromistes
  4. Microsporidies (fungi)
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30
Q

How are protozoa classified?

A

classified according to their mode of locomotion

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31
Q

What are the sub-classifications of amoebas?

A
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32
Q

What are Entamoeba hystolytica?

A

Intestinal parasite (amoeba)

Found across the globe but mostly in tropical and subtropical regions in: Latin America, Africa, and Asia

2nd highest cause of death due to parasitosis: 40k - 100k deaths per year

Infects 500M people a year —> 50M with abscesses in liver

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33
Q

What are the two forms of Entamoeba hystolytica?

A
  1. Trophozoite —> active form
  2. Kyste —> dissemination (resistant in environment)
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34
Q

How are Entamoeba hystolytica transmitted?

A

Fecal-oral (contaminated food and water) and oro-genital sex

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35
Q

Incubation period of Entamoeba hystolytica:

A

Couple days to months —> hepatic abscesses in 8-20 weeks

36
Q

Sx of Entamoeba hystolytica:

A

90% of cases are asymptomatic

but if not… causes intestinal symptoms such as:

  • Wide range of symptoms
  • Mild diarrhoea
  • Dysentery
  • Haemorrhagic or fulminant colitis
37
Q

Dx of Entamoeba hystolytica:

A

Microscope of fresh or fixed faecal matter

Antigenic detection

PCR testing

Serology —> hepatic abscesses

38
Q

Tx of Entamoeba hystolytica:

A

All cases are treated even in asymptomatic:

Asymptomatic:

  • Luminal agents —> work against kystes
  • Paromomycin x 7 days

Intestinal or extra-intestinal infections:

  • Tissular agent —> work against trophozoites
  • Metronidazole x 7-10 days followed by a luminal agent
39
Q

What are the sub-classifications of flagellated?

A
40
Q

What are Giardia lamblia?

A

Intestinal parasitosis

Most frequently found in Canada and US but can be found globally

Prevalent in temperate climates: 2-10% of adults and 25% of children

Tropical climates: 50-80% are carriers

41
Q

What are the two forms of Giardia?

A

Trophozoite —> active form

Kyste —> dissemination (resistant in environment)

42
Q

How is giardia transmitted?

A

Fecal-oral: contaminated food/water or just person to person

43
Q

What is the reservoir for giardia?

A

Mostly in beavers

44
Q

In developed countries… where is giardia most often found?

A

Daycare service

Hikers

HARSAH (hommes ayant des relations sexuelles avec d’autres hommes)

Family members of a patient

Immunosuppressed (IgA deficiency)

45
Q

What is the incubation period of giardia?

A

7-14 days

46
Q

Sx of giardia:

A

small intestine

  • Nausea and vomiting
  • Abdominal cramps
  • Diarrhea
  • Steatorrhea and odour
  • Flatulence

Symptoms last for 2-4 weeks but can turn chronic in some cases

47
Q

Dx of giardia:

A

Microscope: selle fixée or intestinal biopsy

Antigen detection

PCR test and serology

48
Q

Tx of giardia:

A

Who is treated: EVERYONE, symptomatic and asymptomatic (to avoid transmission)

Metronidazole x 5-7 days

49
Q

What are the sub-classification of sporozoa?

A
50
Q

What is Plasmodium sp.?

A

Malaria –> paludism

200M cases a year —> 80% of cases in 16 counties (15 in Sub-Saharan Africa and India)

51
Q

What are the 5 species of plasmodium that infect humans?

A
  1. P. falciparum (mondial)
  2. P. vivax (pas d’Afrique Sub-saharienne
  3. P. ovale (Afrique surtout)
  4. P. malariae (mondial)
  5. P. knowlesi (Borneo et Malaisie)
52
Q

What are the 4 forms of plasmodium?

A
  1. Gametocytes —> germinative form, ingested by mosquitos
  2. Sporozoites —> form injected by mosquitos
  3. Schizont —> disseminated form
  4. Trophozoites —> mature form
53
Q

How are plasmodium transmitted?

A

Through mosquitos

Vector —> anophèle (genus of mosquito)

Mostly in rural regions during rainy season

54
Q

What are the two cycles of plasmodium infection?

A

Hepatocytes (liver)

Erythrocytes (blood)

55
Q

What is the incubation of plasmodium?

A

8-25 days —> fever up to 3 months after returning from trip

56
Q

Sx of Plasmodium infection:

A

Fever and chills

Sweating

Headaches

Weakness and discomfort

Myalgia and arthralgia

Diarrhoea (or constipation) and abdominal cramps

57
Q

What causes a severe rxn to plasmodium?

A

Especially P. falciparum (sometimes vivax)

Causes:

  • Neurological impairment
  • Severe hemorrhage
  • Respiratory distress

Risk factors:

  • People that aren’t immune
  • Children
  • Pregnant women
  • Immunosuppressed individuals
58
Q

Dx of plasmodium infection:

A

Frottis sanguin —> frottis mince, goutte épaisse

Antigen detection (rapid testing, best for P. falciparum and vivax)

Serology and PCR testing

59
Q

Tx of plasmodium infection:

A

Medical emergency!

Depends on: species, region where acquired, severity of infection

Rx available:

  • Atovaquone-proguanil (Malarone ®)
  • Chloroquine
  • Mefloquine
  • Doxycicline
  • Primaquine

IF SEVERE INFECTION = Artesunate IV

60
Q

How can malaria be prevented?

A
  • Traveller education
  • Protection against mosquitoes
    • Insect repellent (Deet 30%)
    • Light-coloured long garments
    • Mosquito nets
  • Limit activities outside from dusk to dawn
  • Drug prophylaxis
61
Q

How are helminthes classified?

A

classified according to their morphology

62
Q

What are the sub-classifications of nematodes?

A

ROUND WORMS

63
Q

What are Enterobius vermicularis?

A

Pinworms (oxyure)

Intestinal parasites

Global, but mostly in temperate climates in children between 5 and 10 years old

64
Q

What are the two main forms of pinworms?

A

Adult worm (8-13 mm)

Eggs

65
Q

How are pinworms transmitted?

A

Females live 2 - 3 months

Fecal-oral transmission:

  • Contaminated food
  • Person to person
  • Self-infection

Indirect contact transmission:

  • Clothing and bedding
  • Surfaces

Aerial transmission of eggs possible

Frequent intra-family transmission

66
Q

What is the incubation period of pinworms?

A

1-2 months

67
Q

Sx associated with pinworms:

A

Infections localized in cecum or appendix

Can be asymptomatic or cause anal itching (prurit anal)

  • Excoriations
  • Possible bacterial superinfections
  • Night agitation and insomnia
  • Digestive sx if infection is more severe
68
Q

Dx of pinworms:

A

Microscopie sur selles —> not very useful

“Scotch Test” test à la cellophane adhésive de Graham —> morning, before shower/bath

69
Q

Tx of pinworms:

A

Antiparasitic with action against nematodes:

  • Mebendazole
  • Albendazole
  • Pyrantel pamoate
70
Q

What are the sub-classifications of cestodes?

A

Tapeworms

71
Q

What are the two forms of tapeworm infections?

A

Humain hôte définitif: Vers matures, Infection tractus digestif

Humain hôte intermédiaire: Larves, Infections extra-intestinalese

72
Q

What Is Taenia solium?

A

Taenia du porc

Mostly in tropical and sub-tropical climates in rural/périurban zones >>> cities

Very frequent cause of convulsions

73
Q

What are the three main forms of Taenia solium?

A
  1. Eggs
  2. Cysticerques (larvae)
  3. Adult worms (2-7 m)
74
Q

How is Taenia solium transmitted?

A

Fecal-oral transmission from consuming contaminated pork, person to person, or auto-infestation

75
Q

Sx of Taenia solium infection:

A

Neurocysticercose

Atteinte SNC ou oculaire

SNC: parenchymateuse ou extra- paranchymateuse

Atteinte parenchymateuse

  • Plus fréquente
  • Convulsion
  • Lésions kystiques ou rehaussantes
76
Q

Dx of Taenia solium:

A

TDM or IRM cérébrale

Serology

Occular examination (everyone)

Biopsy to confirm dx

77
Q

Tx of Taenia solium:

A

Symptomatic patients with variable cysts or degeneration are treated

Combination therapy of antiparasitics

  • Albendazole
  • Praziquantel

Corticosteroids

Anti-convulsants

78
Q

What are the sub-classifications of trematodes?

A
79
Q

What is the Schistosoma sp.?

A

200M people affected annually in 74 countries

S. mansoni: Africa, Middle East, Asia, and Latin America

S. japonicum: China, Southwest Asia, and Indonesia

S. haematobium: Africa and the Middle East

80
Q

What are the two forms of the Schistosoma sp.?

A

Eggs

Adult worms (male and female)

81
Q

How are Schistosoma transmitted?

A

Transcutaneous from contact with water (mostly in children)

82
Q

What is the acute form of a Schistosoma infection?

A

Katayama fever

Incubation: 2-12 weeks, first exposure

Eosiniphilie

Sx: fever, chills, myalgia, abdominal pain, diarrhea

Auto-résolutive

83
Q

What is the chronic form of a Schistosoma infection?

A

Immune response directed towards migrating eggs

Intestinal infection —> portal hypertension

Bladder problems, lung damage, possible SNC infection

84
Q

Dx of Schistosoma:

A

Lab testing (eosinophilia)

Microscope to search for eggs in feces and urine

Serology

85
Q

Tx of Schistosoma:

A

Everyone is treated

Praziquantel and corticosteroids

MD1 SF3 - EXAM 2 (12 decks)

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