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IAHI Block 1 > Parasitology > Flashcards

Parasitology Flashcards

1
Q

Symbiosis

A

A relationship of distinct organisms in close association with one another

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2
Q

Mutualism:
Commensal:
Parasitism:

A

Mutualism: Benefits both
Commensal: Benefits one and neutral for the other
Parasitism: Benefits one and harfmul for the other (parasite vs host)

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3
Q

Human parasites are divided into:

A

Endo (infection inside the body)

Ecto (Infestation or within skin)

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4
Q

Endoparasites are divided into:

A

Protozoan (unicellular)

Helminths (multicellular worms)

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5
Q

Parasite (Biological Definition)

A

An organism that grows, feeds, and is sheltered on or in a host organism to the detriment of that host

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6
Q

Definitive Host

A

Host in which the sexual stage of a parasite life cycle occurs

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7
Q

Intermediate Host

A

Host in which asexual reproduction or development occurs

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8
Q

Incidental Host

A

Host is not an obligate part of parasite life cycle

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9
Q

Reservoir Host

A

Animal hosts that maintain the natural cycle in the wild - often are not really harmed by carriage

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10
Q

Vector Host

A

A host species that transmits an infections form of the parasite to another host species

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11
Q

Worldwide parasitology prevalence of Malaria

A

300-500 million cases per year

655,000 deaths, mostly children

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12
Q

Prevalent parasitologies

A 
Malaria
Leishmaniasis
Chaga's disease
Schistosomiasis
Lymphatic Filariasis
Ascariasis
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13
Q

The 6 Kingdoms

A 
Eubacteria
Archeobacteria 
Protista
Fungi
Plantae
Animalia
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14
Q

Cyst

A

Dormant stage of parasite, found encysted in host (intermediate or definitive)

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15
Q

Cyst, Hydatid

A

Specialized cysitcercal form of the cestode Echinococcus granulosus - found in the intermediate host

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16
Q

Larvae alternative names

A 
Metacercaria
Miracidium
Microfilariae
Cercaria
Filariform
Rhabditiform
Schistosomula
Sporocyst
17
Q

Class Cestoda

A
  • Tapeworms; flattened segmented bodies
  • NO internal digestive system; nutrients absorbed across cuticle
  • Adults attach by anterior end (scolex) to the gut wall of definitive host
  • Segments (proglottids) mature from anterior to posterior; specialized for reproduction
  • Transmission by ingestion of larval cysticerci or eggs
18
Q

Class Trematoda

A
  • Flukes of the lungs, liver and blood
  • Broad flattened bodies with a simple digestive system; a single opening serves as mouth and anus
  • One or more intermediate hosts, one of which is a snail
  • Transmission can be invasive or injestive
19
Q

Tapeworms associated with:

1) Raw Beef
2) Raw Pork
3) Eggs
4) Undercooked fish

A

1) Taenia saginata (intestinal)
2) Taenia solium (Intestinal/lung)
3) Echinococcus granulosus (liver,lungs)
4) Diphyllobothrium (intestinal)

20
Q

Schistosoma spp. (Trematoda)

A

Located in veins to gut/bladder

Cercaria penetrate skin

21
Q 
Pork tapeworm: Taenia solium
Location:
Definitive Host:
Intermediate Host:
Transmission:
Pathology:
Diagnosis:
Immunity:
Treatment:
Prevention:
A

Location: Adults - Intestine; Cysticerci - any tissue
Definitive Host: Humans
Intermediate Host: Pigs or humans
Transmission: Ingestion
Pathology: Abdominal discomfort, occasionally nausea, vomiting, diarrhea, weight loss and obstruction; Cysticercosis can affect brain functioning
Diagnosis:Self; active proglottids
Immunity: Humoral response to adult worms
Treatment: Praziquantel/ Dexamethasone
Prevention: Good public and personal hygiene

22
Q 
Diphyllobothrium latum: Fish tapeworm
Location:
Definitive Host:
Intermediate Host:
Transmission:
Pathology:
Diagnosis:
Immunity:
Treatment:
Prevention:
A

Location: Lumenal, intestinal
Definitive Host: Humans
Intermediate Host: Copepod that infects fish
Transmission: Ingestion
Pathology: Adults absorb 80-100% dietary B12; anemia
Diagnosis: Active proglottids (eggs in feces)
Immunity: None
Treatment: Praziquantel; B12 supplement
Prevention: Good public hygiene

23
Q 
Echinococcosis: tapeworm Echinococcus
Location:
Definitive Host:
Intermediate Host:
Transmission:
Pathology:
Diagnosis:
Immunity:
Treatment:
Prevention:
A

Location: Tissues mainly lungs and liver, but also spleen, kidneys, heart, bone and CNS
Definitive Host: Wild and domestic canines
Intermediate Host:Wild and domestic ungulates (hoofed animals); humans
Transmission: Ingestion of eggs from dogs
Pathology: Hyatid cysts in liver (50-70%) and lungs (20-30%) but also spleen kidney, bone and CNS; releases protoscolices; anaphylaxis
Diagnosis: CAT scan; presents as slow growing tumor; Serology used for confirmation
Immunity: Circulating antibodies to hydatid cyst antigens
Treatment: Percutaneous drainage with instillagion of hypertonic saline or alcohol; surgical removal; albendazole
Prevention:

24
Q

Schistosomiasis (Blood Flukes) - 3 types

A

1) Schistosoma mansoni - inferior mesenteric veins
2) Schistosoma joponicum - superior mesenteric veins
3) Schistosoma haematobium - venous plexus (bladder)

25
Q 
Schistosomiasis
Location:
Definitive Host:
Intermediate Host:
Transmission:
Epidemiology:
Diagnosis:
Immunity:
Treatment:
Prevention:
A

Location: Eggs migrate to descending colon, small intestine, bladder
Definitive Host: Humans
Intermediate Host: Snails
Transmission: Invasive, aquatic cercaria penetrate skin
Epidemiology: 240 million infected globally - contaminated water supply
Diagnosis: Observation of eggs in feces or urine; serology
Immunity: Adults masked by absorption of host serum proteins
Treatment: Praziquantel in single or multiple doses potentiates active immune system killing of worms
Prevention: Reduce source, control intermediate hosts; avoid contact with infested water

26
Q

Schistosomiasis Pathology

A

Early (0-2 wks): Rash from invading cercaria; fever headache nausea as they migrate
Middle (1-2 months): Symptoms from immune response to eggs, intense fever with onset of oviposition; Katayama syndrome
Chronic (5-15 years): Severe liver disease; portal hypertension; fibrosis of bladder

27
Q

Schistosome mating

A

Male and female are attached
Male takes in nutrients
Female produces eggs

28
Q

Pathogenic types of Nematoda (round worm)

A

1) Lumenal - intestinal/anal/colon
2) Hookworm - intestinal soil
3) Tissue Worm - muscle/blood/tissue

29
Q 
Pinworm
Location:
Definitive Host:
Intermediate Host:
Transmission:
Pathology:
Diagnosis:
Immunity:
Treatment:
Epidemiology:
A

Location: Adults in colon
Definitive Host: Humans
Intermediate Host: n/a
Transmission: Ingestion of eggs, direct person to person
Pathology: Intense perianal pruritis (itchy skin); Urogenital invasion in females can lead to bacterial infection; psychological trauma
Diagnosis: Persistent perianal itch, restlessness, insomnia
Immunity: none
Treatment: Pyrantel pamoate, mebendazole, albendazole
Epidemiology: Prevalent in children, day care centers

30
Q 
Whipworm
Location:
Definitive Host:
Intermediate Host:
Transmission:
Pathology:
Diagnosis:
Immunity:
Treatment:
Prevention:
A

Location: Adults attach to colonic mucosa
Definitive Host: Humans only
Intermediate Host: n/a
Transmission: Ingestion of embryonated eggs
Pathology: Low: usually none; High: Disrupted colonic mucosa, bloody stool, prolapse, anemia; heavy - impaired growth in children
Diagnosis: Only by eggs in stool
Immunity: Acquired immunity in natural infections
Treatment: 3 days of ivermectin, mebendazole or albendazole
Prevention: Good personal and public hygiene

31
Q 
Ascariasis
Location:
Definitive Host:
Transmission:
Epidemiology:
Pathology:
Diagnosis:
Immunity:
Treatment:
Prevention:
A

Location: Adults free in upper intestine
Definitive Host: Humans
Transmission: Ingestion of eggs from soil
Epidemiology: 25% of people infected worldwide - considered a US NDP (Neglected disease of poverty)
Pathology: Heavy worm loads can lead to intestinal obstruction; stressed worms migrate to nose, ear, peritoneal
Diagnosis: Eggs in stool
Immunity: Allergic inflammation from larval migration through lungs
Treatment: Mebendazole, albendazole or iermectin
Prevention: Good personal and public hygiene

32
Q 
Hookworms
Location:
Definitive Host:
Transmission:
Epidemiology:
Pathology:
Diagnosis:
Immunity:
Treatment:
Prevention:
A

Location: Small intestine
Definitive Host: Humans
Transmission: Invasive of skin in contact with soil
Epidemiology: US-NDP, poor public sanitation, children and farmers with no shoes
Pathology: Pruritis at penetration sites; heavy infection, larval migration through lungs can cause bronchitis; Exsanguination
Diagnosis: Anemia; confirmed by eggs in stool
Immunity: Asthmatic pathology with repeated infection
Treatment: Pyrantel pamoate, albendazole and mebendazole
Prevention: Good public hygiene, shoes

33
Q 
Strongyloides
Location:
Definitive Host:
Transmission:
Epidemiology:
Pathology:
Diagnosis:
Immunity:
Treatment:
Prevention:
A

Location: Small intestine
Definitive Host: Humans
Transmission: Filariform larvae penetrates skin
Epidemiology: US-NDP, up to 100,000 infections in the US; autoinfection can result in long-term infection
Pathology: Pulmonary manifestation, high burden leads to chronic intestinal malabsorption, rashes due to autoinfection - can lead to immunosuppression and hyperinfection that can be fatal
Diagnosis: Larvae in stool or sputum; serology
Immunity: Asthmatic pathology with repeated infection
Treatment: Treat all cases ivermectin 1st choice thiabenazole 2nd choice
Prevention: Good public/personal hygeine; wear shoes

34
Q

3 Alternative Life cycles of Strongyloides

A

Direct: Like hookworms: Invade skin goes to circulation then lodges in lungs; coughed up and swallowed, matures in intestine
Indirect: Sexual reproduction in soil
Autoinfection: Larvae mature in host, enter through colonic mucosa or perianal skin

35
Q

Diagnostic staining and culture procedures for Strongyloides

A

1) Wet mount of stool
2) Human fecal smear stained with auramine O
3) Agar plate culture method
4) Gram staining of a sputum

36
Q 
Trichinosis
Location:
Definitive Host:
Incidental Host:
Transmission:
Epidemiology:
Pathology:
Diagnosis:
Treatment:
Prevention:
A

Location: Adults in intestine; larvae in muscle
Definitive Host: Meat eating mammals
Incidental Host: Humans are dead end hosts
Transmission: Raw/undercooked meat (pork)
Epidemiology: Developed world, home-made sausage; Hunting (Inuits)
Pathology: Mild pathology from adult worms (nausea, cramps); Inflammation around individual cyst; Severe symptoms - fever, neural dysfunction, conjunctivitis
Diagnosis: Eosinophilia, periorbital edema, myositis, fever - serology > 3 weeks after infection
Treatment: Mebendazole or albendazole
Prevention: Cook food

37
Q 
Toxocariasis
Location:
Definitive Host:
Incidental Host:
Transmission:
Epidemiology:
Pathology:
Diagnosis:
Immunology:
Treatment:
Prevention:
A

Location: In dogs, adult worms free in upper intestine of dog; In humans, larva can be found in any tissue
Definitive Host: Dogs
Incidental Host: Humans
Transmission: Ingestion of embryonated eggs from soil
Epidemiology: More commonly in warmer climates
Pathology: Heavy worm loads can lead to necrosis in any location; enlarged liver, pulmonary complications
Immunology: Asthmatic and immune hypersensitivity common
Diagnosis: ELISA for larval antigens, but can cross with Ascaris
Treatment: Sever cases only, albendazole or mebendazole
Prevention: Disposal of dog waste

IAHI Block 1 (16 decks)

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