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Parasitic Infections Flashcards

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1
Q

Define parasite.

A

An organism living in or on a host and dependent on the host for nutrition – causing damage

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2
Q

What is the difference between an endoparasite and an ectoparasite?

A

Endoparasite – exist INSIDE the host Ectoparasite – exist on the host

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3
Q

What are the two groups of endoparasites?

A

Protozoa Metazoa

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4
Q

State the classes of organisms within the two groups of endoparasites.

A

Protozoa

  • Amoeba
  • Coccidia
  • Ciliates
  • Flagellates

Metazoa

  • Roundworms
  • Flatworms
  • Flukes
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5
Q

Give some examples of amoeba.

A

Entamoeba histolytica Entamoeba dispa

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6
Q

Give some examples of coccidia.

A
  • Plasmodium species
  • Toxoplasma
  • Cryptosporidium
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7
Q

Give an example of a ciliate.

A

Balantidium coli

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8
Q

Give some examples of flagellates.

A
  • Trypanosoma
  • Trichomonas
  • Giardia
  • Leishmania
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9
Q

What is the main difference between the two types of amoeba?

A

Entamoeba histolytica can cause invasive amoebiasis Entamoeba dispar is a normal commensal of the GI tract

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10
Q

What is amoeba infection caused by?

A

Ingestion of mature cysts in food or water contaminated by faeces

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11
Q

Describe how E. histolytica infection causes disease.

A
  • The cysts enter the small intestine and release active amoebic particles (trophozoites)
  • These invade the epithelial cells of the large intestines
  • This causes flask-shaped ulcers
  • Infection can spread from the intestines to other organs
  • Invasive amoebiasis may often cause amoebic liver abscesses
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12
Q

How many nuclei are there in mature cysts?

A

4

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13
Q

What are the treatment options for amoebiasis?

A

Nitroimidazole derivatives (kills trophozoites but not the cysts) Parmomycine or Diloxanide Furoate

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14
Q

What are the five types of plasmodium that cause malaria?

A

Falciparum Malariae Vivax Ovale Knowlesi

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15
Q

What are the two types of host for plasmodium?

A
  • Human
  • Female anopheles mosquito
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16
Q

What are the two stages of malaria in humans?

A

Liver Blood

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17
Q

Describe the symptoms of malaria.

A

PAROXYSMAL (occurs every 4-8 hours) Fever Chills Headaches Vomiting Muscle pain

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18
Q

State some complications of malaria.

A
  • Severe anaemia (due to intravascular haemolysis)
  • Cerebral malaria
  • Liver failure
  • Shock
  • Pulmonary oedema
  • Abnormally low blood sugar
  • Kidney failure
  • Swelling and rupturing of the spleen
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19
Q

What are the treatments for uncomplicated malaria?

A

Chloroquine

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20
Q

What is the treatment for severe malaria?

A

Artemisinin-based combination therapy

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21
Q

How is malaria diagnosed?

A

Blood film (+ Giemsa stain)

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22
Q

What are the routes of infection of toxoplasma gondii?

A

Eating undercooked meat of animals harbouring tissue cysts Consuming food or water contaminated with cat faeces Blood transfusion Organ transplantation Transplacentally from mother to foetus

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23
Q

Which group of patients are particularly vulnerable to toxoplasma infection?

A

Immunocompromised and in pregnancy - the fetus

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24
Q

What can toxoplasma infections cause in immunocomprimised individuals?

A

CNS disease Brain lesions Pneumonitis Retinochoroiditis

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25
What does cryptosporidium cause?
DIARRHOEA (mainly in the immunocompromised)
26
How is it treated?
Fluid rehydration
27
How are most diarrhoeal protozoal diseases diagnosed?
Stool examination
28
What are the reservoirs of balantidium coli?
Primates Rodents Pigs
29
What are the effects of balantidium coli infection in immunocompromised patients?
Persistent DIARRHOEA Dysentery Abdominal pain Vomiting Nausea Note: If left untreated can cause perforation of the colon
30
How can drinking water be cleared of ovoid giardia lamblia cysts?
Filtration Ovoid cysts can survive standard chlorination procedures
31
What is the main symptom of giardiasis?
DIARRHOEA
32
How is giardia transmitted?
Faeco-oral
33
What are the acute symptoms of giardiasis?
Diarrhoea Greasy stools that tend to float Stomach or abdominal cramps Nausea/vomiting Dehydration
34
What is the treatment for giardia?
Metronidazole - doesn't kill cysts only the trophozoites
35
How is trichomonas transmitted?
Sexually transmitted
36
Where does trichomonas infection mainly tend to reside?
Urethra
37
What are the symptoms of trichomoniasis?
Up to 50% aysmptomatic Dysuria Vulval itching Vaginal discharge Offensive smelling urine
38
What effect does trichomonas infection have on HIV transmission?
It enhances HIV transmission
39
What is the treatment for trichomoniasis?
Metronidazole
40
Can adult worms multiply in man?
No
41
In which subset of the population is there a significant burden of worms?
School-aged children – this has a massive impact on their development
42
What are the three groups of Helminths(metazoa)? Give some examples of each.
1. Roundworms (nematodes) * Ascaria * Hookworms * Filaria * Strongyloides 2. Flatworms (cestodes) * Taenia (tapeworms) 3. Flukes (trematodes) * Schistosoma
43
Where do the adult ascaria worms live?
Small intestine
44
Describe the passage of ascaria larvae once they hatch in the small intestine.
* Infective eggs are swallowed * The larvae hatch in the small intestine and invade the intestinal mucosa * They are carried via the portal and systemic circulation to the lungs * The larvae mature further in the lungs, penetrate the alveolar walls, ascend the bronchial tree and are swallowed * When they reach the small intestine, they mature into adult worms
45
How long can adult ascaria live?
1-2 years
46
Describe the symptoms of ascariasis.
Often asymptomatic Infections with a large number of worms can cause abdominal pain or intestinal obstruction Malnourishment (because of worms feeding on contents of small intestine) Loeffler’s pneumonia – penetration of larvae into lungs leads to pools of blood and epithelial cells clogging the airspaces in the lungs (resulting bacterial infections can be fatal)
47
What is the treatment for ascariasis?
Albendazole or Mebendazole
48
How are most helminth infections diagnosed?
Stool examination
49
Describe the passage of hookworm larvae across the body.
The same as ascaria
50
Where do adult hookworms live?
Small intestine Attached by their buccal capsules to the villi of the small intestine
51
What is a key feature of hookworm infection and what is this caused by?
Iron deficiency anaemia – caused by localised bleeding in the small intestine
52
What is the treatment for hookworm infection?
Albendazole or Mebendazole
53
Where do adult whipworms live?
Caecum and ascending colon
54
What are the symptoms of whipworm infection?
Blood diarrhoea and anaemia (due to severe vitamin and iron loss) Inflammation of intestinal wall Can develop rectal prolapse
55
What is the treatment for whipworm infections?
Albendazole or Mebendazole
56
What is a potential therapeutic use of whipworms?
Helminth therapy for allergies and autoimmune diseases
57
Describe the location of microfilariae in the blood.
They are found in the peripheral blood at night They are found in the deep veins during the day
58
How is lymphatic filariasis diagnosed?
Blood smear Antigen detection with immunochromatic test (ELISA)
59
What is a distinguishing feature of Loiasis?
Female worms can get into the eye and cross under the conjunctiva so you see something wriggling in your vision
60
What is the insect vector in Loiasis?
Chyrops fly
61
Describe the symptoms of flatworm infection.
Most people are asymptomatic Abdominal pain Weight loss Loss of appetite Upset stomach NOTE: people with T. saginata infection tend to have more symptoms
62
How is flatworm infection diagnosed?
Stool examination – tapeworm segments are found in the stool or identification of eggs in the stool
63
What important condition does Taenia solium cause?
Cysticercosis - commonest acquired cause of epilepsy worldwide
64
What is the treatment for flatworm infections?
Praziquantel
65
What are the three main types of schistosoma?
Schistosoma mansoni Schistosoma haematobium Schistosoma japonicum
66
What is the intermediate host in schistosoma?
Freshwater snails
67
Where do the adult worms live in schistosomiasis?
Venule
68
Where do the eggs progressively move to?
Small intestine (mansoni and japonicum) Bladder and ureters (haematobium)
69
Describe the symptoms of schistosomiasis.
Possible rash or itchy skin Fever Chills Cough Muscle aches Most people have NO SYMPTOMS in early stages of infection
70
What is the treatment of schistosomiasis?
Praziquantel
71
Name some ectoparasites.
Sarcoptes scabiei – Scabies (causes rash) Pediculus humanis capitis (head louse) Pediculus humanis corporis (body louse) Pthirus pubis (crab louse)
72
How are ectoparasites transmitted?
Direct contact
73
What are the features of protozoa?
 Unicellular  Eukaryotes (membrane bound nucleus)  Some have insect vectors  NO eosinophilia
74
What are the features of metazoa?
 MULTIcellular  They are helminths/worms  Free living, intermediate hosts and vectors  Cause eosinophilia if they invade the blood Cycles involve insects vectors and intermediate hosts For most - few zoonoses
75
What are the reservoirs of E. histolytica?
Humans are the only reservoir
76
What are the complications of Trichomoniasis
Detrimental outcome on pregnancy and is associated with preterm delivery and low birth weight
77
Define parasite
Organism living in or on the host and dependent on it for nutrition - causing damage
78
How do you get infected by a fluke cercaria?
Patient has to be in infected water so cercaria can penetrate the skin
79
How are scabies treated?
Scabicides

Y2 Micro (MCD) (8 decks)

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