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IMED2001 UWA > Medically Important Parasites Part II > Flashcards

Medically Important Parasites Part II Flashcards

1
Q

What is Giardia intestinalis?

A

A mild intestinal disease with global distribution

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2
Q

What is toxoplasma gondii?

A

A parasite that infects 30% of the world’s population and is the most successful parasite

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3
Q

What is the parasite with the highest rate of morbidity and mortality?

A

Malaria

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4
Q

What is the most diverse disease phenotype caused by a parasite?

A

Leishmania

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5
Q

What are the stages of giardiasis?

A

Trophozoite and cyst form

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6
Q

Where is giardiasis located?

A

It is distributed worldwide and is more prevalent in warm climates in water sources.

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7
Q

What ages does giardia commonly infect?

A

It is more common in children but can happen all over the world. It is highly capable of causing disease with only 10 cysts required for infection.

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8
Q

How is giardiasis diagnosed?

A

Faecal sample and biopsy can be done as well. String test Immunological tests (antigen immunoassays, immunofluorescence) Microscopic observation of cysts or trophozoites in faeces Symptoms

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9
Q

How is giardia transmitted?

A

Person to person (hand to mouth (children, siblings, etc and can be caused by some sexual practices) Contaminated food and water (Epidemic if water supply contaminated, unhygienic food handlers)

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10
Q

Why is giardiasis easily transmitted?

A

Infectious dose is very small The cysts are resistant to chlorine and other disinfectants They remain viable for weeks in cold water There are animal reservoirs of some genotypes

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11
Q

How can giardiasis be prevented?

A

Communal, group and personal hygiene Avoidance of potentially-contaminated water and food.

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12
Q

How is giardiasis treated?

A

Metronizadole (widely used and effective) Tinidazole Mepacrine Nitazoxanide Paromomycin Albendazole (similar to metronizadole with fewer side effects and simplified regimen)

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13
Q

How is giardiasis treated?

A

Metronizadole (widely used and effective) Tinidazole Mepacrine Nitazoxanide Paromomycin Albendazole (similar to metronizadole with fewer side effects and simplified regimen)

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14
Q

What does metronidazole act on?

A

DNA

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15
Q

What does tinidazole act on?

A

DNA like metronidazole but slightly more effective. (it is 5-nitrimidazole)

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16
Q

What does mepacrine do?

A

It is cell membrane active and related to mefloquine and causes psychosis.

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17
Q

What kind of reproduction takes place in the cat by toxoplasmosis?

A

Both sexual and asexual reproduction

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18
Q

Why is toxoplasmosis the most successful parasite ever (in Dr. Christopher’s opinion)?

A
  1. It has at least 5 mechanisms of transmission. 2. Despite it having only 1 definitive host it can infect every warm blooded animal and bird. 3. It can infect every nucleated cell 4. It can live inside you for your entire life and you would never know) 5. It does not kill it’s host (normally) 6. However, it does effect your brain to improve it’s chances of transmission 7. It is very hard to treat
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19
Q

What are the symptoms of toxoplasmosis?

A

Often asymptomatic (in 90% of people) Lymphadenopathy with/without fever Eye lesions Myocarditis

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20
Q

How is toxoplasmosis acquired?

A

Acquired from cysts in soil or pseudocysts in undercooked meat Transmission via faecal material in cat or other animals being touched after they have had cysts on them. Direct contact with animal faecal material Organ transplant + immunodeficiency Blood donation

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21
Q

What does toxoplasmosis do to foetal development?

A

Can result in abortion, still birth, hydrocephaly (mental retardation and eye lesions), acquired by vertical transmission across placenta.

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22
Q

What kind of disease does toxoplasmosis cause in immunodeficient people?

A

Reactivation of latent infection Fatal, acute fulminating disease: Necrotising encephalitis Pneumonitis Myocarditis

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23
Q

How does toxoplasmosis cause effects in foetuses?

A

It only has an effect when first contracted during pregnancy

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24
Q

What kind of infection can toxoplamsa gondii cause in immunocompetent?

A

Eye lesions: uveitis, retinochoiditis, choroiditis

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25
How is toxoplasmosis commonly diagnosed via serology?
ELISA Fluorescent antibody Haemagglutination Complement fixation
26
What non-serological methods are there for toxoplasmosis diagnosis?
Biopsy or biopsy materials including bone marrow, spleen, CSF, lymph, brain Inoculation of suspect materials into lab animals such as mice, rabbits, or guinea pigs (Xenodiagnosis) PCR, especially in detecting congenital infections in utero
27
How can toxoplasmosis be prevented?
Adequate cooking of meat Proper disposal of cat faeces Protecting children's play areas especially in household environment
28
How is toxoplasmosis treated?
No satisfactory treatment available. (Synergistic pyrimethamine is found to cause some improvement) Toxoplasmosis is not treated if person is asymptomatic but if the infectious titre is rising treatment is indicated especially when starting immunosuppressive therapy.
29
How are infants treated if they have a toxoplasmosis infection?
Infants are treated with transplacental treatment if the infectious titre is rising
30
What are the possible long term sequelae of toxoplasmosis?
Evidence indicates it being linked to schizophrenia (note that in this study only maternal antibody to genotype I was predictive of increased risk of psychosis in adult offspring) [contradictory results] Significant link to bipolar disorder but not to any unipolar mood disorders Brain cancer Manipulation hypothesis states that T.gondii manipulates host to act in ways that increase probability of transmission Reduces response time associated with car accidents
31
What kind of parasite causes malaria?
Oligate intracellular blood sporozoan found in tropical and sub-tropical climates.
32
Why is malaria limited to tropical and sub-tropical areas?
That's where the vectors are located.
33
What are the causative pathogens of malaria?
5 species: P. falciparum P. vivax P. Malariae P. Ovale
34
Which species of malaria causes the most serious disease?
P. Falciparum
35
How are species of malaria differentiated?
Morphology and staining characteristics Number of merozoites in blood Appearance of infected blood cell Pathology
36
Which mosquito is implicated in transmission of malaria?
Female Anopheles Mosquitos
37
How do the malaria species differ morphologically?
What distinguishes P. falciparum from the others is the 2 banana shaped structures connecting 2 balls
38
How many cases of malaria are there every year?
350 - 500 million and more than 1 million deaths (mostly young children)
39
Where do most malaria cases occur?
90% of malaria cases in Africa
40
How does malaria do its damage?
Mosquito contains male and female gametophytes which combine sexually to form a sporozoite. Sporozoite enters the blood stream and finds the liver and enters hepatocytes Sporozoites reproduce asexually to form merozoites and shizont which eventually ruptures hepatocyte. Merozoites enter the bloodstream and infect RBCs and form trophozoites which then also burst. The resulting trophozoite starts the cycle again. New gametophytes form simultaneously to the merozoites and start the cycle again.
41
How does malaria kill people?
Haemorrhaging in internal organs (thousand of microhaemorrhages) Anaemia Raised intracranial pressure due to sequestered parasites Hypoglycaemia and severe metabolic acidosis
42
Who does malaria typically affect?
Young children and people with immune deficincies.
43
What treatments are commonly used for malaria?
Quinine and related agents (choloroquine) Amodiaquine (pyrimethamine) Proguanil (sulfonamides, mefloquine, atovaquone) Primaquine Artemisin combination therapy Halofantrine Doxycycline Clindamycin Spiroindolones
44
Why is artemisinin combination therapy used?
To combat potential drug resistance
45
How can malaria be prevented?
Prophylaxis therapy
46
What are the types of life cycles that leishmania undergoes?
Digenetic life cycle, zoonosis
47
What are the types of Th responses to leishmania infection?
Cutaneous leishmaniasis creates a Th1 response Mucosal leishmaniasis creates a Th1/Th2 response Visceral leishmaniasis causes immune suppression
48
What species of leishmania cause cutaneous leishmaniasis?
L. major L. tropica
49
What species of leishmania cause mucosal leishmaniasis?
L. braziliensis
50
What species of leishmania cause visceral leishmaniasis?
L. donovani L.infantum
51
What does cutaneous leishmaniasis progress to?
Mucosal leishmaniasis
52
How is leishmaniasis typically diagnosed using parasitology?
Spleen palpation Parastites found in aspirates of bone marrow, lymph nodes or spleen Giemsa stain, culture in blood agar or hamster
53
How is leishmaniasis diagnosed using lab tests?
ELISA (Enzyme linked immunosorbent assay) IFAT (indirect immunofluorescence test) DAT (Direct agglutination test) Formol Gel Test (aldehyde test) Immunochromatographic dipstick test, specific antigen Kd39 Montenegro skin test - cannot differentiate between past and current infections PCR (RFLP)
54
What happens if visceral leishmaniasis is coinfective with HIV?
They both potentiate each others effects and cause drop in CMI
55
How is visceral leishmaniasis diagnosed?
Hard palpable spleen, fever and wasting
56
How is leishmaniasis treated?
Pentavalent antimonials, amphotericin B, paromomycin, pentamidine isethionate, miltefosine and azoles. Cytokine therapy is very expensive All drugs for leishmaniasis are toxic
57
How can leishmaniasis infection be prevented?
Avoiding exposure, protective clothing, bed-nets (sandfly vector), repellents, vector control, and reservoirs control (treatment or elimination of infected dogs)
58
Do any vaccines exist for leishmaniasis?
Only in dogs
59
What is the problem with anti-leishmaniasis drugs?
They are toxic and are prone to resistance
60
What is the vector that is common in leishmaniasis?
Sandflies
61
What are the common symptoms of ascaris lumbricoides?
Often asymptomatic (85% of cases) Worms can cause intestinal obstruction as well as inflammation due to presence in blood. Ascaris metabolites can cause sensitizing phenomena like urticaraia and asthma. It can move around the body and block narrow organs accidentally
62
How can ascaris lumbricoides be diagnosed?
Recovery of eggs from faeces or adult worms
63
How is ascaris infection treated?
Mebebdazole, albendazole (except in pregnancy), Levamisole, thiabendazole, Pyrantel, piperazine – worms can migrate away from gut to avoid drugs
64
How can ascaris infection be prevented?
Clean sanitary toilet and food preparation facilities. Good personal hygiene.
65
What causes schistosomiasis?
3 separate species of trematodes: Schistosoma (S. mansoni, S. japonicum (intestinal), and S. haemotobium (bladder))
66
How do schistosoma species get into people?
Schistosoma contaminate water and then burrow into skin. Enter bloodstream Migrate into lungs and cause eosinophilia (loefflers syndrome) They go to mesenteric vessels or bladder vessels and they pair up near the organs and sexually reproduce to the outside of the body. Fibrosis from the immunogenic eggs produced by these parasites cause damage.
67
What locations can granulomas be found in following schistosomiasis and what kind of symptoms do they produce?
Brain granulomas - epilepsy Lungs - pulmonary hypertension Heart - Cor pulmonale Spinal cord - paraplegia Liver - fibrosis Spleen - Splenomegaly Genitourinary tract - Bladder cancer
68
How can schistosomiasis be diagnosed?
Stool sample: Identify eggs (lateral spined, terminal spined, or small lateral knob) Rectal snip: Proctoscopy: take 6 snips of mucosa, crush between glass slides and look on microscope Serology: indicates past or present infection. CFT/ELISA. Useful for screening Antigen detection: In research laboratories identifies living worms
69
How is schistosomiasis treated?
Praziquantel (single oral dose) Metrifonate (can be used instead for SH 3 doses are given over several weeks) Oxamniquine (for SM. 2 doses on 1 day. Less effective for children
70
How can schistosomiasis be prevented?
Educate public Prevent urine and faeces from contaminating fresh water. Build latrines Improve irrigation and agricultural systems to prevent snail build up. Avoid skin contact with fresh water. Provide cercariae-free water for drinking, washing Identify infected persons and treat.

IMED2001 UWA (44 decks)

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