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Albert Flashcards

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1
Q

What are protozoa?

A

Animal-like eukaryotes. Mostly free-living, some are pathogens. Prevalent in (sub)tropical regions. Can infect tissues/organs: intracellular parasites in cells, extracellular parasites in blood, intestine, urogenital system.

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2
Q

Which drugs are used for prophylaxis of malaria in areas without resistance?

A

Chloroquine or proguanil

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3
Q

Which drugs are used for prophylaxis of malaria in areas with some chloroquine resistance?

A

Proguanil + chloroquine.

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4
Q

Which drugs are used for prophylaxis of malaria in areas with chloroquine resistant P. falciparum? [3]

A
  1. mefloquine
  2. doxycycline
  3. Atovaquone-proguanil (Malarone)
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5
Q

Why is it difficult to create a malarial vaccine? [5]

A
  1. Difficult to grow enough pathogen for attenuated or killed-microbe vaccine.
  2. Natural immunity has not revealed specific antigens that provide protection.
  3. Some antigens exhibit genetic polymorphism
  4. Some antigens show temporal switching of expression - only expressed during one stage of life cycle.
  5. No good animal models for P. falciparum/vivax.
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6
Q

What are the symptoms of malaria?

A

cold stage/shivering, hot stage/fever, sweating stage. Other: headache, body aches, nausea, vomiting, weakness, enlarged spleen.

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7
Q

What are the symptoms of severe malaria?

A

Abnormal behaviour.
Shock
Liver failure, jaundice.
Swelling/rupture of spleen

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8
Q

What does the ABCD for travellers in regards to malaria represent?

A

Awareness of risk
Bite prevention
Chemoprophylaxis
Diagnosis and treatment.

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9
Q

How is malaria diagnosed?

A

Blood smears examined by microscopy: sensitive, labour intensive.
Rapid diagnostic tests: detection of antigens/enzymes. (limited sensitivity)
Other ways: PCR, antibody detection, mass spectroscopy.

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10
Q

What is the immunochromatographic technique for malarial infection diagnosis?

A
  1. Sample (buffer plus blood) is mixed with labelled detection antibodies on a nitrocellulose strip.
  2. The sample + antibody migrates by capillary action across the strip.
  3. When recognised by immobile antibodies, a dark line appears due to high concentration of detection antibody.
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11
Q

What are ACTs?

A

Artemisinin-based combination therapies.

  • rapid parasite clearance
  • rapid resolution of symptoms
  • active on blood stage of all 4 species
  • reduce gametocyte carriage and hence transmission.
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12
Q

How does ACT work?

A

It reduces gametocyte carriage and hence transmission. Active on blood stage of all 4 species.

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13
Q

What is one example of a rapid diagnostic test for malaria?

A

BinaxNow Malaria test.

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14
Q

How many classifications of protozoa are there?

A

4.

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15
Q

What are the 4 classifications of protozoa?

A

Amoeba: move by pseudopodia.
Flagellates: move via flagella.
Ciliates: have cilia.
Apicomplexa: have apical complex, all are parasitic. Plasmodium, Toxoplasma.

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16
Q

What classification of protozoa are all parasitic?

A

Apicomplexa (sporozoa) Plasmodium, Toxoplasma.

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17
Q

What protozoal disease is most common?

A

Giardiasis, intestinal infection.

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18
Q

What causes Malaria?

A

Protozoal parasites.

From the genus plasmodium. 4 species that infect humans.

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19
Q

What species of plasmodium infect humans?

A

P. falciparum: tropics, Africa + SE Asia.
P. vivax: widely distributed, main cause of malaria outside of africa.
P.ovale: tropical africa, SE asia.
P. malariae: rare.

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20
Q

What is the main cause of malaria outside of africa?

A

P. vivax.

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21
Q

What causes the more severe and common form of malaria?

A

P. falciparum.
P. vivax.
P. ovale.
P. malariae.

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22
Q

What causes the more moderate and less common form of malaria?

A 
In order of most common and most severe:
P. falciparum. 
P. vivax.
P. ovale. 
P. malariae.
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23
Q

How is malaria transmitted?

A
  1. Parasites injected within the saliva of blood-feeding female mosquitoes (anopheles sp.)
  2. Multiply in the liver, then infect RBCs.
  3. Mosquitoes the ingest parasites upon feeding on an infected host.
  4. The parasites go through a reproductive phase within the mosquito.
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24
Q

What are the mechanisms of action of the antimalarials?

A
  1. Inhibition mitochondrial metabolism: Atovaquone.
  2. Inhibition haem detoxification: chloroquine, lumefantrine, mefloquine
  3. Antifolate: proguanil, pyrimethamine, sulphadoxine.
  4. ATCs.
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25
Which antimalarials inhibit haem detoxification?
Chloroquine Lumefantrine Mefloquine.
26
Which antimalarials inhibit mitochondrial metabolism?
Atovaquone
27
Which antimalarials are antifolate drugs?
Proguanil, Pyrimethamine, Sulphadoxine.
28
What are helminths?
Multicellular, suckers, hooks or plates for attachment. Partial life cycle in humans, tough cuticle so hard for immune system to eradicate. Blood flukes camouflage themselves by coating themselves with host molecules.
29
What helminths camouflage themselves by coating with host molecules?
Blood flukes.
30
What is the global status of helminths?
Mainly rural/poor areas/overcrowded cities. Low status on public health priorities. Symptoms often mild, but parasites consume nutrients leading to malnutrition. Cattle infection: economic cost.
31
What are the classes of helminths?
1. nematodes (roundworms): cylindrical canal. 2. Cestodes (tapeworms): flat, ribbon shaped, no digestive tract - nutrients absorbed through cuticle. 3. Trematodes (flukes): leaf-shaped, blind-branched alimentary tract.
32
What class of helminth is flat + ribbon shaped?
Cestodes (tapeworms): flat, ribbon shaped, no digestive tract - nutrients absorbed through cuticle.
33
What class of helminth has a blind-branched alimentary tract?
Trematodes (flukes): leaf-shaped, blind-branched alimentary tract.
34
What class of helminth is known as a fluke?
Trematodes (flukes): leaf-shaped, blind-branched alimentary tract.
35
Roundworms belong to which class of helminth?
Nematodes (roundworms): cylindrical canal.
36
Tapeworms are which class of helminth?
Cestodes (tapeworms): flat, ribbon shaped, no digestive tract - nutrients absorbed through cuticle.
37
What is the most prevalent class of helminth?
Intestinal nematode infection. #2,000,000
38
What are some examples of intestinal nematodes?
Large roundworm, | Threadworm, Hookworm, Whipworm.
39
How are intestinal nematode infections spread (generally)?
The Fecal-oral route. | Hookworm is the exception, spread via larvae in soil penetrating skin.
40
How is hookworm spread?
Larvae in the skin penetrate skin.
41
What nematode infection is usually asymptomatic but can cause bloody diarrhoea if heavy infection occurs?
Whipworm.
42
What nematode infection causes mild-anal itching?
Threadworm.
43
Which nematode infection slows growth and development and can cause anaemia?
Hookworm. (spread through larvae in soil penetrating skin)
44
What is ascariasis?
Infection caused by large roundworms. Adult organisms can migrate to other organs.
45
What is the lifecycle of Ascariasis? (large roundworms)
1. Eggs produced by females are excreted in facaes. 2. Eggs mature in the soil (3-2 weeks) 3. Eggs are ingested. 4. Larvae hatch in small intestine and penetrate intestine wall. 5. They then enter blood/lymphatic vessels: carried to liver, heart and lung; larvae grow and molt in alveoli. 6. Coughing and swallowing brings larvae into intestines; mature into adults (live 1-2 years).
46
How do ascariasis larvae enter the intestines from the lungs?
Coughing and swallowing.
47
What are filariae?
Blood and tissue nematodes.
48
What infection can cause enlargement of parts of the body, e.g. arms, legs, scrotum?
Lymphatic filariasis caused by blood and tissue nematodes. Damage to the lymphatic system causes enlargement.
49
What is onchocerciasis better known as and caused by?
River blindness: microfilariae enter the internal tissues of the eye (except lens); causes inflammation, bleeding - leading to blindness.
50
What disease does the adult Loa loa worm cause? (name is hint)
It travels through the subcutaneous tissues, causing inflammation in the skin and eye. Loiasis.
51
What are cestodes?
Tapeworms: flat, ribbon shaped, no digestive tract - nutrients absorbed through cuticle.
52
How do most cestode infections occur?
Ingestion of undercooked meat/fish and the worm then lives in the lumen of the gut.
53
What happens when humans become the secondary host of a cestode?
Larval stages will invade tissues such as the muscle and brain.
54
What helminths can live for decades in tissue or blood vessels?
Trematodes/flukes... | Cause progressive damage to vital organs. use snail as intermediate host - some use secondary host.
55
What helminth infection uses snail as an intermediate host?
Trematodes, bloodflukes.
56
What is schistosomiasis?
Caused by blood-flukes, mainly S. mansoni, S. haematobium, S. japonicum. Main route of infection thru infected water. 2nd greatest economic impact of parasitic diseases after malaria.
57
What are the symptoms of Schistosomiasis?
Days: rash or itchy skin (swimmers itch) Months: fever, chills, cough, muscle aches.
58
What is the main damage caused by Schistosomiasis caused by?
Eggs get stuck in tissues and provoke an immune response which causes organ damage and scarring. Can cause bladder cancer.
59
What is the lifecycle of Schistosomiasis?
1. Free-living larvae (miracidia) hatch from eggs in water, infect snail. 2. In snail forms a larvae with a large swimming tail. 3. The infective larvae penetrate the skin of a swimming human host 4. They then migrate through the blood to the lung, heart and eventually liver. 5. In the liver the worms mature and form male:female pairs that move on. (S. haematobium lives in veins around bladder)
60
How are intestinal nematode/cestode infections diagnosed?
Eggs or larvae can be detected in faecal sample. (sometimes incidental diagnosis: e.g. coughing up or vomiting ascarids.
61
How is schistosomiasis diagnosed?
Eggs in faecal sample or urine.
62
What is a cercariae?
Larvae form of a schistosomiasis infection which forms in a snail, with a large tail.
63
How are tissue nematode infections diagnosed?
Adults in the tissues (difficult) more commonly the microfilariae in the blood are detected.
64
What are some drugs used to treat helminth infections?
``` Ivermectin - filarial nematodes. Albendazole/mebendazole - intestinal nematodes Niclosamide - tapeworms. Piperazine - roundworms, threadworms. Praziquantel - flukes, tapeworms. ```
65
Why might helminths have potential as therapeutics?
Can survive for decades, not cleared as they are able to modulate the immune system. Nematode infections have been shown to protect against allergic diseases: reduced skin reactivity to dust, decreased incidence of asthma.
66
Elephantiasis is caused by?
Filarial nematodes.
67
How do schistosomes normally enter the body?
Infective larvae that penetrate the skin of their host.
68
Consumption of meat that has not been cooked properly can result in:
Tapeworm infection
69
Intestinal helminth infections are usually detected by:
Eggs in faecal sample.
70
What do chloroquine, lumefantrine and mefloquine all have in common? [2]
1. antimalarial drugs. | 2. Inhibition haem detoxification: chloroquine, lumefantrine, mefloquine
71
What do proguanil, pyrimethamine and sulphadoxine all have in common? [2]
1. Antimalarial drugs | 2. Antifolate: proguanil, pyrimethamine, sulphadoxine.
72
What is the mechanism of action of the antimalarial atovaquone?
1. Inhibition mitochondrial metabolism: Atovaquone.
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