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Management of Infection > Lecture 3C - Protozoa > Flashcards

Lecture 3C - Protozoa Flashcards

1
Q

How can protozoan infections be transmitted?

A

they can be ingested or transmitted by blood infusion, enter through wounds and be injected by ectoparasite vectors such as mosquitos

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2
Q

What are protozoa?

A

single cell eukaryotic cells with a membrane bound nucleus, cellular organelles and a surrounding cell membrane

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3
Q

How can protozoa reproduce?

A

asexually and rapidly to grow in very large numbers

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4
Q

What can protozoal parasites invade?

A

cells such as red blood cells, so as to hide from the immune system

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5
Q

What to protozoa use the nutrient pathway for?

A

to fuel their own growth and division

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6
Q

How do protozoa evade the immune system?

A

they often change their surface coats at a rapid rate so that the immune system is faced with trying to hit a moving target

finding constant regions of surface proteins to target with a vaccine is very challenging

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7
Q

Examples of water borne protozoa?

A

Giardia lamblia (500x10^6 infections), cryptosporidium, entamoeba histolytica (0.5x10^6), trichomonas

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8
Q

E. histolytica?

A

amoebic dysentery, also forms abscesses in the brain, liver and lung

can cause ulceration of the gut wall and if this results in gut wall perforation it can be life threatening

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9
Q

Trichomonas?

A

WB

(180x10^6)

infects the urogenital tract, causes vaginitis in women

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10
Q

What do water borne protozoa cause?

A

they infect the gut and cause severe diarrhoea and bloody stools

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11
Q

What are common vectors for protozoal infections?

A

insects

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12
Q

What are protozoal infections a major cause of?

A

disability, illness and death

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13
Q

Trypanosoma?

A

INSECT BORNE

causes sleeping sickness (T.brucei gambiense, Africa)

extracellular in blood first, then CNS or heart depending on species

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14
Q

Leishmania?

A

INSECT BORNE

sand fly
intracellular macrophages

skin sores, swelling of liver and spleen, low white cell count (lysis), can be fatal

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15
Q

Toxoplasmosis?

A

INSECT BORNE

cat faeces are a major source of infection

widespread infection in humans

can cause foetal damage and some suspected linkage to schizophrenia

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16
Q

Plasmodium?

A

INSECT BORNE

cause of malaria, intracellular

causes fever and can be fatal

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17
Q

How many cases of malaria were there worldwide in 2017?

A

219x10^6

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18
Q

What are insect borne protozoa?

A

the insect is the vector of the disease and injects the protozoan when it comes in for a blood meal

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19
Q

What can ticks transmit?

A

lyme disease, typhus, encephalitis

need to be removed with tweezers

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20
Q

What can fleas transmit?

A

typhus and plague

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21
Q

What can sandfly transmit?

A

leishmania

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22
Q

What can the tsetse fly transmit?

A

sleeping sickness

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23
Q

What can the reduvid bug transmit?

A

chagas disease

24
Q

What can the simulum fly transmit?

A

onchocerciasis

25
Q

What % of insects were found to be infected with malarial parasites?

A

5%

from one study

26
Q

What precautions should be taken in a malarious area?

A

bed nets, long sleeved clothing and covering legs, insect repellants, avoiding situations where biting is more likely

27
Q

What else can mosquitos transmit?

A

dengue, yellow fever, chikungunya, elephantiasis

28
Q

What is malaria?

A

a potentially fatal protozoal infection, carried by mosquitoes

29
Q

Untreated malaria results in?

A

cyclic fever, chills

the destruction of red blood cells and sometimes the blockage of cerebral blood vessels

some forms can be fatal

30
Q

Where is 90% of the malaria disease burden?

A

in the tropics

31
Q

What can affect the malarial disease range?

A

travel, military activity and the greenhouse effect

32
Q

How many people are at risk of malaria?

A

2-2.5 billion (40% of world population in 100 countries)

33
Q

How many cases of acute malaria are there annually?

A

300,000,000

34
Q

How many deaths does malaria cause annually?

A

1.5-3 million

35
Q

In Africa, what does malaria cause?

A

1/4 of all deaths in children under 5, this makes up 1/3 of all hospital admissions

36
Q

How many malarial deaths are in children?

A

70% of the deaths

this is because they have a small blood volume and cannot cope with large infections of RBCs

they also have immature immune systems

37
Q

How are malarial sporozoites injected?

A

from the salivary gland of the female mosquito into the human tissue when it bites into the skin for a blood meal

38
Q

Why do male mosquitos not transmit malaria?

A

they are vegetarian

39
Q

Where are the two main phases of the plasmodium life cycle?

A

one in humans and the other in insects

40
Q

When the mosquito bites, where do the injected sporozoites go?

A

rapidly make their way to the liver

41
Q

What do sporozoites occupy?

A

a sinusoid of the liver and there they rapidly multiply

42
Q

What other form can sporozoites take in the liver?

A

they may enter a dormant, hypnozoite phase which can erupt months later

depends on the species

43
Q

What happens when the sporozoite has multiplied up to 1000 fold in the liver?

A

the infected liver bursts and the merozoite form is released into the bloodstream

44
Q

In the blood stream, where does the merozoite form go?

A

into red blood cells where they can mature, multiply and eventually burst the red blood cell

45
Q

What happens when the infected red blood cell bursts?

A

it releases more infectious merozoites and fever stimulating granules of digested haemoglobin

46
Q

What are signs of malaria?

A

fever and anaemia

anaemia due to loss of red blood cells

47
Q

What is plasmodium falciparum

A

the most common and most dangerous form of malaria as it can cause cerebral malaria

48
Q

Life cycle of plasmodium falciparum?

A

appears in blood 5.5 days after initial infection

has a 48 hour life cycle and malignant tertian (3 days) appearance of fever and can be fatal

49
Q

How long can blood donors be infective with plasmodium falciparum?

A

5 years

50
Q

What plasmodium species do NOT have a hyponozoite (dormant) phase?

A

plasmodium falciparum and plasmodium malariae

51
Q

Plasmodium malariae?

A

emerges into the blood 15 days after infection

72 hour cycle benign quartan fever (erupting every 4 days)

less common

blood donors may be infective for years

52
Q

Plasmodium ovale?

A

widespread species, benign tertian malaria

blood donors infective for 7 years

53
Q

Plasmodium vivax?

A

more rare

benign tertian form of malaria

blood donors infective for 5 years

54
Q

What plasmodium species HAVE a hypnozoite stage?

A

plasmodium ovale and plasmodium vivax

55
Q

Plasmodium knowlesi?

A

has a localised prevalence in some parts of south east asia

Management of Infection (36 decks)

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