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Biology and Infectious Disease Control > Mosquitoes (Malaria) > Flashcards

Mosquitoes (Malaria) Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Types of plasmodium which cause malaria in humans:

A 
P. falciparum 
P. vivax
P. malariae
P. ovale
P. knowlesi
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2
Q

Infective stage of plasmodium parasite (for humans)

A

Sporozoite

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3
Q

Why is P.vivax not present in West Africa?

A

High % (95) population are negative for erthyrocytic receptors called Duffy Antigen. Duffy antigen is proinflammatory chemokine receptor used by P. vivax (Langhi and Bordin, 2006).

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4
Q

Diseases that confer malaria resistance

A

Sickle cell anaemia
Thalassemia
G6PD deficiency
- RBC more liley to die from oxidative stress when infected

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5
Q

What happens in the first 1-2 weeks of infection by P. falciparum, P. malariae and P. knowlesi?

A

Multiply asexually and mature from sporozoites to merozoites in the liver.

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6
Q

Where do the malaria parasite first go when they infect a human?

A

Hepatic sclerenchymal cells

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7
Q

Does the liver stage have any outward symptoms?

A

No, asymptomatic.

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8
Q

What happens in the months and years of initial infection by P. vivax and P. ovale?

A

Dormant hepatic stage = hypnozoites (don’t divide)

Wait then turn into merozoites.

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9
Q

Preferred RBC targets for P. falciparum and P. ovale

A

red blood cells of all ages

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10
Q

Preferred RBC targets for P. vivax

A

reticulocytes ( young and immature red blood cells)

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11
Q

Preferred RBC targets for P. malariae and P. knowlesi

A

older red blood cells

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12
Q

Stages of th erythrocytic phase

A

Early trophozoite (ring)
Late trophozoite
Shizont (merozoites inside)
Rupture schizont (releases merozoites)

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13
Q

What does the rupturing of the shizont cause?

A 
Release of inflammatory cytokines
-> temperature spikes (fevers)
Extreme fatigue 
Headaches
Jaundice 
Abnormally enlarged spleen (splenomegaly)
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14
Q

Sexual reproduction stages

A

Human
Early trophozoite -> gametogony
Taken up by mosquito in blood meal
Travel to gut - mature and fuse into zygote
Ookinete
Oocyst - ruptures and releases sporozoites

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15
Q

What are fever paroxyms?

A

The pattern of fever occurrence, e.g. every 24hrs.

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16
Q

What are the different fever paroxysms of the species of malaria that infect humans?

A

P. malariae = 72hrs
P. vivax ad P. ovale = 48hrs
P. knowlesi = 24hrs
P. falciparum = variable (24/48 hrs)

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17
Q

How do malaria parasites get into the mosquito gut?

A

Uses chitinases to burst into gut

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18
Q

How can mosquitos defend agains plasmodium?

A

Encapsulate oocysts

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19
Q

Why do wild-type mosquitoes not encapsulate?

A

The energetic expense of encapsulating oocysts is greater than the fitness cost of being infected.

20
Q

What is the time bomb theory?

A

Parasite is too fast for mosquito immune system.

21
Q

What does Plasmodium use to travel through cells quickly?

A

subtilisin2 (protease)

22
Q

What is the formula for the Ross-MacDonald model for malaria transmission?

A

Ro = (m.a^2.p^n.b)/(-rln(p))

23
Q

What do the letters stands for in this formula: Ro = (m.a^2.p^n.b)/(-rln(p))?

A 
m = bites per person per night 
a = probability of mosquito to take human meal
p = daily mosquito survival rate
n = Number of days to complete mosquito lifecycle
b = susceptibility to infection human/mosquito
r = rate of recovery of infected humans
24
Q

What are the assumptions of the Ross-MacDonald model for malaria transmission?

A

no host immunity (humans)
mosquitoes bite at random
humans and mosquito populations homogenous

25
Q

Ways to sample mosquitoes (7)

A 
Tent trap 
Biting catch 
Plant catch 
Light trap 
Resting catch 
Exit catch 
Spray catch
26
Q

What is exflagellation?

A

Gametocyte bursts to release microgametocytes.

27
Q

What triggers exflagellation?

A

Drop in temperature
Drop in [CO2]
Increase in pH
Presence of xanthurenic acid (broaden pH range exflagellation will occur in)

28
Q

Why does P. falciparum cause the worst infections?

short answer

A

Puts sticky protein coat on infected blood cells

  • > clumping of RBCs
  • > blocking of blood vessels
29
Q

What are the complications of P. falciparum?

A

haemolytic anaemia + ischemic damage

Cerebral malaria
Bilious malaria (liver)
Lungs + Kidneys + Spleen = sepsis-like symptoms
30
Q

What can cerebral malaria cause?

A

Seizures
Coma
Altered mental state

31
Q

What can bilious malaria cause?

A

diarrhoea
vomitting
jaundic
liver failure

32
Q

Diagnosis of malaria

A 
Blood smear
Low platelet count 
Elevated lactate dehydrogenase
Normochromic and normocytic anaemia
PCR
Fever pattern (paroxysms)
33
Q

What are the two types of blood smear and what do they show?

A

Thick blood smear - % of infection (parasite in RBCs)

Thin blood cells - species identification

34
Q

What is normochromic and normocytic anaemia?

A

Normal colour, normal size, low red blood cells

35
Q

What causes elevated lactate dehydrogenase in malaria sufferers?

A

Haemolysis (RBCs)

36
Q

Types of recurrent malaria

A

Recrudescence
Relapse
Reinfection

37
Q

What is recrudescence?

A

The recurrence of malaria in an individual due to ineffective treatment.

38
Q

What is relapse (in terms of malaria infection)?

A

The recurrence of malaria in an individual due to treatment killing merozoites, but live hypnozoites remaining in the liver.

39
Q

What is reinfection?

A

The recurrence of malaria in an individual after effective treatment due to a new infection (no immunity).

40
Q

Methods for prevention of infection (mosquito focus)

A

Full body clothing
Insecticide-covered mosquito nets
Indoor insecticide spray
Empty stagnant water

41
Q

Why does P. falciparum cause RBCs to clump? (survival)

A

With other species, the spleen destroys most infected RBCs. By clumping and blocking blood vessels, it prevents infected cells from going to the spleen.

42
Q

Two scientific options for malaria control

A

Monoclonal anitbodies

Knocking out genes (in mosquito)

43
Q

Current available malaria treatment (humans)

A

Suppressive treatment/chemo prophylaxis
Radical treatment
Therapeutic treatment

44
Q

What is the name of the protein which makes read blood cells sticky in P. falciparum infection?

A

PfEMP1 (Plasmdium falciparum erythrocyte membrane protein 1) - blood group O only
RIFINs to form rosettes with group A RBCs??
(Goel et al., 2015)

45
Q

How does P. falciparum avoid antibodies?

A

Changes sticky membrane protein on outside of infected cells (e.g. PfEMP1 - blood group O only (Goel et al., 2015))

46
Q

What is red blood cell rosetting?

A

the formation of clusters in which uninfected red blood cells (RBCs) aggregate around a central Plasmodium falciparum-infected RBC (iRBC) - because of stickiness?

47
Q

Possible targets for future treatment research

A

Merozoite surface protein 1
Enzymes for entry of gametcytes into mosquito gut - allosamidin (inibits chitinases)
Adhesion to midgut of mosquito (basal lamina)
Enzyme for cutting through cells rapidly (subtilisin2 (protease))

Biology and Infectious Disease Control (5 decks)

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