Malaria

Question 1

what is the most common cause of fever in a returned traveler?

Answer 1

malaria

Question 2

how do many docs misdiagnose malaria?

Answer 2

forget to get a travel history!

Question 3

mosquitoes carry malaria- where do they store it?

Answer 3

salivary gland

Question 4

vector for malaria?

Answer 4

anopheles mosquito

Question 5

non human reservoir for malaria?

Answer 5

none except for macaques with P. knowlesi

Question 6

“hidden plasmodia” dilemma

Answer 6

after infection, the sporozoites circulated free for only about half an hour, and then vanished for several days they hide/go to liver cells!!!

Question 7

sporozoites

Answer 7

come from mosquito

tiny thread like

short lived in the blood –> travel to the hepatocytes

Question 8

schizont

Answer 8

in liver

asymptomatic

contains merozoites (the merozoites are infective for RBCs)

Question 9

merozoites

how many in Pv? Pf?

Answer 9

merozoites are infective daughter cells that invade RBCs

10,000 in Pv

30,000 in Pf

Question 10

what form is transmitted by mosquito saliva?

Answer 10

sporozoites

Question 11

after merozoites infect the RBCs, what do they form?

Answer 11

ring-stage trophozoites

Question 12

ring stage trophozoites turn into …

which do what?

Answer 12

schizonts

schizonts rupture and release merozoites which infect more RBCs

Question 13

hypnozoite

Answer 13

• Dormant liver stage in P. vivax and P. ovale -> can have recurrent infxns
• Release blood stage parasites weeks to months after primary infection

Question 14

which two malaria types can have recurrent infections due to a dormant stage?

Answer 14

P vivax and P ovale

Question 15

Answer 15

1 - mosquito bites and injects sporozoites

2 - sporozoites go to liver and form schizonts which rupture and release merozoites (exo-erythrocytc cycle)

3 - merozoites go to blood and for primary ringed trophozoites

–they can either become gametocyte or mature trohpzoite

4 - mature trophozoite becomes schizont which ruptures and releases more merozoites into blood (erythrocytic cycle)

5 - gametocytes form new gametocytes which can infect new mosquito if an uninfected mosquito bites person

6) sporogenic cycle = gametocytes inside new mosquito create macrogametocyte and then an oocyst which creates new sporozoites

Question 16

how long does it take for malaria symptoms to appear?

P falciparum

P ovale

P vivax

P malariae

Answer 16

Pf 8-11 days

Po/Pv 10-17

Pm 18-40

Question 17

onset of symptoms of malaria coincides with….

Answer 17

the start of the erythrocytic cycle

Question 18

incubation with ______can be up to 20 years due to chronic subclinical erythrocytic stage

Answer 18

P. malariae

Question 19

3 evolutionary defenses against malaria

Answer 19

Duffy antigen negative (P viva uses duffy agent to enter RBCs)

sickle cell trait (selective sickling of falciparum infected RBCs)

G6PD deficiency (malaria parasites grow poorly in G6PD deficient rbcs d/t increased ROS in rbcs)

Question 20

classic triad of symptoms for malaria

Answer 20

fever, chills, headache

Question 21

three clinical types of malaria

Answer 21

acute uncomplicated

severe malaria

hyperreactive malarial syndrome (tropical splenomegaly)

Question 22

uncomplicated (mild) malaria

Answer 22

Occurs with all Plasmodium species

—–sudden episodes of: fevers, chills, and sweats

1. cold stage with shaking – 2. hot stage with high temperature (>104°F) – 3. sweating stage with resolution of fever

episodes last 6-10 hours, and then recur

every 2 days with P. vivax and P. ovale (tertian fever)

and for P. falciparum (malignant tertian fever)

every 3 days with P. malariae (quartan fever)

Question 23

complicated/severe malaria

Answer 23

Can cause any of these:

• Cerebral malaria (change in mental status, coma)

• Respiratory distress

• Severe anemia (hct <15%)

• Renal failure

• Hypoglycemia

• Circulatory collapse (shock) and lactic acidosis
• Bleeding disorder (spontaneous bleeding or evidence of DIC)

******complications primarily occur with P falciparum, usually when parasitemia >2% (% of rbcs infected).

Question 24

complicated malaria is usually with what species?

Answer 24

falciparum

Question 25

why are falciparum infections the most severe?

Answer 25

because it will infect ANY rbcs asexual blood stage parasites of P. falcip. can develop in erythrocytes of all ages there is NO LIMIT ON THE DEGREE OF PARASITEMIA

Question 26

What is the mechanism for tissue harm in malaria?

Answer 26

**tissue hypoxia and lactic acidosis** **RBCs become “sticky”** and clog up vasculature SEQUESTRATION! --\> Erythrocytes containing mature P. falcip. parasites develop “knobs” and express **adhesion molecules** that bind to endothelium of capillaries/venules. Also there is **decreased deformability of infected AND non-infected RBCs,** contributing to sludging, aggregation, and blockage of vessels. This causes **tissue hypoxia and organ failure.**

Question 27

cerebral malaria

Answer 27

•acute encephalopathy not attributable to other causes in a patient with malaria decreased consciousness + delirium + seizures brain has increased mass (swollen) cerebral malaria is driven by sequestered RBC in brain blood vessels

Question 28

cerebral malaria untreated Px and treated Px

Answer 28

untreated - 100% die treated - 20% die

Question 29

cerebral malaria is diven by what process?

Answer 29

RBCs accumulation in brain parenchyma

Question 30

malaria diagnosis - 3 methods

Answer 30

blood smear - thick and thin antigen testing PCR

Question 31

BinaxNow

Answer 31

malaria card test - antigen capture Control line + T1 and T2 - all three lines Pf or combined - just C and T1 --\> Pf - C and T2 --\> Px, Pm, Po

Question 32

enlarged cells + schuffners dots which species?

Answer 32

vivax or ovale

Question 33

Answer 33

vivax or ovale enlarged infected RBCs and schuffners dots

Question 34

Answer 34

TOP vivax - schizont with 12-24 merozoites BOTTOM ovale - schizont that is oval and fewer merozoites (6-12)

Question 35

what species makes band forms?

Answer 35

malariae

Question 36

Answer 36

P malariae

Question 37

Answer 37

P malariae owl eye trophozoite, infected cells are smaller, has yellow/brown pigment

Question 38

features of P malariae

Answer 38

owl eye trohpozoites smaller infected cells yellow/brown pigment

Question 39

Answer 39

P falciparum multiple ringed trophozoites and banana shaped gametocyte

Question 40

multiple ringed trophozoites and banana gametocyte?

Answer 40

p falciparum

Question 41

if malaria smear is negative, keep what?

Answer 41

repeating smears/Ag tests every so often until better

Question 42

prevention of malaria

Answer 42

PPE chemotherapy = –doxycycline –atovaquone/proguanil –mefloquine –Primaquine –Chloroquine (in chloroquine-sensitive areas)

Question 43

admit all patients with \_\_\_

Answer 43

falciparum

Question 44

Patients with P. vivax and P. ovale should receive therapy (primaquine) to

Answer 44

eradicate any remaining hypnozoites after treatment for intraerythrocytic stage.