Malaria

Question 1

Primaquine 3 main safety / tolerability issues

Answer 1

GI upset - take with food
Methemoglobinemia - mild, self-limited with 30mg in young healthy
Haemolytic anaemia in G6PD deficiency

Question 2

hepatic schizonticides

Answer 2

atovaquone-proguanil

primaquine

Question 3

hypnozoticide

Answer 3

primaquine

Question 4

blood-stage schizonticides

Answer 4

atovaquone-proguanil
doxycycline
mefloquine
chloroquine

quinine
artemether
artemether/lumefantrine
artesunate
artesunate + mefloquine
sulfa/pyrimeth
artemether

Question 5

gamectocydial

Answer 5

primaquine
artemether
artesunate
artemether / lumefantrine
artesunate + mefloquine
(atovaquone / proguanial - decreased infectivity)

Question 6

Incubation period

Answer 6

time b/w infection & onset of Sx;

Always longer than pre-patent period, with time difference depending on immune status

Question 7

Relapse

Answer 7

recurrence of asexual parasitaemia in P. vivax and P. ovale malaria from persisting liver stages; occurs when blood stage infection has been eliminated but hypnozoites persist in the liver and mature to form hepatic schizonts.
After variable intervals of weeks to months hypnozoites bursts to release merozoites into the bloodstream.

Question 8

premunition

Answer 8

state of partial immunity (semi-immune);
in areas of stable malaria, with continuous exposure to infective bites;
causes decreased clinical severity, asexual parasitemia & production of gametocytes; lost with loss of exposure (6/12)

Question 9

malaria endemicity

Answer 9

amount or severity of malaria in an area or community

general description of the Rp b/w parasite transmission and malaria disease in a given setting

Question 10

Recrudescence

Answer 10

recurrence of asexual parasitaemia after treatment of the infection with the same infection that caused the original illness.
 results from incomplete clearance of parasitaemia due to inadequate or ineffective treatment.
 Not a relapse or new infection or re-infection

Question 11

Induced malaria

Answer 11

Malaria acquired accidentally or deliberately by blood transfusion, needles, organ transplantation

Question 12

unstable malaria

Answer 12

transmission rates vary from year to year; population immunity is low
- epidemics more likely

Question 13

pyrogenic density (PD)

Answer 13

level of parasitemia at which fever occurs;
a marker of immunity:
- low in nonimmunes (<10 000 Pf/uL)
- higher in immunes (tolerate up to 100 000 Pf/uL)

Question 14

mesoendemic

Answer 14

SR / PR 11-50% in children 2-9yo

Question 15

Reinfection

Answer 15

renewed detection of parasitemia arising from a new infected mosquito bite

Question 16

Entomological inoculation rate

Answer 16

sporozoite positive mosquito bites per unit time (# bites pp/yr)

Question 17

Autochthonous (indigenous) malaria

Answer 17

locally contracted malaria / Naturally present in an area or country

Question 18

Pre-patent period

Answer 18

time b/w infection & patent parasitemia

Question 19

hyperendemic

Answer 19

SR / PR consistently >50% in children 2-9yo;

adult spleen rate also high

Question 20

annual parasite incidence

Answer 20

new parasite confirmed cases per 1000 population

Question 21

Recurrence

Answer 21

repeat intra-erythrocytic infection causing malaria-associated Sx (recrudescence, reinfection or relapse)

Question 22

Sub-patent parasitemia

Answer 22

parasites present in blood but not on microscopy

Question 23

Cryptic malaria

Answer 23

Malaria cases that occur in isolation and are not associated with secondary cases

Question 24

Patent parasitemia

Answer 24

parasitemia detected by optic microscopy

Question 25

introduced malaria

Answer 25

Secondary cases acquired locally but derived from imported cases.

Question 26

Spleen rate

Answer 26

proportion of individuals in a stated age range with enlarged spleens

Question 27

hypoendemic

Answer 27

spleen rate (SR) or parasite rate (PR) </= 10% in children 2-9yo

Question 28

stable malaria

Answer 28

natural transmission occurs over many years, with predictable incidence of illness & prevalence of infection

• transmission generally high
• epidemics unlikely

Question 29

holoendemic

Answer 29

SR / PR consistently > 75% in chlidren 2-9yo;
adult spleen rate low;
parasitemia rate in infants 75%)

Question 30

Imported malaria

Answer 30

Malaria acquired outside a specific area in which it is found

Question 31

Environmental factors

Answer 31

• breeding places
• temp (esp 25-30) (not 35)
• humidity (>60)
• rainfall (seasonal increase, excessive stop)
• altitude, frost
• proximity of human habitation to breeding sites
• SE and housing factors
• man-made changes
• pop displacement

Question 32

Host factors

Answer 32

1. Frequency of exposure - occupation
   - social behaviour
   - migration
2. Development of immunity - premunition
3. Age - all ages in unstable area, esp young children in stable area
4. Pregnancy - always increased risk
   - in stable area: worse in primigravidas; increased anaemia, LBW, placental blood increased parasite densities
   - in unstable, worse in all: T1 abortion, T3 prem labor, IUGR, foetal distress/dth, maternal death, congenital malaria
5. Genetic - HbS: sickle trait protected vs severe disease (PF cer malaria)
   - hereditary ovalocytosis: R to PF and PV (SE Asia)
   - Duffy -ve: RBC lacking Ags Fya, Fyb, R to PV (W Africa, African & American blacks)
   - HLA-Bw53 class 1 antigen: protect vs cer malaria
   - HLA-DRB1… - protect vs severe malarial anaemia
   - B-thal, a-thal, G6PD def, Hb C, E

Question 33

Vector competence factors

Answer 33

• breeding sites
• natural abudance
• flight ranges (2-3km)
• preference for human blood (anthropophily) vs animal blood (zoophily)
• frequency of feeding (T dependent)
• endophily vs exophily
• natural index of infection
• duration of sporogony (T dependent)
• longesvity of the vector (to finish sporogony & transmit inf’n)

Question 34

Malaria medications in pregnancy

Answer 34

Rx - chlorquine, quinine, clindamycin

Proph - mefloquine