Malaria Flashcards
Primaquine 3 main safety / tolerability issues
GI upset - take with food
Methemoglobinemia - mild, self-limited with 30mg in young healthy
Haemolytic anaemia in G6PD deficiency
hepatic schizonticides
atovaquone-proguanil
primaquine
hypnozoticide
primaquine
blood-stage schizonticides
atovaquone-proguanil
doxycycline
mefloquine
chloroquine
quinine artemether artemether/lumefantrine artesunate artesunate + mefloquine sulfa/pyrimeth artemether
gamectocydial
primaquine artemether artesunate artemether / lumefantrine artesunate + mefloquine (atovaquone / proguanial - decreased infectivity)
Incubation period
time b/w infection & onset of Sx;
Always longer than pre-patent period, with time difference depending on immune status
Relapse
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.
premunition
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)
malaria endemicity
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
Recrudescence
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
Induced malaria
Malaria acquired accidentally or deliberately by blood transfusion, needles, organ transplantation
unstable malaria
transmission rates vary from year to year; population immunity is low
- epidemics more likely
pyrogenic density (PD)
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)
mesoendemic
SR / PR 11-50% in children 2-9yo
Reinfection
renewed detection of parasitemia arising from a new infected mosquito bite
Entomological inoculation rate
sporozoite positive mosquito bites per unit time (# bites pp/yr)
Autochthonous (indigenous) malaria
locally contracted malaria / Naturally present in an area or country
Pre-patent period
time b/w infection & patent parasitemia
hyperendemic
SR / PR consistently >50% in children 2-9yo;
adult spleen rate also high
annual parasite incidence
new parasite confirmed cases per 1000 population
Recurrence
repeat intra-erythrocytic infection causing malaria-associated Sx (recrudescence, reinfection or relapse)
Sub-patent parasitemia
parasites present in blood but not on microscopy
Cryptic malaria
Malaria cases that occur in isolation and are not associated with secondary cases
Patent parasitemia
parasitemia detected by optic microscopy
introduced malaria
Secondary cases acquired locally but derived from imported cases.
Spleen rate
proportion of individuals in a stated age range with enlarged spleens
hypoendemic
spleen rate (SR) or parasite rate (PR) </= 10% in children 2-9yo
stable malaria
natural transmission occurs over many years, with predictable incidence of illness & prevalence of infection
- transmission generally high
- epidemics unlikely
holoendemic
SR / PR consistently > 75% in chlidren 2-9yo;
adult spleen rate low;
parasitemia rate in infants 75%)
Imported malaria
Malaria acquired outside a specific area in which it is found
Environmental factors
- 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
Host factors
- Frequency of exposure - occupation
- social behaviour
- migration - Development of immunity - premunition
- Age - all ages in unstable area, esp young children in stable area
- 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 - 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
Vector competence factors
- 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)
Malaria medications in pregnancy
Rx - chlorquine, quinine, clindamycin
Proph - mefloquine
