Malaria plasmodium species Flashcards
P falciparum - key point
Malignant - drives majority of severe malaria and disease burden
Tertain fever [3rd day/48hrs]
Ubiquitous and drives most cases and deaths in sub-Saharan Africa
‘Neat’ pathogen
Normal sized RBCs
Accole forms and multiple parasites
Banana shaped gametocytes
P falciparum - epidemiology
All malarious zones
Foci of transmission in South America
Ubiquitous in sub-Saharan Africa - most cases and deaths
P falciparum - clinical
7-14 days incubation
48hr intra-erythrocytic growth cycle:
-Tertian fever, irregular onset, due to asynchronous rBC cycle
No infection relapses
Drug resistance [ACT]
Diagnostics and Hrp2 deletions [false negative RDTs]
Vast majority of invasive disease, with var encoded PfEMP1 protein facilitating sequestration
Readily cultured in vitro
P falciparum - lab and micro
Neat pathogen
No RBC enlargement
Can see multiple parasites per cell
Double chromatin dots [headphones]
Maurer’s clefts [uneven, fewer]
Schizont not filling cell, with 15-20 merozoites
Gametocytes ‘banana’/crescent
P falciparum - spot associations
Severe malaria and cerebral malaria, PAM, and severe anaemia
Vessel sequestration and PfEMP1 [encoded by var genes]
ACT resistance - SE Asia but creeping into Africa
RDT false negatives
No relapses
Normal sized RBCs, accole forms, headphones, Maurer’s clefts, banana gametocytes
P vivax - key points
Benign
Tertian fever [3rd day/48hours]
Widest distribution [but lower incidence]
Partial Duffy antigen dependence limits Africa’s burden
Can relapse, hyponozoites
‘Messy’ pathogen
Large RBC
P vivax - epidemiology
All malarious zones
Exists in more temperate zones, widest distribution
Partially limited by the Duffy blood group
P vivax - clinical
12-17 day incubation
Benign - low mortality
48hr intra-erythrocytic growth cycle - tertian fever
Relapses occur - relates to hyponozoites stages requiring radical cure
Duffy antigen aids RBC invasion
Control measures not as effective against P vivax [day biting species]
Cannot culture in vitro
P vivax - lab and micro
Prefers larger RBCs and reticulocytes
Schuffner’s dots [even, coarser]
Schizont fills cell, 15-20 merozoites - pigment-rich
Gametocyte large, fills cell
Can see plasticity and unusual shaped RBCs
P vivax - spot associations
Benign relapsing malaria
Hypnozoites
Partial Duffy antigen dependence
Night and day biting mosquitoes
All malarious zones, widest distribution, neglected
Larger RBCs, Schuffner’s dots, Schizont and gametocytes fill cell, plasticity phenomenom
P ovale - key points
Limited to tropics
Tertian fever
Mixed infections
Can relapse
Neat pathogen, oval shape and fimbriation can be seen
Divided in to P ovale curtisi and P ovale walkeri
P ovale - epidemiology
Limited to tropics
Widespread in Africa, present in Asia/Oceania
Absent in South America
P ovale - clinical
12 -17 days incubation
Benign low mortality
48hrs intra-erythrocytic growth cycle - tertian fever
Relapses occur, hypnozoites stage
Low parasitaemia typical
Commonly mixed infections
RDTs fail with Curtisi
Nested PCR fail with Walkeri
P ovale - lab and micro
Neat - RBC large, oval shape, fimbriation
James’ dots [even, corasen over development]
Schizont not filling cell with 8-10 merozoites
Gametocyte not filling cell
Low parasitaemia common
P ovale - spot association
Benign malaria
Absent in South America
Mixed infections
James’ dots, low parasitaemia
P knowlesi - key points
Zoonotic, macaques primary host
Can cause severe disease
SE Asia with foci in Malaysia
Quotidian fever [daily]
P knowlesi - epidemiology
Zoonotic malaria
SE asia
Hot - long and pig-tailed macaques, with human infection rare
Limited by macaques [host], mosquito species [leucosphyrus], and Duffy blood group
P knowlesi - clinical
8-12 day incubation
High fatality rate [10% progress to severe]
Fast growth cycle in blood -24-27 hours
Human invasion uses the DARC receptor [Duffy antigen positive]
Can be cultured in vitro
P malariae - key points
Benign malaria
Quartan fever [4th day/72hours]
Can form chronic malaria presenting years to decades later [renal, spleen]
Mixed infections
Commonly misidentified - can mimic falciparum and vivax
Daisy head schizont
Older smaller RBCs
P malariae - epidemiology
All malarious zones
Rare
P malariae - clinical
Incubation 18-40 days
Benign
72 hour growth
Persistence - chronic malaria [not a latent hypnozoite stage]
Renal and splenic pathologies
Low parasitaemia
P malariae - lab and micro
Old smaller RBCs
No dots [Ziemann’s dot can be faintly seen]
Bird’s eye ring
Band forms
Schizont fills cells, 8-10 merozoites and ‘daisy head’
Gametocyte fills cell, no enlargement - dense scattered pigment
