Extracorpuscular Hemolytic Anemias II Flashcards
T or F. Human malaria is transmitted by male mosquitoes of the Anopheles genus
F! female mosquitoes
T or F. For malaria, humans are almost exclusively the intermediate host
T
The malaria species that affect human
- Plasmodium falciparum (most severe)
- Plasmodium malariae
- Plasmodium vivax (most common)
- Plasmodium ovale
- Plasmodium knowlesi (very rare)
Clinical features of Plasmodium falciparum
- highest level of parasitemia
- vascular obstruction = adhere to endothelial cell wall
- serious complications: cerebral malaria, pulmonary renal problems
- more irregular length of life cycle
P. vivax clinical features
- schizonts mature every 48 hours = cyclical fever
- dormant in liver cells (hypnozoites), can relapse months to years after treatment
- cannot infect persons with ‘Duffy’ blood type
- cannot attach to endothelial cells of blood vessels - rarely fatal
P. ovale clinical features
- schizonts mature every 48 hours = cyclical fever
- “Tertian” malaria
- dormancy in liver stage like vivax
P malariae clinical features
- remain asymptomatic much longer than P. vivax and P. ovale
- fever = every 72 hours
- “Quartan malaria”
- generally mild disease but associated with renal complications
P. knowlesi clinical features
- natural intermediate host is macaque monkeys
- currently considered a zoonotic malaria
- southeast Asia
- morphologically similar to P. malariae but can be clinically severe
- “Quotidian” (daily cycle)
clinical complications of malaria
- severe anemia
- pregnancy complications
- neurological defects
- renal damage
> glomerulonephritis and nephrotic syndrome (esp. P. malariae) - hyper-reactive malarial splenomegaly
> AKA tropical splenomegaly syndrome
T or F. Venipuncture collection for lab diagnosis of malria is collected in an EDTA tube
T, affects staining the least! smear made within one hour of collection and let thick film air dry; don’t fix in methanol!!!
Thin vs Thick film microscopic detection of malaria
Thick = improves chances of detecting light infections + can examine larger amount of blood in less time
- Thin = best for speciation + for determining degree of parasitemia
Plasmodium falciparum vs vivax microscopic speciation differences
- P. falciparum = normally infected RBCs, multiple rings per RBC, delicate rings with 1-2 chromatin, accole forms; rare to see mature trophozoites; crescent or banana-shaped gametocytes
- P. vivax = invades younger, larger, round RBCs, fine Schuffner’s dots (red stippling), ring stages are larker + thicker and have larger chromatin dot, amoeboid appearance
P. ovale vs P malariae microscopic speciation differeences
- P. ovale: RBCs normal to slightly enlarges, round to oval shape, appear fimbrated sometimes, Schuffner’s dots, ring forms similar to vivax
- P. malariae: small, thick, compact rings with small chromatin dot, more compact trophozoites than vivax, band trophs, rosette or daisy-head, gametocytes resemble vivax but smaller, prominent pigment
Why is the new gold standard for malaria diagnosis PCR?
- morphologic characteristics can overlap
- morphology may be altered by drug treatment, partial immunity, or improper storage of specimen
- low level of parasitemia below limit of detection of thick and thin films
- to avoid use of thick smears for faster screening of febrile travellers from endemic areas
T or F. PCR can detect really low levels of parasitemia, even lower than thick films
T! can also speciate BUT expensive, turn around times longer and only in specialized labs
