Malaria Flashcards
In endemic countries for malaria, if a patient presents with complicated malaria, what do you suspect?
HIV
What is terminal prophylaxis?
P.Vivax prophylaxis in its entirety
Take malarone or equivalent when abroad, and then when get home take 14 days of primaquine (no G6PD def) to kill the hypnozoites
Which species is most prominent in Malaysia?
P. knowlesi.
Primate malaria, Zoonosis, All ages of RBCs infected, Increasingly reported in SE Asia. Most cases are mild, Appearance similar to P. malariae
What is the WHO recommendation for a slide to be pronounced negative for malaria?
Slide can be pronounced negative only when a minimum of 100 fields have been carefully examined for the presence of parasites (THICK) and 800 fields (THIN)
What is the definitive host for malaria? What is the intermediate host? What is the reservoir?
Female mosquito. Human. Male mosquito.
What information do you need to know before starting somone on treatment for malaria?
Strain, clinical status of patient, previous Rx, pregnant or not, resistance
Why can ACT not be used for prophylaxis and why is it effective as a treatment for malaria?
act rapidly on blood phase - has a very short half life and so not appropriate as propylaxis
What protective factors are there against malaria?
Iron deficiency, Hbopathy
What types of recurrence are there in malaria?
- Recrudescence - Ineffective initial treatment. Renewed detection of parasitemia arising from survival of undetectable erythrocytic parasites
- Relapse - Renewed detection of parasitemia arising from survival of exo-erythrocytic parasites (Hipnozoites) (no surviving erythrocytic parasites): P.vivax, P. ovale.
- Reinfection- Renewed detection of parasitemia arising from a new infected mosquito bite.
What are the advantages of a RDT for malaria?
Quick - 20mins, does not need expertise, got sensitivity for falciparum
Which drug should you give patient who Is pregnant to Rx uncomplicated falciparum?
Artemethur-lumefantrine
Why is missing one single dose of doxy significant?
Short acting drugs, so miss a day the sporozoites can get into the liver and wait there (doxy only works in blood stream)
Antimalarial prophylaxis if a person is travelling and has HIV?
Doxycycline or chloroquine
Child on efavirenz/nevirapine or zidovudine - which anti malarial not to use?
artesunate/amodiaquine - risk of hepatitis and severe neutropenia
WHO GUIDELINE
Name the 6 species of malaria
vivax, ovale curtisi, ovale wallikeri, malariae, knowlesi, falciparum
What other tests can be used in malaria?
Serology - not routine
PCR - good for low parasitaemia and differentiate species
LAMP - good in non endemic setting
Alternative to primaquine in P.Vivax?
Tafenoquine
What are HIV patients at increased risk of with severe malaria?
Severe anaemia
What level parasitaemia is characterised as severe malaria?
> 2% in non immune, >10% in endemic, CDC says >5%
Which structure and species is this?
Schizont with Schuffners Dots, P.Ovale. Note Pacman ghost appeatance and irregular RBC outline
Child with suspected severe malaria - management immediately?
Pre-referral treatment with rectal artesunate in children
Apart from antimalarials, what else do you give in severe malaria?
IV antibiotics to cover gram negatives (gut translocation)
What are these?
P.Vivax Gametocyte (also here)
Why is Vivax not in Africa?
Duffy antigen
At what level parasitaemia does mortality start to increase?
low transmission setting: mortality begins to increase at
a parasitaemia of 100 000/ul (2%)
Artemethur-lumefantrine interacts with which HIV drugs? Which HIV drug does not interact with A-L?
Efafivinz, nevirapine
Liponavir/riponavir
USE DOLUTEGRAVIR!
HIV test when patient has malaria, problem? What to do?
False positive!
Test for HIV when doesn’t have malaria
What is induced malaria?
Acquired by blood transfusion/needles/transplant
What structure is taken up by mosquito during a blood meal from a malaria infected patient?
Gametocytes - reproduce sexually (sporogony) in intestine of anopheles. Microgametocytes and macro gametocytes taken up. Becomes ookinete then oocyst -> ruptures into lots of sporozoites. Sporozoites then move to salivary gland, and can be transmitted to humans when mosquitos take a blood meal
What is the pyrogenic density?
level of parasitaemia at which fever occurs
Lower in nonimmunes (<10 000 Pf/µL)
Higher in immunes (tolerate up to 100 000 Pf/µL).
What is introduced malaria?
Secondary cases acquired locally but derived from imported cases
What is the Rx for severe (complicated malaria)?
IF ONLY ORAL AVAILABLE: Artemether-lumefantrine (Coartem®) because of its fast onset of action. Other oral options include atovaquone-proguanil (Malarone™), quinine, and mefloquine.
IV artesunate: 2.4 mg/kg. A dose of IV artesunate should be given at 0, 12, and 24 hours.
After the initial course of IV artesunate is completed, if parasite density is ≤1% (assessed on a thin blood smear collected 4 hours after the last dose of IV artesunate) and patient can tolerate oral treatment, a full treatment course with a follow-on regimen must be administered. Artemether-lumefantrine (Coartem®) is the preferred follow-on treatment but adequate alternatives are atovaquone-proguanil (Malarone™), quinine plus doxycycline or clindamycin, or mefloquine
If, after the third IV artesunate dose, the patient’s parasite density is >1%, IV artesunate treatment should be continued with the recommended dose once a day for a maximum of seven days until parasite density is ≤1%
For those patients with parasite density ≤1% but who still cannot tolerate oral medications after completing IV artesunate treatment, clinicians can continue IV artesunate, one dose daily not to exceed a total course of seven days.
Following invasion of a RBC, what happens to merozoites?
Trophozoites -> schizonts -> may rupture and release 8-24 merozoites - causes inflammatory response and fever. Some may then form gametocytes.
What is the vector for malaria? Name some features of this vector.
female anopheles mosquito, night biting
How would you treat uncomplicated P.malariae?
Chloroquine base. 0 = 10mg/kg, 24 = 10mg/kg, 48 = 5mg/kg
3 days, orally
Treatment of uncomplicated malaria caused by P. vivax, P. ovale, P. malariae, P. knowlesi is chloroquine.
Can also use ACT in chloroquine resistant areas.
Who would you not administer primaquine to?
Pregnant women, children <6 months, breastfeeding to children <6 months, G6PD deficiency
Name 2 complications/risks of falciparum in pregnancy?
Stillbirth
LBW
Severe anaemia
What is uncomplicated hyperparasitaemia?
Uncomplicated hyperparasitaemia is present in patients who have ≥ 4% parasitaemia but no signs of severity. They are at increased risk for severe malaria and for treatment failure and are considered an important source of antimalarial drug resistance.
What structure is this?
Schizont, P.malariae (Rossett appearance)
What is severe malaria?
What is a Schuffners dot? Which species
Schuffner’s dots: Caveolae in RBC membrane
Caveola-vesicle complexes in cellular membrane of erythrocytes.
P.Vivax and P.Ovale
What is a hypnozoite?
Malaria dormant in the liver
Why do a thick smear for malaria?
increases sensitivity of parasitic detection (always do both)
HIV and malaria, what to avoid in Rx of malaria?
Avoid artesunate+ amodiaquine if patient is receiving efavirenz
or zidovudine
Which phase of the malaria life cycle are you most likely to see with falciparum?
Usually only see rings trophozoites and gametocytes unless very high burden of infection will see schizonts. Maulers clefts and appliqué forms characteristic.
What is imported malaria?
Acquired outside a specified area in which it is found
What is indigionous malaria?
Naturally present in an area or country
Malarias impact on HIV?
Specificity HIV RDTs decreased
Transient viral load increased
Transient CD4 increased
Progression to AIDS - no impact
HIV transmission may increase
What is an incubation period?
Time between infection and the onset of symptoms
What are the causes of false negative rapid diagnostic testing for malaria?
Low parasitaemia
Non falciparum species
High parasitaemia (prozone)
Gene deletion - HRP2 - more so in South America
Interpretation error
What are the disadvantages for RDTs in malaria?
Still need microscopy, possibility of false positives and false negatives, poor performance in species other than Falciparum
How do you treat uncomplicated P.Vivax in areas of high chloroquine resistance?
Artemisin compounds (artesunate, arthemeter, artemotil, dihydroartemisinin) containing artesemin AND a 2nd shizontocidal drug 3 days
Primaquine base 3 days
Co-trimoxazole prevents which conditions?
Toxoplasmosis
Malaria
Pneumocystis Jirovecii
Criteria for severe malaria in low resource settings?
- Prostration
- Resp distress
-Decreased GCS
Why do you give a partner drug with artemisinin?
Longer acting
Clears remaining parasites to prevent resistance to artemisinin
Post Rx prophylaxis
What is Ziemann’s stippling?
Eosinophilic dots in cytoplasm found in P.Malariae