Malaria (and Toxo) Flashcards
The one exception to the “No vaccines” claim that was given in class
RTSS vaccine for malaria
(50% reduction in cases)
Malaria is caused by the genus ______
Plasmodium
Most severe Plasmodium?
Common in ____
falciparum
common in tropics
Less common plasmodium species?
Why is it less common?
Where is it found?
Vivax
Infection is limited to reticulocytes
Common in subtropics and temerate regions
Third and fourth common plasmodiums?
What are the types of infections they cause?
Ovale = Relapsing malaria
knowlesi = 24 hour life cycle, zoonotic infections
Where is plasmodium ovale found?
West africa
What is the fastest-replicating plasmodium species?
Knowlesi
It has a 24 hour lifecycle, which means it can increase the population very quickly
Plasmodium Life cycle:
- Infected mosquito injects____
- They go to the liver and become _____
- They are released and invade ___ cells
- Once in the cell, these become ______
- This multiplies, giving more ______
- These are released and become _____
- Female mosquito picks them up and _____ are formed
- Sporozoites
- Merozoites
- Red blood cells
- Trophozoites
- New merozoites
- gametocytes
- sporozoites
Which plasmodium forms hypnozoites?
How/where does this form live?
How do you treat for this?
Vivax
Lies dormant in the liver
It only responds to Primaquine
How does plasmodium bind to the placenta?
It binds to chondroitin sulfate A
Three conditions covered in malaria pathogenesis
Cerebral malaria
Severe anemia
Metabolic acidosis
Cerebral malaria pathogenesis
Blood brain barrier disruption (from ROS) = Edema and hemorrhage
Tissue hypoxia (from Microvascular obstruction) = Parenchymal and axonal damage
What causes severe anemia in malaria pathogenesis
Hemolysis of immature RBCs
(Rosetting)
What causes the metabolic acidosis in malaria?
Tissue hypoxia causes lactic acid from anaerobic glycolysis
Three stages of classic, uncomplicated malaria
Cold stage
hot stage
sweating stage
The symptoms of uncomplicated malaria are generally _______
Flu-like
(Chills, headache, myalgias and malaise)
also ANEMIA and JAUNDICE
5 major symptoms of severe malaria
Organ failures (renal)
Cerebral malaria
Anemia
Hemoglobinuria
Acute respiratory distress syndrome
What is malaria during pregnancy called?
Features?
Placental Malaria
Especially during first pregnancy, causes low birth weight and miscarriage
Antimalarials, three categories and what they target:
Tissue schizonticides = kill liver stage
Blood schizonticides = kill erythrocytic forms
Gametocytocides = kill sexual stages and block transmission
All antimalarial compounds are effective against ______
Asexual blood stages
Antimalarials that target Liver stage
Artemisinins
Primaquine
Pyrimethamine
Atovaquone
Antimalarials that target the hypnozoites
Primaquine
Antimalarials that target gametocytes
Artemisinins
Mefloquine
Amodiaquine
Primaquine
Pyrimethamine
Four methods of malaria prevention
Insect repellent
Insecticides
Bed nets
Chemoprophylaxis
5 drugs for prevention of clinical disease
Malarone (atovaquone + proguanil)
Doxycycline
Chloroquine
Mefloquine
Primaquine
Malarone area and preventive course
All areas
start 1-2 days before, continue one week after
Doxy area and preventive course of treatment
All areas
start 1-2 days before, continue 4 weeks after
Chloroquine areas and preventive course
Chloroquine sensitive areas
start 1-2 weeks before and continue 4 weeks after
Mefloquine area and Pretreatment course
Mef-sensitive areas
start more than two weeks before, continue more than four weeks after
Primaquine area and course of pretreatment
If >90 P. vivax in the area
Start 1-2 days before, continue one week after
Uncomplicated malaria (or unidentified species) can be treated with _____ agents
Examples? (area-based)
Oral
Chloroquine sensitive areas:
- chloroquine and hydroxychloroquine sulfate
Chloroquine resistant areas:
- Malarone
- Coartem (artemether + Lumefantrine)
- Quinine Sulfate PLUS Doxy/Tetra//Clinda
- Mefloquine
Treatment for uncomplicated malaria?
P. vivax/ovale (hypnozoites in liver)
**Basically add primaquine to any of the treatments of uncomplicated malaria
P. malariae or Knowlesi
Chloroquine or Hydroxychloroquine
Tx for severe/complicated malaria
Quinidine gluconate (I.V.) PLUS Doxy/Tetracycline/Clinda
Cardio consult!
Alternative Tx for Severe/complicated malaria
Artesunate (= IV only alternative if QG not available or tolerated)
Followed by one of:
- Malarone
- Doxy (Clinda in pregnant women)
- Mefloquone
Artemisinin type
Sesquiterpene lactone endoperoxide
(endoperoxide is the active group)
Artemisinin has low ___ but high ____
Low toxicity
High counterfeit rate
Artemisinin resistance has been observed in _____
SE Asia
Artemisinin MOA
Must be activated (via heme-iron)
Activated artemisinin forms free radicals that target parasite proteins/lipids
Artemisinin Mechanism of Resistance
Mutations in Kelch 13 gene
–>Delays life cycle, alters stress response
Artemisinin has no effect on ___ stage
Liver
Artemisinin half life
1-2 hours
Artemisinin is commonly paired with ______ and ______
Mefloquone or Lumefantrine
Artemisinin is ______ because of the required frequency of dosing
not appropriate for chemoprophylaxis
Artemisinin ROA
It is also _____ with a low ______
Oral only
insoluble with a low bioavailability
Semisynthetic artemisinins are available that allow…
different ROA’s
(oral, IV, IM, rectal)
What is artesunate, what is the ROA, what does it treat?
Semisynthetic artemisinin
IM, IV, rectal
Treatment of severe malaria
Artemisinin antimalarial effect is associated with ___
C-max
Artemisinin derivatives are paired with _____
Longer half life drugs
3 Common combos for artemisinin
Amodiaquine
mefloquine
piperaquine
Artemisinin combos are standard of care for _______
uncomplicated falciparum in most areas
Artemisinin adverse effects
N/V/D
Dizziness
EMBRYOTOXIC in animal studies (not recommended for first trimester for uncomplicated malaria)
Malaria parasites ingest ____ from host cell
This is degraded into ___ and _____, which is toxic
Parasite also polymerizes it to _____,which is nontoxic
Hb
amino acids and heme
hemozoin
Chloroquine accumulates in _____ and inhibits _______
food vacuole
inhibits heme polymerization
Antimalarials generally inhibit _________
The detoxification of heme
4-substituted quinolines interfere with __________
Resistance is associated with lack of _________
Heme polymerization
Lack of accumulation in food vacuole
Hemozoin + Heme/quinoline complex –>
Capped polymer
Chloroquine
- ROA?
- Has a large_____
- Initial/Terminal half-life?
Oral
Large volume of distribution
Initial = 3-5d
Terminal = 1-2d
Chloriquine (CQ) antimalarial effect is associated with…
T>MIC
CQ might cause ____ in pts of african descent
It is contraindicated for which 4 conditions?
prutitis
- psoriasis
- porphyria
- Retina/Visual field abnormalities
- Myopathy
_____ and ____ interfere with the absorption of CQ
Kaolin and antacids
Two possible mechanisms of CQ resistance
Primary = mutation in Pf-CRT1
(localized to food vacuole, causes reduced accumulation of CQ, no cross resistance to mefloquine or quinine)
Secondary = over-expression of Pf-MDR1
(drug transporter)
Quinine isolated from _______
bark of cinchona tree
Mechanism of Quinine is similar to _____
Chloroquine
Quinine’s general catergory
Blood schizontiide
Quinine is the treatment of choice for…
- Chloroquine resistant falciparum (quinine sulfate- oral)
- Severe falciparum (IV only with concurrent cardiac monitoring)
Quinine dosing schedule for chemoprophylaxis?
N/A
Its short half life and higher toxicity make it an inappropriate option for chemoprophylaxis.
Quinine major adverse effect
Cinchonism
(tinnitus, headache, nauses, dizziness, flushing, visual disturb.)
Quinine may result in cell _____. Cause and Effects of this?
Cell hemolysis
- G6PD deficiency
- Blackwater fevere (hemoglobinuria)
Quinine DDI
May raise warfarin and digoxin levels
Metabolized by CYP3A4
*** Severe HoTN***
Mefloquine effective against…
What’s its use?
Effective against erythrocytic forms of falciparum and vivax
(Used for both prophylaxis and Rx)
Major Mefloquine side
Neuropsychiatric toxicity
Other chloroquine drugs
Lumefantrine
Piperaquine
Amodiaquine
Halofantrine
Primaquine metabolism
2D6 metabolism
Required for activity
Primaquine mechanism may involve ____
Free radicals
Primaquine is the drug of choice for _______
Liver stages (ACTIVELY GROWING and HYPNOZOITES)
Of Vivax and Ovale
*** Combo with Chloroquine
Primaquine is a _______ drug against ______
gametocidal
all four parasites
Contraindications for Primaquine
G6PD deficiency
Pregnancy/Breastfeeding
What compound has the same spectrum of activity and toxicity as Primaquine
Tafenoquine
Malarone is a combo of ______
proguanil and atavaquone
(atavaquone bad at monotherapy)
Malarone kills ______ stages, but not ______
liver and blood
NOT hypnozoites
Malarone is effective Tx for __________
uncomplicated malaria and chemoprophylaxis
Atavaquone is used to treat __________
Toxoplasma and P. jiroveci
Atavaquone is a _____ analog that is an inhibitor of ______
-
Ubiquitin
- Electron acceptor for paraste dihydroorotate dehydrogenase
- Cytochrome bc1
Atavaquone works synergisyically with ____
How?
Proguanil
Proguanil is converter to cycloguanil = an inhibitor of plasmodium dihydrofolate reductase-thymidylate synthetase (crucial for purine and pyrim. synthesis)
–> Enhances mitochondrial toxicity of atavaquone
Antibiotics as antimalarial drugs?
What do they target?
Tetracycline/ Doxycycline/ Clindamycin
–> Target Apicoplast
Doxy is paired with ___ or ____ for treatment of ________
Quinine/Quinidine
Falciparum
Doxy is also used for…
chemoprophylaxis in areas with high mefloquone resistance
Third most common food borne illness
Toxo
Toxo life cycle?
Transmission routes?
- -sexual development in cat
- -cysts develop in other mammals
- Oocysts and tissue cysts –> tachyzoites –> neural/muscle –> Bradyzoites
Can be infected by eating raw meat (cysts) or from shedding from cats (oocysts)
DIagnostic stages of toxo (2)
- Serological diagnosis
- Direct ID of parasite from peripheral blood, amniotic fluid, or tissue section
Severe toxoplasmosis common with what diseases?
HIV/AIDS
Transplants
Chemotherapy
Congenital toxo occurs when?
First infection in mom
Drug treatment for toxo
First line = Pyrimethamine + Sulfadiazine
Alternatives: atavaquone or pentamidine