Malaria II Flashcards
History of Fever & Travel
Malaria
What are the different spp. of malaria?
P. ovale P. vivax P. falciparum P. malariae P. knowlesi
What is malaria’s vector?
Reservior?
Anophelene mosquito
Humans (macaques for knowlesi)
What is a hypnozoite and what spp. form them?
Dormant liver stage in vivax and ovale
releases blood stage wks to mos. after primary infection
How long after infection do Sx develop?
falciparum- 8-11 days
ovale and vivax- 10-17 days
malariae 18-40 days (<20 years due to subclinical erythrocytic stage)
corresponds to beginning of erythrocytic cycle
What is the infective stage of malaria?
Sporozoites enter host from mosquito salivary glands and migrate to infect liver cells.
What is the erythrocytic cycle?
Merozoites burst from liver schizonts and infect RBCs
Ring stage–>trophozoite–>early/late schizont–>lysis and reinfection of RBCs
What is Duffy Antigen?
P. vivax uses it to enter RBCs
Classical symptoms of malaria?
Fever
Chills
Headache
What are the three clinical types of malaria?
Acute uncomplicated (mild)
Severe malaria
Hyperreactive Malarial Syndrome (tropical splenomegaly)
What are the classic malarial paroxysms?
- Cold stage with shaking
- Hot stage with fever (>104)
- Sweating stage with fever resolution
each lasts 6-10 hrs then recur
How frequently do fevers relapse in chronic uncomplicated malaria?
Every 2 days P. vivax, ovale, falciparum
Every 3 days P. malariae (quartan fever)
Why is P. falciparum infection more severe?
more protozoa
infect all ages of RBCs
emergency in non-immune patients!
What are important prognostic factors in patients with malaria?
Degree of acidosis
Degree of parasitemia
What is the major cause of acidosis and tissue hypoxia in malaria patients?
Sequestration!
RBCs with mature parasites develop knobs that cause them to adhere to endothelial cells
Decreased deformability of infected and non-infected RBCs contributed to sludging, rosetting, and aggregation
What is cerebral malaria?
Acute encephalopathy not attributable to other causes
Sequestration and coagulation dysfunction plus inflammation hypothesized as cause.
100% mortality without treatment, 20% w/tx
How do you diagnose malaria?
Blood smear (thick and thin)
Antigen testing
PCR
What is the mechanism of severe malaria?
Lactic acidosis due to hypo perfusion from sequestration
Hypoglycemia due to increased demand
Renal failure due to filtered hemolysis products
Anemia due to hemolysis
Pulmonary edema–unknown
Which Plasmodium species cause schuffner’s dots and enlarged infected cells?
P. vivax
P. ovale
What indicates vivax on a smear?
schuffner’s dots and enlarged infected cells
mature schizont with 12-24 merozoites
What indicates P. oval on a smear?
schuffner’s dots and enlarged infected cells
mature schizont with 6-12 merozoites is elongated or oval
What indicates P. malariae on a smear?
Band form
Owl eye trophozoite
Smaller infected cells
yellow/brown pigment
What indicates P. falciparum on a smear?
Multiple ring-shaped trophozoites
Banana-shaped gametocyte
How do you prevent malaria?
PPE Chemoprophylaxis -doxy -atovaquone/proguanil -mefloquine -primaquine -chloroquine
What are the classes of antimalarials?
Quinolines-inhibits parasitic heme polymerization
Antifolates/Sulfa-DHPR DHFR inhibition
Artemisinins-endoperoxidase–> free radicals
Antibiotics-ribosomal function in apicoplast
What are blood schizonticides?
Primaquine, doxycycline, Mefloquine, chloraquine, quinine, Artemisinins, Atovoquone-Proguanil
What are tissue schizonticides?
Primaquine
Atovoquone-Proguanil (some activity)
What are malaria gametocides?
Primaquine
Artemisinins
What is presumptive anti-relapse therapy (PART)?
for people who have prolonged exposure to malaria endemic areas
30mg Primaquine for 14 days
What is the mechanism of Atovaquone?
Inhibits parasite mitochondrial electron transport
Effect potentiated when combined with proguanil
(Malarone)
What are the two types of malaria prophylaxis?
Causal-kills in primary liver stage and blood stage, Continue one week after departure, Atovaquone-proguanil
Suppressive-kills in erythrocytic stage only, mefloquine, doxy, chloroquine. Continue 4 weeks after departure.
What are the side effects of primaquine?
G6PD-hemolysis
What are the side effects of mefloquine?
Vivid dreams Nausea Dizziness/syncope Neuropsychiatric complications <1% Cardiotoxic if combined with quinine/quinidine
First line in pregnancy (cat. B drug)
When would you use chloroquine as a malaria prophylactic?
travel to Haiti or central america
pregnancy
When would you use atovaquone/proquanil as a malaria prophylactic?
In resistant areas
If you have a lot of money (expensive drug)
