Micro: Blood parasites Flashcards
Vector for all Malaria parasites.
Anopheles mosquito
Describe the steps (5-ish) in the malaria life cycle.
- Infected mosquito bites host
- Sporozoite form migrates to the liver and replicate
- Merozoite form migrates from the liver and infects RBCs and replicates forming gametocytes (falciparum only)
- Lysis of RBCs causes symptoms and releases new parasites into the blood
- New parasites can spread to mosquitos that bite the host
Why does Plasmodium vivax cause a relapsing malaria infection?
Forms a unique stage in its lifecycle called Hypnozoites. This stage can remain dormant in the liver for months to years and is resistant to standard anti-malaria meds.
What is hemozoin?
Toxic metabolite of heme degradation formed with enzymes from blood parasites. Normally it is detoxified by the parasite and used for protein synthesis, however, when the RBC is lysed by the parasite some of the hemozoin is released in the circulation without being detoxified.
It is then phagocytosed by host WBCs altering blood cell and platelet formation (leading to low WBC and platelet counts) and causing production of ROS which damage RBCs (leading to hemolysis and symptoms).
Characteristic of RBCs viewed on blood smear indicating P. vivax infection.
Schuffner dots
Charactertic of RBCs viewed on blood smear indicating P falciparum infection
Boomerang gametocyte (or sausage or banana)
Genetic disease most commonly associated with malaria resistance.
Sickle Cell Disease or Trait
DOC for non-severe malaria or areas with resistance.
Chloroquine
DOC for severe malaria cases.
Quinine/Quinidine
can cause renal or ototoxicity
DOC for P. vivax infection.
Chloroquine + Primaquine
primaquine works on the hypnozoite form in the liver to prevent relapse
Anti-malarial MOA of quinolones. (chloroquine, quinine, mefloquine)
Inhibit Heme polymerase preventing metabolism of heme to hemozoin
2 most common side effects of chloroquine.
- Pruritis
2. Retinopathy
Primary indication for mefloquine.
Malaria prophylaxis
Major side effect of mefloquine.
Psychiatric disorders from prolonged use
MOA of Primaquine.
Inhibits electron transport chain in P. vivax.
2 contraindications for using Primaquine.
Glucose-6-phosphate dehydrogenase deficiency patients and pregnant patients.
Will cause hemolytic anemia.
Main toxicity of folic acid antagonists.
Bone marrow depression
MOA of doxycycline as an anti-malaria agent.
Prevents apicoplast function (some thing found in the parasite)
This drug is mainly used as a prophylaxis.
What is the contraindication for doxycycline use?
Not in children younger than 8 or pregnant women as it can lead to bone and teeth malformation
What is Malarone?
Anti-malarial combination of Atovaquone (electron transport inhibitor) and Proguanil (antifolate). Mainly used for prophylaxis
MOA of the Sesquiterpenes: artemether and artesunate.
Bind to the iron in heme to prevent metabolism to hemozoin.
Babesosis is often a co-infection with what other disease?
Lyme Disease
What are symptoms of Babesiosis?
Similar to malaria; nausea, night sweats, weight loss, hematuria, ARDS
What is the vector and reservoir for B. microti?
Black legged ticks are the vector. White-footed mice are the reservoir.
(humans can be a reservoir but unlike malaria where mosquitos can bite an infected human and become a vector for malaria to be transmitted to other humans, ticks rarely bite an infected human and then transmit to another human. The normally bite an infected mouse and then bite a human.)
