Flashcards in Microbes of the blood Deck (24)
- Plasmodium Falciparum
What is the primary malarial vector?
Describe the malaria life cycle
- Mosquito inoculates sporozoites into blood steam
- Invade liver cells and undergo single round of schizogony (7-14 days) releasing merozoites to blood stream
- Merozoites invade RBC and undergo multiple rounds of schizogony (2-3 days)
- Some develop into gametocytes which can then be taken up by mosquitos
- Ovale and Vivax--> hypnozoites in the liver--> relapse
What is a histological finding unique to Ovale and vivax?
- Schuffner's dots
How long after inoculation before patient presents with symptoms?
- 2-5 weeks
What malarial strain produces severe malaria and why?
- P. falciparum
- 20-30% BC infection
- PfEMP1 and other proteins produced on the surface of the RBC cause clumping and rosetting which allows for immune evasion from spleen.
How does rosetting in P. Falciparum contribute to disease?
- Stasis and hypoxia
- Increased cytokine production and cerebral endothelium receptor expression increasing sequestration
- NO and TNF interferes with neuronal signaling
What is the diagnostic approach for malaria?
- Microscopy - Thick and thin smears
- Serologic - antibody
- PCR - specific species
- Rapid diagnostics - HRP-2 --> P.F., LDH --> P. F or Vivax
What diseases protect against malarial infection?
- Sickle cell
- Duffy blood groups
- G6PD deficiency
How does sickle cell protect against malaria?
- Resistance to P. Falciparum
- Low O2
- PfEMP1 malformation
- Micro RNA's inhibit parasite growth
- Heme oxygenase- 1--> antioxidants which inhibit cerebral malaria
How does Duffy blood group confer resistance and to which strains?
- P. vivax and knowlesi
- Duffy negative - lack non-specific cytokine glycosylated protein that parasite uses for infection.
- Common in Africans
What is the transmission and epidemiology of Babesiosis Microti?
- By Ixodes tick vector
- Blood transfusions
- Summer months
- Symptoms seen in elderly, asplenic or immunocompromised in the north east and upper midwest
What is commonly co-infected with Babesiosis?
- Borrelia Burgdorferi, Ehrlichia and Anaplasma
How is Babesiosis identified on blood smear?
- Maltese cross ring troph
- Rings appear oval with no hemozoin
What are the symptoms of Babesiosis?
- Fever, chills, flu like illness
- Hemolysis and anemia
What is the classification of Ehrlichia and Anaplasma?
- Gram negative, intracellular bacteria related to the rickettsia
- Tick borne illness
What cells do Ehrlichia infect?
What cells do Anaplasmosis infect?
How are Erlichia and Anaplasma identified?
- Intracellular morula
What tick transmits Anaplama?
- Ixodes tick
- Peromyscus leucopus
What tick transmits Ehrlichia?
- Ambloyomma americanum (the lone star tick)
How are Ehrlichiosis and Anaplasmosis treated?
How do patients with Ehrlichiosis and Anaplasmosis present?
- Fever, chills, HA, mialgia, malaise