Infections Of RBCs : Malaria And Babesiosis And Sepsis Flashcards
(17 cards)
Name two protozoal parasites that infect human red blood cells.
Plasmodium spp. and Babesia microti.
What are the modes of transmission of Plasmodium spp. and Babesia microti?
Plasmodium spp. is transmitted by the bite of infected Anopheles mosquitoes. Babesia microti is transmitted by the bite of infected Ixodes scapularis (deer ticks).
What are the vectors for Plasmodium spp. and Babesia microti, and where are they found?
Plasmodium is vectored by Anopheles mosquitoes (tropical and subtropical regions). Babesia microti is vectored by Ixodes scapularis ticks (Northeastern and Upper Midwest U.S.).
What are the symptoms manifested in malaria and babesiosis?
Both present with fever, chills, fatigue, and hemolytic anemia. Malaria may also include splenomegaly, jaundice, and cyclic fever; babesiosis may present with dark urine and hepatosplenomegaly.
Which organs are infected during the asexual reproductive cycle of Plasmodium spp. and which stage causes symptoms?
The liver (schizogony) and red blood cells (erythrocytic cycle) are infected. The merozoite stage invading RBCs causes symptoms.
What are the clinical manifestations of malaria?
Cyclical fever, chills, sweating, anemia, jaundice, splenomegaly, and in severe cases cerebral malaria or ARDS (especially P. falciparum).
How does the infected red blood cell cause pathology in malaria?
Infected RBCs adhere to vascular endothelium (cytoadherence), leading to microvascular obstruction, tissue hypoxia, and inflammation.
What immune defenses do we have against Plasmodium spp.?
Innate immunity (macrophages, NK cells), adaptive immunity (antibodies against merozoites), and cytokine responses. The spleen helps clear infected RBCs.
What genetic changes allow humans to coexist with Plasmodium?
Sickle cell trait, thalassemias, G6PD deficiency, and Duffy antigen negativity (protective against P. vivax).
Is there a vaccine for malaria? What population does it protect?
Yes, RTS,S/AS01 (Mosquirix) protects primarily children in endemic regions of sub-Saharan Africa against P. falciparum.
How are these diseases diagnosed?
Blood smear (Giemsa stain), PCR, and serology for both. Malaria shows ring forms, trophozoites, and schizonts; Babesia shows “Maltese cross” forms.
What co-infection can ticks transmit together with babesiosis?
Borrelia burgdorferi (causing Lyme disease) and Anaplasma phagocytophilum (causing anaplasmosis).
What types of microbes can cause sepsis?
Gram-negative bacteria, Gram-positive bacteria, viruses, and fungi.
What host receptors are activated in response to sepsis-causing microbes?
Toll-like receptors (TLRs).
What is the immune consequence of activating TLRs during sepsis?
A cytokine storm is generated, leading to systemic inflammation.
What are the five key clinical features of sepsis?
- Fever and chills
- Disseminated intravascular coagulation (DIC)
- Fall in blood pressure (hypotonic shock)
- Multiorgan failure
- Death
What life-threatening condition can result from a fall in blood pressure during sepsis?
Hypotonic (septic) shock.
