This episode moves from luminal infections to protozoa that invade blood and deep tissues. Drawing from Murray’s Chapter 73, it examines organisms that establish systemic infection, often requiring vector transmission.
Major pathogens include:
Plasmodium species - malaria; intraerythrocytic replication
Babesia species - tick-borne haemoparasites
Trypanosoma species - African sleeping sickness and Chagas disease
Leishmania species - cutaneous and visceral leishmaniasis
Toxoplasma gondii - congenital and immunocompromised disease
These organisms frequently replicate within host cells - red blood cells, macrophages, or neural tissue - evading immune detection.
Clinical manifestations include:
Anaemia
Fever cycles
Organomegaly
Neurological involvement
Conceptually, blood and tissue protozoa illustrate immune evasion through intracellular survival. Clinically, vector exposure, travel history, and host immunity shape risk assessment.
Key Takeaways
Many systemic protozoa are vector-borne
Intracellular replication promotes immune evasion
Malaria involves cyclic red cell destruction
Leishmania survives within macrophages
Toxoplasma poses risk in pregnancy and immunosuppression
