Parasiology 2 Flashcards
What organism transmits African sleeping sickness?
Tsetse flies (Glossina species).
What are the two subspecies of T. brucei that infect humans?
T. b. gambiense (West Africa) and T. b. rhodesiense (East Africa).
Why is T. brucei hard to eliminate by the immune system?
Antigenic variation of its VSG (variable surface glycoprotein) coating.
What is the diagnostic method for T. b. gambiense vs. T. b. rhodesiense?
Lymph node aspirate (gambiense) vs. blood smear (rhodesiense).
Which drug treats late-stage sleeping sickness but has fatal side effects?
Melarsoprol (arsenic-derived, causes encephalopathy).
What vector transmits Chagas disease, and where is it endemic?
Triatomine bugs (“kissing bugs”); endemic in the Americas.
What is the intermediate host for Schistosoma?
Freshwater snails (e.g., Oncomelania hupensis).
How do humans become infected with schistosomiasis?
Skin penetration by cercariae larvae in contaminated water.
What is the diagnostic stage for S. haematobium vs. S. mansoni?
-Eggs in urine (haematobium)
-Eggs in stool (mansoni).
Why does chronic schistosomiasis cause organ damage?
Immune reactions to trapped eggs in tissues (e.g., liver, bladder).
What is the first-line treatment for all Schistosoma species?
Praziquantel (1–2-day course).
How is Ascaris lumbricoides transmitted?
Ingestion of embryonated eggs in contaminated soil/food.
What unique feature protects Ascaris eggs from chlorine?
Thick, mammillated shell resistant to chemicals.
What pulmonary symptoms occur during larval migration?
Loeffler’s syndrome (cough, eosinophilic pneumonia).
Why is reinfection with Ascaris common despite treatment?
Eggs persist in soil for years; poor sanitation enables recurrence.
Name two drugs used to treat ascariasis.
-Albendazole
-Mebendazole (single-dose therapies).
Why are NTDs like Chagas disease “neglected”?
Primarily affect poor regions; limited drug development funding.
What immune response dominates in helminth infections (e.g., Ascaris)?
Th2 response (high IgE, eosinophilia, IL-4 production).
How does COVID-19 impact NTD control efforts?
Diverts healthcare resources; disrupts mass drug administration programs.
