PARASITOLOGY
Definition Parasitology is the study of parasites and their interaction with hosts.
Importance Helps in understanding, diagnosing and treating parasitic diseases.
Basic Terms Parasite – organism living on or inside host and taking nutrients. Host – provides food, shelter or place for parasite.
Types of Parasites Ectoparasite – lives on body surface. Examples: lice, ticks, fleas. Endoparasite – lives inside body. Examples: tapeworm, roundworm, amoeba. Hemoparasite – lives in blood. Examples: Plasmodium, Trypanosoma, Babesia.
Main Groups of Parasites Protozoa Definition – single-celled parasites without cell wall. Examples – Plasmodium, Toxoplasma, Leishmania. Life cycle steps – Sporozoite → Merogony → Gamogony → Sporogony. Memory – Spore-Mer-Gam-Spore.
Helminths Definition – multicellular worms. Examples – Ascaris, Taenia, Schistosoma. Life cycle – Egg → Larva → Adult. Memory – Egg-Larva-Adult.
Arthropods Definition – joint-legged parasites. Examples – lice, fleas, ticks. Life cycle – Egg → Nymph → Adult. Memory – Egg-Nymph-Adult.
Pathogenesis Infection → invasion → multiplication → immune evasion → symptoms.
Clinical Features Malaria – fever, chills, anemia. Toxoplasmosis – flu-like symptoms, eye damage. Schistosomiasis – blood in urine, abdominal pain.
Complications Malaria – severe anemia, organ failure. Toxoplasmosis – congenital defects, brain problems. Schistosomiasis – bladder cancer, liver damage.
Diagnosis Microscopy. Serology. Molecular tests (PCR).
Management Antiparasitic drugs. Prevention (nets, hygiene). Control (sanitation, vector control).
Types of Hosts Definitive host – parasite becomes sexually mature. Example: human for Taenia solium. Intermediate host – parasite develops but not sexually mature. Example: mosquito for Plasmodium. Accidental host – infected by chance. Example: humans with dog tapeworm. Reservoir host – maintains infection in nature. Example: rodents for Leptospira.
Host–Parasite Relationship Symbiosis – close association between two species. Commensalism – one benefits, other unaffected. Parasitism – parasite benefits, host harmed.
Important Definitions Symbiosis – intimate association of two organisms. Commensalism – one gains, other not affected. Parasitism – parasite benefits at host’s cost.
General Pathogenesis Flow Entry → attachment → invasion → multiplication → toxins/mechanical damage → immune response → disease.
Example Life Cycle: Plasmodium Mosquito bite → sporozoites in blood → liver → hepatic schizogony → merozoites → RBCs → asexual cycle → gametocytes → taken by mosquito → sexual reproduction → oocyst → sporozoites in salivary gland.
Memory Tricks S-C-P = Symbiosis, Commensalism, Parasitism. DEF-INT-ACC = Definitive, Intermediate, Accidental.
Quick Recap Parasite = depends on host. Types = ecto, endo, hemo. Host types = definitive, intermediate, accidental, reservoir. Relationships = symbiosis, commensalism, parasitism. Life cycles = follow simple arrow patterns for exams.