Parasitology Revision Quiz

Parasitology Revision

• Parasitology revision covers identification, infective stages, transmission, and treatment.
• Genus is capitalized, species is lowercase.
• Diagnostic stages are also included.

Trematodes

• Trematodes are a type of parasitic flatworm.
• Fasciola species, such as Fasciola hepatica and Fasciola gigantica, are discussed, including their ova, larva, and adult forms. Key differentiators include size and prominence of shoulders.

Fasciola hepatica

• Infective stage: Metacercariae
• Mode of infection: Ingestion of aquatic plants, raw vegetables, watercress containing encysted metacercariae, drinking water with encysted metacercariae, or ingestion of raw liver from infected animals.
• Treatment: Triclabendazole (dose 10mg/kg body weight), Bitinol (30mg/kg for 5-10 days), Praziquantel is less effective.

Heterophyes heterophyes

• Infective stage: Metacercariae
• Mode of transmission: Ingesting undercooked or low-salt fish containing metacercariae
• Treatment: Praziquantel

Schistosoma

• Infective stage: Forked tail cercaria
• Mode of transmission: Skin penetration by forked tail cercaria when contacted with contaminated water
• Treatment: Praziquantel

Nematodes

• Trichuris trichura (whipworm)
• Infective stage: Eggs containing first-stage larvae
• Mode of transmission: Fecal-oral, consuming food or water contaminated with eggs.
• Treatment: Mebendazole, Albendazole, Iron supplements (if anemia)

Wuchereria bancrofti

• Infective stage: Filariform larvae
• Mode of transmission: Bite of infected female anopheles mosquitoes
• Treatment: Antibacterial cream on wound, Diethylcarbamazine, Ivermectine, Albendazole

Strongyloides stercolaris

• Infective stage: Filariform larvae
• Mode of transmission: Filariform larvae penetrate the intact skin, autoinfection (internal/external).
• Treatment: Ivermectin with albendazole

Ascaris lumbricoides

• Infective stage: Eggs containing second-stage rhabditiform larvae
• Mode of transmission: Ingesting mature eggs from contaminated food (green vegetables), water, or hands, house flies carrying eggs to food
• Treatment: Albendazole and mebendazole

Enterobius vermicularis

• Infective stage: Embryonated eggs
• Mode of transmission: Ingestion of eggs through contaminated food or drink, autoinfection, retro-infection, air borne, contact
• Treatment: Mebendazole, Pyrantel pamoate (initial dose, second dose in 2 weeks). Local treatment like mercurial ointments.

Trichinella spiralis

• Infective stage: Trichinella encysted (larva)
• Mode of transmission: Eating raw or undercooked pork containing infective encysted larvae
• Treatment: Albendazole, Mebendazole

Ancylostoma duodenale

• Infective stage: Infective filariform larva
• Mode of transmission: Penetrates intact skin, oral, transmammary/transplacental
• Treatment: Albendazole, Pyrantel, Mebendazole, Iron/vitamin/protein supplementation

Cestodes

• Taenia (solium and saginata)

• Infective stage: Cysticercus (solium, bovis); gravid segments

• Mode of transmission: Saginata: Eating undercooked beef containing cysticercus bovis. Solium: Eating undercooked pork containing cysticercus cellulosae

• Treatment: Saginata: Niclosamide, Praziquantel. Solium: Praziquantel (Niclosamide avoided)

Echinococcus granulosus

• Infective stage: Hydatid cyst
• Mode of transmission: Dogs and herbivores ingest hydatid cysts. Humans ingest eggs from contaminated food/vegetables
• Treatment: Surgery, mebendazole (pre-op), sterilization of fluid in cysts (formalin).

Hymenolepis nana

• Infective stage: Embryonated eggs
• Mode of transmission: Direct/indirect contact with infected host, autoinfection (internal/external), contamination with food or water, carried under nails
• Treatment: Praziquantel

Protozoa

• Entamoeba histolytica
• Infective stage: Entamoeba histolytica mature cyst
• Mode of transmission: Fecal-oral route (contaminated food/water/hands), flies, and contaminated food.
• Treatment: Iodoquinol, paromomycin, diloxanide furoate (for luminal infection), metronidazole, tinidazole (for more complex cases)

Balantidium coli

• Infective stage: Balantidium coli cyst
• Mode of transmission: Fecal-oral route (contamination from hands, food, drink)
• Treatment: Metronidazole, Tetracyclines (supportive treatment).

Giardia intestinalis

• Infective stage: Giardia intestinalis mature cyst
• Mode of transmission: Ingestion of cysts in contaminated water/food, hands
• Treatment: Metronidazole

Trypanosoma gambiense

• Infective stage: Metacyclic trypomastigotes
• Mode of transmission: Mechanical/direct transmission; infected tsetse fly injecting trypomastigotes into skin
• Treatment: Pentamidine isethionate, suramine (blood stage), Melarsoprol (CNS cases).

Plasmodium malaria

• Infective stage: Sporozoites
• Mode of transmission: Infected mosquito bite, injecting sporozoites into human body.
• Treatment: Chloroquine

Toxoplasma gondii

• Infective stage: Oocysts in cat stool, tissue cyst in raw meat
• Mode of transmission: Ingesting food/water contaminated with cat feces, consuming undercooked meat contaminated with tissue cysts, blood transfusion, organ transplantation, transplacental transmission
• Treatment: Pyrimethamine, sulfadiazine (combined therapy)

Virology

• Influenza (Flu) Viruses and Human Rhinovirus (HRV): Communicable, >100 known types; upper respiratory tract infections

• Adenoviral infections: Specific key symptoms such as Fever, tiredness, continuous cough, loss of taste or smell, breathing difficulty.

• Mumps, Measles, Rubella, Poliovirus and Hepatitis C: Specific symptoms and complications are presented.

• Rabies: Specific transmission and treatment are discussed.