Parasitology Notes Overview

Parasitology Key Facts

• Leishmania: Transmitted by sandflies, primarily infects macrophages.
• Leishmania chagasi: Not present in Sudan.
• Hymenolepis nana: Known as dwarf tapeworm, measures 4 cm, with its eggs being the infective stage.
• Ascaris lumbricoides: Referred to as giant roundworm.
• Balantidium coli: Largest protozoan known.
• Fasciola buski: Largest intestinal fluke.
• Taenia solium: Gravid proglottid displays fewer uterine branches compared to Taenia saginata.
• Infective stages:
  • T. saginata: Cysticercus bovis.
  • T. solium: Cysticercus cellulosae.
• Scolex characteristics:
  • T. saginata has 4 suckers and hooks.
  • T. solium has 4 suckers without hooks.
• Intermediate hosts:
  • T. saginata: Cattle.
  • T. solium: Pigs.
• Definitive host for both tapeworms: Humans.
• Trypanosoma cruzi causes Roman's sign, an inflamed eye condition.
• Echinococcus granulosus's main definitive host is dogs, while sheep and humans act as intermediates.
• Both herpes and pox viruses are classified as DNA enveloped viruses.
• Giardia lamblia: Infective stage is the cyst, while diagnostic stages include both cysts and trophozoites.
• Diphyllobothrium latum: Infective stage is plerocercoid or sparganum larvae; definitive host is humans.
• D. latum eggs hatch in freshwater environments.
• Fasciola hepatica infective stage is metacercariae.
• Liver flukes include F. hepatica and Clonorchis sinensis, while F. buski is distinguished as an intestinal fluke.
• Intermediate hosts for Wucheria bancrofti: female mosquitoes (Anopheles, Culex).
• Intermediate host for Onchocerca volvulus: female blackfly (Simulium).
• Loa loa transmission vector: deer fly (Chrysops).
• Loa loa microfilaria: diurnal periodicity and sheathed.
• O. volvulus microfilaria: diurnal periodicity and unsheathed.
• Best detection time for W. bancrofti in blood: 10 p.m. – 4 a.m. (nocturnal periodicity).
• O. volvulus lifespan: Up to 10 years.
• Best diagnostic sample for O. volvulus: Skin snip; blood samples for Loa loa detection.
• Hookworms: Oviparous, not true filarial worms; can lead to megaloblastic anemia.
• Toxoplasma gondii: Infective stage is the oocyst found in domestic cat feces, with no central nervous system invasion.
• Schistosoma: Classified as trematodes, can lead to hypertension.
• Schistosoma eggs lack an operculum.
• Complications from schistosomiasis arise from the presence of eggs, leading to granuloma formation, not from the adult worms.
• Adult Schistosoma are not present in stool samples.
• Plasmodium falciparum: Trophozoite is referred to as a ring stage, categorized as a haemoparasite.
• ICT for malaria detects:
  • HRP2 (Histidine-rich protein).
  • pLDH (species-specific lactate dehydrogenase).
  • Aldolase enzyme.
• The line thickness on an ICT test correlates with parasitemia levels.

Summary Tables of Parasites

• Entamoeba histolytica:

  • Infective stage: Cysts.
  • Diagnostic stage: Cysts +trophozoites.

• Giardia lamblia:

  • Infective stage: Cysts.
  • Diagnostic stage: Cysts +trophozoites.

• Balantidium coli:

  • Infective stage: Cysts.
  • Diagnostic stage: Cysts +trophozoites.

• Ascaris lumbricoides:

  • Infective stage: Embryonated eggs.
  • Diagnostic stage: Unfertilized or fertilized eggs.

• Taenia saginata:

  • Intermediate host: Cattle.
  • Definitive host: Human.
  • Infective stage: Cysticercus bovis.
  • Diagnostic stage: Eggs + proglottids.

• Taenia solium:

  • Intermediate host: Pig.
  • Definitive host: Human.
  • Infective stage: Cysticercus cellulose.
  • Diagnostic stage: Eggs + proglottids.

• Diphyllobothrium latum:

  • Intermediate hosts: 1st - Cyclops, 2nd - Fish.
  • Definitive host: Human.
  • Infective stage: Plerocercoid sparganum larvae.
  • Diagnostic stage: Unembryonated eggs.

• Fasciolopsis buski:

  • Intermediate host: Snail.
  • Definitive host: Human, pig.
  • Infective stage: Metacercariae.
  • Diagnostic stage: Unembryonated egg.

• Plasmodium species (falciparum, vivax, ovale, malariae):

  • Intermediate host: Human.
  • Definitive host: Mosquito.
  • Infective stage: Sporozoites.
  • Diagnostic stage: Trophozoites + Schizonts + Gametocytes.

• Toxoplasma gondii:

  • Intermediate host: Human.
  • Definitive host: Cat.
  • Infective stage: Oocyst.
  • Diagnostic stage: Tissue cysts.