Parasitology Flashcards
An organism completely depending on another organism (host) for shelter and nourishment.
Parasite
Eukaryotic, unicellular non-photosynthetic organism. Belong to Kingdom Protista, Domain Eukarya.
Protozoans
Utilizes pseudopods (false feet) for locomotion. Example: Entamoeba histolytica
Amoeba
Equipped with whip-like structures called the flagella which aid the parasite in locomotion. Example: Giardia lamblia
Flagellates
Utilizes hair-like structures called cilia for locomotion. Example: Balantidium coli
Ciliates
Motile but do not have special organs for locomotion. Example: Plasmodium species
Sporozoans/Coccidians
Parasitic Worms
Helminths
Roundworms
Nematodes
Giant Intestinal Roundworm
Ascaris lumbricoides
Whipworm
Trichuris trichiura
Old World Hookworm
Ancylostoma duodenale
New World Hookworm
Necator americanus
Threadworm
Strongyloides stercoralis
Pinworm, Seatworm
Enterobius vermicularis
Tapeworms
Cestodes
Pork Tapeworm
Taenia solium
Beef Tapeworm
Taenia saginata
Fish Broad Tapeworm
Diphyllobothrium latum or Dibothriocaptalus latus
Flukes
Trematodes
Flukes that has both male and female sex organs.
Monoecious Flukes
Sheep Liver Fluke
Fasciola hepatica
Lung Fluke
Paragonimus westermani
Flukes that was separated male and female sex organs.
Dioecious Flukes
i. Schistosoma japonicum
ii. Schistosoma mansoni
iii. Schistosoma haematobium
Dioecious Flukes
1250 to 1200 BC: Described “fiery serpents” which is most likely Dracunculus medinensis (Guinea worm) which struck down the Israelites in the region of the Red Sea after the Exodus from Egypt.
Bible
Contains the first written records of intestinal worms that were confirmed by the discovery of calcified helminth eggs in mummies dating from 1200 BC. Detailed account of aat swelling in the limbs among some ancient Egyptians; aat appears as the nature of infection with Dracunculus medinensis and techniques for removing the worm. Gave detailed description of aaa (possibly Hookworm infection) among ancient Egyptians.
Ebers Papyrus
Described worms from fishes, domesticated animals, and humans.
Hippocrates
Were familiar with Ascaris lumbricoides, Enterobius vermicularis and tapeworms belonging to genus Taenia.
Roman Physicians Celsus and Galen
Clearly described Ascaris, Enterobius, and tapeworms; Also gave good clinical descriptions of their respective infections.
Paulus Aegineta
Arabic physician who recognized the guinea worm, Dracunculus medinensis.
Avicenna
Father of Taxonomy
Described & named six helminth worms
i. Ascaris lumbricoides
ii. Ascaris vermicularis (now Enterobius vermicularis)
iii. Gordius medinensis (now Dracunculus medinensis)
iv. Fasciola hepatica
v.Taenia solium
vi. Taenia lata (now Diphyllobothrium latum)
Carolus Linnaeus
Discovered Giardia lamblia, the first parasitic protozoan in humans.
Anton van Leeuwenhoek (1681)
Discovery of Entamoeba histolytica, the causative agent of amoebiasis.
Friedrich Losch/ Fedor Lesh (1873)
Identified Trypanosoma brucei gambiense which causes chronic sleeping sickness.
Everett Dutton (1902)
Identified Trypanosoma brucei rhodesiense that causes acute sleeping sickness.
J.W.W Stephens & Harold Fantham (1910)
Discovered that malaria is caused by protozoans known as the Plasmodium species.
Alphonse (Charles) Laveran (1880)
Discovered that mosquitoes can transmit can transmit malaria to birds. Establish mosquitoes (Female Anopheles) as vectors. Contributed significantly to the study of the life cycle of Plasmodium spp.
Ronald Ross (1897)
Gave the first detailed anatomy of A. lumbricoides.
Edward Tyson
Gave another detailed description of A. lumbricoides. The publications by Tyson and Redi marked the beginnings of the subdiscipline of helminthology, which reached a peak in the 19th century.
Francesco Redi
Demonstrated that ingestion of eggs of A.
lumbricoides as correct mode of transmission.
Casimir Joseph Davaine (1862)
Validated Davaine’s work; Infected himself with
eggs of A. lumbricoides & subsequently found eggs in his feces.
Giovanni Battista Grassi (1862)
DiscoveredthelifecycleofA.lumbricoidesincludingthemigrationoflarval stages around the body. Infected a volunteer and himself; Subsequently found large numbers of larvae in his sputum.
Shimesu Koino (1922)
Scientists used the term ‘Egyptian chlorosis’ to describe the greenish
pallor associated with Hookworm infection.
19th Century
Found hookworms in a human patient.
Angelo Dubini (1838)
Established the association between Hookworm
infection and the (then) unknown disease characterized by anemia, greenish
yellow pallor and laziness.
Wilhelm Griesinger (1854)
Established the real connection between pallor and
Hookworm infection while investigating the diseases of miners in the St. Gothard tunnel.
Edoardo Perroncito (1879)
“Hookworm & Strongyloides stercoralis larvae enter the body by boring through the skin”. Accidentally infected himself with the hookworm larvae. Deliberately placed S.stercoralis on his skin; Found larvae in his feces 64 days later.
Arthur Looss (End of 19th century)
Discovered T.spiralis worm in humans.
James Paget (1835)
Discovery of the adult worms of T. spiralis.
Rudolf Virchow (1859) and Friedrich Zenker (1860)
Recognized the clinical significance of infection;
Concluded that infections come from eating raw and improperly cooked pork.
Friedrich Zenker (1860)
Scientific observations on the tapeworms of humans, dogs, and other animals. Recognize the “head” (scolex) of a tapeworm.
Edward Tyson (Late 17th Century)
First to state that intermediate hosts are involved in the life cycles of Taenia. Observed that the scolices of the tapeworm in humans resembled cysts in the muscle of pigs.
Johann Goeze (1784)
Middle of the 19th century: Recognized the difference between Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm). 1850s: In a much-criticized experiment, fed pig meat containing Taenia solium to criminals condemned to death and recovered adult tapeworms after they had been executed.
Friedrich Heinrich Kuchenmeister
Confirmed that eating “measly” beef causes tapeworm infections.
Edoardo Perroncito (1877)
Laboratory Examination of Stool Samples
Routine Fecalysis
Observation of Color, and Stool Consistency
Macroscopic Examination
Passage of black , tarry stools are called as melena Causes of black, tarry stools. Upper gastrointestinal (GI) bleeding (esophagus, stomach, duodenum). Ingestion of iron, charcoal, or bismuth.
Black, Tarry Stool
Passage of stools with fresh blood due to lower gastrointestinal (GI) bleeding is called as hematochezia Causes of a bright red stools. Lower GI bleeding (colon, rectum) Medications such as Rifampin and foods including beets.
Bright Red Stool
Caused by blockage of bile duct or use of
barium sulfate.
Pale/Chalky Stools
Observed in patients taking oral antibiotics and
increased intake of green vegetables or food coloring.
Green Stools
Caused by ingestion of milk diet, cornmeal, rhubarb
and fats.
Yellow Stool
Normal Stool Color
Light to Dark Brown
Stool Consistency
Soft to Well-Formed
Stool Quantity
100-250 Grams Per Day
Stool Odor
Foul to Offensive
Stool ph Level
7.0-8.0
Necessary to identify helminth eggs and larvae as well as protozoans.
Microscopic Examination
One or two drops of normal saline solution (NSS) is aspirated and transferred onto a glass slide. A clean wooden applicator stick is then used to acquire a representative portion of the fecal sample. The wooden stick (now containing the sample) is then applied over the NSS to prepare a fecal emulsion. A cover slip is placed on top followed by microscopic examination.
Saline Wet Mount
Similarly prepared as saline wet mount, only that a solution of iodine (Lugol’s iodine) is used instead. Best in highlighting details of protozoan cysts, thus, it may aid in correct identification.
Iodine Wet Mount
Most frequently performed fecal chemical examination. Used to detect “occult” or “hidden” blood that may be present in fecal samples. Necessary because any bleeding in excess of 2.5 mL/150 g of stool is PATHOLOGICALLY SIGNIFICANT and there may be no visible signs of bleeding with
this amount of blood.
Fecal Occult (Hidden) Blood Testing (FOBT)
For the early detection of colorectal cancer. Recommended by the American Cancer Society especially for those >50 years old.
Mass Screening Procedure
