Parasites Flashcards
What are the three different groups of parasites?
Protozoa
Helminths
Ectoparasites
Amoeba are protozoan parasites. What is the name of their cytoplasmic protrusions and what are their 2 different forms may occur as?
Amoeba have cytoplasmic protrusions called pseudopodia. They may occur as trophozoites which are the active growing forms or as cysts which are environmentally protected forms (like spores)
Entamoeba histolytica is a gut amoeba pathogen. What are the symptoms it causes and how and how is it transmitted?
E. histolytica symptoms range from asymptomatic to acute or chronic diarrhea caused by burrowing into the colonic wall causing bleeding. Transmitted by feces, oral, contaminated food/water
Giardia lamblia is a flagellated protozoan parasite that has the same transmission and symptoms as E. histolytica. How is it diagnosed?
Microscopy of stool or detection of antigen in stool via EIA
What is the flagellated protozoan parasite responsible for vaginitis? What is the special feature of its life cycle that influences its transmission? How is it detected?
Trichomonas vaginalis. It lacks a cyst form and can therefore only be transmitted in the trophozoite form which is very fragile. It is detected by microscopy of discharge for live organisms or with staining for non-viable organisms
Trypanosoma species are responsible for a number of disease. What are the specific species responsible for African sleeping sickness and South American chagas disease? What is the vector for each disease?
African: T. brucei, Tse-tse fly
South american: T. cruzi, reduvid bug
What morphological characteristic could you use to distinguish between Trypanosoma brucei and Trypanosoma cruzi?
Brucei are more “C” shaped than cruzi
Describe the basic characteristics of the protozoan phylum Apicomplexa and the 3 disease the pathogenic species cause
Apicomplexa are obligate intracellular parasites whose mature forms are non-motile. The 3 diseases they cause are malaria, cryptosporidiosis and toxoplasmosis
What is malaria and the organism responsible for the disease? How is it detected?
Malaria is episodic fevers and anemia caused by protozoan parasites Plasmodium spp.
Malaria is detected by staining blood samples and looking for parasites
What type of disease does cryptosporidium spp. cause? How is the disease transmitted and detected?
Cryptosporidium may cause watery diarrhea. They are transmitted fecal-oral, water or zoonotic. Can be detected by microscopy of stool or antigen detection in stool by EIA
What group of people are most at risk for severe disease from Toxoplasma gondii infection and why? How is the protozoan transmitted and detected?
Usually asymptomatic infection but can cause fetal defects during pregnancy. Transmitted by poorly cooked meat or cat stool. Detected by serology
What type of worms are platyhelminthes?
Flat worms
What type of flat worm are cestodes? Descibe their morphology
Tape worms. They are ribbon-like and segmented. They lack a digestive system and attach to the host gut wall via a scolex
Describe the life cycle of cestodes (tape worms)
The gut of the definitive host contains adult worms which lay eggs (ova) that get passed into the environment. An intermediate host will ingest the ova. The ova develop into larvae in the intermediate host tissue. The definitive host ingests the intermediate host and becomes infected with larvae. The larvae develop into the adult form in the host gut.
What are the 2 principle cestode pathogens, the disease they cause, their intermediate hosts and how they’re detected in the definitive host
Taenia saeginata (beef) and Taenia solium (pork). They can cause abdominal discomfort in humans. Detected by the presence of ova or adult segments in stool.
