Parasites Flashcards
Protozoa are/need?
- Single celled
- Ingest solid particles
- Require aquatic environment
- Reproduce by binary fission
- Classified by means of locomotion
Helminths are ?
multicellular, macroscopic “worms” with organized internal structure
helminths can be subdivided into ?
flatworms and roundworms
What are ectoparasites?
insects and arachnida found living on the skin
What are 4 adaptations to a parasitic existence that some organisms have adopted?
- loss of structures/enzymes
- pathogenic adaptations like attachment mechanisms
- defense mechanisms
- increased reproductive capacity
Protozoa are classified based on..
means of locomotion
What two forms do Amoebae have?
trophozoites (active, growing) and cyst (environmentally protected)
What kind of movement mechanism do amoeba use?
pseudopodia
What is a pathogenic species of amoeba?
Entamoeba histolytica
What are the range of diseases that Entamoeba histolytica can cause?
from aymptomatic diarrhea to dystentery and liver disease
What is the transmission like for Entamoeba histolytica?
fecal oral
- contaminated water and food
Giardia lamblia is part of which phylum and order?
phylum metamonada
order diplomonadida
Giardia lamblia is a …. because it has..
flagellate, propelled by flagella
What gives giardia their shape?
rigid outer wall
What forms can giardia exist in?
cyst and troph form
What is the range of disease caused by giardia?
asymptomatic to acute/chronic diarrhea
What is the transmission of giardia?
fecal-oral and waterborne
What tools can you use to diagnose giardia?
microscopy of stool sample
EIA of antigens in stool
What is another flagellate (besides giardia) that does not infect the blood?
Trichomonas vaginalis
What does trichomonas vaginalis cause?
vaginitis
What is the transmission like for T. vaginalis ?
sexual
How do you detect T. vaginalis?
Microscopy of discharge (wet mount of discharge for live organisms, or gram stained for nonviable organisms) , culture (large or research centres only).
What is unusual about T. vaginalis compared to other flagellates
doesnt have a cyst form
Where can non-pathogenic trichomonas spp. be found?
in the oral cavity and gut
The Trypanosoma spp. are in which phylum and order?
phylum: euglenozoa
order: trypanosomatida
What are the two sp. of trypanosoma and what disease do they cause? Where? what is the vectori?
- T.b. gambiense: causes african sleeping sickness
- spread by the tse tse fly - T. cruzi: causes Chagas disease
- spread by the reduvid bug
What is another flagellate that infects the blood (other that trypanosoma) and is found in tropical areas?
leishmania
What does leishmania cause?
Leishmaniasis
- cutaneous or visceral infection
- often leading to hepatosplenomegaly
What are 3 features of the Apicomplexa phylum?
- mature forms are non-motile
- obligate intracellular parasites
- have complex life cycles
What are 3 diseases caused by members of the apicomplexa phylum?
- Malaria
- Cryptosporidiosis
- Toxoplasmosis
What are the symptoms of malaria?
episodic fevers and anaemia due to lysis of RBCs
What is used to detect malaria?
parasites stained on thick and thin smears of blood
What does cryptosporidium cause?
watery diarrhea that can become chronic in immunosuppressed people
How is cryptosporidium transmitted?
fecal-oral, water-borne, animals (zoonotic)
How is cryptosporidium detected?
Microscopy of stool with special stains or detecting antigen in stool with an EIA
What is the typical presentation of a toxoplasma gondii infection? When is it a problem?
Mainly asymptomatic but new infections during pregnancy can cause fetal malformations
Also infections in immunosuppressed people an issue
How is T. gondii transmitted?
by poorly cooked meat or ingestion of cat stoll
How is T. gondii detected
serology
The flatworms belong to which phylum of helminths?
platyhelminthes
What are the “tapeworms” called?
cestodes
What are some morphological features of the cestodes?
- Ribbon like
- Segmented
- No digestive system
- Hermaphroditic
- Attach to gut wall by scolex
- Larval forms in tissue
For the cestodes, who is the definitive host?
humans because the adult worms are found in the gut
What happens in the intermediate hosts of cestodes?
larva encyst in the tissues
How does the larval stages of the cestode get into the definitive host?
the definitive host eats the intermediate host and the larva can mature in the gut
What are the 2 principle cestode pathogens and what intermediate host do they come from?
- T. saginata in beed
2. T. solium in pork
How can you identify a cestode infection?
ID of ova or adult segments in stool
What is cysticercosis?
T. solium larvae in the tissues forming cysts throughout the body
How is cysticercosis transmitted?
Ingestion where mature proglottid ends up in the stomach, releasing the eggs that are distributed throughout the body
The flukes are another name for the..
trematodes
What are some features of trematodes?
- Leaf shaped
- hermaphroditic
- primative gut
- suckers for attachment
What is different about he life cycle of the trematodes vs. the cestodes?
the trematodes have 2 intermediate hosts
What pathogen that we discussed is a member of the trematodes?
Schistosoma spp/
What does schistosomiasis cause?
inflammation, hematuria, swelling of the abdomen due to blockage
How are schistosoma spread?
by penetration of the skin
How are schistosoma infections detected?
ova in stool/urine depending on the species
the “round worms” are part of which order/phylum?
Nematodes: Phylum Nemathelminthes
are the nematodes hermaphroditic?
nope they have separate sexes
Where do the nematodes inhabit? What do they cause
the GI tract
abdominal pain and discomfort
What is an example of a pathogenic nematode?
Ascaris lumbricoides
How are nematodes transmitted?
fecal oral
How is a nematode infection identified?
recognition of ova in the stool using microscopy OR identification of adult worms
Another type of nematode are…
hookworms
What disease/pathology do hookworms cause?
chronic blood loss
How are hookworms transmitted?
through penetration of skin by larvae
How do you detect hookworms?
identification of ova or larvae in the stool
What animal hookworm infection are you at risk of getting in the caribbean?
Cutaneous Larva Migrans
Filaria cause what kind of disease?
elephantiasis/fevers
Where do the adults/larvae inhabit in filarial infections?
Adult lives in and damages the lymphatic system
Larvae are released into the blood
What is the transmission of filarial infections?
mosquito borne
How can you detect a filarial infection?
staining of the parasite on a blood film
What is the difference between ectoparasites and micropredators?
Ectoparasites colonize the body while micropredators only bite
What are the two kinds of ectopredators and give 2 examples of each?
- Insects (6 legs) like fleas and lice
2. Arachnida (8 legs) like ticks and mites
What is the definition of definitive host?
the organism in which the adult or sexually mature stage of the parasite lives
What is the definition of the intermediate host?
the organism in which the parasite lives during a period of its development only
What is the definition of zoonosis?
a parasitic disease in which an animal is normally the host - but which also infects man
What is the definition of a vector?
a living carrier (i.e. arthropod) that transports a pathogenic organism from an infected to a non-infected host
