Parasitology Flashcards
Apicomplexia
Protozoa, include parasites that affect the GI tract and parasites that may affect blood and tissue
Plasmodium
Include vivax, ovale/malariae, falciparum. Causes malaria
Describe the life cycle of malaria
- anopheles mosquito bites human
- Sporozoite enters liver cell, matures into merozoite and enters blood
- Develop into trophozoite, RBC rupture releasing merozoite
- Some become gametocytes which are ingested by mosquito
- Gametocytes develop into sporozoite in mosquito, cycle begins
Clinical presentation of malaria
Hx of recent travel to tropics and subtropics. Fever due to RBC rupture. Anemia due to RBC destruction
Taenia saginata
cestode, beef tapeworm
Taenia solium
cestode, pork tapeworm
Cysticercus
larval of taenia solium which forms in human tissue. Most commonly in brain causing neurocysticercus
Cysticercosis
cyst like lesions in the muscle, skin and brain caused by the ingestion of T. solium eggs. “measly” lesions look similar to infected pork
How do we diagnosis intestinal taenia infections?
Finding characteristic eggs in the patient’s stool.
Cysticercosis is dx by specific EIA and confirmed by radiographic evidence of multiple tissue cysts
Diphyllobothrium latum
fish tapeworm
Often seen in northern Europe and Japan. Megaloblastic anemia due to B12 deficiency
schistosomiasis
trematodes- contact with freshwater contaminated with larval forms of schistosomes which penetrate skin.
Include: S. Mansoni, S. Japonicum (blood flukes) and S. Haematobium (bladder fluke)
S. Mansoni and S. Japonicum
Acute infection: “katayama’s fever” including abdominal pain, diarrhea, fever and hepatosplenomegaly
Diagnosed by stoop O&P for recovery of ova
S. Haematobium
causes bladder infection- hematuria and pyuria.
Diagnosed by urine for recovery of ova
nematodes
multicellular metazoan
have a cylindrical body and complete digestive tract
Also called roundworms. Can infect the GI tract or the blood and tissues of humans
Enterobius vermicularis
pin worm- most common helminthic infection in US
often in children, transmitted via fecal-oral
perianal itching
Trematodes
flukes
Definitive host (humans) Intermediate host (fresh water snails)
transmission: penetration of the skin or ingestion of cysts in undercooked fish or crab
cestodes
tapeworms
Consists of Scolex (rounded head) and flat body
Transmission: ingestion of undercooked meat/fish containing larvae
infects GI or blood/tissue
protozoa
single celled
reproduce sexually or by simple binary division
Trophozoite: mobile feeding and reproducing form
Cyst: non-mobile, dormant form
Classes of protozoa
amoebas, flagellates, ciliates and apicomplexia
How is Giardia acquired?
one of the most common parasitic infections in the US.
Acquired by drinking contaminated water. Trophozoite coats the small intestine, interfering with fat absorption.
greasy diarrhea
How do we diagnosis Giardia
stool O&P
stool or serum for antigen testing
serology
treatment for Giardia
Metronidazole (Flagyl)
Trichomonas
Flagellate that causes STD
frothy, green, malodorous discharge.
Amebiasis
caused by Entamoeba histolytica.
Causes dysentery so pts may present with blood diarrhea. Can also go to liver from colon and cause liver abscess.
Ingested RBCs can be seen in cytoplasm
Name the 4 protozoa that cause malaria
Plasmodium falciparum-most common/deadly
Plasmodium vivax- chronic liver disease
Plasmodium ovale
Plasmodium malaria
Clinical presentation of malaria
fever, chills, sweats. hx of recent travel
life cycle of malaria
- Mosquito (vector) carries organisms within its salivary glands and injects them into humans while it feeds
- Sporozoites enter liver and sporozoites mature into merozoites
- organism grows in liver and spread RBCs which then burst
- Can lead to anemia and sticky RBCs that clot in organs
- Plasmodium vivax and plasmodium ovale create hypozoites in liver (latent form) which causes relapses.
How do we diagnosis malaria?
exam blood under microscope (can see trophozoites in RBCs)
antigen detection tests
how can we prevent malaria
long sleeved clothes/pants
insect repellant
prophylactic drugs prior to travel
Trichuris trichiura
whipworm
usually seen in tropical climates
pts often asymptomatic but may have abdominal pain and diarrhea
Ascaris lumbricoides
large intestinal worm
most common helminthic infection worldwide
may be asymptomatic
worms vomited up/removed from nares
Necator americanus
hookworm
causes severe nutritional deficiency
seen in sub-saharan Africa, latin america and Caribbean
Anclyostoma duodenale
hookworm
causes severe nutritional deficiency
Strongyloides stercoralis
can result in life-threatening, disseminated hyper infections in immunosuppressed people
Trichinella spiralis
usually acquired by eating undercooked pork
Echinococcus granulosus
hydatid disease- pain as cyst containing the larva grow in the liver and lung.
Intermediate hosts: sheep, goat and pigs.
Definite host: dogs
Echinococcus multilocularis
alveolar disease
Acanthamoeba
CNS infection. Keratitis in people who wear contacts
free living in contaminated water and soil
Naegleria fowleri
trophozoite enters nasal mucosa goes to CNS. Causes amebic meningoencephalitis (fatal)
contracted during recreational water activities in fresh and warm water
Trypanosoma brucei rhodeisense
and
Trypanosoma brucei gambiense
African sleeping sickness by tsetse fly
causes changes in behavior,
confusion and changes in sleeping cycle
Trpanosoma cruzi
Chagas disease by reduviid (kissing bug)
Leishmania
sandfly bites human, transmitting promastigote, infecting macrophages
Cryptosporidium parvum/hominis
severe chronic diarrhea in HIV patients
Cyclospora cayetanensis
severe diarrhea in immunocompromised
acid-fast stain
