Parasitology Flashcards
(13 cards)
Terminology
Symbiosis, Mutualism, Commensalism, Parasitism
Symbiosis: Two species live together usually to mutual benefit
Mutualism: symbiotic relationship where each member benefits
Commensalism: 1 species benefit, other species neither benefit nor harm
Parasitism: 1 species lives at expense of other, inflicts injury/damage
Terminology
Host, Definitive Host, Intermediate Host, Accidental Host, Paratenic Host
Host: organism in which parasite lives
Definitive Host: harbors adult (sexual) stage of parasite
Intermediate Host: harbors larval (asexual stage of parasite)
Accidental Host: harbors organism not ordinarily parasitic in particular species
Paratenic Host: harbors form of parasite that does not undergo further development
Terminology
Reservoir, Vector, Zoonosis, Autochthonous
Reservoir: animal (definitive) host that enables a parasite to persist
Vector: Insect that transmits infectious microorganisms from one host to other
Zoonosis: disease/infection naturally transferrable between animals and humans
Autochthonous: indigenous; infection acquired in AREA it is diagnosed
Terminology
Cestode, Nematode, Trematode
Cestode: tapeworm
Nematode: roundworm
Trematode: flatworm/fluke
Pathogenic v. Non-pathogenic Protozoa
Non-pathogenic: E. dispar, E. moshkovskii, E. Bangladeshi, E. coli, E. hartmanii
Dientamoeba fragilis, Endolimax nana, Iodamoeba buetschlii
Chagas Disease (CP, Testing)
Chagas Disease: (American Trypanosomiasis: Trypanosoma cruzi)
CP: Acute – periorbital edema: inflammatory lesion at site of entry (scratched in)
Fever, anorexia, hepatomegaly, lymphadenopathy, infant death
Chronic - Myocarditis – pseudocyst in myocardium - cardiomyopathy
GI disease (Megaesophagus, Megacolon) – pseudocyst in SMC
Loss of bowel muscle tone – dilation – megaly
Testing: Blood donor and organ donor screenings; SEROLOGIC
African Sleeping Sickness (CP, Testing)
African Sleeping Sickness: (African Trypanosomiasis: Trypanosoma brucei)
CP: Acute – abrupt fever, headache, occipital lymphadenopathy, bite reaction
Chronic – Meningoencephalitis, subtle personality changes – coma – death
Testing: Identification of trypomastigotes in blood smear/CSF
Leishmaniasis (CP, Testing)
CP: Visceral Leishmaniasis (L. donovani)
parasites in macrophages of reticuloendothelial system
fever, hepatosplenomegaly, pancytopenia
Cutaneous Leishmaniasis, Old World (L. tropica, L. aethiopica)
Chronic, non-healing ulcer with heaped-up margins
Cutaneous/Mucosal Leishmaniasis: New World (L. brazillensis/panamensis)
Feared complication of spreading to sinus mucosa – mutilating cartilage
Testing: Skin biopsy lesion/culture look for amastigotes
Malaria (CP, Testing)
CP: RBC lysis & progressive anemia, fever, systemic inflammatory response
Disordered coagulation, capillary leak syndrome, sepsis, acidosis
Capillary occlusion: jaundice, renal failure, CNS injury
Testing: History – recurrent fever spikes (Malariae - 3 days, knowlesi - 1 day, ovale/vivax - 2 days, falcip - erratic), blood smear,
rapid Dx (non-falcip and falcip tests), PCR
Schistosoma life cycle
Eggs excreted in feces/urine – contaminate fresh water
Miracidium hatches from egg and penetrates snail
In snail, develops from miracidium to sporocyst to cercariae – released into water
Cercariae penetrate human skin develop to schistosomulae travel to portal circulation
Adult worm pair lives in portal circulation, produces eggs
(Egg – miracidium – sporocyst – cercariae – schistosomulae – makes eggs)
Plasmodium Life Cycle
Sporozoites injected via blood meal of mosquito
Sporozoites infect Kuppfer cells (liver macrophage) – amplify/release merozoites
Persist as hypnozoites latently in liver
Merozoites infect RBCs, differentiate in RBC to trophozoite,
Then to schizont (replicative form), then merozoites (progeny)
Schizont can also differentiate to gametocytes – taken up by mosquito meal
In mosquito, gametocytes differentiate/sexually replicate to sporozoites
(Sporozoites – hypnozoites & merozoites – schizont – merozoites & gametocytes)
Risk factors for echinococcosis
Near Wild Canines/Pet Dogs - from feces
Wolbachia
Infect filariae (W. bancrofti, B. malayi, O. volvulus, NOT LOA LOA)
Mutualistic endosymbiont – needed for filariasis survival in host and reproduction
Dying filariae – release of Wolbachia antigens to elicit inflammation
Higher Wolbachia numbers in Savanna strain of O. volvulus contribute to added
Blindness (due to more inflammation and swelling)
