Parasitic Infection Flashcards
What causes a parasitic disease?
Consequence of prolonged, repeated, or high burden infection
What do most parasites require to complete their life cycle?
Human AND nonhuman hosts.
What are the two types of parasitic infections?
Protozoa and helminths
What causes disease from protozoa infection?
Disease is consequence of parasite replication to high numbers (small inoculum required to initiate infection)
In what cells do intracellular protozoa grow?
RBC and macrophages
Where do extracellular protozoan grow?
Lumen of GI tract
What are helminths?
Worms
Are helminths capable of completing their life cycle in humans?
Not typically
What type of infections helminths cause?
- Usually chronic infections that are tolerated by the human host.
- Disease is NOT a consequence of parasitic replication. (Number of worms in is highest number of worms possible)
What arthropod is associated with malaria?
Female Anopheles mosquito
What is a reservoir?
Sources of parasites that do not participate DIRECTLY in transmission
What are the three different types of parasite entry?
Oral ingestions (contaminated food/water); Penetration of the skin (doesn’t have to be broken); Arthropod-borne (bug bites)
What determines the spread and multiplication of parasites?
Species, tissue tropisims, and temperatures.
What is the most important of all the protozoan diseases?
Malaria
What type of cells does malaria target?
RBC
What type of RBC does Plasmodium falciparum target?
All ages of RBC
What type of RBC does Plasmodium vivax/Plasmodium ovale target?
reticulocytes and young RBC
What type of RBC does Plasmodium malariae target?
Older RBC
What is the reproductive process for Plasmodium?
Enter body (through bite) as sporozoites and travel to liver. Become Merozoites which leave liver and attack RBC. Mature into Trophozoite in RBC or gametocytes which can be picked up by other bug bites.
What is a typical paroxysm?
Simultaneous lysis of many RBCs and release of large number of merozoites and other parasitic molecules every 48-72 hours.
What drug can be used to battle malaria? What does it do?
Choloroquine - targets parasites food vacuole where hemoglobin is degraded.
What does Babesia do?
Destroy red blood cells - easily confused with P. falciparum
What is the babesia life cycle?
Merozoites injected by tick bite. RBCs are invaded (NO LIVER STAGE) replication via binary fission. Lyse RBCs ticks feed on infected RBCs to keep cycle.
Toxoplasma gondii targets what type of cell?
Tissue (Monocytes)
What syndromes can be a result of Toxoplasma?
Mononucleosis-like; Congenital infection; Brain/heart (immunocompromised)
How is toxoplasmosis consumed?
Consumption of inadequately cooked meat (tissue cysts) or food contaminated with cat feces (oocysts)
The cyst of toxoplasma with transform into what?
Tachyzoites (target intestinal wall)
How are Leishmania transmitted?
By sandflies
What is Leishmania’s life cycle?
Begins as flagellated Promastigote which binds to macrophages (produces superoxide dismutase). While in macrophage, sheds flagella and becomes amastigote which eventually kills macrophage. It then goes and finds more macrophages to feed on.
What causes Chagas’ disease?
Trypanosoma cruzi
How are trypanosoma cruzi transferred?
Reduviid (kissing) bug bites and deposits feces into bite.
What does trypanosoma brucei cause?
African sleeping sickness
What transfers African sleeping sickness?
Tsetse flies (Glossina). Trypanosoma brucei is introduced directly into the bloodstream.
What is Giardia lamblias reproductive cycle?
Cysts exist in the environment. What they encounter stomach acid, they are stimulated to transorm to vegetative trophozoites
What is different about Giardia lamblia infections and Entamoeba infections?
Giardia lamblia causes mild persistant diarrhea while Entamoeba causes bloody diarrhea.
What causes vaginitis?
Trichomonas vaginalis (15% or more of women)
What cells does Entamoeba histolytica target?
Host colon cells.
How does Entamoeba histolytica damage the host?
Attachment kills the colon cells; After killing cells they ingest them to meet nutritional needs
Why are antibodies not likely effective against Entamoeba histolytica?
Produce cysteine protease that digests IgA, and IgG.
What are required for ascaris infection to occur?
Eggs require several weeks in environment to mature and become ingested. Hatch in small intestine and release larvae that travel to lung to be swallowed and mature in GI lumen. Eggs released in stool
How does Enterobius (pinworms) differ from ascaris?
Enterobius DO NOT require maturation stage outside of body.
How do hookworms get into the body?
DO NOT REQUIRE INGESTION OR CUT. Can attach and burrow through skin. Travel through vessels through heart/lung where they are coughed up and swallowed where life cycle resumes.
What happens when one has a hookworm infection?
Suffer from chronic anemia. Hookworm attaches to intestinal wall and sucks blood. Severity is proportional to worm burden.
How are tissue and blood helminths acquired?
Ingestion acquired
