Holmes Parasite Review Flashcards
Define parasite.
an organism which lives upon or within another living organism at whose expense it obtains some advantage.
Which parasite causes the most death worldwide every year?
Malaria
What is the definitive host?
The host in which sexual reproduction occurs
What is the intermediate host?
The host in which sexual reproduction does not occur
T or F: Most protozoan parasites can replicate in humans.
TRUE
T or F: Most worm parasites can replicate in humans.
False. Most develop but do not replicate in humans
What is tropism?
The ability of parasites ot infect specific tissues
What is essential for preventing and understanding parasitic diseases?
Understanding the parasite life cycle
What are some mechanisms parasites have to evade the host immune system?
Encapsulation, intraluminal location, immunosuppression, acquisition of host antigens
T or F: Drugs that work on parasites often target bacteria and viruses.
False.
What are the two main classes of human parasites?
worms and protozoa
Where are most schistosomes found?
Africa, SA, some equatorial Asia
T or F: The morphology of the parasite is much more important in making a diagnosis than in bacterial infections.
TRUE
Describe the lifecycle of the schistosome.
Asexual reproduction in snail, swimming cercariae released into water which can burrow into skin, enter human circulation (lose tail), migrate to blood vessels and grow up, sexually reproduce, release eggs into circulation, eggs find ways into feces
What is most of the schistosome toxicity associated with?
Immune response to schistosome eggs, which can result in liver scarring
T or F: Humans are the intermediate host of schistosomes.
False. Definitive host
What is cercarial invasion?
Dermatitis 2-3 days after skin invasion
What are the short term complications of schistosomiasis?
Acute Schistosomiasis (Katayama fever) - A serum-sickness illness with lymphadenopathy and hepatosplenomegaly 4-8 weeks after skin invasion
What is the major cell type see to expand in parasite infection?
Eosinophils
List some control strategies for schistosomes. (5)
1.) Avoid contact with infected water 2.) Construct wells and latrines 3.) Mass treat populations 4.) Kill the snails 5.) Ongoing research on tests, vaccines, and drugs
Describe the location of malaria.
Southern hemisphere africa, asia, middle east, south america.
What is the intermediate host for malaria (plasmodium)?
Mosquito
Which species of plasmodium cause the most severe disease?
P. falciparum
Describe the life cycle of malaria parasites.
Human injected with sporozoites by a female mosquito, Sporozoites become merozoites in the liver and infect RBCs, merozoites become gametocytes which reproduce to gametes and can then be picked up by mosquito again.
What are some of the symptoms of malaria?
Anemia, splenomegaly, nephritis, DIC, tissue hypoxia due to microvasculature damage (leading to multiple organ system effects)
Why does P. falciparum cause such severe disease?
Cause membrane protuberances on RBCs which damage microvasculature, cause RBCs to stick together and to blood vessels
T or F: Acquired immunity prevents high level disease and prevents reinfection.
False. Can get reinfection.
T or F: There are malaria vaccines available.
FALSE
What type of RBCs to P. falciparum preferentially infect?
Young RBCs, but can infect cells of all ages.
Which genetic diseases increase resistance to Falciparum malaria?
Sickle cell disease, G6PD deficiency, thalassemia, ovalocytosis
