Parasitology Exam Questions With 100% Correct Answers 2024

Parasitology Exam Questions With 100% Correct Answers 2024 How does chloroquine work to treat plasmodium infection? - answer-drug diffuses through erythrocyte, into parasite digestive vacuole -drug inhibits conversion of heme to hemezoin -heme builds up in toxic levels, causing lysis What are the mechanisms of drug resistance? - answer-inhibiting drug uptake -excreting drug -blocking drug activation -inactivating drug How does combination therapy help avoid multidrug resistance? - answer-in an infection, there are some parasites resistant to drugs -using combination of drugs allows all parasites to be killed, even those with a resistance to a specific drug -treating with a single drug would allow the resistant ones to survive, reproduce, and mutate to get further resistance What factors can contribute to natural transmission of malaria? - answer1. Human & animal reservoirs- prevalence of infection and level of parasitemia in humans & other primates 2. Vectors- suitability of mosquito breeding habitats 3. New hosts- vector competence & availability of non-immune hosts 4. Local environmental conditions- climate, geographical conditions, human migration, and human activities that determine accessibility of mosquito breeding areas Mosquito control programs for malaria - answer-Insecticide (DDT) treatment of breeding habitats - Genetically-modified mosquitoes (e.g. resistant to parasite infection or by introduction of sterile males) - Introduction of mosquito-eating fish (e.g. Gambusia) in ponds - Insecticide-treated sleeping nets Treatments for malaria - answer-Chloroquine and derivatives (primaquine, mefloquine, pyrimethamine), sulfonamides, tetracycline - Artemisinin (traditional herbal medicine) - Vaccines (e.g. Mosquirix) recently approved & others currently under development Toxoplasma gondii is the cause of? - answertoxoplasmosis which can persist as a chronic infection Toxoplasma gondii is found? - answerthroughout the world- estimated that up to 1/3 of the world's population is chronically infected Toxoplasma gondii reproduction has both - answersexual and asexual phases Toxoplasma gondii sexual phase occurs only in? - answercats and other felines The definitive host of Toxoplasma gondii is? - answercats/felines Toxoplasma gondii can have predator-prey transmission between? - answercats and rodents The asexual phase of Toxoplasma gondii can occur in? - answerany warm blooded vertebrate The intermediate hosts of Toxoplasma gondii are - answerwarm blooded vertebrate The three infectious stages of Toxoplasma gondii are? - answer-oocysts -tachyzoites -tissue cysts Toxoplasma gondii oocysts contain? - answersporozoites Toxoplasma gondii tachyzoites - answerrapidly proliferation stage found in any cell of the intermediate host or in non intestinal epithelial cells of the definitive host Toxoplsma gondii tissue cysts - answer-contain bradyzoites -slowly replicating intracellular stage Toxoplsma gondii tissue cysts are most commonly found in? - answermuscle and brain Toxoplasma gondii life cycle - answer-Felids ingest intermediate host containing tissue cyst -merogony followed by gametogony in cat intestine results in production of unsporulated oocysts, which are passed in cat feces -oocysts directly infective to cats or ingested by intermediate host -oocyte ingested by intermediate host, sporozoites released -sporozoites invade intestinal epithelial cells and then macrophages which disseminate the parasite -following a phase in which fast dividing tachyzoites are found in host cells, more slowly replicating bradyzoites develop in host cells, and become encapsulated to form tissue cyst Cats/felines usually get infected with Toxoplasma gondii infection by? - answerconsumption of an intermediate host containing the tissue cyst or sometimes via tachyzoites or ingestion of oocysts from environment Toxoplasma gondii cat life cycle - answerBradyzoites invade cat small intestine → merozoites/meronts → infect other intestinal cells → development of male & female gametes → sexual reproduction → zygote → sporozoites →Sporozoites encyst (thick-walled) → unsporulated oocysts shed in cat feces In Toxoplasma gondii formation of infective sporulated oocysts occurs? - answeroutside of hosts Toxoplasma gondii sporulated oocysts can survive? - answercold & dehydration (remain infectious in moist soil for up to 18 months), and are resistant to disinfectants How much of the domestic cat population has Toxoplasma gondii? - answer74% Describe the experiment to determine how Toxoplasma knows what host it is in? - answer- constructed cat intestinal "organoids" (simple, miniature three dimensional versions of organs made in vitro) -infected cat intestinal organoids with Toxo bradyzoites, and saw that the development into gametes and oocysts was weak -supplemented with linoleic acid, and development was strong How does Toxoplasma gondii know whether it is in a cat? - answer-linoleic acid is the dominant fatty acid in cat serum -most mammals convert it into arachidonic acid -cats lack the necessary enzyme to convert Ingestion of infectious Toxoplasma gondii oocyte by intermediate host releases? - answersporozoites that invade the gut epithelial cells, and multiply In the intermediate host, Toxoplasma gondii sporozoites sometimes leave the intestinal cells to invade? - answermacrophages, then enter the circulation and invade other cells before transforming into tachyzoites If Toxoplasma gondii sporozoites spread in the intermediate host circulation and transform into tachyzoites, it results in? - answerhost cell being consumed by tachyzoites and dying. Tachyzoites are released to infect new cells, causing acute infection What happens in acute Toxoplasma gondii infection? - answer-sporozoites spread in the intermediate host circulation and transform into tachyzoites -host cell is consumed by tachyzoites and dies -Tachyzoites are released to infect new cells Toxoplasma gondii tachyzoites are typically found in the? - answerreticuloendothelial system Toxoplasma gondii infection acute phase is followed by? - answertransformation of tachyzoites into bradyzoites (chronic phase) Toxoplasma gondii infection chronic phase occurs when - answertachyzoites transform into bradyzoites Toxoplasma gondii tissue cysts can b