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Questions and Answers
What is the primary route of transmission of Trypanosoma brucei?
What is the primary route of transmission of Trypanosoma brucei?
What is the characteristic of the chancre that forms during the bite reaction stage of African trypanosomiasis?
What is the characteristic of the chancre that forms during the bite reaction stage of African trypanosomiasis?
What is the main reservoir for Trypanosoma brucei gambiense?
What is the main reservoir for Trypanosoma brucei gambiense?
What is the characteristic of the CNS stage of African trypanosomiasis?
What is the characteristic of the CNS stage of African trypanosomiasis?
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What is the purpose of examining cerebrospinal fluid in African trypanosomiasis?
What is the purpose of examining cerebrospinal fluid in African trypanosomiasis?
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What is the mechanism of replication of trypomastigotes in the host?
What is the mechanism of replication of trypomastigotes in the host?
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What is the stage of the parasite that transforms into metacyclic trypomastigotes in the tsetse fly?
What is the stage of the parasite that transforms into metacyclic trypomastigotes in the tsetse fly?
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What is the treatment of choice for the blood stage of African trypanosomiasis?
What is the treatment of choice for the blood stage of African trypanosomiasis?
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What is the primary mechanism of transmission of malaria from an infected mosquito to a human host?
What is the primary mechanism of transmission of malaria from an infected mosquito to a human host?
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Which stage of the malaria parasite's life cycle is responsible for multiplying in the human liver?
Which stage of the malaria parasite's life cycle is responsible for multiplying in the human liver?
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What is the term for the process by which the malaria parasite multiplies in the mosquito?
What is the term for the process by which the malaria parasite multiplies in the mosquito?
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What is the typical periodicity of fever in P. malariae infections?
What is the typical periodicity of fever in P. malariae infections?
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What is the primary effect of malaria on the human body's red blood cell production?
What is the primary effect of malaria on the human body's red blood cell production?
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What is the term for the stage of the malaria parasite that invades the midgut wall of the mosquito?
What is the term for the stage of the malaria parasite that invades the midgut wall of the mosquito?
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Which of the following is NOT a symptom of malaria?
Which of the following is NOT a symptom of malaria?
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What is the term for the stage of the malaria parasite that infects red blood cells?
What is the term for the stage of the malaria parasite that infects red blood cells?
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What is the primary host of Toxoplasma gondii?
What is the primary host of Toxoplasma gondii?
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What is the timeframe for oocysts to become infective after excretion?
What is the timeframe for oocysts to become infective after excretion?
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What is the most common location of tissue cysts in humans?
What is the most common location of tissue cysts in humans?
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What is the result of congenital toxoplasmosis?
What is the result of congenital toxoplasmosis?
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What is the typical outcome for immunocompromised individuals infected with Toxoplasma gondii?
What is the typical outcome for immunocompromised individuals infected with Toxoplasma gondii?
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What is the treatment for acute toxoplasmosis?
What is the treatment for acute toxoplasmosis?
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Study Notes
Toxoplasmosis
- Caused by the parasite Toxoplasma gondii, which is transmitted through carnivorism
- The life cycle of Toxoplasma gondii involves:
- Ingestion of tissue cysts or oocysts by a cat
- Release of viable organisms that invade epithelial cells of the small intestine
- Asexual and sexual cycles in the small intestine, followed by formation of oocysts
- Excretion of oocysts, which take 1-5 days to sporulate and become infective
- In humans, the parasites form:
- Tissue cysts (bradyzoites) in skeletal muscle, myocardium, and brain
- Blood tachyzoites that can infect the fetus through the bloodstream
Infection and Symptoms
- Asymptomatic in normal individuals
- Congenital toxoplasmosis can result in:
- Abortion
- Serious brain and eye damage to the fetus
- Retino-chorditis or mental retardation in childhood
- In immunocompromised individuals, infection can result in:
- Generalized parasitemia
- Involvement of brain, liver, lung, and other organs
- Often death
- Acute infection may produce flu-like symptoms, sometimes associated with lymphadenopathy
Diagnosis and Treatment
- Suspected toxoplasmosis can be confirmed by:
- Isolation of the organism from blood
- Serological testing
- PCR
- Treatment involves:
- Pyrimethamine in combination with sulfadiazine
- No treatment is needed for healthy individuals
Trypanosomiasis
- Caused by the parasite Trypanosoma brucei
- The life cycle of Trypanosoma brucei involves:
- Ingestion of infected blood by a tsetse fly
- Transformation into procyclic trypomastigotes, which multiply by binary fission
- Transformation into epimastigotes, which reach the fly's salivary glands and multiply by binary fission
- Transformation into metacyclic trypomastigotes
- The cycle in the fly takes approximately 3 weeks
- Humans are the main reservoir for Trypanosoma brucei gambiense, but it can also be found in animals
- Wild animals are the main reservoir of T.b. rhodesiense
Stages of Infection
- Bite reaction: A painful, itchy chancre forms within 1-3 weeks after the bite and lasts 1-2 weeks, leaving no scar
- Hemolymphatic stage: Marked by fever, malaise, insomnia, headache, and lymphadenopathy
- CNS stage: Marked by lack of interest, mental retardation, and uncontrollable urge to sleep, leading to death from coma or cardiac failure
Diagnosis and Treatment
- Detection of parasite (trypomastigotes) in the bloodstream, lymph secretions, and enlarged lymph node aspirate provides a definitive diagnosis in early stages
- Cerebrospinal fluid must always be examined for organisms
- Immuno-serology (enzyme-linked immune assay, immunofluorescence) may be indicative but does not provide definite diagnosis
- The blood stage of African trypanosomiasis can be treated with reasonable success with Pentamidine isethionate or Suramin
Malaria
- Caused by four Plasmodium species: P.falciparum, P.vivax, P.ovale, and P.malariae
- Vector: Anopheles mosquito
- Life cycle:
- Sporozoites infect liver cells and mature into schizonts
- Schizonts rupture and release merozoites
- Merozoites infect red cells and mature into trophozoites
- Trophozoites undergo schizogony and merogony in red cells, which ultimately burst and release daughter merozoites
- Some merozoites transform into male and female gametocytes
- Gametocytes are ingested by an Anopheles mosquito during a blood meal
- The parasites multiply in the mosquito, forming oocysts, which rupture and release sporozoites
Symptoms and Diagnosis
- Fever is the most constant symptom of malaria, occurring in paroxysms when lysis of red cells releases merozoites
- Typical paroxysms occur every 2nd day or more frequently in P.falciparum, every 3rd day in P.vivax and P.ovale, and every 4th day in P.malariae
- Other symptoms include:
- Vomiting
- Diarrhea
- Convulsions
- Pallor, resulting from the lysis of red blood cells and reduced synthesis of red blood cells in the bone marrow
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Description
This quiz covers the life cycle of Toxoplasma Gondii, a parasitic protozoan, including its transmission and infection processes. Learn about the different stages of its life cycle, from tissue cysts to oocysts, and how it affects humans and animals.
