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Questions and Answers
Which of the following genera infect humans?
Which of the following genera infect humans?
- Seven genera, including Plasmodium, Babesia, and others (correct)
- Only Toxoplasma and Sarcocystis
- Only Plasmodium and Babesia
- All protozoan parasites
What is a characteristic of the life cycles of Apicomplexa?
What is a characteristic of the life cycles of Apicomplexa?
- Only asexual reproduction
- Complex life cycles with both sexual and asexual reproduction phases (correct)
- Only sexual reproduction
- No reproduction phases
What is the role of humans in the life cycle of Apicomplexa?
What is the role of humans in the life cycle of Apicomplexa?
- Only as definitive hosts
- Only as intermediate hosts
- Neither as intermediate hosts nor definitive hosts
- Both as intermediate hosts and definitive hosts (correct)
How many species of Plasmodium cause human malaria?
How many species of Plasmodium cause human malaria?
Which Plasmodium species has the widest geographic distribution?
Which Plasmodium species has the widest geographic distribution?
What percentage of infections are caused by P. vivax and P. falciparum?
What percentage of infections are caused by P. vivax and P. falciparum?
Which Plasmodium species is associated with the most deaths in underdeveloped countries?
Which Plasmodium species is associated with the most deaths in underdeveloped countries?
How many deaths occur annually worldwide due to malaria?
How many deaths occur annually worldwide due to malaria?
What percentage of erythrocytes may be infected with P.falciparum?
What percentage of erythrocytes may be infected with P.falciparum?
What is a common complication of P.malariae infection?
What is a common complication of P.malariae infection?
What is a characteristic of blackwater fever?
What is a characteristic of blackwater fever?
What is a result of high-level parasitemia with P.falciparum infection?
What is a result of high-level parasitemia with P.falciparum infection?
What is a complication of P.falciparum infection?
What is a complication of P.falciparum infection?
What is a consequence of P.malariae infections?
What is a consequence of P.malariae infections?
What is the typical duration of the fever stage in a malarial paroxysm?
What is the typical duration of the fever stage in a malarial paroxysm?
Which of the following is a possible route of transmission for malaria?
Which of the following is a possible route of transmission for malaria?
What is a result of tissue anoxia in P.falciparum infection?
What is a result of tissue anoxia in P.falciparum infection?
What is the term for the pigment deposited in the liver and spleen during long-term malaria infection?
What is the term for the pigment deposited in the liver and spleen during long-term malaria infection?
What percentage of erythrocytes are infected in P.malariae infections?
What percentage of erythrocytes are infected in P.malariae infections?
What is the term for the cycle of symptoms that repeats itself at regular intervals in malaria?
What is the term for the cycle of symptoms that repeats itself at regular intervals in malaria?
What is the reason for anaemia in malaria?
What is the reason for anaemia in malaria?
What is the purpose of calculating the level of parasitemia?
What is the purpose of calculating the level of parasitemia?
What is the typical duration between the bite of an infected mosquito and the start of symptoms?
What is the typical duration between the bite of an infected mosquito and the start of symptoms?
What is the role of the female Anopheles mosquito in the life cycle of Plasmodium?
What is the role of the female Anopheles mosquito in the life cycle of Plasmodium?
Which of the following is NOT a symptom of the prodromal phase of the paroxysm?
Which of the following is NOT a symptom of the prodromal phase of the paroxysm?
Which species of malarial organisms are generally associated with fewer complications?
Which species of malarial organisms are generally associated with fewer complications?
What is the purpose of RBC exchange in cases of high-level parasitemia?
What is the purpose of RBC exchange in cases of high-level parasitemia?
What is the earliest stage of human infection by Plasmodium?
What is the earliest stage of human infection by Plasmodium?
Where does the exoerythrocytic phase of the life cycle of Plasmodium occur?
Where does the exoerythrocytic phase of the life cycle of Plasmodium occur?
What is the result of the schizogony phase of the life cycle of Plasmodium?
What is the result of the schizogony phase of the life cycle of Plasmodium?
How do humans acquire Plasmodium infection?
How do humans acquire Plasmodium infection?
What signals the beginning of the erythrocytic phase of the life cycle of Plasmodium?
What signals the beginning of the erythrocytic phase of the life cycle of Plasmodium?
What is the method of diagnosing malaria that uses a fluorescent dye?
What is the method of diagnosing malaria that uses a fluorescent dye?
What type of smears are examined to identify the species of malaria?
What type of smears are examined to identify the species of malaria?
How many oil immersion fields should be examined before considering a smear negative?
How many oil immersion fields should be examined before considering a smear negative?
What type of tests use monoclonal antibody directed against an antigen specific to P. falciparum?
What type of tests use monoclonal antibody directed against an antigen specific to P. falciparum?
What is the purpose of examining multiple sets of smears within a 36-hour period?
What is the purpose of examining multiple sets of smears within a 36-hour period?
What is the advantage of nucleic acid amplification tests?
What is the advantage of nucleic acid amplification tests?
What is the principle used in RDTs?
What is the principle used in RDTs?
What type of protein is detected by some RDTs?
What type of protein is detected by some RDTs?
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Study Notes
Apicomplexa Phylum
- Includes blood and tissue parasites that represent age-old pathogens and newly recognized agents of opportunistic infection
- Seven genera infect humans: Plasmodium, Babesia, Cryptosporidium, Cyclospora, Isospora, Sarcocystis, and Toxoplasma
Plasmodium spp.
- Cause malaria, which is endemic throughout the world in tropical and subtropical countries
- Estimated 300 million to 500 million individuals are infected
- Four species of Plasmodium cause human malaria: Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium falciparum
- A fifth species, Plasmodium knowlesi, causes malaria in macaque monkeys and has been implicated in cases of zoonotic human malaria in Malaysia and the Philippines
Malaria
- Major cause of death in underdeveloped countries, with annually between 1 million to 2 million deaths worldwide primarily due to P. falciparum infection
- Death in children who have malaria is also significantly associated with P. falciparum infection
- P. vivax has the widest geographic distribution and is the species most likely to be found in temperate climates
- P. vivax and P. falciparum cause more than 95% of infections
Clinical Infections
- Usually transmitted through the bite of an anopheline mosquito, but can also be transmitted through blood transfusion and infected needles
- Transplacental infection has also been documented
- The malarial paroxysm, which begins 10 to 15 days after the bite of an infected mosquito, is associated with the growth of the parasites in RBCs and high levels of cytokines
- Symptoms are linked to the rupture of RBCs and release of merozoites, malarial metabolites, and endotoxin-like substances into the bloodstream
Life Cycle
- Involves sexual reproduction (sporogony) and asexual reproduction (schizogony)
- Sporogony is the formation of oocysts containing sporozoites that results from the division of a zygote
- Schizogony produces merozoites by the process of multiple fission
- The female Anopheles mosquito serves as the biological vector and definitive host
Laboratory Diagnosis
- Examination of Giemsa-stained thick and thin smears remains the classic method of diagnosing malaria
- The thick smear is used to detect malarial parasites, while the thin smear is used to identify the species
- Trophozoites, schizonts, and gametocytes may be seen in the blood smear
- At least 200 to 300 oil immersion fields should be examined on either type of smear before the smear is considered negative
- Nucleic acid amplification tests and immunoassays (RDTs) are other methods for diagnosing malaria
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