Apicomplexa: Parasites and Opportunistic Infections
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Questions and Answers

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?

  • 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?

  • 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?

    <p>5</p> Signup and view all the answers

    Which Plasmodium species has the widest geographic distribution?

    <p>P. vivax</p> Signup and view all the answers

    What percentage of infections are caused by P. vivax and P. falciparum?

    <p>95%</p> Signup and view all the answers

    Which Plasmodium species is associated with the most deaths in underdeveloped countries?

    <p>P. falciparum</p> Signup and view all the answers

    How many deaths occur annually worldwide due to malaria?

    <p>1 million to 2 million</p> Signup and view all the answers

    What percentage of erythrocytes may be infected with P.falciparum?

    <p>Up to 50%</p> Signup and view all the answers

    What is a common complication of P.malariae infection?

    <p>Nephrotic syndrome</p> Signup and view all the answers

    What is a characteristic of blackwater fever?

    <p>Hemoglobinuria</p> Signup and view all the answers

    What is a result of high-level parasitemia with P.falciparum infection?

    <p>Anemia</p> Signup and view all the answers

    What is a complication of P.falciparum infection?

    <p>Cerebral malaria</p> Signup and view all the answers

    What is a consequence of P.malariae infections?

    <p>Recrudescence</p> Signup and view all the answers

    What is the typical duration of the fever stage in a malarial paroxysm?

    <p>2 to 4 hours</p> Signup and view all the answers

    Which of the following is a possible route of transmission for malaria?

    <p>Transplacental infection</p> Signup and view all the answers

    What is a result of tissue anoxia in P.falciparum infection?

    <p>Tubular necrosis</p> Signup and view all the answers

    What is the term for the pigment deposited in the liver and spleen during long-term malaria infection?

    <p>Hemozoin</p> Signup and view all the answers

    What percentage of erythrocytes are infected in P.malariae infections?

    <p>2% to 5%</p> Signup and view all the answers

    What is the term for the cycle of symptoms that repeats itself at regular intervals in malaria?

    <p>Malarial paroxysm</p> Signup and view all the answers

    What is the reason for anaemia in malaria?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of calculating the level of parasitemia?

    <p>To follow the effectiveness of treatment</p> Signup and view all the answers

    What is the typical duration between the bite of an infected mosquito and the start of symptoms?

    <p>10 to 15 days</p> Signup and view all the answers

    What is the role of the female Anopheles mosquito in the life cycle of Plasmodium?

    <p>Definitive host and biological vector</p> Signup and view all the answers

    Which of the following is NOT a symptom of the prodromal phase of the paroxysm?

    <p>Diarrhea</p> Signup and view all the answers

    Which species of malarial organisms are generally associated with fewer complications?

    <p>P. vivax and P. ovale</p> Signup and view all the answers

    What is the purpose of RBC exchange in cases of high-level parasitemia?

    <p>To decrease the level of parasitemia and increase the effectiveness of the drug</p> Signup and view all the answers

    What is the earliest stage of human infection by Plasmodium?

    <p>Ring-form trophozoite</p> Signup and view all the answers

    Where does the exoerythrocytic phase of the life cycle of Plasmodium occur?

    <p>Liver</p> Signup and view all the answers

    What is the result of the schizogony phase of the life cycle of Plasmodium?

    <p>Production of merozoites</p> Signup and view all the answers

    How do humans acquire Plasmodium infection?

    <p>Through the bite of an infected female Anopheles mosquito</p> Signup and view all the answers

    What signals the beginning of the erythrocytic phase of the life cycle of Plasmodium?

    <p>Release of mature merozoites from liver cells and invasion of RBCs</p> Signup and view all the answers

    What is the method of diagnosing malaria that uses a fluorescent dye?

    <p>QBC system</p> Signup and view all the answers

    What type of smears are examined to identify the species of malaria?

    <p>Thin smears</p> Signup and view all the answers

    How many oil immersion fields should be examined before considering a smear negative?

    <p>200 to 300</p> Signup and view all the answers

    What type of tests use monoclonal antibody directed against an antigen specific to P. falciparum?

    <p>RDTs</p> Signup and view all the answers

    What is the purpose of examining multiple sets of smears within a 36-hour period?

    <p>To rule out the presence of malarial organisms</p> Signup and view all the answers

    What is the advantage of nucleic acid amplification tests?

    <p>They are sensitive in detecting low levels of P. falciparum infection</p> Signup and view all the answers

    What is the principle used in RDTs?

    <p>Antigen capture immunochromatographic principle</p> Signup and view all the answers

    What type of protein is detected by some RDTs?

    <p>Histidine-rich protein</p> Signup and view all the answers

    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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    Description

    Learn about the phylum Apicomplexa, including its diverse morphology, transmission methods, and complex life cycles. Understand how seven genera infect humans, including Plasmodium, Babesia, and Toxoplasma.

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