Podcast
Questions and Answers
In cases of malaria caused by Plasmodium falciparum, which of the following complications is most directly associated with the parasite's ability to induce the expression of parasite antigens on the surface of infected erythrocytes?
In cases of malaria caused by Plasmodium falciparum, which of the following complications is most directly associated with the parasite's ability to induce the expression of parasite antigens on the surface of infected erythrocytes?
- Nephrotic syndrome due to immune-complex deposition.
- Cerebral malaria, resulting from the adherence of infected erythrocytes to blood vessel endothelium. (correct)
- Black water fever, characterized by massive intravascular hemolysis.
- Algid malaria, leading to hypotension and circulatory collapse.
A patient presents with repeated malaria attacks despite prior treatment with chloroquine, and lab tests confirm the presence of Plasmodium falciparum. Which of the following best describes the most likely underlying cause for the recurring symptoms?
A patient presents with repeated malaria attacks despite prior treatment with chloroquine, and lab tests confirm the presence of Plasmodium falciparum. Which of the following best describes the most likely underlying cause for the recurring symptoms?
- Reactivation of persistent hypnozoites in the liver.
- Incomplete quinine therapy leading to drug resistance. (correct)
- Re-infection due to presence of low parasitemia.
- Autoimmune reaction against infected red blood cells.
Why are individuals with sickle cell anemia often resistant to Plasmodium falciparum infection?
Why are individuals with sickle cell anemia often resistant to Plasmodium falciparum infection?
- Individuals with sickle cell anemia produce antibodies that neutralize the parasite.
- The altered red blood cell environment in sickle cell anemia impairs parasite development. (correct)
- Sickle cell anemia enhances the efficacy of antimalarial drugs.
- Sickle cell anemia prevents the mosquito vector from transmitting the parasite.
Following diagnosis of malaria, a patient is prescribed primaquine. What is the primary goal of this medication in the context of malaria treatment?
Following diagnosis of malaria, a patient is prescribed primaquine. What is the primary goal of this medication in the context of malaria treatment?
A patient who has been living in a malaria-endemic area presents with dysentery, gastrointestinal bleeding and anemia. Considering the complications associated with malaria, which pathological process is most likely contributing to these symptoms?
A patient who has been living in a malaria-endemic area presents with dysentery, gastrointestinal bleeding and anemia. Considering the complications associated with malaria, which pathological process is most likely contributing to these symptoms?
How does chemoprophylaxis primarily function in preventing malaria infections?
How does chemoprophylaxis primarily function in preventing malaria infections?
A patient is suspected of having a malaria infection. After performing a rapid diagnostic test (RDT), the result comes back negative. Given this result, what is the most appropriate next step in confirming or ruling out the diagnosis?
A patient is suspected of having a malaria infection. After performing a rapid diagnostic test (RDT), the result comes back negative. Given this result, what is the most appropriate next step in confirming or ruling out the diagnosis?
In the context of malaria, what is the significance of the Duffy antigen concerning Plasmodium vivax infections?
In the context of malaria, what is the significance of the Duffy antigen concerning Plasmodium vivax infections?
During which stage of the malaria parasite's life cycle does the mosquito become infected?
During which stage of the malaria parasite's life cycle does the mosquito become infected?
In the pathogenesis of malaria paroxysm, what triggers the cyclical pattern of cold, hot, and sweating stages?
In the pathogenesis of malaria paroxysm, what triggers the cyclical pattern of cold, hot, and sweating stages?
Flashcards
Malaria Vector
Malaria Vector
Female Anopheles mosquito
Malaria Diagnostic Stage
Malaria Diagnostic Stage
Gametocytes or merozoites
Malaria Infective Stage
Malaria Infective Stage
Sporozoites
Malaria Paroxysm Pathogenesis
Malaria Paroxysm Pathogenesis
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P. vivax
P. vivax
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P. falciparum
P. falciparum
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Severe Anemia (Malaria)
Severe Anemia (Malaria)
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Hyper-reactive splenomegaly
Hyper-reactive splenomegaly
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Black Water Fever
Black Water Fever
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CBC results for Malaria
CBC results for Malaria
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Study Notes
- Malaria is a parasitic disease transmitted by female Anopheles mosquitoes.
Malaria Life Cycle
- The life cycle includes stages in both the mosquito and human hosts.
- In the mosquito, the stages are oocyst, ookinete, and sporozoites.
- The mosquito takes a blood meal and injects sporozoites into the human host.
- In the human liver, the parasite undergoes exo-erythrocytic cycle producing schizonts.
- Schizonts rupture, releasing merozoites that infect red blood cells (RBCs).
- In RBCs, the parasite goes through erythrocytic cycle, developing into trophozoites and schizonts, eventually producing gametocytes.
- Mosquitoes ingest gametocytes from infected humans, completing the cycle.
- Infective stage: sporozoites.
- Diagnostic stage: gametocytes or merozoites.
Malaria Species
- Plasmodium vivax: causes benign tertian malaria.
- Plasmodium ovale: causes ovale tertian malaria.
- Plasmodium malariae: causes benign quartan malaria.
- Plasmodium falciparum: causes malignant malaria.
Clinical Presentation
- Malaria paroxysm is the immediate attack.
- Immune responses are evoked by the rupture of infected RBCs and release of parasite metabolites.
- Cold stage: lasts for 15 minutes.
- Hot stage: lasts for 2-6 hours.
- Sweating stage: lasts for 2-6 hours.
Hemolytic Anemia
- P. vivax invades reticulocytes only, leading to restricted anemia.
- P. ovale invades reticulocytes only, leading to restricted anemia.
- P. malariae invades old RBCs only, leading to restricted anemia.
- Severe anemia occurs when P. falciparum invades RBCs at any age.
- Hepatosplenomegaly results from enhanced phagocytosis of remnants of ruptured red cells and schizonts.
Complications
- Nephrotic syndrome:
- Type III hypersensitivity reaction occurs after chronic P. malariae infection
- Immune complexes deposit on the glomeruli and kidneys
- Knobs Formation: Occurs with P. falciparum infections (types 2, 3, and 4)
- Parasite antigens are expressed on the surface of infected RBCs, forming knobs.
- These knobs adhere to receptors on endothelium of blood capillaries, leading to anoxia and necrosis of internal organs
- Clinical signs and symptoms:
- Brain: headache, drowsiness, convulsions, coma.
- GIT: diarrhea, dysentery, gastrointestinal bleeding.
- Lungs: pulmonary edema, difficulty in breathing.
- Algid malaria: hypotension, circulatory collapse, shock.
- Kidneys: acute renal failure.
- Liver: hypoglycemia.
- Hyper-reactive splenomegaly: tropical splenomegaly syndrome
- Is due to the reduction of T-suppressor cells, leading to a markedly enlarged spleen with increased IgM
- Black water fever:
- Caused by repeated attacks of P. falciparum infection and incomplete quinine therapy
- Autoimmune reaction occurs (antibodies against infected RBCs), leading to massive intravascular hemolysis
- Is characterized by anemia, hemoglobinuria, and jaundice
Diagnosis
- Pancytopenia due to splenomegaly
- Diagnosis can be determined through rapid diagnostic test (RDT)
- Giemsa-stained blood films are used to demonstrate the parasite.
- Serology detects circulating parasite antigens and antibodies.
- DNA and RNA probes detect parasite DNA and RNA in patient's blood.
Treatment
- During clinical attack: Chloroquine (blood schizonticides + blood gametocytes).
- Prophylaxis of relapse: Primaquine (Tissue schizonticides + blood gametocytes).
- Drug resistant cases: Coartem (combined drug).
- Chemoprophylaxis: Tissue schizonticides + blood schizonticides.
Control
- Is done by treatment of cases, Mosquito control, chemoprophylaxis, vaccination trials, wire screens and nets, mosquito repellents
- Tissue schizonticides: pyrimethamine or primaquine.
- Blood schizonticides: chloroquine or mefloquine.
- Blood gametocytes: chloroquine or primaquine.
Notes
- Sickle cell anemia provides resistance to P. falciparum.
- Duffy antigen is essential for P. vivax infection.
- Relapse involves reactivation of persistent hypnozoites in the liver (occurs in P. ovale and P. vivax).
- Recurrence is reinfection with malaria due to presence of low parasitemia (occurs in P. falciparum and P. malariae).
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