Malaria Flashcards
(83 cards)
1
Q
What is the type of pathogen for malaria?
A
Protozoan parasites
2
Q
Where do spore-like oocysts form in protozoan parasites of malaria?
A
Intracellularly
3
Q
Taxonomic classification of malaria
A
Phylum : Apicomplexa
Class: Sporozoan
Order: Haemosporida
Genus: Plasmodium
4
Q
What type of vector transmits malaria?
A
Transmitted by female Anopheles mosquitoes.
5
Q
What causes malaria in humans?
A
Protozoan parasites of the genus Plasmodium.
6
Q
5 species of human plasmodium
A
P. falciparum
P. malariae
P. ovale
P. vivax
P. knowlesi
7
Q
What species post greatest threat to human?
A
P. falciparum
P. vivax
8
Q
What part of world has highest case of malaria?
A
African region
9
Q
How many Anopheles mosquito species are significant malaria vectors?
A
Out of more than 400 species of Anopheles mosquitoes, around 30 species are significant malaria vectors.
10
Q
Where do Anopheles mosquitoes lay their eggs?
A
In water, where they hatch into larvae and eventually develop into adult mosquitoes.
11
Q
Why do female Anopheles mosquitoes seek a blood meal?
A
to nurture their eggs.
12
Q
What is the incubation period for malaria, and which species show shorter or longer periods?
A
The incubation period for malaria ranges from 7 to 30 days:
Shorter periods: P. falciparum
Longer periods: with P. malariae
13
Q
What is the characteristics of infected RBC?
A
- Adhesive knob
- Malaria parasites multiply in RBC
14
Q
Who is the definitive host of malaria parasites with (sexual phase) ?
A
Female Anopheles mosquito
15
Q
Who is the intermediate host of malaria parasites (asexual phase) ?
A
Humans
16
Q
In asexual phase, what is schizogony, and where does it occur?
A
Schizogony: Process by which the malaria parasite multiplies by division or splitting.
Occurs in:
Red blood cells (erythrocytic phase)
Liver cells (exoerythrocytic phase)
17
Q
What are the products of schizogony called?
A
Merozoites.
18
Q
What is the exoerythrocytic (or pre-erythrocytic) stage in malaria?
A
The exoerythrocytic stage occurs in liver cells, where sporozoites multiply and develop into shizoints before releasing merozoites.
19
Q
What clinical significance do hypnozoites have?
A
Hypnozoites can cause relapses of malaria by becoming activated over time, developing into schizonts, and releasing merozoites that infect red blood cells.
20
Q
In what plasmodium, latent stage occur (exoerythrocytic) ?
A
P. vivax and P.ovale
21
Q
For latent stage, what are the two kinds of sporozoites seen?
A
- Sporozoites that can multiply inside hepatic cells to form shizoints
2.Sporozoites that persist and remain dormant (resting phase) called as hypnozoites
22
Q
State mechanism of hypnozoites in liver cell
A
From time to time, some hypnozoites activated to become shizoints and release merozoites which will infect RBCs
23
Q
What drug is used to eliminate hypnozoites, and what is its contraindication?
A
Primaquine is used to eliminate hypnozoites in liver cells.
It is contraindicated in G6PD deficiency.
24
Q
where does sexual phase occur and where does it originate from
A
- Happen in female Anopheles mosquito
- Originate in the human red blood cells.
25
What processes occur in the female Anopheles mosquito during the sexual phase of the malaria parasite?
* maturation and fertilization
* leading to the production of a large number of sporozoites.
26
What is the sexual phase of the malaria parasite life cycle called, and what is its significance?
The sexual phase is called sporogony. It is significant because it produces sporozoites, which are transmitted to humans during a mosquito bite, continuing the infection cycle.
27
What causes the clinical symptoms of malaria?
caused by the asexual erythrocytic (blood stage) parasites, which multiply in red blood cells.
28
What happens when the malaria parasite develops in red blood cells?
Waste substances such as hemozoin pigment and other toxic factors accumulate. These are released into the bloodstream when the infected red blood cells lyse and release merozoites.
29
What are some of the toxic substances released when infected red blood cells lyse
* hemozoin
* glucose phosphate isomerase (GPI)
30
What is the effects of toxic substances released when infected RBC lyse?
* Stimulate macrophages and other cells to produce cytokines and other soluble factors
* Contribute to fever and rigors.
* Influence severe pathophysiology associated w malaria
31
What are the clinical symptoms?
Fever
Chills
Sweats
Headaches
Nausea and vomiting
Body aches
General malaise (discomfort)
32
What are the signs of malaria?
Elevated temperatures
Perspiration (sweat)
Increased respiratory rate
Pallor
Weakness
Enlarged spleen
Mild jaundice
Enlargement of the liver
33
What are the severe complications of malaria?
- Cerebral malaria, with abnormal behavior, impairment of consciousness, seizures, coma, or other neurologic abnormalities
-Severe anemia
-Hemoglobinuria
-Acute respiratory distress syndrome (ARDS)
-Abnormalities in blood coagulation
-Low blood pressure caused by cardiovascular collapse
-Acute kidney injury
-Hyperparasitemia, where more than 5% of the red blood cells are infected by malaria parasites
-Metabolic acidosis
-Hypoglycemia
34
Why is severe malaria considered a medical emergency?
Severe malaria is a medical emergency because it can lead to life-threatening complications such as cerebral malaria, respiratory distress, kidney failure, and severe anemia. Immediate and aggressive treatment is necessary to prevent death or permanent damage.
35
What are the main causes of anemia in malaria?
1. Destruction of red blood cells (RBCs) by complement-mediated and autoimmune hemolysis.
2. Suppression of erythropoiesis in the bone marrow.
3. Increased clearance of both parasitized and non-parasitized RBCs by the spleen.
4. Failure to recycle iron-bound hemozoin pigment.
5. Antimalarial therapy in G6PD-deficient patients, which can cause hemolysis.
36
How does the spleen contribute to anemia in malaria?
By increasing the clearance of both parasitized and non-parasitized red blood cells.
37
Why does the failure to recycle hemozoin pigment contribute to anemia in malaria?
Because the body is unable to properly reuse the iron that is released from the destruction of red blood cells, leading to iron deficiency.
38
How can antimalarial therapy affect patients with G6PD deficiency?
In patients with G6PD deficiency, antimalarial therapy can cause hemolysis (destruction of red blood cells), worsening the anemia associated with malaria.
39
What is the origin of the name Plasmodium falciparum?
comes from the characteristic sickle shape of its gametocytes.
40
Why is Plasmodium falciparum considered highly pathogenic?
* Associated with malignant tertian or pernicious malaria
* Has a high rate of complications
* Fatal if left untreated.
41
What is cytoadherence in the context of Plasmodium falciparum malaria?
Process by which infected erythrocytes (red blood cells), containing mature trophozoites, attach to receptors on venular capillary endothelium, leading to the blockage of capillaries and venules.
42
How do infected erythrocytes contribute to the pathogenesis of severe malaria?
By blocking capillaries and venules and forming rosettes with uninfected erythrocytes. This leads to sequestration of infected erythrocytes in vital organs, such as the brain, kidney, heart, lungs, spleen, intestines, bone marrow, and placenta, disrupting microcirculatory flow and metabolism
43
What is sequestration, and why is it significant in severe malaria?
* Sequestration is the accumulation of mature infected erythrocytes in vital organs, where they block blood flow and disrupt microcirculatory flow.
* Contributes to the serious complications of Plasmodium falciparum malaria, such as cerebral malaria and organ failure.
44
What are some of the serious complications caused by cytoadherence and sequestration in Plasmodium falciparum malaria?
cerebral malaria, kidney failure, respiratory distress, and other severe organ dysfunctions due to impaired blood flow and metabolism in vital organs.
45
How does Plasmodium falciparum merozoite invade human red blood cells?
Plasmodium falciparum merozoites attach to and invade mature (RBCs), where the parasite develops within a parasitophorous vacuole (PV)
46
What are the different stages of Plasmodium falciparum development within the red blood cell?
1. Ring stage (0-24 hours)
2. Trophozoite stage (24-36 hours)
3. Schizont stage (40-48 hours)
47
What happens during the mature stages of Plasmodium falciparum development (>24 hours)
In mature-stage parasites, membrane-bound structures appear in the RBC cytoplasm, and knobby deformations form on the RBC membrane. After approximately 48 hours, the infected RBC ruptures, releasing 16-32 daughter merozoites.
48
What is the role of hemoglobin degradation in Plasmodium falciparum development?
- The parasite degrades hemoglobin within the RBC, leading to the formation of crystals of hemozoin in a digestive vacuole.
- These crystals are a byproduct of the parasite's digestion of hemoglobin.
49
What is PfEMP1 and its significance in Plasmodium falciparum infection?
- A protein expressed on the surface of infected RBCs.
- It plays a crucial role in cytoadherence and sequestration
- Helping the parasite evade the immune system and contribute to the pathogenesis of malaria.
50
What is the geographical distribution of Plasmodium vivax?
Plasmodium vivax has the widest geographical distribution, extending through the tropics, subtropics, and even some temperate regions.
51
What percentage of all malaria infections are caused by Plasmodium vivax?
Plasmodium vivax accounts for approximately 80% of all malaria infections worldwide.
52
Where is Plasmodium vivax most commonly found?
in Asia and America
53
What type of malaria does Plasmodium vivax cause, and what is a characteristic feature of this infection?
* causes benign tertian malaria
* characterized by frequent relapses due to the persistence of dormant forms (hypnozoites) in the liver.
54
How does the fever pattern caused by Plasmodium ovale compare to Plasmodium vivax?
Plasmodium ovale produces a tertiary fever similar to Plasmodium vivax, but with milder symptoms, prolonged latency, and fewer relapses.
55
What is the geographical distribution of Plasmodium ovale?
- rarest of the malaria species infecting humans
- found primarily in tropical Africa, especially along the West Coast.
56
Why is Plasmodium ovale considered rarer than other malaria species?
- least common
- more limited geographical distribution
57
What type of malaria does Plasmodium malariae cause, and what is its characteristic fever pattern?
Causes quartan malaria, in which febrile paroxysms (episodes of fever that occur in sudden bursts or attacks) occur every fourth day, with 72-hour intervals between bouts
58
How does Plasmodium malariae differ from other malaria species in terms of disease severity and persistence?
Plasmodium malariae usually causes mild disease, but it can stay in the bloodstream for a very long time, often for 50 years or more at undetectable levels. This long persistence is rare in other malaria species.
59
What factors can provoke the recrudescence of Plasmodium malariae?
Recrudescence of Plasmodium malariae can be provoked by splenectomy (removal of the spleen) or immunosuppression.
60
How does the development of Plasmodium malariae compare to other malaria species?
The development of Plasmodium malariae in both humans and mosquitoes is much slower than with other malaria species.
61
Where is Plasmodium malariae commonly found?
found in tropical Africa, Sri Lanka, Burma, and other parts of India.
62
Can other animals be infected by Plasmodium malariae, and if so, which animal?
Yes, chimpanzees can be naturally infected with Plasmodium malariae, and they may serve as a natural reservoir for quartan malaria.
63
What is Plasmodium knowlesi, and how is it transmitted?
- zoonotic malaria parasite
- mainly spread between monkeys by Anopheles mosquitoes.
- can also infect humans when the parasite, mosquito, monkeys, and humans come into contact.
64
How do most human cases of Plasmodium knowlesi present, and what can happen in severe cases?
Most human cases of Plasmodium knowlesi are chronic and symptomatic, but some can become severe, potentially leading to death.
65
What makes Plasmodium knowlesi particularly dangerous in terms of parasitemia?
- shortest asexual replication cycle
- leading to rapidly increased parasitemia levels which can worsen the disease.
66
Why is it difficult to distinguish Plasmodium knowlesi from Plasmodium malariae using microscopy?
can appear very similar under microscopy
67
What is the most reliable diagnostic method for Plasmodium knowlesi?
PCR
68
Why is early diagnosis and treatment of malaria important?
reduce disease severity and prevent deaths
69
What is the microscopy method used for diagnosing malaria?
thick and thin blood smears stained with Giemsa to demonstrate malarial parasites
70
What is the role of the Rapid Diagnostic Test (RDT) in malaria diagnosis?
- detects malaria antigens through immunochromatographic method
- providing results in 30 minutes or less for parasitological confirmation.
71
What is molecular diagnosis in malaria, and how is it done?
DNA probes and PCR (Polymerase Chain Reaction) to identify malaria parasites more accurately
72
What are some additional laboratory findings in malaria?
mild anemia
thrombocytopenia (decrease in blood platelets)
elevation of bilirubin
elevation of aminotransferase (enzyme in liver)
73
- Antimalaria : The best available treatment, particularly for P. falciparum malaria, is artemisinin-based combination therapy (ACT)
- Chloroquine
- Quinine
- Primaquine
- Doxyclycline
- Pyrimethamine
74
Prevention
- Vector control:
1. insecticide-treated mosquito nets 2. indoor residual spraying (are effective in a wide range of circumstances)
75
How can malaria be prevented in travelers?
chemoprophylaxis, which suppresses the blood stage of malaria infections, thereby preventing the disease.
76
What is the recommended preventive treatment for pregnant women in malaria-endemic areas?
For pregnant women living in moderate-to-high transmission areas, the WHO recommends at least 3 doses of intermittent preventive treatment with sulfadoxine-pyrimethamine at each scheduled antenatal visit after the first trimester.
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78
What is the recommended preventive treatment for infants in high-transmission areas of Africa?
For infants living in high-transmission areas of Africa, the recommended treatment is 3 doses of intermittent preventive treatment with sulfadoxine-pyrimethamine
79
WHO Global technical strategy for malaria 2016-2030
reducing malaria case incidence by at least 90% by 2030
- reducing malaria mortality rates by at least 90% by 2030
- eliminating malaria in at least 35 countries by 2030
- preventing a resurgence of malaria in all countries that are malaria-free.
80
What is the RTS,S/AS01 (RTS,S) malaria vaccine, and what species does it protect against?
The RTS,S/AS01 (RTS,S) vaccine protects against Plasmodium falciparum malaria, but it does not offer protection against P. vivax, which is more common in areas outside of Africa.
81
When was the RTS,S vaccine recommended by WHO, and where was it first introduced?
In January 2016, the RTS,S vaccine was recommended by the WHO for pilot introduction in selected areas of three African countries.
82
What is the R21/Matrix-M malaria vaccine, and when was it approved for use?
The R21/Matrix-M vaccine is a newer malaria vaccine with promising efficacy, particularly in areas with seasonal malaria. It was approved for use in some countries in 2023.
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