Pathophysiology of Malaria Quiz

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Questions and Answers

What is the meaning of 'malaria' in Italian?

Marshy area

Tropical region

Bad air (correct)

Severe disease

How many species of the genus Plasmodium are known to cause malaria in humans?

5 (correct)

Which species of Plasmodium causes severe malaria in humans?

Plasmodium malariae

Plasmodium vivax

Plasmodium knowlesi

Plasmodium falciparum (correct)

In which century was the first documented trial to treat malaria conducted?

2nd century BC Signup and view all the answers

What did the Chinese use for the treatment of fever and chills, which was later discovered to be effective against malaria?

Artemisia annua Signup and view all the answers

What is a major challenge in developing drugs and vaccines for malaria?

Host-specific nature of the parasites Signup and view all the answers

What is the active substance isolated by Dr. Youyou Tu from the plant Artemisia annua?

Artemisinin Signup and view all the answers

When was DDT's insecticide properties discovered?

1939 Signup and view all the answers

Which species is the most prevalent and pathogenic species of malaria in Africa?

P. falciparum Signup and view all the answers

How many different species of Anopheles mosquitoes are known to transmit malaria?

30 Signup and view all the answers

Which stage of the malaria parasite life cycle involves the interaction of merozoites with red blood cells?

Erythrocytic infection Signup and view all the answers

Which parasite prefers senescent erythrocytes?

P. malariae Signup and view all the answers

What mediates the transmission of the malaria parasite from the mammalian host to the mosquito?

Gametocytes Signup and view all the answers

Where does the conversion of zygotes into ookinetes occur in the mosquito?

Midgut basal lamina Signup and view all the answers

At what stage does the rupture of infected hepatocytes result in the release of merozoites?

Hepatic phase Signup and view all the answers

What happens to some merozoites during P. vivax and P. ovale infections?

They remain dormant hypnozoites within hepatocytes. Signup and view all the answers

What is observed in recent years that has compromised the impact of long-lasting impregnated nets (LLINs)?

The emergence of resistance to the insecticide in mosquito populations. Signup and view all the answers

Which compound has proven activity against malaria and is being widely used in combination therapies worldwide?

Artemisinin Signup and view all the answers

What is the proposed two-step mechanism of action for quinolone derivatives as antimalarial agents?

Capping the growing hemozoin crystals and complexing with free heme Signup and view all the answers

Which enzyme do Class I antifolate agents inhibit in the malaria parasite?

Dihydropteroate synthase (DHPS) Signup and view all the answers

What is the proposed mechanism of action of artemisinin and its derivatives against the malaria parasite?

Interacting with intraparasitic heme and getting activated into toxic free radicals Signup and view all the answers

Under which condition is suppressive prophylaxis indicated for malaria chemoprophylaxis?

In areas where P. falciparum malaria is prevalent Signup and view all the answers

Which of the following is NOT one of the four drugs approved for chemoprophylaxis against malaria?

Chloroquine Signup and view all the answers

Which method of vector control involves covering the walls and floors of a house with insecticide to prevent the entry of mosquitos?

Indoor residual spraying (IRS) Signup and view all the answers

According to WHO, which chemical class used for indoor residual spraying is NOT included in the prequalified list?

Organochlorines Signup and view all the answers

What is the focus of malaria vaccines that are classified as pre-erythrocytic vaccines?

Blockage of P. falciparum sporozoite Signup and view all the answers

Which recombinant protein vaccine has been recommended by WHO for use on children in sub-Saharan Africa and other regions with moderate-to-high transmission of P. falciparum?

RTS, S/AS01 Signup and view all the answers

How many doses of RTS, S/AS01 are recommended by WHO for children starting from the age of 5 months?

4 doses Signup and view all the answers

What is the primary activity provided by insecticide-treated bed nets?

Providing a physical impediment against insects Signup and view all the answers

What role does pyrethroid–piperonyl butoxide (PBO) play in vector control?

Quenching insecticide action by inhibiting parasitic metabolic enzymes like mixed-function oxidases Signup and view all the answers

What is the primary reason for the ongoing pilot program in Ghana, Kenya, and Malawi?

To test the 4th dose of a malaria vaccine Signup and view all the answers

What is the significance of the resistance to anti-malarial agents?

It necessitates the need for discovering new anti-malarial agents Signup and view all the answers

When was the first case of chloroquine resistance by P. falciparum observed in Africa?

1978 Signup and view all the answers

What is the mechanism primarily associated with resistance to quinolones?

Elevated level of drug efflux Signup and view all the answers

What is P. falciparum Kelch 13 (PfKelch13) used as a molecular marker for?

Mapping the geographical distribution of artemisinin resistance Signup and view all the answers

What has been stagnating despite declining for decades?

Malaria incidence and malaria-related deaths Signup and view all the answers

What is the main conclusion drawn from the text?

'Front-line' artemisinin-based combination therapy is facing resistance Signup and view all the answers

What does the emergence of resistant strains of malaria call for?

A focus on developing new antimalarial agents with better safety and efficacy profile Signup and view all the answers

What does 'Pfmdr1' overexpression primarily lead to?

Reduced responsiveness of the parasite to chloroquine and other quinolone antimalarial agents. Signup and view all the answers

What is the result of genetic change in relation to antifolate antimalarial agents?

A structurally different enzyme. Signup and view all the answers

What does the text imply about the future development priorities in health science?

Studies to develop new antimalarial agents with distinct targets and well-characterized safety profile should be a priority. Signup and view all the answers

What is the major player in the pathogenesis of severe malaria?

Cytoadherence Signup and view all the answers

Which gene family encodes the P. falciparum erythrocyte membrane protein 1 (PfEMP1)?

var Signup and view all the answers

What is the periodicity of fever in P. vivax and P. ovale malaria?

Every 48 hours Signup and view all the answers

What is the phenomenon called when parasitized erythrocytes bind to vascular endothelium and translocate from the peripheral circulation into various tissues and organs?

Sequestration Signup and view all the answers

Which receptor binding for parasitized RBC to the endothelium is implicated in causing cerebral malaria?

Cluster of differentiation 36 (CD36) Signup and view all the answers

Which molecule is implicated in inducing the overproduction of cytokines by macrophages in severe malaria?

Glycosylphosphatidylinositol (GPI) Signup and view all the answers

What diagnostic technique for malaria is based on immunologically detecting different malaria antigens such as lactate dehydrogenase (LDH), aldolase, and histidine-rich protein-2 (HRP-2) in a small amount of blood?

Rapid diagnostic test (RDTs) Signup and view all the answers

What is recommended by WHO to prevent or delay the spread of antimalarial drug resistance?

Combination therapy for all episodes of malaria with at least two effective antimalarial agents having a different mechanism of action Signup and view all the answers

Which type of antimalarial agents are active against the erythrocytic stage of the parasite?

Quinoline derivatives Signup and view all the answers

Which antimalarial agent is active against the hepatic stage of the parasite and gametocytes?

Primaquine Signup and view all the answers

What technique is recommended by WHO for all episodes of malaria to prevent or delay the spread of antimalarial drug resistance?

Combination therapy with at least two effective antimalarial agents having a different mechanism of action Signup and view all the answers

Which diagnostic technique for malaria has poor accuracy due to the resemblance of clinical symptoms with other tropical diseases and the possibility of incidence of coinfection?

Clinical diagnosis Signup and view all the answers

Study Notes

Malaria Overview

'Malaria' translates to "bad air" in Italian.
Six Plasmodium species are known to cause malaria in humans, specifically noted with the most pathogenic being Plasmodium falciparum.

Historical Context

The first documented trial to treat malaria occurred in the 17th century.
Chinese traditional medicine used Artemisia, later recognized for its effectiveness against malaria.

Drug Development Challenges

Developing drugs and vaccines for malaria faces major challenges due to complex life cycles and resistance evolution.

Antimalarial Agents

Dr. Youyou Tu isolated artemisinin from Artemisia annua, which has significant antimalarial properties.
DDT's insecticide properties were discovered in 1939.
Quinolone derivatives function through a proposed two-step mechanism of action against malaria.

Epidemiology and Transmission

Plasmodium falciparum is the most prevalent and pathogenic malaria species in Africa.
Approximately 430 species of Anopheles mosquitoes transmit malaria.
Interaction of merozoites with red blood cells occurs during the blood stage of the malaria parasite life cycle.

Plasmodium Species Preferences

Plasmodium vivax and Plasmodium ovale infections result in dormant stages, known as hypnozoites, leading to relapses.

Vector Control and Resistance

Long-lasting impregnated nets (LLINs) face decreased efficacy due to insecticide resistance.
Pyrethroids, in combination with piperonyl butoxide (PBO), enhance vector control by increasing insecticide effectiveness.

Vaccine Development

Pre-erythrocytic vaccines target early stages of malaria infection.
WHO recommends the RTS,S/AS01 vaccine for children starting at 5 months of age, requiring four doses.

Preventative Measures

Insecticide-treated nets primarily focus on preventing mosquito bites.
Indoor Residual Spraying (IRS) involves covering surfaces with insecticide to reduce mosquito entry.
WHO's prequalified list does not include certain chemical classes for indoor residual spraying.

Resistance Monitoring

Resistance to antimalarial agents poses a considerable concern, with the first observed case of chloroquine resistance occurring in Africa during the 1980s.
PfKelch13 is used as a molecular marker to monitor resistance patterns in Plasmodium falciparum.
Pfmdr1 overexpression contributes to decreased effectiveness of various antimalarial drugs.

Pathogenesis of Severe Malaria

The pathogenesis of severe malaria is largely driven by the P. falciparum erythrocyte membrane protein 1 (PfEMP1) gene family.
The periodicity of fever in P. vivax and P. ovale malaria occurs every 48 hours.

Clinical Manifestations

Binding of parasitized erythrocytes to vascular endothelium causes serious complications, including cerebral malaria.
Cytokine overproduction in severe malaria is induced by macrophages in response to specific molecules.

Diagnostic Techniques

Malaria diagnostics often utilize immunological techniques to detect antigens like LDH and HRP-2.
Clinical symptoms resembling other tropical diseases can hinder the accuracy of parasitological diagnosis.
WHO recommends continuous monitoring of drug resistance and proper diagnostic practices to combat malaria effectively.

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Test your knowledge of the pathophysiology of malaria, including fever, erythrocyte rupture, macrophage ingestion, and parasite species. Understand the role of tumor necrosis factor α (TNF-α) in mediating fever associated with malaria infection.