Malaria History and Introduction
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Questions and Answers

Which age group is most commonly affected by malaria, with 65% of cases occurring within this group?

  • Teenagers aged 15-19
  • Children under 15 years (correct)
  • Adults aged 20-30
  • Children under 5 years

Which demographic is especially vulnerable to malaria infections?

  • Infants under 1 year
  • Pregnant women (correct)
  • Athletes
  • Elderly men

In which region do most malaria deaths occur?

  • Sub-Saharan Africa (correct)
  • Southeast Asia
  • Western Europe
  • North America

What environmental factors contribute to the prevalence of malaria?

<p>Rainfall and high humidity (A)</p> Signup and view all the answers

Which statement about the distribution of malaria is true?

<p>Malaria is prevalent in tropical and subtropical regions. (A)</p> Signup and view all the answers

What percentage of childhood deaths in developing countries was attributed to malaria in 2002?

<p>10.7% (A)</p> Signup and view all the answers

Where was Plasmodium spp. pathogenic for domestic poultry recently identified?

<p>American Samoa (A)</p> Signup and view all the answers

How many people are diagnosed with malaria each year?

<p>350-500 million (D)</p> Signup and view all the answers

What process occurs when female and male gametes fuse during the life cycle of Plasmodium?

<p>Zygote formation (B)</p> Signup and view all the answers

What is the first stage of parasite survival for relapse after treatment in malaria?

<p>Dormant hypnozoites (C)</p> Signup and view all the answers

How many microgametes are typically developed from one male gametocyte in Plasmodium?

<p>5-8 (D)</p> Signup and view all the answers

What characteristic distinguishes recrudescence from relapse in malaria infections?

<p>Timing of symptom reappearance (D)</p> Signup and view all the answers

Which process involves the maturation of zygotes into oocysts inside a mosquito?

<p>Sporogony (A)</p> Signup and view all the answers

What does reinfection imply in relation to malaria?

<p>New introduction of the parasite after previous elimination (C)</p> Signup and view all the answers

Which malaria species is known for having the longest reported incubation period?

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

What is one main result of the high levels of mortality and morbidity caused by malaria?

<p>Selective pressure on the human genome (C)</p> Signup and view all the answers

What is the typical incubation period for P.falciparum?

<p>9 to 14 days (C)</p> Signup and view all the answers

What is a classic symptom of malaria?

<p>Paroxysm (A)</p> Signup and view all the answers

Which symptoms occur in birds infected with Plasmodium spp.?

<p>Loss of appetite (D)</p> Signup and view all the answers

What is the typical range of signs and symptoms for malaria to begin after infection?

<p>8-25 days (B)</p> Signup and view all the answers

What severe complication can occur from a Plasmodium infection in humans?

<p>Kidney failure (C)</p> Signup and view all the answers

What does significant weakness in malaria patients typically prevent them from doing?

<p>Walking (C)</p> Signup and view all the answers

In what range can the incubation period for P.vivax and P.ovale vary?

<p>7 days to several months (B)</p> Signup and view all the answers

Which of the following could be a gross lesion associated with Plasmodium infection?

<p>Enlargement and discoloration of liver (A)</p> Signup and view all the answers

What role do activated NKT cells play in T cell differentiation?

<p>They regulate the differentiation based on natural-killer-complex loci expression. (A)</p> Signup and view all the answers

What happens to recruited monocytes during the immune response to malaria?

<p>They differentiate into macrophages and can become stuck in brain microvessels. (D)</p> Signup and view all the answers

Which statement best describes malarial hepatopathy?

<p>It is often associated with pre-existing liver conditions. (C)</p> Signup and view all the answers

What is one of the consequences of activated macrophages in the context of malaria?

<p>They promote the sequestration of platelets. (B)</p> Signup and view all the answers

Which of the following is NOT a direct effect of the immune response to cerebral malaria?

<p>Infiltration of neutrophils into brain microvessels. (B)</p> Signup and view all the answers

What is the significance of the incubation period in malaria?

<p>It is defined as the time from infection to symptom appearance. (C)</p> Signup and view all the answers

What effect do chemokines have after being produced by activated macrophages during malaria?

<p>They amplify the infiltration of immune cells. (A)</p> Signup and view all the answers

What can be a potential outcome of endothelial damage during malaria?

<p>Neurotransmitter and metabolic changes. (B)</p> Signup and view all the answers

What does the presence of schizonts indicate in a bird's tissues?

<p>The bird has likely been infected (A)</p> Signup and view all the answers

Which type of blood film is more sensitive for detecting malaria parasites?

<p>Thick films (B)</p> Signup and view all the answers

Which species of Plasmodium is associated with tertian periodicity but does not have a liver phase?

<p>Plasmodium falciparum (C)</p> Signup and view all the answers

What does the term 'parasitemia' refer to?

<p>The level of parasite presence in blood (B)</p> Signup and view all the answers

In the diagnosis of malaria, what is a limitation of using thin blood films?

<p>They are less sensitive than thick films (C)</p> Signup and view all the answers

What advantage do antigen-based rapid diagnostic tests (RDTs) have over blood smears?

<p>They can provide results without trained staff (D)</p> Signup and view all the answers

What characteristic is common among the early trophozoites of all four major Plasmodium species?

<p>They look identical in the ring form (B)</p> Signup and view all the answers

For areas lacking microscopy, what is a preferred alternative for diagnosing malaria?

<p>Rapid antigen-based tests (D)</p> Signup and view all the answers

What type of malaria is associated with acute, life-threatening complications?

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

What should be done if there is uncertainty about drug sensitivity of the malaria parasite?

<p>Presume resistance and use quinine or artemisinin (B)</p> Signup and view all the answers

What is the recommended treatment method for all cases of severe malaria?

<p>Injectable antimalarials (A)</p> Signup and view all the answers

Which of the following conditions does NOT require modification of anti-malarial treatment?

<p>Heart disease (C)</p> Signup and view all the answers

Which anti-malarial drug is contraindicated in the first trimester of pregnancy?

<p>Mefloquine (A)</p> Signup and view all the answers

What is the recommended suppressive chemoprophylaxis for pregnant women with P.vivax malaria?

<p>500 mg of chloroquine weekly (A)</p> Signup and view all the answers

Which of the following is a common complication associated with both malaria and anti-malarials?

<p>Hypoglycemia (C)</p> Signup and view all the answers

Why is oral administration of certain newer antimalarial drugs discouraged in severe malaria?

<p>They have delayed onset of action (A)</p> Signup and view all the answers

Flashcards

Malaria Susceptibility in Birds

Passerine birds are commonly asymptomatic carriers of Plasmodium, while other bird species can be affected.

Malaria in Humans/Mammals

Humans, reptiles, and other mammals, and non-human primates are susceptible to the disease.

Malaria's Age Susceptibility

Children under 15 years old are the most frequent victims of malaria, making up 65% of cases.

Malaria's Sex Susceptibility

Pregnant women are highly susceptible, with approximately 125 million at risk annually.

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Malaria Global Distribution

Malaria is found in Africa, Asia, the Middle East, Central/South America, Hispaniola, and Oceania.

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Malaria Deaths Globally

Over 1 million people die annually from malaria, overwhelmingly in sub-Saharan Africa, and children are most affected.

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Malaria Distribution in Urban/Rural

Malaria is more common in rural areas than cities but can exist in both, but generally risk is less in cities.

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Malaria Predisposing Factors

Rainfall, high temperatures, high humidity, and stagnant water contribute to malaria outbreaks due to mosquito breeding.

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Exflagellation

The process of microgametes developing from a microgametocyte in the mosquito's mid-gut.

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Sporozoites

Infectious forms of the malaria parasite that develop inside the mosquito and are transmitted to humans.

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Recrudescence

Return of malaria symptoms because the treatment was ineffective.

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Relapse

Return of malaria symptoms after the parasite has been eliminated from the blood, but persists as dormant hypnozoites in the liver cells.

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Reinfection

A new malaria infection after the previous one has been cleared.

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Hypnozoites

Dormant forms of malaria parasites that can survive in the liver for long periods before reactivating and causing a relapse.

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Genetic Resistance

The ability of some people to resist malaria due to inherited traits.

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Malaria Recurrence

The reappearance of malaria symptoms, classified as recrudescence, relapse or reinfection, after a period of absence.

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Activated NKT cells

Cells that regulate the differentiation of CD4+ T cells into TH1 or TH2 cells based on expressed natural-killer-complex loci.

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CD4+ T cells

A type of T cell involved in the immune response, influenced by activated NKT cells.

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Chemokines

Molecules that recruit immune cells like monocytes and neutrophils.

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Malarial Hepatopathy

Liver dysfunction from malaria, often due to other pre-existing liver conditions, not liver inflammation itself.

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Macrophages

Cells that differentiate from monocytes and become part of the immune response in a microenvironment.

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Incubation Period

The time between initial infection and the appearance of symptoms.

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Endothelial-Cell Damage

Damage to the inner lining of blood vessels, possibly caused by immune cells, leading to broader issues.

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Cytokines

Chemicals that mediate communication between cells (immune system)

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Plasmodium Incubation Period

The time it takes for malaria symptoms to appear after infection. Varies depending on the parasite species, ranging from a few days to several months.

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Malaria Symptoms in Birds

Birds infected with Plasmodium show various symptoms, including loss of appetite, dry/ruffled feathers, leg weakness, nervous signs, diarrhea, enlarged liver/spleen, and anemia.

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Malaria Symptoms in Humans

Humans experience symptoms like decreased consciousness, significant weakness, breathing problems, and various organ failures (e.g., kidney failure).

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Malaria Paroxysm

A cyclical pattern of sudden coldness, shivering, fever, and sweating, defining the malaria infection's symptomatic stages.

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P. falciparum Incubation

P. falciparum malaria generally incubates in 9-14 days.

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Incubation Period Variation

Incubation time can differ greatly based on various factors such as treatment and parasite type, sometimes lasting several months.

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Malaria Infection Signs (Birds)

Signs of malaria infection in a bird may include reduced appetite, dry legs, ruffled feathers, and neurological symptoms such as head twisting, as well as digestive issues.

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Malaria Severe Signs (Humans)

Severe malaria in humans manifests as organ damage, low blood pressure, severe breathing difficulties, and other concerning symptoms such as low blood glucose and blood in urine.

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Malaria Diagnosis

Typically done through microscopic examination of blood films (thin and thick) or antigen-based rapid diagnostic tests (RDTs).

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Thin Blood Film

Preserves parasite appearance for species identification.

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Thick Blood Film

Screens larger blood volume, more sensitive than thin film.

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Parasite Species Identification

Difficult in early stages (ring forms) as all look similar; requires several trophozoites.

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Rapid Diagnostic Tests (RDTs)

Antigen-based tests used for malaria diagnosis in areas with limited microscopic facilities; require only a small blood sample.

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Malaria Parasite Detection

Microscopic examination allows for the detection of malaria parasites in both thin and thick blood films and by antigen-based diagnostics.

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Plasmodium species

Different types of malaria parasites with distinct characteristics (different appearances, periodicity, and liver persistence behaviour).

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Species Identification in Blood Films

Precise identification of Plasmodium species is dependent on examining multiple trophozoites in blood films, as the early stages (ring forms) are indistinguishable across species.

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Severe Malaria

Malaria with life-threatening complications, usually caused by P. falciparum.

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Treatment Uncertainty

If parasite drug sensitivity is unclear, treat like chloroquine-resistant malaria.

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Hospital Admission

All severe malaria cases require hospitalization for proper care and monitoring.

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Injectable Antimalarials

Severe malaria requires injectable drugs (e.g., chloroquine, quinine, artemisinin) for optimal absorption and blood levels.

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Pregnancy & Malaria

Chloroquine is safe in pregnancy. Artemisinin and quinine are generally safe. However, mefloquine, pyrimethamine/sulphadoxine, halofantrine, tetracycline, and doxycycline are contraindicated in specific trimesters or completely.

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Malaria & Epilepsy

Malaria and its treatments can trigger seizures. Careful consideration required.

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Host Factors (treatment)

Treatment also considers patient age, weight, and functional capacity.

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Associated Conditions

Malaria treatment needs modification based on other existing health problems.

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Study Notes

Introduction

  • Malaria is a mosquito-borne infectious disease caused by Plasmodium parasites.
  • It involves a bite from an infected female mosquito.
  • The infection spreads to the liver, where the parasites mature and reproduce.
  • Symptoms include fever and headache, potentially progressing to coma or death.
  • Malaria is widespread in tropical and subtropical regions around the equator.
  • Historically, the term "malaria" originated from Italian, meaning "bad air," relating to its previous association with swamps and marshland.

History

  • Quinine was first purified from tree bark in 1820, traditionally used to treat malaria.
  • Charles Louis Alphonse Laveran identified the malaria parasite in 1880.
  • Sir Ronald Ross demonstrated that mosquitoes transmit malaria in 1898.
  • Hans Andersag discovered Chloroquine in 1934, an anti-malarial drug, whose widespread use came after WWII.
  • Paul Hermann Muller tested DDT in 1939.
  • Elimination of malaria in the U.S. by 1952.

Avian Malaria

  • Avian malaria is primarily caused by Plasmodium relictum.
  • Several other Plasmodium species infect birds, especially relevant to the poultry industry.

Human Malaria

  • Four Plasmodium species cause human disease: falciparum, vivax, ovale, and malariae.
  • Plasmodium knowlesi is another species that can infect humans.

Monkey Malaria

  • Several Plasmodium species infect monkeys. Examples include cynomolgi, brasilianum, schwetzi, inui, simium.

Scientific Classification

  • Malaria parasites are classified into the Eukaryota Domain, Apicomplexa Phylum, and Plasmodiidae Family, amongst other classifications.

Epidemiology

  • Susceptible species: Many bird species host Plasmodium
  • Susceptible hosts: Humans, reptiles, and other mammals and non-human primates.
  • Susceptible age: Children under 15 show high incidence.
  • Susceptible sex: Pregnant women are at elevated risk.
  • Malaria statistics: High burden in Sub-Saharan Africa, Asia.

Types of Malaria

  • Plasmodium falciparum: Most serious form, predominantly in Africa.
  • Plasmodium vivax: Milder, widespread globally; potentially fatal if untreated; liver stage.
  • Plasmodium ovale: Milder, widespread globally; potentially fatal if untreated; liver stage.
  • Plasmodium malariae: Milder, widespread globally; potentially fatal if untreated; liver stage.
  • Plasmodium knowlesi: Can infect humans and is widespread in Southeast Asia.

Transmission

  • The transmission vector involves Anopheles mosquitoes.
  • Mosquito takes blood containing the parasites and the parasites mature in the mosquito's gut.
  • The parasites then migrate to the mosquito's salivary glands, readying transmission to a new host upon a second bite.
  • Some human-to-human transmission can occur through blood transfusions, organ transplants, or shared needles/syringes.

Life Cycle of Plasmodium species

  • Pre-erythrocytic Schizogony: Parasites develop within liver cells.
  • Erythrocytic Schizogony: Parasites infect and multiply in red blood cells.
  • Gametocytes: Sexual forms enabling transmission to a mosquito.

Pathogenesis

  • Parasitized red blood cells (PRBCs) adhere to brain microvascular endothelial cells
  • Local expression of cell-adhesion molecules and production of cytokines and chemokines.

Recurrent Malaria

  • Symptoms may recur after periods without apparent symptoms (recrudescence, relapse).
  • The recurrences are caused by persistent dormant parasites in the liver.
  • Reinfection occurs with a new parasite infection.
  • Recent treatments and prevention strategies are focused on the reduction of recrudescence.

Genetic Resistance

  • Sickle cell trait, thalassemia traits, and Duffy antigens show some resistance to malaria.
  • Malaria has placed selective pressures on the human genome, leading to genetic adaptations.

Malaria Hepatopathy

  • Rare liver dysfunction associated with malaria, often due to pre-existing conditions.
  • Malarial hepatitis presents with a range of symptoms and correlates with increased morbidity and mortality.

Signs and Symptoms (Humans)

  • Incubation periods vary depending on the parasite species.
  • Symptoms generally include fever, chills, headache, weakness.
  • Other signs and symptoms may include: loss of appetite, weakness, discolored skin, or breathing problems.

Signs and Symptoms (Birds)

  • Loss of appetite, ruffled feathers, skin changes.
  • Symptoms typically arise within a week of a mosquito bite.
  • Signs include weight loss, tremors, leg weakness, and diarrhea.

Diagnosis

  • Microscopic examination of blood smears for parasites.
  • Rapid Diagnostic Tests (RDT) provide quick results, especially in resource-limited settings.

Treatment

  • Treatment depends on factors like parasite type, severity, host status, and associated conditions.
  • Various drugs, including artemisinins, chloroquine, and quinine, are used.
  • Treatment protocols consider the risks/benefits of specific combinations of drugs.

Prevention

  • Vector control (insecticide-treated nets or spraying) reduces mosquito bites.
  • Prophylactic drugs (such as chloroquine) can delay malaria development.
  • Educational campaigns promote awareness regarding prevention and early treatment measures.

Malaria Control and Prevention

  • Mosquito-eradication programs (DDT, ITNs).
  • Vaccination efforts are underway.
  • Community-level interventions, including education and awareness campaigns, are necessary for controlling malaria.

References

  • Information supplied appears to be from a textbook or academic article, not a citation.

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