Hema-Immuno-Case-2-Malaria-(Unofficial)

Treatment and prophylaxis not included

What causes malaria in humans

P. falciparum, P. vivax, P. ovale (curtisi and wallikeri), P. malariae, P. knowlesi

How is malaria transmitted

By the bite of infected female Anopheles mosquitoes

What happens during the inoculation stage of malaria

Plasmodial sporozoites enter the bloodstream and travel to the liver

What occurs in the liver during malaria infection

Sporozoites invade hepatic cells and undergo asexual reproduction (schizogony)

How many daughter merozoites are produced by one sporozoite in malaria

10,000 to >30,000 daughter merozoites

What happens when infected liver cells burst

Merozoites are released into the bloodstream and invade RBCs

What is the incubation period for P. knowlesi and P. malariae

P. knowlesi: 24 h, P. malariae: 72 h

What is the role of hypnozoites in malaria

They are dormant forms in P. vivax and P. ovale, causing relapses

How do P. falciparum merozoites invade erythrocytes

By binding to glycophorin A via erythrocyte binding antigen 175

What does the Duffy blood group antigen do in malaria

It plays a role in the invasion of erythrocytes by P. vivax

What is a schizont in malaria

A parasite that has grown inside an RBC and undergone nuclear divisions

What leads to the rupture of RBCs in malaria

Schizonts consume hemoglobin and release daughter merozoites

What stage of malaria causes disease in humans

The asexual blood-stage parasites cause RBC invasion and destruction

What is the role of gametocytes in malaria

They are sexual forms that transmit malaria to mosquitoes

How does the mosquito stage of malaria begin

Male gametocytes exflagellate and fuse with female gametocytes to form a zygote

Where does the zygote mature in the mosquito during malaria transmission

In the mosquito’s midgut, forming an ookinete

What completes the life cycle of malaria

Sporozoites migrate to the mosquito's salivary gland for inoculation into a new human host

How does the parasite detoxify toxic heme

By lipid-mediated crystallization to form inert hemozoin (malaria pigment)

What changes occur in the RBC membrane after parasite invasion

It alters transport properties, exposes cryptic antigens, and inserts parasite-derived proteins

What are "knobs" in P. falciparum infections

Protuberances on the RBC surface that extrude erythrocyte membrane adhesive protein (PfEMP1)

What is the role of PfEMP1 in malaria

It mediates cytoadherence to receptors on venular and capillary endothelium

What vascular receptors are important for cytoadherence in the brain and placenta

ICAM-1 and endothelial protein C receptor in the brain, chondroitin sulfate B in the placenta

What processes are central to the pathogenesis of falciparum malaria

Cytoadherence, rosetting, and agglutination

How do infected RBCs interfere with microcirculatory flow in malaria

They block capillaries and venules, causing sequestration in vital organs

Why do only young ring forms of the parasite circulate in falciparum malaria

Sequestered parasites develop out of reach of the spleen's filtration

How does malaria affect uninfected erythrocytes in severe cases

They become less deformable, impairing their passage through capillaries

How is parasite development in P. vivax and P. ovale different from P. falciparum

All stages of development are visible on peripheral blood smears in P. vivax and P. ovale

What type of erythrocytes do P. vivax and P. ovale prefer

They show a preference for young RBCs

What type of erythrocytes does P. malariae prefer

P. malariae prefers older erythrocytes

Why can P. falciparum cause higher parasite densities than other malaria species

It can invade erythrocytes of all ages

What contributes to high parasite densities in P. knowlesi infections

The shorter 24-hour asexual life cycle leads to rapid increases in parasite densities

How does the host initially respond to malaria infection

By activating nonspecific defense mechanisms, including splenic clearance of erythrocytes

What is "pitting" in malaria

The spleen removes damaged ring-form parasites from within RBCs and returns the cells to circulation

What triggers fever in malaria infections

Release of proinflammatory cytokines during schizont rupture

What effect do temperatures ≥40°C have on malaria parasites

They damage mature parasites and synchronize the parasitic cycle

What regular fever patterns were characteristic of untreated malaria

Quotidian (daily), tertian (every 2 days), quartan (every 3 days)

What genetic disorders provide protection against falciparum malaria

Thalassemias, sickle cell disease, hemoglobins C and E, hereditary ovalocytosis, and G6PD deficiency

How does sickle cell trait (HbA/S) reduce malaria severity

It impairs parasite growth at low oxygen levels and reduces cytoadherence

What protective effect does hemoglobin C have in malaria

It reduces cytoadherence of infected RBCs due to less surface PfEMP1 presentation

How does G6PD deficiency protect against malaria

It provides protection against severe P. falciparum and has a stronger effect against P. vivax infections

What is premunition in malaria

Asymptomatic parasitemia that provides protection from disease but not infection

What is the significance of PfEMP1 in malaria immunity

PfEMP1 is a key variant surface adhesin targeted by the immune system

How do maternal antibodies protect infants from malaria

They provide partial protection from severe malaria in the first months of life

Why does malaria immunity decline outside endemic areas

Immunity fades after several months of living away from transmission regions

How do malaria parasites evade the immune system

They lack MHC antigens on RBCs, induce immune unresponsiveness, and express variant antigens

How long can P. malariae persist without treatment

Parasites can persist for decades if left untreated

What are the first symptoms of malaria

Nonspecific symptoms like headache, fatigue, abdominal discomfort, muscle aches, and fever

What symptoms may suggest a diagnosis other than malaria

Prominent headache, chest pain, abdominal pain, cough, arthralgia, myalgia, or diarrhea

How does headache in malaria differ from meningitis

Malaria lacks neck stiffness and photophobia seen in meningitis

How does myalgia in malaria compare to dengue fever and leptospirosis

Myalgia is less severe in malaria than in dengue and muscles are not tender as in leptospirosis

What classic symptom is associated with P. vivax or P. ovale malaria

Classic malarial paroxysms with regular fever spikes, chills, and rigors

How does the fever pattern in falciparum malaria differ from other malarias

The fever in falciparum malaria may never become regular

What temperature changes are common in nonimmune individuals with malaria

Temperature often rises above 40°C (104°F) with tachycardia and sometimes delirium

What type of seizures are associated with falciparum malaria

Generalized seizures, potentially indicating cerebral malaria

What physical findings are common in uncomplicated malaria

Fever, malaise, mild anemia, and sometimes a palpable spleen

What causes anemia in young children in malaria-endemic areas

Frequent vivax malaria relapse and compromised antimalarial drug efficacy

How long does it take for the spleen to become palpable in nonimmune individuals with acute malaria

Several days after onset of the disease

What is a common sign of repeated malaria infections in endemic areas

Splenic enlargement in otherwise healthy individuals

What is a common finding in the liver in malaria, particularly among young children

Slight liver enlargement

What type of jaundice is associated with malaria

Mild jaundice, especially in adults, resolving in 1–3 weeks

Is malaria associated with a rash

No, malaria is not associated with a rash

What rare symptom may occur in severe falciparum malaria

Petechial hemorrhages in the skin or mucous membranes

What is the definitive diagnosis of malaria based on

Demonstration of asexual forms of the parasite in stained peripheral blood smears

What stain is preferred for diagnosing malaria

Giemsa at pH 7.2

What allows more rapid diagnosis of malaria but not speciation

Staining of parasites with fluorescent dye acridine orange

Why are both thin and thick blood smears examined for malaria diagnosis

To improve diagnostic sensitivity and accuracy

How is the density of parasitemia expressed in a thin blood smear

As the number of parasitized erythrocytes per 1000 RBCs

What is the advantage of thick blood films in malaria diagnosis

Concentrates the parasites, increasing diagnostic sensitivity

How are parasites and WBCs counted in thick blood films

By calculating the number of parasites per unit volume based on total leukocyte count

What is assumed WBC count for calculating parasitized erythrocytes per microliter

8000/μL

How many WBCs should be counted under oil immersion to confirm negative thick smear

A minimum of 200 WBCs

Why does low-density parasitemia have low specificity in high-transmission areas

Asymptomatic parasitemia is common, making it hard to identify malaria as the cause of illness

What rapid diagnostic tests (RDTs) are used for malaria diagnosis

Antibody-based tests detecting PfHRP2, lactate dehydrogenase, or aldolase antigens

What is a disadvantage of PfHRP2-based RDTs in high-transmission areas

Prolonged positivity after acute infection, potentially leading to false conclusions

Why is quantifying parasitemia important in malaria prognosis

High parasite densities (>105 parasites/μL) indicate an increased risk of death

What does the presence of phagocytosed malarial pigment in >5% of neutrophils indicate

Recent schizogony and a poor prognosis

When does gametocytemia peak in P. falciparum infections

One week after the peak of asexual parasite densities

Does persistent gametocytemia after treatment indicate drug resistance

No, it does not mean drug resistance if a full course of treatment was given

What does phagocytosed malarial pigment in monocytes suggest

Recent infection even if malaria parasites are not detectable

Why is PCR more sensitive than microscopy or rapid diagnostic tests for malaria

It detects malaria parasites and defines malarial species more accurately

How is PCR useful in epidemiologic surveys

Identifies asymptomatic infections as control and eradication programs reduce parasite prevalence

What is the role of serologic diagnosis in malaria

Useful for screening blood donors and measuring transmission intensity but not for diagnosing acute illness

What type of anemia is usual in acute malaria

Normochromic, normocytic anemia

What is the usual leukocyte count in acute malaria

Generally normal but may be raised in severe infections

What are the changes in white blood cell counts during acute malaria

Slight monocytosis, lymphopenia, eosinopenia

What happens to lymphocytes and eosinophils after acute malaria infection

Reactive lymphocytosis and eosinophilia

What is the typical platelet count in acute malaria

Usually reduced to ~105/μL

What happens to erythrocyte sedimentation rate, plasma viscosity, and C-reactive protein levels in acute malaria

Elevated

What are the coagulation abnormalities in severe malaria

Prolonged prothrombin and partial thromboplastin times, severe thrombocytopenia

What happens to Antithrombin III levels in malaria

Reduced even in mild infection

What are the typical plasma concentrations of electrolytes, BUN, and creatinine in uncomplicated malaria

Usually normal

What are common findings in severe malaria

Metabolic acidosis, low glucose, sodium, bicarbonate, phosphate, albumin, and elevated lactate, BUN, creatinine, urate, muscle and liver enzymes, bilirubin