Malaria Diagnosis and Prevention Quiz

Malaria-2 Lecture Outline

• Malaria-2 lecture is presented by Dr. Nantha Kumar Jegaprakasam, PhD, from the Center for Toxicology and Health Risk Studies (CORE), Faculty of Health Science (FSK), Universiti Kebangsaan Malaysia (UKM).

Lecture Outline

• Subtopic 6: Complications of malaria
• Subtopic 7: Laboratory diagnosis (microscopy & molecular techniques)
• Subtopic 8: Treatment for malaria
• Subtopic 9: Prevention & control for malaria

Complications of Malaria

• Cerebral malaria:
  • Most severe complication
  • Fatal, featuring headache, neck stiffness, disorientation, coma, and death
  • Multi-factorial process involving sequestration, inflammation, and endothelial dysfunction in the brain's microvasculature, leading to coma
  • Late stage Plasmodium falciparum schizonts secrete proteins forming knobs on the surface of red blood cells (RBCs)
  • Knobs promote adhesion of infected RBCs to other RBCs and capillary endothelial cells, blocking cerebral microvasculature, leading to anoxia, ischaemia, and haemorrhage.
• Hemolytic anemia:
  • Destruction of large numbers of RBCs via complement-mediated and autoimmune hemolysis
  • Impaired erythropoiesis in the bone marrow
  • Increased clearance of parasitized and non-parasitized RBCs by the spleen
  • Failure of the host to recycle iron bound in hemozoin pigment
  • Antimalarial therapy in G6PD deficient patients
• Blackwater fever:
  • Seen in falciparum malaria, particularly with repeated infections and insufficient quinine treatment
  • Clinical manifestations including bilious vomiting, prostration, and passage of dark red or black urine (blackwater)
  • Pathogenesis due to massive intravascular hemolysis caused by anti-erythrocyte antibodies, resulting in hemoglobinuria
  • Potential complications include renal failure, acute liver failure, and circulatory collapse
• Gastrointestinal syndrome:
  • Characterized by jaundice, hepatomegaly, epigastric pain, nausea, vomiting, and diarrhea
• Algid malaria:
  • Adrenal insufficiency-like syndrome leading to shock, low blood pressure, rapid pulse, difficulty breathing and hemoconcentration.
• Hypoglycemia:
  • Especially during pregnancy, potentially causing neurological problems like restlessness, dyspnea, convulsions, and loss of consciousness
  • Possible factors include liver glycogen depletion from decreased oral intake, glucose consumption by the parasite, and the hypoglycemic effect of Tumor Necrosis Factor (TNF).
• Pulmonary oedema (PO):
  • Increased TNF level may cause pulmonary oedema.
• Acute renal failure:
  • Severe cases potentially due to tubular necrosis.
• Septicemic malaria:
  • High fever characterizes it
  • Dissemination of the parasite causes multi-organ failure
  • High mortality rate (80%)

Complications (P. vivax & P. ovale)

• Develop serious disease, but complications are rare.

Complications (P. malariae)

• Mild infection, often becoming chronic.
• Main complication is nephrotic syndrome.
• Immune complexes may lead to structural glomerular damage and nephrotic syndrome.

Complications (P. knowlesi)

• Single or multi-system failure, potentially including acute respiratory distress syndrome, acute renal failure, hepatic dysfunction, metabolic acidosis, hypoglycemia, hypotension, and thrombocytopenia/lymphopenia

Recrudescence & Relapse

• Recrudescence: Persistence of parasites at a low level in circulation, occurring within a few weeks to months of a prior attack; seen in P. falciparum and P. malariae
• Relapse: Reactivation of hypnozoites in the liver; occurs weeks to years after the primary attack; seen in P. vivax and P. ovale

Laboratory Diagnosis

• History from the patient and their signs/symptoms
• Laboratory investigations (blood films) confirming diagnosis
• Blood smears stained with Romanowsky stains (Giemsa/Field stain) show bluish cytoplasm and reddish nuclear chromatin.
• Thin and thick blood films are used.

Investigating Suspected Malaria

• Blood films should be done immediately. Repeat another sample if initial results are negative, especially at peak fever.
• Full blood count (FBC) may show relative lymphopenia or neutrophilia (suggestive of secondary infection or severe disease) and thrombocytopenia (over 90% of non-immune patients).
• Blood Urea and Serum Electrolytes (BUSE), and CRP level check for low sodium, calcium, and albumin, which usually resolve with treatment. CRP is raised.
• Liver profile and blood glucose may reveal abnormalities (bilirubin, liver enzymes) which may indicate other conditions, particularly in cases of high parasitemia or quinine treatment
• Sodium, calcium and albumin are often low, resolving with treatment

Demonstration of Parasite by Microscopy

• Two types of smears are prepared from peripheral blood: thin and thick blood smears.

Thick Blood Film

• Main use is detecting infection due to higher blood volume
• Cannot identify species due to red blood cell lysis.

Thin Blood Film

• Identifies species due to lack of red blood cell lysis
• Allows study of shape and size of infected red blood cells.

Diagnosis: Identification of Malaria Parasite

• Size of infected RBC: Enlarged in P. vivax (rarely)
• Shape of infected RBC: Oval in P. ovale; Enlarged in general in symptomatic malaria cases
• Shape of gametocyte: Banana or crescent shape in P. falciparum; round in other species.
• Shape of trophozoite in RBC: Band form (P. malariae & P. knowlesi); ring form (other species).
• Stippling (dots) in RBCs is species-specific.

Overall Morphological Characteristics of Malaria Parasites in Blood

• Charts and diagrams of various malaria species' morphology presented.

P. falciparum

• Ring Form (early trophozoite)
• Mature Schizont
• Microgametocyte
• Macrogametocyte

Diagnosis: (Further P. falciparum characteristics)

• Trophozoites display small ring forms within the red blood cells.
• Accole form: Trophozoites in the RBC

P. vivax

• Ring Form (early trophozoite)
• Immature Schizonts: Cytoplasmic Material, Chromatin mass
• Microgametocyte: Halo/colorless to pale

P. vivax Characteristics

• "Reticulocyte" (immature RBC) only;
• Schuffner's dots

P. malariae

• Ring form (early trophozoite)
• Mature Schizont

P. malariae Description

• Single chromatin dot
• Cytoplasm ring; thicker than P. falciparum.
• Bird's-eye forms may occasionally appear
• No enlargement of infected RBCs

P. ovale

• Ring form trophozoites: Usually a single chromatin dot, but double dots are possible in some cases.

Specie Differentiation

• Charts distinguishing various species based on RBC shape, stippling, trophozoite shape, chromatin, and developmental stage features (i.e., schizont counts).

Serodiagnosis

• Useful for epidemiological studies to assess population immunity
• Can identify infected donors, particularly in transfusion malaria
• Less useful in acute cases due to antibody presence.
• Indirect hemagglutination (IHA), indirect fluorescent antibody (IFA), and enzyme-linked immunosorbent assay (ELISA) are the tests used.

Rapid Diagnostic Tests (RDTs)

• Detect circulating parasite antigens in blood.
• Supplementary to microscopy for situations where expertise or time are limited.
• Results should always be interpreted alongside microscopy readings, completed by experienced technicians.

Molecular Diagnosis

• Whole blood in EDTA or dried blood spot on filter paper are preferred for PCR analysis.
• PCR is suitable when parasite is absent in blood film, in mortality cases and cases with P. malariae appearance.

Morphological Similarities between Human & Simian Plasmodium

• Charts showing comparable morphological characteristics of human and simian malaria parasites.

Molecular Detection Methods for Simian Plasmodium

• Nested PCR, Real-time PCR, Single step PCR, and LAMP methods for diagnosis.

Treatment for Malaria

• Specific antimalarial drug therapy used to terminate parasitaemia, prevent relapse, recrudescence and transmission, and for prophylaxis
• Drug selection depends on country policies, types of malaria infection, and drug resistance

Supportive Treatment

• Aimed at relieving symptoms like fever, rehydration, and blood replacement for severe anemia.
• Also includes control of convulsions using anticonvulsant drugs, and treatment of DIC (disseminated intravascular coagulation)

Anti-malarial Drugs

• Drug selection influenced by parasite species, strain, and stage.
• Tissue schizonticides (e.g., primaquine) act on tissue schizonts to prevent symptomatic malaria
• Blood schizonticides (e.g., chloroquine, quinine) act on infected red blood cells (RBCs), treating malaria and used for prophylaxis.
• Gametocidal agents act on gametocytes (e.g., primaquine).
• Artemisinin-based combination therapy (ACT) is currently recommended for P. falciparum treatment. ACTs provide high efficacy, fast action, and reduced resistance to developing

Specific Treatments (Further Details)

• Artemisinin-based combination therapy (ACT) is recommended; various drugs such as dihydroartemisinin, artesunate, and artemether.
• Chloroquine is a commonly used first-line treatment for P. vivax and P. ovale.
• Primaquine is used for liver stage parasites of P. vivax.

Quinine and Related Drugs

• Quinine and related drugs as alternative treatments for multi-drug resistant strains
• Mefloquine, and halofantrine and Qinghaosu

Prevention & Control

• Awareness about risk, incubation period, and symptoms
• Bite prevention (avoid mosquitoes, especially during dawn and dusk)
• Chemoprophylaxis (using antimalarial drugs when appropriate)
• Diagnosis (seeking medical help if fever develops a week after exposure)
• Treatment/Treatment of cases, vector control (eliminating standing water, insecticide spray), personal protection (bed nets, insect repellant, long sleeves), and vaccine development
• WHO's ABCD of Malaria Prevention measures highlighted