Malaria Prof. Ahmed A Adeel

Malaria Species Four species of malaria : – Plasmodium falciparum: malignant tertian malaria – Plasmodium vivax: benign tertian malaria – Plasmodium ovale : benign tertian malaria – Plasmodium malariae: quartan malaria

Estimated incidence malaria episodes(caused by any species) resulting from local transmission, country level averages, 2004

Exo-erythrocytic (hepatic) cycle Hypnozoites Sporozoites Salivary Gland LIFE CYCLE OF MALARIA Gametocytes Erythrocytic Cycle Zygote Oocyst Stomach Wall Pre-erythrocytic (hepatic) cycle sporozoites

Components of the Malaria Life Cycle Mosquito Vector Human Host Sporogonic cycle Infective Period Mosquito bites gametocytemic person Mosquito bites uninfected person Prepatent Period Incubation Period Clinical Illness Parasites visible Recovery Symptom onset

CLINICAL SIGNS & SYMPTOMS Hot stage Cold stage Sweating

Plasmodium falciparum:: Plasmodium vivax, Plasmodium ovale Plasmodium malariae\:

Chronic Disease Chronic Asymptomatic Infection Placental Malaria Anemia Infection During Pregnancy Developmental Disorders; Transfusions; Death Low Birth weight Increased Infant Mortality Acute Disease Non-severe Acute Febrile disease Cerebral Malaria Death CLINICAL PICTURE

Uncomplicated malaria Uncomplicated malaria is defined as: Symptomatic infection with malaria parasitemia without signs of severity and/or evidence of vital organ dysfunction.

Malarial Paroxysm cold stage feeling of intense cold vigorous shivering lasts minutes hot stage intense heat dry burning skin throbbing headache lasts 2-6 hours sweating stage profuse sweating declining temperature exhausted and weak → sleep lasts 2-4 hours

Severe malaria Severe malaria is defined as symptomatic malaria in a patient with P. falciparum asexual parasitaemia with one or more of the following complications: – Cerebral malaria ( unrousable coma not attributable to other causes). – Generalised convulsions ( > 2 episodes within 24 hours) – Severe normocytic anaemia ( Ht<15% or Hb < 5 g/dl) – Hypoglycaemia (g lood glucose < 2.2 mmol/l or 40 mg/dl ) – Metabolic acidosis with respiratory distress (a rterial pH < 7.35 or bicarbonate < 15 mmol/l) – Fluid and electrolyte disturbances – Acute renal failure ( urine <400 ml/24 h in adults; 12 ml/kg/24 h in children) – Acute pulmonary oedema and adult respiratory distress syndrome – Abnormal bleeding – Jaundice – Haemoglobinuria – Circulatory collapse, shock, septicaema (algid malaria) – Hyperparasitaemia (>10% in non-immune; >20% in semi-immune)

Complications of malaria : Cerebral malaria

Complications of malaria : Pulmonary oedema

Child with severe malaria anaemia and no other malaria complication Complications of malaria : anaemia

Child with severe malaria anaemia in conjunction with acidosis and respiratory distress

Clinical Picture : Patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency may develop intravascular haemolysis and haemoglobinuria precipitated by primaquine and other oxidant drugs, even in the absence of malaria. Haemoglobinuria associated with malaria (“blackwater fever”) is uncommon and malarial haemoglobinuria usually presents in adults as severe disease with anaemia and renal failure. Malarial haemoglobinuria

Laboratory diagnosis of malaria

CCMOVBD Plasmodium falciparum CCMOVBD Plasmodium vivax CCMOVBD Plasmodium malariae Malaria Tutorials, Wellcome Trust Plasmodium ovale Laboratory diagnosis of malaria

Features of Plasmodium CCMOVBD Nucleus/chromatin dot Cytoplasm Stippling Vacuole Laboratory diagnosis of malaria

3. Gametocyte The Malaria Parasite Three developmental stages seen in blood films: 1.Trophozoite 2. Schizont CCMOVBD Trophozoites CCMOVBD GametocyteSchizont CCMOVBD Laboratory diagnosis of malaria

Plasmodium falciparum (trophozoite stage) Diagnostic Points: Small, regular, fine to fleshy cytoplasm Infected RBCs not enlarged Numerous, multiple infection is common Ring, comma, marginal or accole forms are seen; often have double chromatin dots Maurer’s dots not clearly visible CCMOVBD Multiple infection Double chromatin Marginal form Laboratory diagnosis of malaria Plasmodium facliparum

Laboratory diagnosis of malaria Rapid diagnostic tests detect malaria antigens Laboratory diagnosis of malaria

Plastic cassette format of RDT Rapid diagnostic tests detect malaria antigens

ACTION OF ANTIMALARIAL DRUG IN THE DIFFERENT LIFE STAGES OF THE MALARIA PARASITE Wellcome Trust (Modified) Tissue Schizontocides PrimaquinePrimaquine PyrimethaminePyrimethamine TetracyclineTetracycline ProguanilProguanil Anti-relapse (P.vivax) primaquine Blood Schizontocides Chloroquine Sulfadoxine/Pyrimethamine Quinine Quinidine Artemisinins GametocyidePrimaquine Sporontocides PrimaquinePrimaquine PyrimethaminePyrimethamine ProguanilProguanil

Main Malaria Control Measures 1.Early diagnosis and treatment of cases 2.Vector control : adult mosquitoes :insecticides mosquito larvae: draining breeding sites 3.Reducing vector-human contact: bed nets, repellents 4.Early detection and control of epidemics

Malaria Prevention in Travelers: (1)Specific chemoprophylaxis ( ) (2) Avoiding contact with malaria vectors ( repellents, bed nets) (3) Stand-by treatment, early diagnosis and treatment