Malaria 2024 PDF

Malaria Dr. Shaimaa Helmy Ass. Professor of Medical parasitology Acting Head of Parasitology Department Faculty of Medicine Helwan University  Plasmodium species (blood protozoa) Causes Human Malaria Mal = Bad Aria = Air...

Malaria Dr. Shaimaa Helmy Ass. Professor of Medical parasitology Acting Head of Parasitology Department Faculty of Medicine Helwan University  Plasmodium species (blood protozoa) Causes Human Malaria Mal = Bad Aria = Air Plasmodium vivax Benign tertian malaria Most widely distributed Plasmodium ovale Ovale tertian malaria Confined to West Africa Plasmodium malariae Quartan malaria Rare except in Africa Plasmodium falciparum Malignant tertian malaria Most predominant in Africa Global Distribution of Malaria  Mode of Infection Life Cycle of Malaria Infective female Anopheles injects sporozoites with its saliva at the site of bite When a female Anopheles mosquito bites a patient, it Infective Stage ingests infected RBCs 1- Liver Phase hypnozoite (P. vivax & P. ovale) Now Symptoms 2- Blood Phase During liver phase, appear the patient is asymptomatic Rupture of infected red blood cell occurs every 3rd d ay in P. vivax & P. ovale Diagnostic 4th day in P. malarie stages irreg. in P. falciprum  Pathogenesis of Malaria Incubation period followed by influenza-like symptoms Malaria paroxysms (clinical attack) appears: Symptoms coincide with: Rupture of infected RBCs Release of parasite metabolites Host immunologic response  Clinical Picture of Malaria The patient passes into 3 consecutive stages 1. Cold stage The patient has sudden chill, extreme cold and his temperature rises (15 minutes) 2. Hot stage The patient has headache, high fever and hot, dry and flushed skin (2-6 hours) 3. Sweating stage The patient has profuse sweating and temperature falls (few hours)  Clinical Picture of Malaria (cont.) Clinical attacks gradually decrease & finally disappear (2 weeks or more) As patients’ immune cells clear the circulation from most of Blood merozoites, Plasmodium metabolites & Malaria pigment Clinical attacks reappear due to Presence of hypnozoites in the liver [Relapse] Occurs in Plasmodium vivax & Plasmodium ovale infection Presence of low-grade parasitaemia when the patient becomes immunosuppressed [Recrudescence] Occurs in Plasmodium malariae & Plasmodium falciparum infection  Clinical Picture of Malaria (cont.) Hemolytic anemia The severity of anemia varies according to the invading Plasmodium species Plasmodium vivax & Plasmodium ovale prefer to invade young RBCs Less severe anaemia Plasmodium malariae prefers to invade old RBCs Less severe anaemia Plasmodium falciparum invades RBCs of any age severe anaemia  Clinical Picture of Malaria (cont.) Hepatosplenomegaly Due to enhanced phagocytosis of remnants of ruptured red cells, Blood merozoites, Plasmodium metabolites & Malaria pigment (Haemozoin)  Complications Plasmodium vivax, Plasmodium ovale & Plasmodium malariae are relatively benign Chronic Plasmodium malariae infection is complicated by Nephrotic syndrome Plasmodium malariae parasite produces excess amount of antigen Blood protein Patient’s immune system produces excess amount of antibody Immune complexes are produced and circulate to deposit on glomerular wall to activate complement cascade MAC Kidney tissue damage Protein in urine  Complications (cont.) Plasmodium falciparum infection is complicated by 1- knob formation on the surface of infected RBCs Theses knobs adhere to receptors found on endothelium of blood capillaries of internal organs Blood supply Death of organ tissue  Complications of Malignant Malaria (cont.) Examples of affected organs & tissues The brain (cerebral malaria) drowsiness, convulsions & coma The intestine diarrhoea, dysentery The lungs Lung oedema, difficulty in breathing The liver impaired glycogenolysis Hypoglycaemia The kidney Acute renal failure Circulation (Algid Malaria) hypotension, circulatory collapse & shock (Adrenal Failure Syndrome)  Complications of Malignant Malaria (cont.) 2- Hyper-reactive malarial splenomegaly (Tropical splenomegaly syndrome) Exaggerated immune response to repeated attacks of malaria The spleen is markedly enlarged with increased IgM production  Complications of Malignant Malaria (cont.) 3- Black water fever Massive intravascular haemolysis occurs The patient presents clinically with: I- Fever, Anaemia II- jaundice III- hemoglobinuria Occurs: when? - Repeated attacks of Plasmodium falciparum infection - Incomplete quinine therapy Cause: May be due to an autoimmune reaction Laboratory Diagnosis of Malaria  Laboratory Diagnosis of Malaria 1- Thin & thick blood film examination to demonstrate the parasite stages Thin blood film One drop of blood spread on a slide Giemsa-stained blood films Thick blood film 4 drops of blood spread in a small circle on a slide  P. vivax P. ovale P. malariae P. falciparum Infected RBC Enlarged, rounded Enlarged, oval Normal size & shape Ring 1/ 3 Ring Ring Ring 1/ 6 Ring RBC size 1/ RBC size 3 1/ RBC size 3 RBC size Multiple rings Malaria pigments (Haemozoin) Trophozoite Band- shaped X Maurer’s clefts Schuffner’s dots Ziemann’s dots Schizont X Not seen in peripheral blood Gametocyte Lab Diagnosis of Malaria (continued)  Lab Diagnosis of Malaria (continued) Malaria pigments = Haemozoin It is the remnants of haemoglobin that was digested by Plasmodium parasite Schuffner’s dots Ziemann’s dots called: Stippling Maurer’s clefts It is degeneration process occurring in Plasmodium infected RBCs  Lab Diagnosis of Malaria (continued) 2- Detection of circulating parasite antigen using monoclonal antibodies (rapid Dipstick Test) 3- Detection of parasite DNA and RNA in patient’s blood using PCR  Treatment of Malaria Groups of Drugs Used to Treat Malaria include Tissue schizonticides: e.g. pyrimethamine or primaquine Blood schizonticides: e.g. chloroquine or mefloquine Blood gametocyticides: e.g. chloroquine or primaquine  Treatment of Malaria (continued) Recommended regimen for treatment of malaria During clinical attack: Blood Schizonticides Chloroquine Radical treatment after clinical attack: Tissue schizonticides Primaquine (Plasmodium vivax and Plasmodium ovale) Treatment of drug-resistant cases: Give combination of drugs (recently artimisinin) Chemoprophylaxis: for healthy human entering an endemic area: Pyrimethamine or Primaquine before entering an endemic area Chloroquine or Mefloquine if man has already entered an endemic area  Epidemiology of Malaria Circumstances that are responsible for existence of Malaria in a certain locality 1- Infected human (gametocyte carrier) 2- Suitable species of Anopheles mosquito vector 3- Human (susceptible to infection) People that are naturally resistant to malaria infection Are those having the following medical problems: - Absence of Duffy antigen Resistant to P.vivax infection - Haemoglobin S (in sickle-cell disease) Shape of RBC and type of haemoglobin are not suitable for Plasmodium falciparum parasite growth - Deficiency of G6PD enzyme Plasmodium falciparum parasite needs this enzyme for its growth Control of Malaria - Treatment of cases - Mosquito control - Chemoprophylaxis - Vaccination trials: RTS, S/AS01" was engineered using genes from the outer protein of Plasmodium falciparam