MALARIA (Recent updates-Harrison) - Dr. Sunil Bhawariya

This PPT provides comprehensive and updated information on commonly encountered protozoal infection in humans i.e. MALARIA.

1. MALARIA DR. SUNIL BHAWARIYA DNB RESIDENT CIVIL HOSPITAL, PANCHKULA

2. INTRODUCTION Malaria is a protozoan disease transmitted by the bite of infected female Anopheles mosquitoes. Malaria presents as an acute febrile illness that is often but not always characterized by the classic malaria paroxysm: chills and rigors , followed by fever spikes up to 40°C (104°F), and then profuse sweating that can ultimately give way to extreme fatigue and sleep. Causative Agent:- Six species of the genus Plasmodium :- P. falciparum, P. vivax , T wo species of P. ovale ( curtisi and wallikeri ), P. malariae , P. knowlesi

3. Plasmodium Life-Cycle

4. PATHOPHYSIOLOGY The microscopic motile forms of the malaria parasite are carried rapidly via the blood- stream to the liver, where they invade hepatic parenchymal cells and begin a period of asexual reproduction. By this amplification process (known as intrahepatic or preerythrocytic schizogony), a single sporozoite may produce from 10,000 to >30,000 daughter merozoites . These few swollen infected liver cells eventually burst, discharging motile merozoites into the bloodstream. The merozoites then invade red blood cells (RBCs) to become trophozoites and, in non-immune subjects, multiply six- to twentyfold every 48 h (P. knowlesi , 24 h; P. malariae , 72 h). When the parasites reach densities of ~50/ μ L of blood (~100 million parasites in total in the blood of an adult), the symptomatic stage of the infection begins. In P. vivax and P. ovale infections, a proportion of the intrahepatic forms do not divide immediately but remain inert for a period ranging from 2 weeks to ≥1 year. These dormant forms, or hypnozoites , are the cause of the relapses that characterize infection with these species.

5. In P. vivax and P. ovale infections, a proportion of the intrahepatic forms do not divide immediately but remain inert for a period ranging from 2 weeks to ≥1 year. These dormant forms called hypnozoites , are the cause of the relapses that characterize infection with these species. P. falciparum merozoites bind via erythrocyte binding antigen 175 to glycophorin A and via EBL140 to glycophorin C. The other glycophorins (B and D) also contribute. P. vivax binds to receptors on developing erythrocytes. The Duffy blood-group antigen Fya or Fyb plays an important role in invasion. By the end of the intraerythrocytic life cycle, the parasite has consumed two- thirds of the RBC’s hemoglobin and has grown to occupy most of the cell. It is now called a schizont. The infected RBC then ruptures to release 6–30 daughter merozoites , each potentially capable of invading a new RBC and repeating the cycle. Some of the blood-stage parasites develop into morphologically distinct, longer-lived sexual forms (gametocytes) that can transmit malaria . PATHOPHYSIOLOGY

6. T he PfEMP-1 (erythrocyte membrane adhesive protein) proteins exposed on knobs have binding domains that adhere to host molecules, including CD36, intercellular adhesion molecule 1 (ICAM-1), thrombospondin , platelet endothelial cell adhesion molecule (PECAM/CD31),87,97–100 chondroitin sulfate A (CSA),73,101 and endothelial protein C receptor, which is involved in the deadly sequestration of parasitized erythrocytes that leads to cerebral malaria. PATHOPHYSIOLOGY

7. Erythrocyte Changes After invading an erythrocyte, the growing malarial parasite progressively consumes and degrades intracellular proteins, principally hemoglobin. toxic heme is detoxified by lipid-mediated crystallization to biologically inert hemozoin (malaria pigment). The parasite also alters the RBC membrane by changing its transport properties, exposing cryptic surface antigens, and inserting new parasite-derived proteins. The RBC becomes more irregular in shape, more antigenic, and less deformable. In P. falciparum infections, membrane protuberances appear on the erythrocyte’s surface 12–15 h after cell invasion. These “knobs” extrude a high-molecular-weight, antigenically variant, strain-specific erythrocyte membrane adhesive protein (PfEMP1) that mediates attachment to receptors on venular and capillary endothelium ( cytoadherence ). PATHOPHYSIOLOGY

8. Erythrocyte Changes intercellular adhesion molecule 1 and endothelial protein C receptor are important in the brain, chondroitin sulfate B predominates in the placenta, and CD36 binds parasitized RBCs in most other organs. Erythrocytes containing more mature parasites stick inside and eventually block capillaries and venules . These infected RBCs may also adhere to uninfected RBCs (to form rosettes) and to other parasitized erythrocytes (agglutination). The processes of cytoadherence , rosetting, and agglutination are central to the pathogenesis of falciparum malaria. They result in the sequestration of infected RBCs in vital organs (particularly the brain), where they interfere with microcirculatory flow and metabolism. PATHOPHYSIOLOGY

9. In severe malaria, uninfected erythrocytes also become less deformable, which compromises their passage through the partially obstructed capillaries and venules and shortens their survival. HOST RESPONSE Splenic immunologic and filtrative clearance functions are augmented, and the removal of both parasitized and uninfected erythrocytes is accelerated. The spleen also removes damaged ring-form parasites (a process known as “pitting”) from within the red cell and returns the once-infected cells back to the circulation, where their survival is shortened. The parasitized cells escaping splenic removal are destroyed when the schizont ruptures. The material released induces monocyte/macrophage activation and the release of proinflammatory cytokines, which cause fever and other pathologic effects. PATHOPHYSIOLOGY

10. Temperatures of ≥40°C (≥104°F) damage mature parasites; in untreated infections. The effect of such temperatures is to further synchronize the parasitic cycle, with eventual production of the regular fever spikes and rigors that originally characterized the different malarias. These regular fever patterns (quotidian, daily; tertian, every 2 days; quartan, every 3 days) are seldom seen today as patients receive prompt and effective antimalarial treatment. Passive transfer of maternal antibody contributes to the partial protection of infants from severe malaria in the first months of life. P. vivax  induces more inflammation compared to P. falciparum for the given parasite density. PATHOPHYSIOLOGY

11. lack of a sense of well-being, fatigue Headache, abdominal discomfort, Nausea, Vomiting Mild anemia muscle aches Palpable spleen followed by fever spikes (The temperature of nonimmune individuals and children often rises above 40°C (104°F), with accompanying tachycardia and sometimes delirium. orthostatic hypotension childhood febrile convulsions may occur with any of the malarias, generalized seizures are associated specifically with falciparum malaria and may lead to the development of encephalopathy (cerebral malaria). CLINICAL FEATURES

12. Typically malarial fever paroxysm has: • Cold stage (20–60 min) wherein individual experiences intense chills with rigors • Hot stage (2–6 hours), where temperature may reach up to 40°C • Wet stage/Diaphoresis (20–30 min) associated with profuse sweating CLINICAL FEATURES

13. Cerebral Malaria manifests as a diffuse symmetric encephalopathy; focal neurologic signs are unusual. eyes may be divergent, and bruxism and a pout reflex are common signs of meningeal irritation are absent corneal reflexes are preserved, except in deep coma. classic histopathologic finding of fatal cerebral falciparum malaria is the intense sequestration of infected erythrocytes in cerebral microvessels . Metabolic acidosis, hypoglycemia , hyperpyrexia , and nonconvulsive status epilepticus can contribute significantly to the cerebral malaria presentation. SEVERE FALCIPARUM MALARIA

14. Hypoglycemia Hypoglycemia in malaria can cause coma and convulsions and thus may contribute substantially to the morbidity and mortality In children, hypoglycemia is associated with impaired hepatic gluconeogenesis and increased consumption of glucose by hypermetabolic peripheral tissues. Large amounts of glucose are also consumed by intraerythrocytic parasites. In adults, hypoglycemia is often associated with hyperinsulinemia , which may result from pancreatic islet cell stimulation by parasite-derived factors or parenteral quinine or quinidine therapy, or both. Depletion of liver glycogen stores after decreased food intake during the prodromal period may also contribute to hypoglycemia . SEVERE FALCIPARUM MALARIA

15. Anemia intravascular lysis and phagocytic removal of infected erythrocytes Excess removal of uninfected erythrocytes may account for up to 90% of erythrocyte loss and may be mediated by processes (e.g., oxidative stress) that accelerate the senescence and reduce the deformability of erythrocytes. Release of inflammatory cytokines (e.g., TNF) is associated with impaired production of erythropoietin, decreased responsiveness of erythroid progenitor cells to adequate levels of erythropoietin, and increased erythrophagocytic activity. These pathogenic processes account for the normochromic normocytic anemia seen in malaria and explain the notable absence of a robust reticulocyte response. SEVERE FALCIPARUM MALARIA

16. Pulmonary Edema and Respiratory Distress Sequestration of infected erythrocytes in the lungs is thought to initiate regional production of inflammatory cytokines that increase capillary permeability, leading sequentially to pulmonary edema , dyspnea, hypoxia, acute lung injury, and acute respiratory distress syndrome. Iatrogenic fluid overload and acute renal failure may contribute to the development or worsening of pulmonary edema . SEVERE FALCIPARUM MALARIA

17. Metabolic (Lactic) Acidosis caused by reduced delivery of oxygen to tissues, from the combined effects of anemia (decreased oxygen-carrying capacity), sequestration (microvascular obstruction), and hypovolemia (reduced perfusion) resulting from fluid losses caused by fever, decreased oral intake, vomiting, and diarrhea . These effects produce a shift from aerobic to anaerobic metabolism and cause lactate levels to increase. These factors may also contribute to metabolic acidosis: production of lactate by anaerobic glycolysis in sequestered parasites; reduction of hepatic blood flow, leading to diminished lactate clearance; induction of lactate production by TNF and other proinflammatory cytokines; impairment of renal function; and ingestion of exogenous acids (e.g., salicylate) SEVERE FALCIPARUM MALARIA

18. Renal Dysfunction Acute kidney injury is common in severe falciparum malaria. Pathogenesis is related to erythrocyte sequestration and agglutination interfering with renal microcirculatory flow and metabolism. Mostly this syndrome manifests as acute tubular necrosis. Early dialysis or hemofiltration considerably improves the chances of survival. Oliguric renal failure is rare among children. SEVERE FALCIPARUM MALARIA

19. Liver Dysfunction Mild hemolytic jaundice is common in malaria. Severe jaundice is associated with P. falciparum infection Jaundice results from hemolysis , hepatocyte injury, and cholestasis . Liver failure does not occur. When accompanied by other vital-organ dysfunction (often renal impairment), liver dysfunction carries a poor prognosis. Hepatic dysfunction contributes to hypoglycemia , lactic acidosis, and impaired drug metabolism. SEVERE FALCIPARUM MALARIA

20. Other Complications 1. HIV/AIDS and malnutrition predispose to more Severe malaria in nonimmune individuals. 2. Malaria anemia is worsened by concurrent infections with intestinal helminths, eg. Hookworm. SEVERE FALCIPARUM MALARIA

21. Placental malaria results in maternal morbidity and mortality, intrauterine growth retardation, premature delivery, low birth weight, and increased newborn mortality. Infected erythrocytes and increased numbers of maternal phagocytic cells, especially monocytes, in the intervillous space. These infected erythrocytes are immunologically distinct from infected erythrocytes found in nonpregnant individuals: they express a specific class of variant surface antigen (pregnancy-associated malaria variant surface antigen [VSA-PAM]) that mediates adhesion of infected erythrocytes to chondroitin sulfate A (CSA) on the syncytiotrophoblast lining the intervillous space Adherence of erythrocytes expressing VSA-PAMs to the surface of syncytiotrophoblast appears to stimulate an inflammatory response. This results in monocyte migration and release of humoral factors, such as tumor necrosis factor-alpha (TNF-alpha), into the intervillous circulation that may promote preterm labor  Hemozoin (malaria pigment) deposition in phagocytic leucocytes and within fibrin deposits in the intervillous space. Malaria in Pregnancy

22. HYPERREACTIVE MALARIAL SPLENOMEGALY Chronic or repeated malarial infections produce hypergammaglobu - linemia ; normochromic , normocytic anemia ; and, in certain situations, splenomegaly. Some residents of malaria-endemic areas in tropical countries exhibit an abnormal immunologic response to repeated infections that is characterized by massive splenomegaly, hepatomegaly, marked elevations in serum IgM and malarial antibody titers , hepatic sinusoidal lymphocytosis , and (in Africa) peripheral B-cell lymphocytosis . This syndrome has been associated with the produc - tion of cytotoxic IgM antibodies to CD8+ T lymphocytes, antibodies to CD5+ T lymphocytes, and an increase in the ratio of CD4+ to CD8+ T cells. Respiratory and skin infections are common and many patients die of overwhelming sepsis. Chronic Complications of Malaria

23. QUARTAN MALARIAL NEPHROPATHY Chronic or repeated infections with P. malariae may cause soluble immune complex injury to the renal glomeruli, resulting in the nephrotic syndrome. The histologic appearance is that of focal or segmental glomerulonephritis with splitting of the capillary basement membrane. Subendothelial dense deposits are seen on electron microscopy, and immunofluorescence reveals deposits of complement and immunoglobulins and P. malariae antigens are often visible. A coarse-granular pattern of basement membrane immunofluorescent deposits (predominantly IgG3) with selective proteinuria carries a better prognosis than a fine-granular, predominantly IgG2 pattern with nonselective proteinuria. Chronic Complications of Malaria

24. BURKITT’S LYMPHOMA AND EPSTEIN-BARR VIRUS INFECTION M alaria-related immune dysregulation provokes infection with lymphoma viruses. Childhood Burkitt’s lymphoma is strongly associated with Epstein-Barr virus (EBV) and with high transmission of P. falciparum. Chronic P. falciparum malaria drives large numbers of EBV-infected cells through the lymph node germinal centers and deregulates activation-induced cytidine deaminase, resulting in DNA damage, c-myc translocations, and sometimes lymphoma. Chronic Complications of Malaria

25. S mear examination via light microscopy is the standard tool for diagnosis of malaria; RDTs should be used if microscopy is not readily available. Molecular techniques for detection of genetic material are limited to research settings. LIGHT MICROSCOPY Detection of parasites on Giemsa-stained blood smears by light microscopy is the standard tool for diagnosis of malaria. Two types of blood smears are used in malaria microscopy: thin and thick smears. Thin smear preparation maintains the integrity and morphology of erythrocytes so that parasites are visible within red blood cells. Thin smears allow identification of the infecting parasite species and can be used to measure parasite density. Thick smear preparation involves mechanical lysis of red blood cells so that malaria parasites can be visualized independent of cell structures. It allow to see large quantity of blood and are typically used to screen for presence or absence of parasites and to estimate parasite density. DIAGNOSIS

26. RAPID DIAGNOSTIC TEST important diagnostic tools in resource-limited endemic settings give results within 15 to 20 minutes can be performed successfully even by health workers with limited training provide a qualitative result but cannot provide quantitative information regarding parasite density RDTs are based on antigen detection detect one or more of the following: histidine-rich protein 2 (HRP2; for detection of P. falciparum),  Plasmodium lactate dehydrogenase (pLDH; for detection of all species or specific detection of P. falciparum or P. vivax ), and aldolase (for detection of all species).  DIAGNOSIS

27. MOLECULAR TESTS Use of molecular tests for malaria detection is generally limited to reference laboratories and is primarily for research and epidemiologic purposes. Nucleic acid tests (eg, PCR) are typically used as a gold standard in efficacy studies for antimalarial drugs, vaccines, and evaluation of other diagnostic agents . Nested PCR is the most sensitive nucleic acid amplification technology; its sensitivity is 400 parasites/mL. Loop-mediated isothermal amplification (LAMP) assays for detection of malaria parasite DNA are being developed to facilitate use of molecular technology in endemic areas . DIAGNOSIS

28. Treatment of Uncomplicated Malaria TREATMENT

29. Treatment of Uncomplicated Malaria Treatment of Uncomplicated Falciparum Malaria World over  P. falciparum  has developed resistance to chloroquine. Hence, artemisinin combination therapy (ACT) is indicated for falciparum malaria. Artemisinin monotherapy is banned in India in view of potential for emergence of resistance.  A rtemisinin, with short half-life has to be administered with a partner drug with longer half-life, to prevent recrudescence. Acute treatment of  P. falciparum  should be followed by a single dose of primaquine 0.75 mg/kg to kill the gametocytes to prevent transmission. TREATMENT

30. Treatment of Uncomplicated Malaria Treatment of Uncomplicated Vivax Malaria P. vivax  in India remains sensitive to chloroquine. Schizonticidal treatment with chloroquine should be followed by primaquine, a hypnozoitocidal drug for 14 days to prevent relapses in all cases of  P. vivax  malaria In G6PD deficiency individuals, primaquine may induce hemolysis . In such patients with known G6PD deficiency, primaquine 0.75 mg/kg may be administered weekly for 8 weeks with supervision and adequate patient counseling about symptoms of hemolysis . Recently, another 8 aminoquinoline , Tafenoquine 300 mg single dose is approved by US FDA as an antirelapse therapy; however, it is not approved in India yet. TREATMENT

31. Treatment of Uncomplicated Malaria Treatment of  P. ovale , P. malariae  and P. knowlesi Malaria P. ovale  should be treated as  P. vivax ;  confirmed  P. malariae should be treated with chloroquine.  P. knowlesi  malaria should be treated as  P. falciparum . TREATMENT

32. Treatment of Uncomplicated Malaria Note:- 1. ACT is not to be given in 1st trimester of pregnancy. Sulfadoxine /Pyrimethamine (SP) is not to be prescribed for children <5 months of age and should be treated with alternate ACT. 2. Primaquine is contraindicated in infants, pregnant women and individuals with G6PD deficiency. 3. In North Eastern India,  P. falciparum   has developed resistance to SP. Hence, SP cannot be used along with artemisinin. TREATMENT

33. Treatment of Severe Malaria in India 1. Initial parenteral treatment for at least 24 hours:  Choose one  of following four options: Artesunate : 2.4 mg/kg IV or IM given on admission (time = 0), then at 12 h and 24 h, then once a day    Or Artemether : 3.2 mg/kg IM given on admission then 1.6 mg/kg per day    Or Arteether : 150 mg daily IM for 3 days in adults only (not recommended for children)    Or Quinine: 20 mg quinine salt/kg bodyweight on admission (IV infusion or divided IM injection) followed by maintenance dose of 10 mg/kg 8 hourly; infusion rate should not exceed 5 mg/kg per hour. Loading dose of 20 mg/kg should not be given, if the patient has already received quinine TREATMENT

34. Treatment of Severe Malaria in India 2. Follow-up treatment, when patient can take oral medication following parenteral treatment: • Full oral course of area-specific ACT: ○ In North Eastern states: ACT- AL for 3 days + PQ Single dose on second day ○ In other states: Treat with: ACT-SP for 3 days + PQ Single dose on second day • Oral Quinine 10 mg/kg three times a day plus • Doxycycline 3 mg/kg once a day for 7 days treatment    OR • Clindamycin 10 mg/kg BID in pregnant women and children under 8 years of age for 7 days TREATMENT

35. Note : • Sulfadoxine /Pyrimethamine (SP) is ineffective against  P. vivax ; Alternative artemisinin combination therapy (ACT) should be used. • SP is not to be prescribed for children <5 months of age and should be treated with alternate ACT. (AL: artemether lumefantrine ; SP: sulfadoxine pyrimethamine) Treatment of Malaria in Pregnancy Artemisinin combination therapy is contraindicated in first trimester of pregnancy. Primaquine and doxycycline are contraindicated throughout pregnancy and lactation. 

36. Tools for human protection from malaria infection include: protection from mosquito bites, chemoprevention , and vaccination. P rotection from mosquito bites by use of Repellants:- Effective repellents include synthetic preparations such as DEET ( N,N-diethyl-m-toluamide ), Picardin (KBR3023), and IR 3535, as well as PMD ( P-MENTHANE-3,8-DIOL ), which is derived from lemon eucalyptus Long-lasting insecticide-treated nets (LLINs) MALARIA PREVENTION

37. Chemoprevention :- MALARIA PREVENTION

38. Malaria Vaccination:- Different vaccine candidates targeting different stages such as pre-erythrocytic stage, sporozoites, merozoites , and gametocytes are being developed. The world’s sole licensed vaccine against  P. falciparum  malaria, RTS, S/AS01, is a recombinant vaccine against pre-erythrocytic stage of the parasite in which regions of  P. falciparum   circumsporozoite protein are fused to hepatitis B surface antigen. Three doses of the malaria vaccine administered intramuscularly in children ≥5 months, with a minimum interval of 4 weeks between doses, followed by a fourth dose at 15–18 months following the third dose is recommended by WHO for large scale pilot implementation in Sub Saharan Africa. MALARIA PREVENTION