Plasmodium spp.pptx

P. falciparum, 
P. vivax, 
P. ovale, 
P. malariae, and 
P. knowlesi

1. Plasmodium spp. Prof. Dr. Ibrahim Aboulasaad Malaria

2. OVERVIEW Malaria , which predominantly occurs in tropical areas, is a potentially life-threatening disease caused by infection with Plasmodium protozoa transmitted by an infective female  Anopheles  mosquito. The 5  Plasmodium  species known to cause malaria in humans are: P. falciparum ,  P. vivax ,  P. ovale ,  P. malariae , and  P. knowlesi Each  Plasmodium  species has a defined area of endemicity, although geographic overlap is common.

3. P. Vivax and P. falciparum are the most common. P. Falciparum cause the most severe disease P. knowlesi: The natural primate host of  P. knowlesi  is the  macaque . Naturally acquired human infections were thought to be extremely rare until a large focus of human infections was reported in Malaysian P. malariae   is a relatively mild form of malaria. Deaths associated with  P. malariae  are not from acute infection but rather caused by end-stage renal disease  (nephrotic syndrome caused by an immune complex), P. ovale   causes a relatively mild form of malaria that is very rarely severe or fatal.  Although  P. ovale  has been reported from all continents, it is edemic only in tropical Africa OVERVIEW

4. Cosmopolitan especially in temperate, subtropical and tropical zones. In Egypt, P. vivax malaria cases were identified in village of the Aswan and Faiyum Governorates Worldwide, an estimated 300-500 million cases occurring annually. Malaria is responsible for approximately 1-3 million deaths per year, typically in children in sub-Saharan Africa. P. falciparum  is the primary species responsible for increased morbidity and mortality.   Epidemiology Young children aged 6 months to 3 years who live in endemic areas are at an increased risk of death due to malaria. Travelers without immunity are at an increased mortality risk, regardless of age. Geographical distribution:

5. P. vivax P. ovale   P. malariae P. falciparum Infected R.B.C: size shape + distorted + Oval - Round - Round Trophozoite: Ring Ameboid Large vacuoled Large compact Large Band like Small, 2 or more. Compact Schizont (merozoites No.) 12-24 4-12 6-12 rare 12-30 Gametocytes Large, round Large, round Compact, round Crescent shape Stippling Schuffner’s dots Schuffner’s dots Ziemann’s dots Maurer’s dots Hemozoin Fine granules Light brown Scatered Light brown Coarse granules Dark brown One or 2 solid masses. Dark Differentiation of  Plasmodium species Morphology

6. In the cytoplasm of the parasite Malarial pigment (hemozoin): Hemozoin is formed in the developing intra-erythrocytic parasites, as toxic heme remaining after digestion of hemoglobin. Hemozoin released after the lysis of infected RBC is phagocytosed by the RES, where it is readily observed within macrophages of the bone marrow and spleen. In the cytoplasm of the erythrocyte Stippling (Punctate granulations): Granules appear in the cytoplasm of the infected RBCs demonstrated in stained thin blood film, due to alterations in/on the erythrocyte (as a consequence of being parasitized by the plasmodia) and are not in the trophozoites. It is named Schuffner’s dots (in vivax & ovale infections), Ziemann’s dots (in malariae infection) and Maurer’s dots (in falciparum infection)

7. Habitat R.B.Cs. and liver cells Hosts: D.H.: (invertebrate host): female Anopheles mosquito; where sexual cycle takes place (sporogony). I.H. : man; where the asexual cycle occurs (asexual multiplication by schizogony). R.H. : Chimpanzee may be a reservoir host for P. malariae in some parts of Africa. Infective stage : Sporozoite transmitted by female Anopheles Erythrocytic stages (except gametocytes) in induced malaria Life cycle

8. Modes of infection: Biological transmission by female Anopheles mosquito. Blood transfusion from an infected donor (No hepatic phase). The use of contaminated syringes as in addicts (No hepatic phase). Rarely congenital transmission through the placenta (No hepatic phase). Organ transplantation from a donor infected with P. falciparum or with P. vivax and P. oval (hypnozoites in the liver).

9. D.H I.H HEPATIC PHASE ERYTHROCYTIC PHASE

10. Pathogenesis and clinical picture

11. The incubation period: defined as the time between sporozoite inoculation and the onset of symptoms.   P falciparum  9-14 days P vivax  12-17 days P ovale  16-18 days P malariae  18-40 days During the hepatic phase: No clinically manifestations or slight enlargement and tenderness of the liver. During erythrocytic phase: Rupture of the infected RBCs and release of merozoites, malarial pigment, and toxins into the circulation cause the main clinical manifestations of malaria.

12. The erythrocytic phase: Pathology associated with all malarial species is related to the rupture of infected erythrocytes and the release of parasite material and metabolites, malaria pigment and cellular debris  clinical manifestations of malaria: Pathogenesis and clinical picture After the incubation period (8-30 days according to the species), the following clinical aspects occur in all types of malaria: The pre-erythrocytic phase: Affects only a very few hepatocytes. This phase passes off as a ‘silent’ phase without any symptoms or very slight enlargement and tenderness of the liver.

13. Clinical Picture During the initial days of following the incubation period: The classical clinical manifestations of malaria may not be seen in many patients, as schizogonic cycles are not synchronized and parasite populations are heterogeneous, resulting in irregular or continuous fever, or no fever with prodromal symptoms.

14. Synchronous RBC membrane and schizont rupture release of: Merozoites, Malarial pigment, Proteinaceous debris, Toxins Classical pattern of Malarial paroxysm Malarial paroxysm

15. Malarial paroxysm After the incubation period and the initial days post infection, synchronization of schizont rupture is established producing the classical pattern of malarial paroxysm:

16. Cold stage: feeling of extreme cold, rigors and chattering of teeth. Hot stage: fever (39-41°C), flushed face, restlessness, rapid pulse, intense frontal headache, nausea and vomiting, disorientation or even delirium and convulsions especially in children. Sweating stage: profuse sweating, decline of fever and relief of symptoms. Following the sweating stage, the temperature becomes normal, the patient is exhausted and falls asleep. Between paroxysms the patient feels well , whereas, the trophozoites complete their cycle in erythrocytes till its rupture. Malarial paroxysm

17. Periodicity and duration of malarial paroxysms Species Disease Periodicity Duration P. vivax  Benign tertian malaria 48 hours cycles 3-8+ weeks P. ovale Benign tertian malaria 48 hours cycles 2-3 weeks P. falciparum Malignant tertian malaria Irregular (1-3 days) 2-3 weeks P. malariae Quartan malaria 72 hours cycle 3-24 weeks P. knowlesi Quotidian malaria 24 hour cycle undefined

18. Hemolytic anaemia and jaundice due to destruction of a large number of red blood cells. Hepatosplenomegaly due to hyperplasia of the reticuloendothelial cells as a result of engulfment of merozoites, malarial pigment, proteinaceous and toxins Grey or black pigmentation of visceral organs due to deposition of malarial pigment. The consequences of the repeated malaria paroxysms: In areas with endemic malaria, older children and adults are immune to clinical illness and hence may not have fever despite parasitemia. However, loss of immunity due to pregnancy or immunosuppression can result in severe disease.

19. Severe malaria primarily involves  P falciparum  infection. P. falciparum infection causes malignant malaria due to: Short hepatic cycle Asynchronized maturation and rupture of the schizonts. Adhesion phenomenon Pernicious malaria Malignant Malaria Short hepatic cycle (6 days) with large numbers of merozoites in liver schizont (40,000). These merozoites invade RBCs of all ages resulting in high parasitaemia , more severe anaemia and jaundice. Erythrocytic schizogony is completed in 36-48 hours, so, schizogonic cycles are not synchronized leading to irregular paroxysm pattern and difficult diagnosis.

20. Adhesion phenomenon: Infected erythrocytes tend to adhere to each other and to the capillary endothelium in internal organs forming thrombi and obstruction of the small blood vessels. Ischemia and anoxia of these organs in addition to rupture of the blocked capillaries and haemorrhage cause destruction of the surrounding tissue Pernicious malaria : are the result of capillary blockage arises from agglutination of parasitized erythrocytes in the internal organs. So, it is a consequence of adhesion phenomenon. The clinical manifestations are variable according to the affected organ and the degree of ischemia and tissue damage

21. Complications of malaria: Severe anemia Pernicious syndrome Respiratory symptoms Complications in Pregnancy Black water fever Nephrotic syndrome Metabolic complications Hyperreactive malarial splenomegaly Recrudescence and Relapse

22. The anemia associated with malaria is multifactorial due to: Rupture of infected RBCs may occur with all Plasmodium species especially P. falciparum infection. Autoimmune hemolysis of uninfected RBCs due to hypersplenism Impaired hemopoiesis due to toxic bone marrow suppression. Severe anemia Pernicious syndrome In P. falciparum Infection: The adhesion phenomenon  ( vascular obstruction + ischemia + hemorrhage)  Pernicious syndrome In Pernicious syndrome the clinical manifestations are variable according to the affected organ and the degree of tissue damage as follows:

23. Cerebral malaria: severe headache, hyperpyrexia, delirium, paralysis, convulsions, coma, and death. Gastrointestinal manifestation: thrombosis in the capillary bed of the intestinal wall, ischemia and bleeding leading to: Hematemesis Cholera-like diarrhoea Dysentery Algid malaria: shock, collapse and peripheral circulatory failure due to generalized vascular thrombosis, haemorrhage in gastrointestinal tract and adrenal glands necrosis . Renal failure: Infected erythrocytes adhere to the microvasculature in the renal cortex, often resulting in acute tubular necrosis and renal failure . Loss of vision: due to malarial retinopathy or retinal haemorrhage

24. Maternal: Immuno-suppression and loss of acquired immunity to malaria cause severe malaria Fetal: Placental hemorrhage and insufficiency lead to spontaneous abortion or still birth, Low birth weight, and placental spread of the infection to the fetus can result in congenital malaria. Complications in Pregnancy Metabolic acidosis and pulmonary edema  Signs of malarial hyperpneic syndrome include: Alar flaring, Intercostals retraction, Use of accessory muscles for respiration, or Abnormally deep breathing. Respiratory symptoms

25. Black water fever: Acute massive intravascular haemolysis as an autoimmune reaction occurs with inadequate quinine treatment or repeated infection with P. falciparum in partially immune (previously infected) patients. It usually occurs during the malarial paroxysm and is characterized by fever, severe hemolytic anemia, jaundice, haemoglobinaemia and haemoglobinurea with dark red or black urine. Blocking of the kidney tubules may lead to anurea , renal failure and death.

26. Immune complex deposition in the renal glomeruli may occur in chronic Plasmodium malariae infection especially in children. It is characterized by oedema and ascites, hypertension and proteinuria. Nephrotic syndrome Hypoglycemia; Hypoglycemia often occurs in young children and pregnant women Lactic acidosis; This occurs when the microvasculature becomes clogged with  P falciparum Metabolic complications

27. Also known as Tropical splenomegaly syndrome Etiology: immunological over-stimulation to repeated attacks of malarial infection over a long period of time.   Condition is usually seen in malaria-endemic areas like Africa and India.     Hyperreactive malarial splenomegaly It is characterized by: Massive splenomegaly, hepatomegaly, marked elevations in levels of serum anti-malarial antibodies. Peripheral smear for malarial parasite is usually negative. Condition may show features of hypersplenism Splenic rupture may occur spontaneously or after a minor trauma.

28. Recrudescence and Relapse Relapse: In P. vivax and P. ovale, some of the sporozoites remain dormant in the liver cells (as hypnozoites ) to be reactivated later resulting in relapses usually 3~6 mon after “cured”. Recrudescence: In all species of plasmodium, persistence of drug resistant parasite leads to a low-grade parasitaemia that can not initiate a paroxysm and may persist for a long period (even up to 20 years in P. malariae ) leading to or reappearance of paroxysms if the patient becomes debilitated or immunosuppressed for any reason.

29. Clinical Diagnosis: History of visiting or living in endemic areas Characteristic clinical manifestations. Clinical findings should always be confirmed by a laboratory test for malaria. Direct Laboratory diagnosis: Microscopic examination of blood films, The quantitative buffy coat technique. Ascoli’s test Bone marrow puncture Indirect Laboratory diagnosis (immunologic tests): Antibodies Detection Antigen Detection (Rapid diagnostic test) Molecular Diagnosis: PCR is useful for diagnosis and identification of species of Plasmodium . Imaging studies:

30. Microscopic examination of blood films Identification of the parasites on a thin or thick blood smear ( stained with Giemsa or leishman stains) reveal all erythrocytic stages except in P. falciparum (only ring & gametocyte stages). Thick smears are 20 times more sensitive than thin smears, but speciation may be more difficult.  The parasitemia can be calculated based on the number of infected RBCs, so, it is a quantitative test. Thin smears are less sensitive than thick smears, but they allow identification of the different species. This should be considered a qualitative test.

31. Thin blood smears

32. Alternative direct diagnostic tests: The quantitative buffy coat technique. Ascoli’s test. Bone marrow puncture. The quantitative buffy coat (QBC): Detection of acridine orange-stained erythrocytic stages that fluoresce when viewed by a fluorescent microscope. It is a technique that is as sensitive as thick smears. Ascoli’s test: Helpful in case of light chronic infections 0.5 ml of 1/1000 adrenaline injected subcutaneously will lead to contraction of the spleen and passage of the parasites to the circulation.

33. Bone marrow puncture: Bone marrow aspiration studies are of vital importance in diagnosing malarial infection in endemic areas as being one of the cause of pancytopenia or thrombocytopenia. Plasmodium can be detected in the bone marrow aspirate Bone marrow aspirate demonstrates hemozoin pigment. Bone marrow aspirate can be used for PCR analysis

34. Indirect Laboratory diagnosis (immunologic tests) Antibodies Detection: Serology detects antibodies against malaria parasites, using either indirect immunofluorescence (IFA) or enzyme-linked immunosorbent assay (ELISA). Disadvantage: Serology does not detect current infection but rather measures past exposure. Antigen Detection (Rapid Diagnostic Test) (RDT) is an alternate way of quickly establishing the diagnosis of malaria infection by detecting specific malaria antigens in a person’s blood.  Disadvantage: The RDT may not be able to detect some infections with lower numbers of malaria parasites circulating in the patient’s bloodstream. 

35. Molecular Diagnosis: Polymerase chain reaction assay; PCR assay testing is a very specific and sensitive means of diagnosis. It is very effective at detecting  Plasmodium  species in patients with low parasitemia. However, PCR assay tests are not available in most clinical situations.

36. Imaging studies Chest radiography may be helpful if respiratory symptoms are present. Computed tomography of the head, if central nervous system symptoms are present, to evaluate evidence of cerebral edema or hemorrhage.

37. Once the diagnosis of malaria has been made, appropriate antimalarial treatment must be initiated immediately. Treatment should be guided by the following four main factors: Treatment of Malaria Infecting Plasmodium species; Clinical status of the patient; Expected drug susceptibility of the infecting parasite as determined by the geographic area where the infection was acquired; and Previous use of antimalarials, including those taken for malaria chemoprophylaxis. In this case, the treatment regimen should not involve the drug or drug combination used for prophylaxis.

38. Determination of the infecting Plasmodium species for treatment purposes is important for three main reasons : P. falciparum infections can cause rapidly progressive severe illness or death, while the other species, P. vivax, P. ovale, and P. malariae , are less likely to cause severe disease. P. vivax and P. ovale infections also require treatment for the hypnozoites, which remain dormant in the liver and can cause relapsing episodes. P. falciparum and P. vivax species have different drug resistance patterns in different geographic regions of the world. Clinical status of the patient: Patients diagnosed with malaria are generally categorized as having either uncomplicated or severe malaria: Patients diagnosed with uncomplicated malaria can be effectively treated with oral antimalarials. patients who have one or more of complications, are considered to have manifestations of severe disease and should be treated aggressively with intravenous antimalarial therapy

39. Antimalarial Therapy Objective Explanation Drugs Causal prophylaxis Tissue schizonticides: eliminate developing or dormant liver forms. Primaquine, proguanil and pyrimethamine Clinical cure Blood schizonticides act on erythrocytic parasite Chloroquine, quinine, tetracyclines, mefloquine, pyrimethamine-sulfadoxine and artemisinin Radical cure Eliminate both hepatic & erythrocytic stages Primaquine Tafenoquine Prevent transmission Gametocytocidal: prevent transmission of infection to the mosquito Primaquine, proguanil pyrimethamine and quinine Chemoprophylaxis Protection of non-infected people traveling to an endemic area Chloroquine, doxycycline, mefloquine and primaquine

40. chloroquine-sensitive malaria: Chloroquine phosphate; Dose: orally total dose 1.5 gm (10 tablets) 4 tablets [600 mg] initial dose. 2 tablets [300 mg] after 6 hours 2 tablets [300 mg] daily x 2 days For prevention of relapses in vivax and ovale malaria, using primaquine 15mg / day x 14 days to destroy hypnozoites in the liver. Therapy of Uncomplicated malaria ( P. falciparum or species not identified): chloroquine-resistant malaria: Mefloquine: 15mg/kg in a single oral dose. Combined chemotherapy is the best: Quinine sulfate 650 mg tds x 3-7 days orally + one of the followings: Doxycycline, Tetracycline or Clindamycin Artemisinin-based combination therapy: Companion drugs with Artemisinin  in one tablet include lumefantrine, mefloquine, amodiaquine, or sulfadoxine /pyrimethamine, Atovaquone(250 mg )/ proguanil (100 mg)   ( Malarone ®) 4 tabs qd x 3 days

41. Therapy of Uncomplicated P. malariae Chloroquine as above  Therapy of Uncomplicated P. vivax or P. ovale Chloroquine-sensitive: Chloroquine plus primaquine: Chloroquine treatment as above, and primaquine: 30 mg base qd x 14 days. Chloroquine-resistant: Quinine plus either doxycycline or tetracycline . For prevention of relapses in vivax and ovale malaria. For radical cure primaquine is using (15mg / day x 14 days) to destroy hypnozoites in the liver. Mefloquine plus primaquine for radical cure

42.   Therapy of Complicated P. falciparum (A) Quinine: 16.7 mg/kg loading diluted in 10 ml/ kg isotonic fluid by IV infusion over 4 hrs , then 8.3 mg base/ kg by IV infusion over 4 hrs , repeated 8 hourly for up to 72 hrs or until can swallow, then quinine tablets to complete 3-7 days of treatment Or, Quinidine: 15 mg/kg loading diluted in 10 ml/ kg isotonic fluid by IV infusion over 4 hrs , then 7.5 mg/kg by IV infusion over 4 hrs , repeated 8 hourly for up to 72 hrs or until can swallow, then Quinidine tablets to complete 3-7 days of treatment Plus, Doxycycline, Tetracycline, or Clindamycin, (either concurrently with quinine/ quinidine or immediately after) (B) Alternative: Artimesinin or one of its derivatives as artemether (in a dose of 3.2 mg/ kg IM followed by 1.6mg/kg daily for one week) are used for multi-resistant malaria or when quinine is contraindicated as in black water fever.

43. Is essential for non-immune travelers to an endemic area. Starts 2 weeks before exposure, during stay, and 1-4 weeks after leaving the endemic area. Chemoprophylaxis Drug indication contraindication Chloroquine, 300 mg/week Chloroquine sensitive Chloroquine resistant Mefloquine, 250 mg once weekly Can be used in pregnancy Mefloquine resistant Doxycycline, 100 mg daily For last minute travelers Child and pregnant Primaquine , 15 mg/ day Terminal prophylaxis: for vivax and ovale malaria on leaving G-6-PD (Severe Hemolysis)

44. Prevention and control: Mass treatment of cases + eradication of gametocytes by giving a single dose of 4 tablets of primaquine to prevent transmission of infection to mosquito. Mosquito control. Personal protection by: Using repellants and insecticides. Screening of doors and windows. Chemoprophylaxis for non-infected persons traveling to an endemic area. Vaccination: still under trial.