Malaria and Babesiosis.pptx mbbsmbbsmbbs

Malaria and babesiosis for mbbs students

1. Malaria and Babesiosis

2. MALARIA 2

3. History 3 “Mal” means bad and “aria” means air -“disease is spread by air pollution through stagnant water and marshy lands” Alphonse Laveran (1880) discovered the causative agent Plasmodium , in the RBC of a patient in Algeria. Sir Ronald Ross (1897) - described the sexual cycle of the parasite in female Anopheles mosquito in Secunderabad , India.

4. Agent 4 Human infection is mainly caused by five species such as: P. vivax causes benign tertian malaria (periodicity of fever is once in 48 hours) P. falciparum causes malignant tertian malaria (severe malaria, periodicity of fever is once in 48 hours) P. malariae causes benign quartan malaria (periodicity of fever is once in 72 hours)

5. Agent (Cont..) 5 P. ovale causes ovale tertian malaria (periodicity of fever is once in 48 hours) P. knowlesi causes quotidian or simian malaria (fever periodicity is once in 24 hours, i.e. recurs every day). It is a parasite of monkey but can also infect humans and many cases affecting man were recently reported from Asia.

6. Life Cycle 6 Host: Plasmodium completes its life cycle in two hosts: Definitive host - Female Anopheles mosquito(sexual cycle) Intermediate host – Man (asexual cycle)

7. Life Cycle 7 Mode of Transmission and Infective Form Man acquires infection by the bite of female Anopheles mosquito Rarely, it can also be transmitted by blood transfusion or transplacental transmission—here, trophozoites (or merozoites) act as the infective form.

8. Life Cycle – Human cycle 8 Pre-erythrocytic (Hepatic) Stage Erythrocytic schizogony Gametogony

9. Life Cycle – Mosquito cycle 9 A female Anopheles mosquito during the blood meal, takes both asexual and the sexual forms. The asexual forms get digested whereas the sexual forms, i.e. the gametocytes undergo further development.

10. Life Cycle (Cont..) 10

11. Relapse and recrudescence in malaria 11 Relapse Recrudescence Seen in Plasmodium vivax and P. ovale infections Although seen in all species, more common in P. falciparum followed by P. malariae Few sporozoites do not develop into pre- erythrocytic schizont , but remain dormant (known as hypnozoites ) for 3 weeks to one year In f alciparum malaria—recrudescence is due to persistence of drug resistant parasites, even after the completion of treatment Reactivation of hypnozoites leads to initiation of erythrocytic cycle and relapse of malaria In P. malariae infection, long-term recrudescences are seen for as long as 60 years This is due to long-term survival of erythrocytic stages at a low undetectable level in blood

12. Relapse and recrudescence in malaria (Cont..) 12 Relapse Recrudescence Concept of secondary exo or pre- erythrocytic stage: Formerly, it was postulated that relapse occurs due to secondary exo or pre- erythrocytic stage where a proportion of hepatic merozoites released from pre- erythrocytic schizont , again attack the liver cells But now, it is believed that secondary pre- erythrocytic stage does not occur and relapse occurs due to sporozoites undergoing dormancyduring the primary pre- erythrocytic stage

13. Differences between malaria parasites 13 Properties Plasmodium vivax Plasmodium falciparum Plasmodium malariae Plasmodium ovale Relapse (Hypnozoites) Seen Not seen Not seen Seen Recrudescence Not seen Seen Seen (Up to 60 years) Not seen Erythrocytic cycle 48 hours 36–48 hours 72 hours 48 hours Prepatent period 8 days 5 days 13 days 9 days Incubation period 14 days 12 days 28 days 17 days R-G interval 4–5 days 10–12days 11–14 days 5–6 days Extrinsic IP 8–10 days 9–10 days 25–28 days 14–16 days

14. Plasmodium knowlesi 14 It is a malaria parasite of monkeys but can also rarely affect humans. Anopheles leucosphyrus is the main vector. Epidemiology: The first human case was documented in 1965 - cases in humans increasingly being reported from Asia since 2008. India: The only report of P. knowlesi infection has documented from Andamans .

15. Plasmodium knowlesi (Cont..) 15 Clinical features - Acute illness and relatively high parasitemia Paroxysms of fever occur daily (quotidian malaria) because of short RBC cycle (24 hours) Clinically it resembles P. vivax , but severe malaria is seen more frequently (7–10%), compared to 3% of P. vivax - Infects RBCs of all ages.

16. Plasmodium knowlesi (Cont..) 16 Laboratory diagnosis: On blood smear examination, early trophozoite of P. knowlesi is indistinguishable from P. falciparum , sometimes shows multiple ring forms, accole forms and double dot ring forms The late trophozoites (with band forms), and round gametocytes are morphologically similar to that of P. malariae .

17. Plasmodium knowlesi (Cont..) 17 Laboratory diagnosis (Cont..): Currently, no specific rapid diagnostic tests (RDTs) are available to detect P. knowlesi P. knowlesi specific nested PCR assays - primers Pmk8 and Pmkr9 targeting small subunit rRNA .

18. Pathogenesis and Clinical Feature – Benign malaria 18 Benign malaria is milder in nature. Caused by all four species Characterized by a triad of febrile paroxysm, anemia and splenomegaly.

19. Pathogenesis and Clinical Feature - Benign malaria (Cont..) 19 Febrile Paroxysm: Fever comes intermittently depending on the species. Occurs every fourth day (72 hour cycle for P. malariae ) and every third day (48 hour cycle for other three species). Paroxysm corresponds to the release of the successive broods of merozoites into the bloodstream, at the end of RBC cycle.

20. Pathogenesis and Clinical Feature - Benign malaria (Cont..) 20 Febrile Paroxysm (Cont..): Each paroxysm of fever is comprised of three stages. 1. Cold stage (15mins to 1hour) 2. Hot stage 3. Sweating stage (2-4hrs)

21. Pathogenesis and Clinical Feature - Benign malaria (Cont..) 21 Febrile Paroxysm (Cont..): The classical paroxysm - not be present always due to maturation of generations of parasites at different times In P. falciparum - fever is more irregular or even continuous with marked prostration, headache and nausea.

22. Pathogenesis and Clinical Feature - Benign malaria (Cont..) 22 Anemia: Patient develops normocytic normochromic anemia - attributed to various factors. Parasite induced RBC destruction—Lysis of RBC due to release of merozoites Splenic removal of both infected RBC and uninfected RBC coated with immune complexes Bone marrow suppression leading to decreased RBC production.

23. Pathogenesis and Clinical Feature - Benign malaria (Cont..) 23 Splenomegaly : After a few weeks of febrile paroxysms, spleen gets enlarged and becomes palpable. Splenomegaly is due to massive proliferation of macrophages that engulf parasitized and nonparasitized coated RBCs.

24. Pathogenesis and Clinical Feature - Falciparum Malaria ( Malignant Tertian Malaria) 24 An important feature of the pathogenesis of P. falciparum - ability to sequester (holding back) the parasites in the blood vessels of deep visceral organs like brain, kidney, etc. This leads to blockage of vessels, congestion and hypoxia of internal organs.

25. Pathogenesis and Clinical Feature - Falciparum Malaria ( Malignant Tertian Malaria) ( Cont ..) 25 Sequestration is mediated by: Cytoadherence : Binding of infected erythrocytes to endothelial cells - mediated by a specialized antigen called as P. falciparum erythrocyte membrane protein-1 (PfEMP-1), which binds to specific receptors present on the vascular endothelium of deep organs.

26. Pathogenesis and Clinical Feature - Falciparum Malaria ( Malignant Tertian Malaria) ( Cont ..) 26 Sequestration is mediated by (Cont..): PfEMP-1 - helps in binding of infected RBCs to uninfected RBCs by a process called rosetting . Since the parasites are sequestrated back in deep vessels - avoid frequent spleen passage, hence can escape splenic clearance.

27. Pathogenesis and Clinical Feature - Falciparum Malaria ( Malignant Tertian Malaria) ( Cont ..) 27 Sequestration is mediated by (Cont..): PfEMP undergoes frequent antigenic variation - helps the parasite in evading the host immune response.

28. Complications - Falciparum Malaria 28 Cerebral malaria Pernicious anemia Black water fever Algid malaria Septicemic malaria Pulmonary edema and adult respiratory distress syndrome Hypoglycemia

29. Complications - Falciparum Malaria (Cont..) 29 Renal failure Bleeding/disseminated intravascular coagulation Severe jaundice Severe normochromic, normocytic anemia Acidosis

30. Chronic Complications of Malaria 30 Tropical splenomegaly syndrome Quartan malarial nephropathy Promotes Burkitt’s lymphoma

31. Transfusion Malaria 31 Transmitted by blood transfusion, needle stick injury, or organ transplantation. Clinical features and management of these cases are same as for naturally acquired infections (mosquito borne) but differs in many other ways: Infective form - intraerythrocytic forms such as merozoites , trophozoites or schizonts but not gametocytes

32. Transfusion Malaria (Cont..) 32 There is no pre- erythrocytic stage of development and no relapse Incubation period - short Radical chemotherapy with primaquine is unnecessary as there is no relapse.

33. Malaria in Pregnancy 33 Increases the risk of fetal distress - result in premature labor, low birth weight and still birth. In areas with high malaria transmission, pregnant women are particularly vulnerable to severe anemia, hypoglycemia and acute pulmonary edema.

34. Malaria in Children 34 Nearly one million children die of falciparum malaria each year in endemic countries. Complications - convulsions, coma, hypoglycemia, metabolic acidosis and severe anemia. Other complications - jaundice, acute renal failure, and acute pulmonary edema are unusual in children.

35. Immunity against Malaria 35 Both innate and acquired immunity contribute to the resistance against malaria.

36. Innate Immunity 36 Refers to inherent mechanisms of host resistance against malaria parasite. This depends upon various factors: Age of RBCs Nature of hemoglobin Hereditary ovalocytosis G6PD deficiency Duffy negative red blood cells Nutritional status

37. Acquired Immunity 37 Both cellular and humoral immunity contribute to the resistance against malaria. Premunition

38. Epidemiology of Malaria 38 Malaria is the most lethal parasitic disease of humans. Transmitted in 108 countries containing 3 billion people.

39. Predisposing Factors 39 The transmission of malaria is directly proportional to: Density of the vector and number of human bites per day per mosquito Time of mosquito bite (more after the dusk) Mosquito longevity (as sporogony lasts for 7–30 days, thus, to transmit malaria, the mosquito must survive for >7 days) Optimum temperature (20–30°C), humidity (60%) and rainfall

40. Situation in World (WHO Malaria Report, 2018) 40 In 2018, 228 million cases of malaria with about 4 lakh deaths occurred worldwide. Africa affected the worst (93%), followed by South-East Asia (3.4%). Incidence rate - About 57 cases per 1000 population at risk. P. falciparum - most common species worldwide - accounting for 99.7% of malaria cases in African region.

41. Malaria Situation in India (NVBDCP Report) 41 According to National Vector Borne Disease Control Programme (NVBDCP), 3.3 lakh malaria cases were reported from India in 2019, with 73 deaths. Over the last decade, Eastern Indian states - Odisha, Chhattisgarh and Jharkhand - maximum malaria cases - P. falciparum - predominant species

42. Malaria Situation in India (NVBDCP Report) (Cont..) 42 In 2018 and 2019 - Uttar Pradesh - highest malaria burden in India - majority of cases were due to P. vivax . P. vivax - most common species in India (>50%), followed by P. falciparum (46%).

43. Malaria Situation in India (NVBDCP Report) (Cont..) 43 P. malariae infections - <1% and are reported from - Karnataka ( Tumkur and Hassan districts, largest foci), Chhattisgarh ( Bastar area), Odisha, West Bengal, Madhya Pradesh, Tamil Nadu, Kerala and Assam. P. ovale - confined to tropical Africa. Only few cases are reported from India - Odisha ( Koraput district, 1st case of India), Chhattisgarh ( Bastar area), Delhi, Assam, Gujarat and Kolkata.

44. Malaria Elimination in India 44 Malaria control in India has been operated through NVBDCP since 2006. WHO has initiated The Global Technical Strategy for Malaria (2016–2030) - aims at elimination of malaria by year 2030. Till date 38 countries have already achieved the elimination status from WHO.

45. Malaria Elimination in India (Cont..) 45 In line with WHO, NVBDCP India has launched National Framework for Malaria Elimination (NFME) in 2016 with vision of malaria elimination by 2030. All states/ UTs of India are stratified into four categories based on annual parasite incidence (API).

46. Malaria Elimination in India (Cont..) 46 The objectives set for malaria elimination in India include: Eliminate malaria from all Category 1 and 2 transmission states and union territories (UTs) by 2022. Interrupt indigenous transmission of malaria throughout the entire country, including states/UTs in Category 3 by 2027 Prevent re-introduction of local transmission of malaria in areas where it has been eliminated and maintain national malaria free-status by 2030 and beyond.

47. Stratification of States/UTs in India based on annual parasite incidence (API) 47 Categories Definition Category 0 (Prevention of re- establishment phase) States/UTs with zero indigenous cases of malaria Category 1 (Elimination phase) States/UTs including their districts with API of < 1/1,000 population at risk Category 2 (Pre-elimination phase) States/UTs with API <1/1,000 population, but some of their districts are reporting API of ≥1/1,000 population at risk Category 3 (Intensified control phase) States/UTs with API of ≥1/1,000 population at risk

48. Observations 48 World Malaria Day: Every year, 25 th April is being celebrated as “World Malaria Day” Antimalarial month is celebrated every June.

49. Laboratory diagnosis of malaria 49 Microscopic tests: Peripheral blood smear - gold standard Thick smear - more sensitive Thin smear - speciation can be done based on the following features: P. vivax - amoeboid ring form and schizont

50. Laboratory diagnosis of malaria (Cont..) 50 Microscopic tests (Cont..): P. falciparum - ring forms (multiple ring form, accole form, headphone shaped ring forms), banana shaped gametocyte P. malariae - band forms P. ovale - enlarged fimbriated oval RBC with ring forms

51. Laboratory diagnosis of malaria (Cont..) 51 Microscopic tests (Cont..): Fluorescence microscopy (Kawamoto’s technique) Quantitative buffy coat examination —parasitized RBCs appear as brilliant green dots.

52. Laboratory diagnosis of malaria (Cont..) 52 Non-microscopic tests: Antigen detection tests (RDTs) or ICTs - detect pan malarial Ag (LDH, aldolase), falciparum specific Ag (HRP-II) Culture - RPMI 1640 medium Molecular diagnosis - PCR targeting 18S rDNA

53. Peripheral Blood Smear 53 It is the simple and gold standard confirmatory test Specimen - Peripheral blood is collected from ear lobe or by finger prick or great toe (in infants). Time for taking blood: Collected few hours after the height of the paroxysm of fever and before taking antimalarial drugs.

54. Peripheral Blood Smear (Cont..) 54 Frequency: Smears should be examined at least twice daily until parasites are detected. Types of peripheral blood smear- (1) thin and (2) thick smears.

55. Peripheral Blood Smear (Cont..) 55 Smears are stained with one of the Romanowsky’s stains such as Leishman’s, Giemsa and Field’s, Wright’s or JSB stain Thin smear has to be screened first . It is screened near the feathery tail end.

56. Peripheral Blood Smear (Cont..) 56 Advantages : Thick smear is useful in - (1) Detecting the parasites: It is 40 times more sensitive than thin smear, can detect as low as 5–10 parasites per μL of blood; (2) Quantification of parasitemia ; (3) Demonstrating the malaria pigments

57. Peripheral Blood Smear (Cont..) 57 Advantages : Thin smear is useful in speciation of malaria parasites.

58. Peripheral Blood Smear (Cont..) 58 Disadvantages : (1) It is labor intensive and requires experienced microscopist ; (2) Low sensitivity - the detection limit of thin smear is >200 parasites per μL of blood.

59. Thin blood smear showing different forms of Plasmodium vivax 59 A. Ring form; B. Amoeboid form; C. Schizont ; D. Male gametocyte; E. Female gametocyte

60. Thin blood smear showing different forms of Plasmodium falciparum 60 A B C D E A . P. falciparum ring forms such as multiple rings (blue arrow), accole form (red arrow) and head phone-shaped ring form (black arrow); B . Female gametocyte of P. falciparum; C . Male gametocyte of P. falciparum; D . Band form of P. malariae ; E . Ring form of P. ovale

61. Quantitative Buffy Coat Examination 61 Blood (60 µL) is collected in a capillary tube coated internally with acridine orange. Capillary tube is centrifuged - causes separation of components of blood according to their densities, forming discrete layers as RBCs, WBCs, lymphocytes and platelets Examination of capillary tube at the buffy coat region under ultraviolet (UV) light source

62. Quantitative Buffy Coat Examination (Cont..) 62 Interpretation: QBC capillary tube with magnified view Crescent shaped gametocytes of P. falciparum Ring forms of Plasmodium falciparum seen as fluorescent dots

63. Antigen Detection by Rapid Diagnostic Tests 63 1) Parasite lactate dehydrogenase ( pLDH ): Produced by trophozoites and gametocytes of all Plasmodium species. Currently available test kits can differentiate pan malarial pLDH common to all species and pLDH specific to P. falciparum 2) Parasite aldolase : Produced by all Plasmodium species.

64. Antigen Detection by Rapid Diagnostic Tests (Cont..) 64 3) Plasmodium falciparum specific histidine rich protein-2 (Pf-HRP-II): It is produced by trophozoites and young gametocytes of P. falciparum

65. Antigen Detection by Rapid Diagnostic Tests (Cont..) 65 A. Schematic diagram of rapid diagnostic test kit showing negative, non-falciparum, pure or mixed infection with Plasmodium falciparum and invalid result of malaria; B. Real image of rapid diagnostic test kit

66. Advantages of Rapid Diagnostic Tests 66 Simple to perform, do not need extra equipment or trained microscopist . Sensitivity: More than 90% sensitive at >100 parasites/µL. But the sensitivity is markedly reduced at <100 parasites/µL Prognosis: pLDH is produced by the viable parasites, hence it is used to monitor the response for treatment (microscopy is the best to assess prognosis).

67. Advantages of Rapid Diagnostic Tests 67 Pregnancy: HRP-II is a reliable marker to diagnose malaria in pregnancy Severity: Intensity of the band is directly proportional to the parasitemia and severity of the disease.

68. Disadvantages of Rapid Diagnostic Tests 68 Cannot differentiate between the non-falciparum malaria species Expensive than peripheral smear Gametocytes cannot be detected Low sensitivity: The lower limit to detect HRP-II is 40 parasites/µL and pLDH is 100 parasites/µL RDT has not been developed for P. knowlesi yet

69. Comparison of peripheral smear, quantitative buffy coat and rapid diagnostic tests 69 Features Peripheral smear Quantitative buffy coat Rapid diagnostic tests Method Cumbersome Easy Easy Time Longer, 60–120 minutes Faster, 15–30 minutes Faster, 15–30 minutes Sensitivity Detection limit: 5 parasites/µL in thick   film 200 parasites/µL in thin   film Claimed to be more sensitive, at least as good as a thick film >100 parasites/µL, sensitivity   >90% <100 parasites/µL, sensitivity   falls Specificity Gold standard False   positives—artifacts   may   be   reported   as positive by nontrained   technicians False positive in RA factor (rheumatoid arthritis) positive cases

70. Comparison of peripheral smear, quantitative buffy coat and rapid diagnostic tests (Cont..) 70 Features Peripheral smear Quantitative buffy coat Rapid diagnostic tests Speciation Accurate, gold standard Difficult Detect Plasmodium falciparum but cannot differentiate non-falciparum species Cost Inexpensive Costly equipment and consumables Kits are costly but no extra equipment required. Good for field study Experienced Microscopist Required Not required, minimal training is sufficient Not required, minimal training is sufficient

71. Antibody Detection 71 Antibodies persist even after the clinical cure. Serology does not detect current infection, but only measures past exposure. Therefore, Government of India has banned the use of antibody detection tests for malaria diagnosis.

72. Culture 72 Culture techniques are mainly used for preparation of malaria antigens, not for diagnosis. Trager and Jensen method using RPMI 1640 medium (Roswell Park Memorial Institute) - most widely used technique for culture of malaria parasite.

73. Antimalarial drugs and their activity 73 Class Drugs Active against parasitic stages Quinolines and related compounds Chloroquine Asexual RBC stages Quinine Gametocytes (except Plasmodium falciparum ) Mefloquine Asexual RBC stages Primaquine Liver stages and hypnozoites , gametocytes Artemisinin and its derivatives Artemisinin, artemether and arte-ether Asexual RBC stages and gametocytes Hydroxynaphthoquinones Atovaquone Asexual RBC stages, Liver stages (only for P. falciparum ) Biguanide derivative Proguanil

74. Antimalarial drugs and their activity (Cont..) 74 Class Drugs Active against parasitic stages Diaminopyrimidines Pyrimethamine Asexual RBC stages, Liver stages (+/-) Sulfonamides Sulfadiazine and sulfadoxine Tetracyclines Tetracycline and doxycycline Asexual RBC stages (+/-)

75. Treatment of Vivax Malaria (NVBDCP guideline, India) 75 Chloroquine 25 mg/kg, divided over three days, i.e. 10 mg/kg on day 1 and 2 and 5 mg/kg on day 3 Primaquine 0.25 mg/kg body weight; daily for 14 days; should be given under supervision, aiming to kill hypnozoites of P. vivax (to prevent relapse) Contraindicated in infants, pregnant women and individuals with G6PD deficiency

76. Treatment of Falciparum Malaria (NVBDCP guideline, India) 76 North- Eastern States ACT-AL , i.e. co-formulated tablet of artemether and lumefantrine ; total dose of 80 mg/480 mg (in adults), given over twice daily for 3 days plus Primaquine (0.75 mg/kg) single dose on second day aiming to kill gametocytes of P. falciparum . (ACT-AL is contraindicated in 1st trimester pregnancyand children <5 kg weight) Other states ACT-SP , i.e. artesunate (4 mg/kg) for 3 days plus sulfadoxine (25 mg/kg)/ pyrimethamine (1.25 mg/kg), 1 tablet given on first day plus Primaquine (0.75 mg/kg) single dose on second day

77. Treatment of Falciparum Malaria (NVBDCP guideline, India) 77 In uncomplicated P. falciparum cases in pregnancy: First trimester : Quinine salt 10 mg/kg 3 times daily for 7 days Second/third trimester : Area-specific ACT; as given above In mixed infection ( P. vivax plus P. falciparum ) ACT-AL and ACT-SP as per geographical area as given above plus Primaquine (0.25 mg/kg) for 14 days

78. Severe Malaria 78 Characterized by ≥1 of the following features: Impaired consciousness/coma Repeated generalized convulsions Renal failure (Serum creatinine >3 mg/ dL ) Jaundice (Serum bilirubin >3 mg/ dL ) Severe anemia ( Hb <5 g/ dL ) Pulmonary edema/acute respiratory distress syndrome Hypoglycemia (Plasma glucose <40 mg/ dL ) Metabolic acidosis Circulatory collapse/shock (Systolic BP <80 mm Hg, <50 mm Hg in children) Abnormal bleeding and disseminated intravascular coagulation (DIC) Hemoglobinuria Hyperpyrexia (Temperature >106°F or >42°C) Hyperparasitemia (>5% parasitized RBCs)

79. Treatment options available for severe malaria 79 Drugs Dosage Artesunate 2.4 mg/kg IV, given on admission, then at 12 and 24 hours, then once a day Quinine Loading dose of 20 mg/kg at admission (IV infusion in 5% dextrose over a period of 4 hours) followed by maintenance dose of 10 mg/kg 8 hourly Artemether 3.2 mg/kg IM, given on admission then 1.6 mg/kg body weight per day Arteether 150 mg daily IM, for 3 days in adults only (not recommended for children)

80. Drug Resistance in Falciparum Malaria 80 World’s Highest Burden: Border areas of Thailand, Cambodia, and Myanmar possess the highest risk for resistance to chloroquine and other classes of antimalarial drugs. Many of the strains of P. falciparum are multiple-drug resistant (MDR), defined as resistance to at least ≥3 classes of antimalarial drugs Resistance to artemisinin has not be reported

81. Drug Resistance in Falciparum Malaria (Cont..) 81 India: Chloroquine resistance in P. falciparum has been reported since 1973 (first case from Assam). Northeast states show a higher proportion of chloroquine resistance in P. falciparum

82. Drug Resistance in Falciparum Malaria (Cont..) 82 The factors that contribute to emergence of resistance are: Longer half-life of drug Mutation in the parasitic gene Inadequate and irregular usage of drug Host immunity

83. Drug Resistance in Vivax Malaria 83 Only sporadic cases of resistance to chloroquine and/or primaquine have been reported from some areas of India, Burmah , Indonesia and few others.

84. Mechanism of Drug Resistance 84 Chloroquine resistance in P. falciparum : Mutations in the genes encoding the transporter proteins such as PfCRT (P. falciparum chloroquine resistance transporter) and PfMDR1 (P. falciparum multidrug resistance gene 1). Such mutation results in impaired transport of chloroquine

85. Mechanism of Drug Resistance (Cont..) 85 Resistance to antifolates such as pyrimethamine is due to point mutation in DHFR ( dihydrofolate reductase) gene Resistance to artemsinins - not be reported yet however it is observed in experimental animals. Monotherapy with artemisinins is banned in India - promotes resistance.

86. WHO Guideline for Assessing Degree of Resistance 86 The degree of resistance is assessed based on two factors - Persistence of clinical manifestations and Level of parasitemia following administration of the antimalarial drug.

87. Prophylaxis against Malaria 87 Chemoprophylaxis Vector control strategies Vaccine prophylaxis.

88. Chemoprophylaxis 88 For short-term chemoprophylaxis (<6 weeks): Doxycycline is recommended, at a dose of 100 mg daily in adults and 1.5 mg/kg for children. The drug should be started 2 days before travel and continued for 4 weeks after leaving the malaria endemic area.

89. Chemoprophylaxis (Cont..) 89 Long-term chemoprophylaxis (>6 weeks): Mefloquine is recommended at a dose of 5 mg/kg weekly and administered two weeks before, during and four weeks after leaving the area.

90. Vector Control Strategies 90 Anti-adult measures Residual insecticide spraying: Dichloro diphenyltrichloroethane (DDT), malathion and fenitrothion is highly effective against adult mosquito Space application of pesticide in the form of fog Individual protection: by using insecticide treated bed nets, repellents and protective clothing.

91. Vector Control Strategies (Cont..) 91 Anti-larval measures Larvicide : Use of mineral oil or Paris green to kill mosquito larvae and pupae Source reduction (mosquito breeding sites): Includes environmental sanitation, water management and improvement of the drainage system. Biological larvicide : Gambusia affinis (fish) and Bacillus thuringiensis (bacteria) can be used to kill the mosquito larva.

92. Vaccination for Malaria 92 Pre- erythrocytic vaccine targeting sporozoites and liver schizonts - Aims at preventing infection, disease and transmission. Erythrocytic vaccine targeting merozoites , blood schizonts - help in preventing the disease - useful for people living in hyperendemic areas of malaria

93. Vaccination for Malaria (Cont..) 93 Sexual stage vaccine targeting gametocytes: They are transmission-blocking ; do not have prevent malaria in the individual taking the vaccine, but antibodies are passed to the mosquito during blood meal, block the further transmission of the parasite

94. Vaccination for Malaria (Cont..) 94 The main problems in malaria vaccine include: The vaccine candidates are poor inducer of cell-mediated immune response Antigenic variation in malarial antigens such as PfEMP Different immune mechanisms occur in different stages of malaria life cycle.

95. Vaccination for Malaria (Cont..) 95 RTS, S/AS01 It is the only vaccine candidate that has successfully completed phase III trial. It is pre- erythrocytic vaccine containing PfCSP ( circumsporozoite protein of P. falciparum ) fused with hepatitis B surface antigen and a chemical adjuvant (AS01)

96. BABESIOSIS 96

97. BABESIOSIS 97 Malaria like illness seen in cattle and sheep. B. microti - most common species, others being B. bovis and B. divergens . It is similar to malaria parasite in its life cycle and pathogenesis except for the following differences: Hard tick ( Ixodes scapularis ) is the primary vector (definitive host) of the parasite.

98. BABESIOSIS (Cont..) 98 No liver-stage, sporozoites enter directly into RBCs Clinical feature : It differs from falciparum malaria being less severe, low parasitemia , no cerebral involvement, less severe anemia and no periodicity seen in fever cycle.

99. BABESIOSIS (Cont..) 99 Epidemiology: Endemic in temperate area of USA and Europe; not reported from India yet. Diagnosis: Peripheral blood smear examination reveals ring forms inside RBC arranged in pair or tetrads (called as Maltese cross forms) - often confused with the multiple ring forms of P. falciparum - differentiated by lack of pigments and lack of crescentic gametocytes.

100. BABESIOSIS (Cont..) 100 Giemsa stained blood smear showing Maltese cross form: A. Schematic diagram; B. Peripheral blood smear

101. BABESIOSIS (Cont..) 101 Treatment: Atovaquone plus azithromycin is given for treatment.