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Malaria

Malaria. Dr R.N.Roy Associate Professor Department of Community Medicine. Malaria. A febrile illness caused by asexual plasmodium parasite transmitted by infected female anopheles mosquito Plasmodium genus of parasite infect RBC in human Occasional infections of monkey with P. knowlesi ,.

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Malaria

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  1. Malaria Dr R.N.Roy Associate Professor Department of Community Medicine

  2. Malaria • A febrile illness caused by asexual plasmodium parasite transmitted by infected female anopheles mosquito • Plasmodium genus of parasite infect RBC in human • Occasional infections of monkey with P. knowlesi,

  3. Magnitude of problems • About half the world’s population (3.3 billion) in live in areas(109 countries & territories) endemic for malaria • Estimated 247 million malaria cases in 2006, of which 91% were due to Pf • Around 40% of the global population at risk of malaria resides in SEA Region

  4. AFRO: African Region AMRO: Region of the Americas SEARO: South-East Asia Region WPRO: Western Pacific region EMRO: Eastern Mediterranean

  5. Malaria Burden in India • During Pre- control era(1953) Annual Incidence was 75 mil / (22% of population) and 0.8mil death/ yr • During 2008 incidence was 1.53 million & half of these were Pf & 1055 deaths reported • About 88% of malaria cases & 97% of deaths reported from Northeastern (NE) States, Chhattisgarh, Jharkhand, MP,  Orissa,  AP  Maharashtra Gujarat  Rajasthan, W B Karnataka

  6. Problem in India Major epidemiological types in India • Tribal malaria • Urban malaria • Malaria in project area • Border malaria Serious problem in NE states • Perennial malaria transmission • Predominance of falciparum • Drug resistance

  7. EPIDEMIOLOGY OF MALARIA :Agent factors • Four species : (1)P. Vivax – causes BTM (2) P.Falciparum-causes MTM (3) P.Malariae-causes quartan malaria (4) P.Ovale (not in India)

  8. Host factors • Age: Parasitemia is low during infancy due to maternal antibody • During first few weeks show resistance to Pf infection due to fetal Hb • Pregnancy: increase risk in pregnancy :anemia , LBW delivery.

  9. Epidemiology Reservoir of infection: Human • (Exception- chimpanzee in Africa may carry P. malariae) Conditions for a successful reservoir: • Must harbor viable & mature gametocyte of both sexes in sufficient density

  10. Route of transmission • By bite of infected female anopheles mosquito • Blood transfusion, needle stick injury, sharing needles, organ transplantation • Congenital malaria- mother to foetus

  11. Genetic factors • HbF and Thalassaemia protect against malaria • Sickle cell trait (AS Hb) have higher immunity against P. falciparum • Person with ‘Duffy negative ‘ RBC are resistant to vivax infection

  12. Environmental conditions • Urbanization, • Industrialization and construction projects • Consequent migration, • Deficient water and solid waste management • Indiscriminate disposal of articles (tyres, containers, junk materials, cups, etc

  13. LIFE CYCLE OF PLASMODIUMMOSQUITO • Mosquito is definitive host (sexual multiplication takes place) • Mosquito picks up gametocytes from infected person  in gut converted into gamete, zygote, ookinets, oocist, sporozoites finally sporozoites reach the salivary gland (takes about 8- 25 days)

  14. Other factors: • Poor socioeconomic and housing conditions, • population mobility • some human habits like • sleeping out of door • Nomadism • refusal of spray activities etc contribute to causation of malaria .

  15. LIFE CYCLE OF PLASMODIUM IN HUMAN • Man -intermediate host (undergo asexual reprodn.) • Hepatic phase : Mosquito bite  inoculate sporozoites - reaches hepatocyte by 30mts  multiply to form hepatic schizonts  mature to daughter merozoites and released in sinusoids • Erythrocytic phase: Merozoites reach blood stream invade RBC in RBC multiply & develops schzoints  RBC ruptures 48 or 72 hourly releasing cytokinin, TNF pirogens  • Some merozoites convert & develop into gametocyte

  16. Pathophysiology • Incubation period: infective mosquito bite to onset of sign and symptoms = 9-30 days • IP depend upon species of parasite, host immune status, infecting doses and use of antimalarial treatment • Only erythrocytic parasitic stage causes clinical disease • Relapse: after primary attack with out subsequent mosquito bite. • Recrudescence: Reappearance of clinical malaria or M.P in blood, which remain dormant in RBC.

  17. VECTOR Only female Anopheles mosquito carry parasite and infect human

  18. Vector factors for transmission • Vector density • Man biting rate & frequency of blood meal • Time and place of man - mosquito contact • Man - cattle ratio • Flight range • Vector’s susceptibility to infection

  19. IMPORTANT VECTORS OF MALARIA IN INDIA

  20. Critical density for transmission

  21. ENTOMOLOGICAL INDICES  • Vector density (Man Hour Hand Captures ): Nos anopheles collected per man hr. catch • Mosquito infection rate • Man biting rate • Human Blood Index-indicate anthrophilism • Av. nos of larva per dip

  22. ENTOMOLOGICAL INDICES …. PER MAN HOUR DENSITY: No. of mosquitoes collected =--- ---------------------------------------X100 No. of man hours spent in search • High vector density indicates high potential for transmission SPOROZOITE RATE (%): No. of females positive for sporozoites = --------------------------------------------------x 100 Nos. dissected

  23. Suspected case of malaria A patient with fever but without any other obvious cause of fever • Cough and other signs of respiratory infection • Running nose and other signs of cold • Pelvic inflammation indicated by severe low backache, vaginal discharge , urinary symptoms • Skin rash suggestive of eruptive illness • Burning micturition • Skin infections e.g. boils, abscess, infected wounds • Painful swelling of joints • Diarrhoea • Ear discharge

  24. Lab diagnosis: All suspected fever cases be investigated • Blood smear examination/Microscopy • Rapid diagnostic test (RDT)

  25. How & when to use RDT / Smear Exam Where microscopy result is available within 24 hrs.  (Only microscopy done)  Treatment based on slide-result Where microscopy result is not available within 24hrs (Pf RDT + Slide taken) RDT +Ve  Treat Pf  Discard slide RDT –Ve  Slide microscopy  Treatment

  26. EPIDEMIOLOGICAL SURVEILLANCE

  27. ASSESSMENT OF PROBLEM (MALARIOMETRIC MEASUREMENT) • EPIDEMIOLOGICAL SURVEY • Proportional case rate • Spleen rate • Infant parasite rate • Children parasite rate-(% of 2-10 yr children ē MP in blood) • Annual Parasite Incidence (API) • Annual Blood Examination Rate (ABER) • Slide Positivity Rate (SPR) • Slide falciparum Rate (SFR) • Annual falciparum rate (AFR)

  28. Child Spleen Rate(CSR) • % of 2-10 yr children ē enlarged spleen Significance : 25-40%= Endemic >40%=Hyper endemic

  29. Infant parasite rate(IPR) Most sensitive index for recent transmission of malaria. # Positive for MP IPR= -----------------------------------------X100 # Blood slide examined from infants

  30. Annual Blood Examination Rate (ABER) Nos of smears examined & (RDTs +Ve) in a Yr. ABER = ----------------------------------------------------------X100 Total Population under surveillance • Index of operational efficiency of surveillance • ABER should be equal to fever rate in the locality • ABER should be > 10% of population • Monthly Blood Examination Rate should be >1% of population during the transmission season

  31. Annual Parasite Incidence (API) # of +Ve smears & +Ve RDTs in a year API=------------------------------------------------ X 1000 # Population under surveillance • Used to stratify malarious areas • Disease burden in community

  32. Slide Positivity Rate : % of slide positive for parasite Slide Falciparum Rate : % of slide positive for Pf SFR pinpoints areas of Pf preponderance for prioritizing control measures P.falciparum percentage (Pf %)

  33. Surveillance in malaria • Passive Case Detection- Collection of blood slides in Clinic/ institution & treatment. • Active Case Detection- system of detecting malaria cases (blood slide collection ) by HW through domiciliary visits • Mass blood survey- Examination of blood from all persons in a community (during epidemiological investigation around positive cases)

  34. DRUG SCHEDULE FOR MALARIA

  35. Age-specific drug schedules

  36. Chemoprophylaxis Short term chemoprophylaxis (up to 6 wks) (e.g. travelers from non-malarious areas) • Doxycycline 100 mg daily in adults or (1.5mg / kg OD)above in children , started 2 days before reaching endemic area continued for 4 weeks after leaving • Contraindication : Pregnancy & children < 8 years. Chemoprophylaxis for longer stay (> 6 wks) (e.g Military & paramilitary troops in malarious areas duty ) • Mefloquine 250 mg weekly for adults • Mefloquine 5 mg/kg for children • Contraindication of Mefloquine : H/O convulsions, & neuropsychiatric problems

  37. MALARIACONTROL ACTIVITIES & PROGRAMME IN INDIA

  38. Continued..

  39. Continued …

  40. Continued .. Continued ..

  41. NATIONAL ANTI-MALARIA PROGRAMME1999 Under NVBDCP Objectives: • Prevention of deaths due to malaria • Prevention of morbidity due to malaria • Maintenance of ongoing socioeconomic development

  42. Strategies • Surveillance and case management • Case detection (passive and active) • Early diagnosis and treatment • Integrated Vector Management (IVM) • Environmental Management • Stratification of the problem • Area with API<2 • Area with API ≥2 • Community Participation & BCC • Monitoring and Evaluation of the programme

  43. Integrated Vector Management (IVM) • Use of a range of biological, chemical and physical interventions of proven efficacy, separately or in combination, in order to implement cost-effective control and reduce reliance on any single intervention

  44. IVM Includes: • Rotation and & safe use of insecticides including management of resistance • Indoor Residual Spray (IRS) • Insecticide Treated bed Nets (Tins) / Long Lasting Insecticidal Nets (LLINs) • Antilarval measures including source reduction

  45. Vector control methods • Methods of reducing human-vector contact: • Mosquito nets & insecticide treated nets (Synthetic pyrethroid) • House protection with screening of windows, doors etc. • Use of repellents • Anti adult measures: • Indoor residual spraying with DDT/ • Space spraying of insecticides • Anti larval measures: • Larviciding • Biological Control • Source reduction by environmental management

  46. Anti adult measures • Indoor residual spraying with -Organo chlorine compound : DDT - OP-compounds : Malathion, Fenitrothion -Carbamate :Propoxur -Synthetic pyrethroids: Deltamethrin • Space spray: Pyrithrum • Out door space spray :Malathion, Pyrethrum

  47. Anti larval measures • Larviciding with MLO, Temephos ( abate), Fenthion etc. • Biological Control • Use of larvivorous fish (Gambusia affinis & Poecilia reticulata) • Use of biocides: bacillus thuringiensis • Source reduction by environmental management • Drainage /Filling /flushing/change of salinity

  48. Community Perticipation & BCC • Process of learning that empowers people to take rational and informed decisions through appropriate knowledge • Clear messages, communicated through different, credible channels are most likely to bring about change. Ignorance, prejudices must be replaced by knowledge Awareness campaign programme-observe malaria week • Legislative measures: • Model civic bye-laws:

  49. ‘High risk areas’ • Recorded deaths due to malaria • Doubling of SPR during last 3 yrs provided the SPR in 2nd / 3rd yr reaches ≥ 4% • Average SPR of the last 3 yrs ≥ 5% • P.falciparum proportion ≥ 30% provided SPR is ≥ 3% during any of the last 3 yrs • Any area with focus of CQ resistant P.f. cases • Aggregation of labour in project area & new settlements in endemic/receptive & vulnerable areas

  50. Thank you

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