1 / 18

MALARIA

MALARIA. causative agent = Plasmodium species 40% of world’s population lives in endemic areas 3-500 million clinical cases per year 1.5-2.7 million deaths (90% Africa) known since antiquity early medical writings from India and China Hippocrates usually credited (500 BC)

jovan
Download Presentation

MALARIA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. MALARIA • causative agent = Plasmodium species • 40% of world’s population lives in endemic areas • 3-500 million clinical cases per year • 1.5-2.7 million deaths (90% Africa) • known since antiquity • early medical writings from India and China • Hippocrates usually credited (500 BC) • Laveran identified parasite (1880) • Ross demonstrated mosquito transmission (1898) • Garnham described liver stage (1940’s)

  2. Clinical Features • characterized by acute febrile attacks (malaria paroxysms) • periodic episodes of fever alternating with symptom-free periods • manifestations and severity depend on species and host status • immunity, general health, nutritional state, genetics • recrudescences or relapses can occur over months or years • can develop severe complications (especially P. falciparum)

  3. Malaria Transmission • natural (sporozoites/Anopheles) • blood transfusions • shorter incubation period • fatality risk (P. falciparum) • no relapses possible (vivax/ovale) • syringe sharing • congenital • relatively rare although placenta is heavily infected

  4. Prodromal Symptoms • end of incubation period • 2-3 days before 1st paroxysm • includes: malaise, fatigue, lassitude, headache, muscle pain, nausea, anorexia (i.e., flu-like symptoms) • can range from none to mild to severe • Febrile Attack (Malaria Paroxysm) • periodic febrile episodes alternating with symptom-free periods • initially fever may be irregular before developing periodicity • may be accompanied by splenomegaly, hepatomegaly (slight jaundice), anemia

  5. cold stage • feeling of intense cold • vigorous shivering, rigor • lasts 15-60 min

  6. hot stage • intense heat • dry burning skin • throbbing headache • lasts 2-6 hours

  7. sweating stage • profuse sweating • declining temperature • exhausted, weak  sleep • lasts 2-4 hours

  8. Malaria Paroxysm • paroxysms associated with synchrony of merozoite release • temperature is normal and patient feels well between paroxysms • falciparum may not exhi-bit classic paroxysms • continuous fever • 24 hr periodicity tertian malaria quartan malaria

  9. Karunaweera et al (1992) PNAS 89:3200 sweating rigor • TNF = tumor necrosis factor-a () • proinflammatory cytokine (produced in response to malarial antigens?)

  10. Other Features of the Paroxysms • may be accompanied by spleno-megaly, hepatomegaly (slight jaundice), hemolytic anemia • P. falciparum can be lethal in non-immune (eg., children, expatriates) • paroxysms become less severe and irregular as infection progresses • semi-immune may exhibit little (1-2 days fever) or no symptoms

  11. Anti-Parasite Immunity • immune response prevents merozoite invasion, eliminates infected erythrocytes, etc. • Anti-Disease Immunity • eg., neutralization of exo-antigens or toxic effects • Immunity • slow to develop • short lived • ‘premunition’ • non-sterilizing • lower parasitemia • less symptoms

  12. Current Distribution of Malaria • tropical and subtropical climates • formerly widespread in temperate zones (ague) • 40% of worlds population live in endemic regions

  13. Distribution of Malarial Parasites • P. vivax • most widespread, found in most endemic areas including some temperate zones • P. falciparum • primarily tropics and subtropics • P. malariae • similar range as P. falciparum, but less common and patchy distribution • P. ovale • occurs primarily in tropical west Africa

  14. Malaria Epidemiology • Stable or Endemic Malaria • ~constant incidence over several years • includes seasonal transmission • immunity and disease tolerance correlates with level of endemicity (especially adults) • Unstable or Epidemic Malaria • periodic sharp increase in malaria • little immunity • high morbidity and mortality • Endemicity • Levels: • holo- • hyper- • meso- • hypo-

  15. Roper et al (1996) AJTMH 54:325 • eastern Sudan (mesoendemic, seasonal) • rainy season June-Sept. • peak symptomatic malaria Oct.-Nov. • followed cohort of 79 individuals using thick films and PCR (P. falciparum)

  16. Mosquito Transmission • susceptibility of anopheline species • feeding habits • density • longevity • climatic factors • temperature, humidity, rainfall, wind, etc "Everything about malaria is so moulded by local conditions that it becomes a thousand epidemiological puzzles." Hackett (1937) Anopheles

  17. Malaria Control • Reduce Human-Mosquito Contact • impregnated bed nets • repellants, protective clothing • screens, house spraying • Reduce Vector • environmental modificaton • larvacides/insecticides • biological control • Reduce Parasite Reservoir • diagnosis and treatment • chemoprophylaxis

More Related