Malaria () Local names: Pathophysiology, diagnosis, epidemiology and control 1 Human malarial parasites Plasmodium malariae (Quartan malaria) P. vivax (Benign tertian malaria) P. falciparum (Malignant tertian malaria) P. ovale (Ovale tertian malaria) Primate malaria parasites infecting man e.g. Plasmodium knowlesi 2 Life Cycle Anopheles Human Sporogony Schizogony (Asexual phase) (Sexual phase) 3 Life cycle of malaria parasites 4 Tissue schizont and hypnozoite vivax, ovale hypnozoite 5 Malarial infections 1. Bitten by an infected anopheline 2. Blood transfusion 3. Congenital 6 Course of infection Prepatent period (days) Incubation period (days) av.(range) Patent period (yr) av./max Pv ( ) 2/8 Po ( ) 1/5 Pf (9-14) 1/4 Pm (18-90) 4/53 7 Infection DEATH Infection RECRUDESCENCE Infection Treatment RECRUDESCENCE (R1 RESISTANCE) Re-infection RELAPSE (hypnozoite) Possible outcome of malaria infections PF All PF All PV, PO Parasite density Time (Blood stages) 8 Vivax and ovale malaria (Benign tertian malaria) Non-specific symptoms 2-3 days followed by febrile paroxysm (malaria paroxysm) every other day Cold stage 5-60 min Hot stage 2-6 hr Sweating stage 2-4 hr Clinical aspects malaria paroxysm 9 Days C o 37 Febrile paroxysm P. vivax, P. ovale 10 Malariae malaria (Quartan malaria) Febrile paroxysm every 72 hr. Nephrotic syndrome - the presence of nephrotic-range proteinuria, edema, hyperlipidemia, and hypoalbuminemia 11 Days C o 37 Febrile paroxysm P. malariae 12 non-specific symptoms fever (every day or every other day) chill, headache, influenza-like, pains of limbs and back, nausea etc. Falciparum malaria (Malignant tertian malaria) 13 Complications of severe falciparum malaria Cerebral malaria Anaemia Renal failure Hypoglycaemia etc. 14 Malaria relapse Recrudescence (Pf, Pv, Po, Pm) caused by low parasitaemia Recurrent (Pv, Po) caused by hypnozoites in the liver 15 Malaria Pathology - rupture of infected and uninfected rbc - release of toxins, malarial pigment - packing capillaries (cytoadherence) in brain, kidney, etc.(only Pf) - enlarged spleen - black water fever 16 Liver 17 Kidney 18 Malaria immunity Natural immunity Animal malarias Human P. vivax Duffy bl. gr. Neg. P. falciparum HbS P. falciparum G-6-PD def. Acquired immunity Active: experience infections Passive: congenital Imm. 19 Malaria epidemiology and Control Endemic area Area with cases occurring at a constant but relatively high rate in the population Epidemic area Area with new cases in a given human population, during a given period, at a rate that substantially exceeds what is "expected," based on recent experience 20 Climate & Environment Human Vector Agent Malaria epidemiology 21 22 23 Key terms used in malaria epidemiology Indigenous malaria - Malaria is natural to an area or country (Autochthonous malaria) or Locally contracted malaria Imported malaria - Malaria acquired outside the specified area in which it was found Introduced malaria - Secondary case contracted locally, but derived from an imported case Induced malaria- Accidental infection by blood transfusion, needles, organ transplant etc. Anophelism without malaria - A situation when anopheles mosquito is present in the area but there is no case of human malaria (e.g. malaria-free Soviet Armenia in ) 24 25 Endemicity TransmissionSpleen rate ( 20/field) Count no. leucocytes against 500 parasites e.g X 8,000 = 400,000 51 Parasite count using thin films Count parasites against red blood cells (~ 10,000 20,000 rbc) Should know 1. Average no. of rbc (~ ) per oil imm. field. 2. 5,000,000 rbc/ul in male. 3. 4,500,000 rbd/ul in female. 52 e.g. No. rbc/field = 250 No. parasites in 50 fields = 30 No. rbc with 30 parasites = 250 x 50 = 12,500 No. parasite per ul = 30 x 5,000,000 = 12,000 12,500 53