Malaria - A Review

Views:
 
Category: Education
     
 

Presentation Description

No description available.

Comments

By: krishnendhu (21 month(s) ago)

this ppt is realy informative

Presentation Transcript

In the Name of God, Most Gracious, Most Merciful : 

In the Name of God, Most Gracious, Most Merciful

MALARIA : 

MALARIA Etiopathogenesis, Clinical features & Diagnosis - A Review - Dr. Mohammed Sadiq Azam PG – M : I

ETIOLOGY : 

ETIOLOGY Vector: Female Anopheles mosquito Parasite: Genus Plasmodium Species: P.vivax, P.falciparum, P.ovale, P.malariae

Slide 4: 

Picture

Slide 5: 

P. ovale P. malariae P. falciparum P. vivax Who am I ??

PLASMODIUM: LIFE CYCLE : 

PLASMODIUM: LIFE CYCLE

EPIDEMIOLOGY : 

EPIDEMIOLOGY Agent – Host – Environment P.falciparum: Africa, New Guinea, Haiti P.vivax: Central America Vivax=Falciparum: India, South America, Eastern Asia, Oceania P.malariae: Most endemic areas, sub-Saharan Africa P.ovale: < 1% isolates

EPIDEMIOLOGY : 

EPIDEMIOLOGY Defined in terms of: Parasitemia rates Spleen palpable rates (children 2-9y) Hypoendemic (<10%) Mesoendemic (11-50%) Holoendemic (51-75%) Hyperendemic (>75%)

EPIDEMIOLOGY - AGENT : 

EPIDEMIOLOGY - AGENT Stable Transmission Unstable Transmission Determinants of transmission: Number (= Density) Human biting habits (square of) Longevity of anopheline mosquitoes (10th power of 1 day survival)

EPIDEMIOLOGY - AGENT : 

EPIDEMIOLOGY - AGENT Entomologic inoculation rate: No. of sporozoite positive mosquito bites per person per year Most common measure of malaria transmission Rate: <1 (Lat Am/SEAR) to >300 (trop Africa)

ERYTHROCYTE CHANGES : 

ERYTHROCYTE CHANGES Degrades Hb – produces Haemozoin Alters RBC membrane – exposes cryptic surface Ag – inserts new proteins Irregular, more antigenic, less deformable RBCs Shorter RBC survival

ERYTHROCYTE CHANGES : 

ERYTHROCYTE CHANGES P.falciparum: Membrane protuberances “Knobs” (12-15h) Strain spf erythrocyte membrane adhesie protein : Pf EMP1 – Cytoadherance

ERYTHROCYTE CHANGES : 

ERYTHROCYTE CHANGES P.falciparum: Vascular receptors: ICAM -1 (Brain), Chondrotin sulfate B (Placenta) & CD36 Rosettes vs. Agglutination Sequestration – impede / escape / hideout

HOST FACTORS : 

HOST FACTORS Non specific defense mechanisms Removal of RBC exaggerated Activation of macrophages, release of proinflammatory cytokines Temp ≥ 40oC damage mature parasites Effect to synchronize the cycle – spikes and rigors Characteristic periodicity – SEEN NO MORE.

HOST FACTORS : 

HOST FACTORS Diseases decreasing risk: Sickle cell disease (6x  risk) Ovalocytosis Thalassemia G6PD deficiency

HOST FACTORS : 

HOST FACTORS Factors retarding development of CMI: Absence of MHC Ag on surface of infected RBC – no T cell recognition Malaria Ag specific immune unresponsiveness Enormous strain diversity

VACCINE SOON??? : 

VACCINE SOON??? NO THANK U! Why?? Complexity of immune response Sophistication of parasite’s escape mechanisms Lack of a good in vitro correlate with clinical immunity

CLINICAL FEATURES : 

CLINICAL FEATURES History: Non specific symptoms Nausea, vomiting, orthostatic hypotension. Malarial paroxysms : fever spikes, chills & rigors – if + ? P.vivax/ P.ovale Irregular fever / tachycardia / delirium Generalised seizures

CLINICAL FEATURES : 

CLINICAL FEATURES Examination: Mild anaemia Palpable spleen Nonimmune individuals: several days Endemic areas: Healthy individuals Mild Hepatomegaly (esp. Children) Mild jaundice ( P.falcipaum, resolves in 1-3 wks) NO RASH (? Petechiae : rarely in severe falci. malaria)

DIAGNOSIS : 

DIAGNOSIS Main stay: Demonstration of asexual forms of parasite in stained P/S. Stains: Giemsa (pH 7.2), Wright’s, Field’s or Leishman’s. Thin (fixed) smear / Thick (non-fixed) smear.

DIAGNOSIS : 

DIAGNOSIS Labs: Normocytic normochromic anaemia WBC: Normal Slight monocytosis, lymphopaenia, eosinopaenia with reactive lymphocytosis & eosinophilia in wks following acute infection. ESR, plasma viscocity, CRP & other Acute phase proteins: 

DIAGNOSIS : 

DIAGNOSIS Labs: Platelet count: ~ 1,00,000/µl Severe infections:  PT / PTT / severe thrombocytopaenia Antithrombin III:  (even in mild infections) Electrolytes, BUN, Creatinine: Normal Hypergammaglobinemia: immune & semi-immune cases. CUE: Normal

THE LAST WORD : 

THE LAST WORD Inspite of promising new control & research initiative, it remains today as it has forever been: A heavy burden on tropical communities A threat to non endemic countries A danger to travellers