malarial pathogenesis

Malarial Pathogenesis

By: Kareem Waleed Hamimy

6th Year Medical Student

Kasr Al Ainy - Cairo University

A short introduction

MalariaWhy?What?How?Who?Where?

Pathogenesis Clinical picture

Why Malaria ?

One of the most common infectious diseases & an enormous public-health problem.

Each year, it causes disease in approximately 650 million people & kills 1-3 million, most of them young children in Africa.

At least one death every 30 seconds.

What is Malaria ?

Malaria is a vector-borne infectious disease caused by protozoan parasites of the genus plasmodium.

The most serious forms of the disease are caused by Plasmodium falciparum and Plasmodium vivax.

How?

Who?

Malaria is a disease which can be transmitted to people of all ages, bitten by a vector

Young children and pregnant women in high transmission areas are at a large risk.

Where?

Malarial Pathogenesis

Hepatic phaseSporozoites infect hepatocytes, multiplying

asexually & asymptomatically for a period of 6–15 days.

Then they differentiate into merozoites rupture the hepatocytes escape to blood stream undetected (wrapping itself in the cell membrane of the infected host liver cell).

Malarial Pathogenesis

Erythrocytic phase Within the red blood cells the parasites

multiply further, again asexually, periodically breaking out of their hosts to invade fresh red blood cells.

p.vivax and p.ovale do not immediately develop into merozoitesThey develop first to Hypnozoites (dormant

form) for 6-12 month leading to long incubation and late relapses

Malarial Pathogenesis

PfEMP1Plasmodium falciparum erythrocyte

membrane protein 1Adhesion (protective) protein produced by

p.falciparum expressed on surface of RBCs causing it to stick to the walls slowing its lysis in spleen.

Block endothelial venules cerebral & placental malaria.

Extreme diversity not a good immune targets.

Pathogenesis of clinical picture

Prodromal symptoms (influenza like)Hepatic phase where the parasite asexually

and asymtomatically multiply. Malarial paroxysms

Decreased osmotic fragility rupture of RBCs

Release of metabolites & toxinsRelease of cytokines such as TNF and

interleukin-1 from macrophages, resulting in chills and high grade fever.

Pathogenesis of clinical picture

AnemiaFebrile paroxysmal hemolysisImmune & Non Immune hemolysisIncreased splenic clearanceDyserythropoeisis in BMDrug induced hemolysis

Bone marrow Iron sequestration DyserythropoeisisDysthrombopoeisis

Pathogenesis of clinical picture

SpleenSplenomegaly

○ Edema of the pulp○ RES hyperplasia○ Increased phagocytic function○ New guinea “Tropical splenomegaly syndrome”

LiverHepatomegaly (hepatic phase)Malarial pigments greyish blackFalciparum malarial hepatitis

Pathogenesis of clinical picture

Due to adherence factor of falciparum blocking of venules of organs lead to a lot of manifestations asCerebral malaria (severe headache,

drowsiness, confusion, coma) Placental malaria (premature delivery,

intrauterine growth retardation iURD)Dysenteric malaria (abdominal pain,

vomiting, GIT bleeding )

Pathogenesis of clinical picture

CVSAnemia leads to

○ Hypotension○ Tachycardia○ Muffled heart sounds

KidneyImmune complexes Nephrotic syndrome

○ Albuminuria○ Edema○ hypertension

Clinical Picture

Malarial Infections

High Grade Fever

Anti Malarial Drugs

Secondary Infection

Any Questions ?

THANK YOU