DEADLY CLEAR---WHY DOES'N'T THE JUDGE SEE? MINISTERIAL...REALLY??
Why Malaria is so Deadly?
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Transcript of Why Malaria is so Deadly?
MALARIA…
FAHAD
Some Imp.Terminologies
• Incubation Period: From the injection of sporozoite to the point of first manifestation of clinical illness.
• It varies from 8 to 40 days in its four diff. species
• Microscopic threshold: The minimum level of parasitaemia necessary for their detection in the blood
• Fever threshold: Clinical disease develop only after further multiplication .
• Primary Attack: First Clinical illness that marks the end of incubation period.
Pathogenesis
• Malaria is initiated by the bite of an infected female anopheline mosquito & injects the malaria parasite into blood.
• Sporozoite multiply in the parenchymal cells of liver
• After maturation averg. 1- 2 weeks, merozoites are released and invade the erythrocytes. Microscopic threshold.
• The infected erythrocytes rupture and release gametocytes, merozoites, pyrogens and toxins. Fever threshold
• The febrile paroxysm comprises three successive stages.
• Cold stage : the patient experiences intense cold & uncontrollable shivering, lasting 15 to 60 minutes.
• Hot stage : the patient feels intensely hot fever mounts to 41C, lasting 2 to 6 hours.
• Headache, Nausea and vomiting are common during this period.
• Sweating stage : the patient is drenched in profuse sweat, the temp. drops rapidly and patient usually falls into deep sleep.
The paroxysm usually begins in early afternoon and lasts 8 to 12 hrs
• P. malariae have afebrile period of 72hours while it is 48 hours for P. falciparum, vivax and ovale
• During the second blood meal , the RBCs infected with gametocyte are taken up by the mosquito from infected human.
• The male & female gametes fertilize, to ultimately form the sporozoite, in the gut.
• From the gut parasite reach the Anophele’s Salivary glands.
• When such a Anopheles mosquito bites a human, these sporozoites repeat the Plasmodium life cycle.
What are the Reasons behind Clinical Manifestations ?
• All clinical manifestations are due to:
1 ) The products of Erythrocytic schizogony, following completion of erythrocytic schizogony.
2) The host’s reaction to them.
What are these Products?
• Red cell fragments • Merozoites• Malarial pigments.• Parasitic debris.• Macrophage and polymorph release endogenous pyrogens..• Cytokines
MALIGNANT TERTIANIt is because….. this is the most highly pathogenic of all plasmodia. P. Falciparum • The erythrocytic schizogony occurs in deeper capillaries of various organs..
• In acute falciparum malaria , following heavy infection of RBCs the RBCs becomes Deformed & sticky and adhere to one another & the capillaries of internal organs
• Thus the infected cells are held back in the capillaries and block them leading to blockage, congestion and hypoxia related necrosis of tissues.
• In severe cases the rate of parasitized cells may even be up to 50%
• The cycle completes in 2- 3 weeks.. COMPLICATIONS• CEREBRAL MALARIA hyperpyrexia, coma, paralysis.• ALGID MALARIA circulatory collapse, cold clammy skin.• SEPTICAEMIC MALARIA Alveolar, coronary & renal capillaries are
congested.
• Occurs in all types of malaria.• Anemia is hemolytic.• Decreased erythropoiesis.
SPLENOMEGALY• Spleen is always enlarged in malaria.• Cellular hyperplasia, dilated sinusoids &
accumulation of macrophages accentuate enlargement.
ANAEMIA
Some Major Complications
BLACK WATER FEVER
• Massive intravascular haemolysis caused by antierythrocytic antibodies
• Mostly associated with repeated attacks of Falciparum
• Inadequate treatment with quinine..• Manifestation : • Bilious vomiting, • prostration,• dark red or blackish urine..
TSS ( Tropical Splenomegaly syndrome)
• A Chronic mild condition….
• Results from abnormal immunological response to malaria.
• Features :
• High titres of circulating antimalarial antibody.
• Absence of malaria parasites,
• Hyper Ig aemia, cryoglobulinemia.
MEROZOITE-INDUCED MALARIA• Malaria is sporozoite induced • Injection of merozoites can directly lead to infection of
RBCs.• Its self limiting.
• This may occur in:
• Transfusion Malaria • Therapeutic Malaria• Congenital Malaria
What is the Role of Immune system in MALARIA ?
• Innate -• It seems to play a very obscure role !• For e.g. – Does not multiply in sickle cell, Individuals
lacking Duffy blood group Ag are resistant
• Acquired –• Immune System induces specific immunity with a clinical
cure.• the parasite is continuously prevalent in blood at
subclinical levels, premunition.• Immunity is strain specific thus infection by diff. strain of
the same species is not protective.
IMMUNOPATHOLOGY
• Malaria is known to produce some depression of the immune system.
• For e.g : Responsible for conditions such as – Burkitt’s lymphoma a Lymphoma due to EBV
• Autoimmunity –
• Erythrocytes undergo antigenic changes due to infection leading to auto immune phenomena.
WHY IS IT THAT PLASMODIUM
AFFECTS ONLY HUMANS AND NOT
MOSQUITOES ?
Manifestations of Severe Malaria
• Prostration• Impaired consciousness/coma• Multiple convulsions• Circulatory shock• Jaundice• Severe anemia• Acute renal failure• Disseminated intravascular coagulation• Hemoglobinuria