Malaria. Background Definition of malaria Malaria is an infectious disease caused by protozoan...

Malaria

Background

Definition of malariaMalaria is an infectious disease caused by protozoan organisms of the genus Plasmodium (falciparum, ovale, vivax, malariae). It is characterized by

high fever and erythrocytic infection resulting in anemia..

• life cycle:

asexual phase (schizogony) sexual phase (sporogony)

human hostThere are four species of malaria that infect humans. All of them are transmitted in

the same way ,Mosquito bites humanSporozoites injected into human host during blood mealSporozoites infect liver cells, develop into schizonts, which release merozoites into the blood stream by rupturing the liver cells.

Merozoites penetrate red blood cells and form schizonts; red blood cells release merozoitesSome merozoites differentiate into male gametocytes or female gametocytes.Gametocytes are taken in by mosquito from a blood meal.

Mosquito stageParasites undergo sexual reproduction, develop into oocysts which release sporozoites that invade the mosquito's salivary glands.

And the cycle continues on……

Sporogonous Cycle:

Mosquito Stages

Gametocytes

P. falciparum

P. vivaxP. ovaleP. malariae

Human Liver Stages

Exo-erythrocytic(hepatic) Cycle:

Human Blood Stages

Erythrocytic Cycle:

Malaria Lifecycle

Epidemiology

Malaria is the most important cause of fever and morbidity in the tropical world.

Clinical Manifestations

The clinical manifestations of malaria range fromasymptomatic infection to fulminant illness and

.Death.Febrile paroxysms

classic symptoms of the febrile paroxysms of malaria include high fever, rigors, sweats, andV:48h o:48h m:72h headache.

:Relapse Short-term relapse Longterm relaps

Malaria: Clinical manifestations

• • Febrile paroxysms have 3 classic stages• – Cold stage• Pt feels cold and has shaking chills• - mins. prior to fever• – Hot stage• 41°• Lassitude, loss of appetite, bone and joint aches• Tachycardia, hypotension, cough, HA, back pain, • N/V, diarrhea, abdo pain, altered consciousness• – Sweating stage• Marked diaphoresis followed by resolution of fever, • profound fatigue, and sleepiness• hours after onset of hot stage

Malaria: Clinical manifestations• • Other symptoms depend upon the strain of malaria• • P. vivax, ovale and malariae: few other sxs• • P. falciparum: • – Dependent upon host immune status• No prior immunity/splenectomy high levels of

parasitemia • : profound hemolysis• – Vascular obstruction and hypoxia• Kidneys: renal failure• Brain: hypoxia, CNS dysfunction, coma, • seizures• Lungs: pulmonary edema• – Jaundice and hemoglobinuria (blackwater fever)

Laboratory and Imaging Studies

The diagnosis of malaria is established by identification of organisms on stained smears of

peripherd blood .timing of the smears is less important than their being obtained several times each day over 3 successive days.

.Thick smears are used to scan large numbers of .Erythrocytes quickly

Thin smears allow for positive identification of the malaria species.

Diagnosis

Key of diagnosis is to identify P. falciparumNew assays:

–ELISA for antigen, immunoassay for LDH ,PCR PCR

Anemia, elevated LDH, increased reticulocytes ,thrombocytopeniaElevated unconjugated bilirubin without increases

in hepatic enzymesElevated serum creatinine, proteinuria ,

hemoglobinuria, hypoglycemia

Differential Diagnosis

the possibility of malaria in any child who has fever, chills, splenomegaly, anemia, or decreased level of consciousness with a history of recent travel or residence in an endemic area, regardless of the

use of chemoprophylaxis .DDX :

tuberculosis, typhoid fever, brucellosis, relapsing fever,infective endocarditis, influenza, polio, yellow fever,trypanosomiasis, kalaazar, and amebic liver abscess .

All Plusmudim Species Except Chloroquine-Resistant P. Falciparum

• Oral Drug of Choice chloroquine phosphate

• Parenteral Drug of Choice quinidine gluconate

chloroquine-Resistant P. Falciparum

• Oral drug of Choice Quinine sulfate plus tetracycline‘• Alterative Oral regimens:• Quinine sulfate plus pyrimethamine-sulfadoxine• Mefloquine• Atovaquone Plus proguanil

chloroquine-Resistant P. Falciparum

• Parenteral Dnrg of Choice: Quinidine gluconate

• Primaquine phosphate (after completion of chloroquine)

Prevention of Relapses: P. viva and P. ovale

Complications• Cerebral malaria : is a complication of P.falciparum infection and a

frequent cause of death (20% to 40%), Especially among children and nonimmune adults occur among patients with intense parasitemia (~5%).• Other complications include splenic rupture,renal

failure, severe hemolysis (blackwater fever), pulmonary edema, hypoglycemia, thrombocytopenia, and• algid malaria (sepsis syndrome with vascular

collapse).

Prognosis

• Death may occur with any of the malarial species,• is most frequent with complicated P. falciparum malaria. • The likelihood of death is increased in children with preexisting health problems, such as measles, intestinal parasites, schistosomiasis, anemia, and malnutrition. Death is much more common in poor developing

countries