Malaria in children : Summarized

Malaria

Dr Nimrah Shehzadi

It is a mosquito born infectious disease affecting human and other animals caused by parasite protozoan belonging to plasmodium type.

Etiology:

Caused by intracellular plasmodium protozoan transmitted to humans by female anopheles mosquitoes .

5 species of plasmodium cause malaria in humans:

·         P.falciparum(most fatal )

·         P.ovale (least common)

·         P.malariae(mildest and most chronic)

·         P.vivax

·         P.knowlesi

Mode of transmission :

·         Mosquito bites

·         Blood transfusions

·         Contaminated needles

·         Transplacentally from mother to fetus

Pathogenesis:

2 phased of life cycle for plasmodium species:

·         Asexual phase (in humans)

·         Sexual phase (in mosquito)

1. Asexual phase :

·         Exoerythrocytic phase : involves

    Sporozoite

    Shizont

    Merozoites

·         Erythrocytic phase   :  involves

    Ring form

    Trophozoites

(Both these forms are identified by GIEMSA STAIN)

 4 pathologic processes are identified:

·         Fever :rupture of Rbcs

·         Anemia:hemolysis and bone marrow suppression

·         Immunopathologic events :(production of TNF)

·         Tissue anoxia: cytoadherence of infected erythrocytes to vascular endothelium ,obstruction of blood flow, vascular leakage of blood ,proteins )

Recurrence :

  It occurs due to immune evasive strategies of parasite :

·         Intracellular replication

·         Vascular cytoadherence

·         Rapid antigenic variance

·         Alteration of host immune response

Human blood resistant to malarial growth:

·         HbS

·         Rbcs lacking duffy blood group antigen

·         HbF

·         Newborns born in hyperendemic areas due to passive maternal antibody and high levels of maternal hemoglobin

Clinical menifestations:

·       Asymptomatic during incubation period

9-14 days for p.falciparum

12-17 days for  p.vivax

16-18 days for p.ovale

18-40 days for p.Malariae

·       Symptomatic:

·          Paroxysms of high grade fever (coinciding with rupture of                               

     Schizont, every 48 hrs for p.vivax and p.ovale ,   

    Every 72 hrs for P.Malariae)

·         Fatigue

·         Sweats

·         Headache

·         Drowsiness

·         Anorexia

·         Nausea

·         Vomiting

·         Diarrhea

Signs :

·       Splenomegaly

·       Hepatomegaly

·       Pallor

Congenital malaria :

Common in endemic areas, causes

·         Abortions

·         Miscarriages

·         Stillbirths

·         Premature births

·         IUGR

·         Neonatal deaths

Symptoms in neonates appear typically btw 10 and 30 days of age. These  include

·         Fever

·         Restlessness

·         Drowsiness

·         Pallor

·         Jaundice

·         Poor feeding

·         Vomiting

·         Diarrhea

·         Cyanosis

·         Hepatosplenomegaly

Diagnosis:

Clinical : fever or unexplained systemic illness in a child who has travelled to endemic area in within previous year should be considered life threatening malaria until proved otherwise.

Laboratory :

·         CBC ( anemia,thrombocytopenia, normal or low leukocyte count )

·         ESR ( raised )

·         Giemsa staining (thick smear :confirmation of malaria, thin smear : identification of species ,Smears should be taken several times a day over 3 successive days, with the spike of fever as it releases parasite into blood with RBC rupture)

·         PCR

BINAXNOW malarial rapid diagnostic test

Differential diagnosis:

·        Enteric fever (the patient of enteric fever looks toxic throughout, while the patient of malaria looks toxic only when there is fever and looks well as fever subsides during episodes)

·       Influenza

·       Hepatitis

·       Sepsis

·       Pneumonia

·       Meningitis

·       Encephalitis

·       Endocarditis

·       Gastroenteritis

·       Pyelonephritis

·       Babesiosis

·       Brucellosis

·       Letospirosis

·       Tuberculosis

·       Relapsing fever

·       Yellow fever

·       Viral hemorrhagic fever

·       Amebic liver abscess

·       Hodgkin disease

·       Collagen vascular disease

Treatment :

Uncomplicated cases :

For P.falciparum

·         Artemether -lumefantrine 1.6 /kg twice daily for 3 days

For chloroquine sensitive P. Vivax, malariae, ovale, knowlesi:

·         Chloroquine 10 mg base /kg stat followed by 10 mg /kg at 24hr and 5mg/kg at 48 hr

 Severe malaria:

·        Artesunate 2.4mg/kg IV or IM followed by 2.4 mg/kg at 12 hr and 24 hr ..then OD daily if needed.

·        Artemether 3.2mg/kg IM stat followed by 1.6 mg/kg daily for 3 days

Complications:

·         Severe malarial anemia (hb<5 g/dl)

·         Cerebral malaria

·         Respiratory distress(poor prognostic)

·         Seizures

·         Algid malaria (circulatory collapse)

·         Long term cognitive impairment

·         Tropical splenomegaly syndrome

·         Jaundice

·         Prostration

Chemoprophylaxis/ Prevention while travelling to Malaria endemic areas:

>>If the destination  is Chloroquine sensitive,

Start prophylaxis with Chloroquine phosphate 2 weeks prior to travelling, in the dose of 5mg/kg once weekly (max 300mg).

>> if the destination is Chloroquine resistant :

   Give Doxycycline 2mg/kg/day (max 100mg) ( do not give to children  <8yrs , consider Mefloquine in these cases)