Introduction To Malaria

Malaria is a disease caused by a Plasmodium parasite that is transmitted through the bite of female Anopheles mosquitoes. A patient with a fever for more than 48 hours in the endemic area should always be suspected for malaria.

Plasmodium Species
Plasmodium is an obligate intracellular protozoa and there are four species that includes:

1. Plasmodium Falciparum: causing the most serious infection with complications.
2. Plasmodium Vivax: have hepatic stages and may cause relapses of infection
3. Plasmodium Ovale: may cause a relapse similar to vivax
4. Plasmodium malariae

Life Cycle of the Parasite
Plasmodium exists in a variety of forms and has a complex life cycle that enables survival in different cellular environments in the human host and the mosquito vector. There are two major phases in the life cycle:

1. Asexual Phase(Schizogony): it occurs in the humans. The Erythrocytic phase of plasmodium asexual development begins when the merozites released from exoerythrocytic schizonts in the liver penetrate erythrocytes. When inside the erythrocyte , the parasite transforms into the ring form, which enlarges to become a trophozite.

2. Sexual Phase(sporogony): it occurs in the mosquito when the mosquito bites an infected human and gets the trophozoites which then complete the sexual cycle and becomes the sporozoite that travels to the salivary glands and can be then transmitted to another human by the mosquito bite.

Mode of transmission
The parasites usually are transmitted to humans by female Anopheles mosquitoes. Malaria can also be transmitted through blood transfusion, via contaminated needles, and transplacentally to a fetus.

Clinical Manifestations
The clinical signs and symptoms usually appear 8 to 15 days after infection with high fever, chills, rigors and sweating which classically occur in a cyclical pattern depending on the type of Plasmodium species involved. The febrile paroxysms coincide with the rupture of the schizonts.

Headaches, abdominal pain, arthralgia, diarrhoea and vomiting are very common in malaria. Special attention should be given if achild with diarrhoea and /or vomiting have fever as it can be due to malaria.

Other features and complications that can be seen with malaria include:

• Pallor and Jaundice that occurs secondary to hemolysis.
• Hepatosplenomegaly is more common in chronic infetion.
• Nephrotic syndrome may occur with P.malariae because of immune complex deposition in the kidney.
• Cerebral malaria a comlication with P.falciparum may present with confusion, fits or coma.
• Renal failure with acute tubular necrosis or Black water fever as a result of hemoglobinuria resulting from acute , severe intravascular hemolysis is also a complication of P.falciparum infection.

Diagnosis
Malaria can be diagnosed by rapid diagnostic tests or by microscopy.

1 Rapid Diagnostic test
WHO has recommended the use of rapid diagnostic test for the diagnosis of malaria has it is easy to use and gives a quick result with a good sensitivity and specificity.

2. Microscopy
The diagnosis of malaria can be confirmed by examination of organism on stained smears of peripheral blood. Both thick and thin blood smears should be examined. Thick smears are used to scan large number of erythrocytes quickly and allows the detection of parasite whereas the thin smear allow for positive identification of malaria species and determination of percentage of infected erythrocytes.

Treatment
Different treatment options are available depending upon the severity of the disease and species resistance to a particular treatment.

1. For a case of uncomplicated malaria the best treatment option is the combination of Artemether and lumefantrine for 3 days and the dose adjusted according to the weight of the child.

2. If a child is less than 5 kg then it is preferable to give artesunate 4mg/kg loading dose and then 2 mg/kg for the next 7 days per rectally.

3. If the disease is severe and with complications it is important to admit the child in the hospital and provide inpatient care.

4. Always look and treat for hypoglycemia.

5. In severe cases and in cases resistant to chloroquine; Quinine is the drug of choice which is given 25 mg/kg/day in three divided doses for 3 to 7 days.

6. In chloroquine sensitive areas Chloroquine can be given as 10 mg/kg base for day 1 and 2 followed by 5 mg/kg base on day 3.

7. It is important to prevent malaria by eradicating and avoiding the mosquitoes by the use of mosquito net and insecticides.