Malaria is an acute and chronic parasitic disease transmitted by the bite of infected mosquitoes and it is confined mainly to tropical and subtropical areas.
This disease causes more disability and heavier economic burden than any parasitic disease.
Countries where malaria is endemic as of 2003 Malaria generally occurs in areas where environmental conditions allow parasite multiplication in the vector. Thus, malaria is usually restricted to tropical and subtropical areas (see map) and altitudes below 1,500 m. However, this distribution might be affected by climatic changes, especially global warming, and population movements. Both Plasmodium falciparum and P. malariae are encountered in all shaded areas of the map (with P. falciparum by far the most prevalent). Plasmodium vivax and P. ovale are traditionally thought to occupy complementary niches, with P. ovale predominating in Sub-Saharan Africa and P. vivax in the other areas; however these two species are not always distinguishable on the basis of morphologic characteristics alone; the use of molecular tools will help clarify their exact distribution.
Protozoa of genus plasmodia
1. The disease is caused by four species of protozoa:
a. Plasmodium falciparum (malignant tertian)
· This is considered as the most serious malarial infection because of the development of high parasitic densities in blood (RBC) with tendency to agglutinate and form into microemboli.
· This is most common in the Philippines.
b. Plasmodium vivax (Benign tertian)
· This is nonlife threatening except for the very young and the old.
· It is manifested by chills every 48 hours on the 3rd day onward especially if untreated.
c. Plasmodium malariae (Quartan)
· It is less frequently seen.
· This specie is nonlife threatening.
· Fever and chills usually occur every 72 hours usually on the 4th day after onset.
d. Plasmodium ovale is the rare type of protozoan species.
· This is rarely seen in the Philippines.
2. The primary vector of malaria is the female Anopheles mosquito which has the following characteristics:
a. It breeds in clear, flowing, and shaded streams usually in the mountains.
b. It is bigger in size than the ordinary mosquito.
c. It is brown in color.
d. It is a night-biting mosquito.
e. It usually does not bite a person in motion.
f. It assumes a 36º position when it alights on walls, trees, curtains, and the like.
- 12 days for P. Falciparum
- 14 days for P. vivax and ovale
- 30 days for P. malariae
Period of Communicability:
Untreated or insufficiently treated patient may be the source of mosquito infection for more than three years in P. malariae, one to two years in P. vivax, and not more than one year on P. falciparum.
- The disease is transmitted mechanically through the bite of an infected female anopheles mosquito
- It can be transmitted parenterally through blood transfusion.
- On rare occasions, it is transmitted from shared contaminated needles.
- However, transplacental transmission of congenital malaria is a rare case.
- Paroxysms with shaking chills
- Rapidly rising fever with severe headache
- Profuse sweating
- Myalgia, with feeling of well-being in between
- Splenomegally, hepatomegally
- Orthostatic hypotension
- Paroxysms may last for 12 hours, then, maybe repeated daily or after a day or two.
- In children:
- Fever maybe continuous
- Convulsions and gastrointestinal symptoms are prominent
- In cerebral malaria
- Changes in sensorium, severe headache, and vomiting
- Jacksonian or grand mal seizure may occur
- Malarial smear – In this procedure, a film of blood is placed on a slide, stained, and examined microscopically.
- Rapid diagnostic test (RDT) – This is a blood test for malaria that can be conducted outside the laboratory and in the field. It gives a result within 10 to 15 minutes. This is done to detect malarial parasite antigen in the blood.
- The parasite enters the mosquito’s stomach through the infected human blood obtained by biting or during blood meal.
- The parasite undergoes sexual conjugation.
- After 10 to 14 days, a number of young parasites are released which work their way into the salivary gland of the mosquito.
- The organisms are carried in the saliva into the victim when the mosquito bites again.
- The female alone plays the role of a vector and definitive host in conveying the disease from man to man (sexual propagation).
- In humans, the organisms invade the RBC where they grow and undergo sexual schizogony.
- Erythrocytic merozoites are produced leading to the rupture of RBC upon the release of the tiny organisms.
- Young merozoites invade a new batch of RBC, to start another schizonic cycle.
1. The patient must be closely monitored.
a. Intake and output should be closely monitored to prevent pulmonary edema.
b. Daily monitoring of patient’s serum bilirubin, BUN creatinine, and parasitic count
2. If the patient exhibits respiratory and renal symptoms, determine the arterial blood gas and plasma electrolyte
3. During the febrile stage, tepid sponges, alcohol rubs, and ice cap on the head will help bring the temperature down.
4. Application of external heat and offering hot drinks during chilling stage is helpful.
5. Provide comfort and psychological support.
6. Encourage the patient to take plenty of fluids.
7. As the temperature falls and sweating begins, warm sponge bath maybe given.
8. The bed and clothing should be kept dry.
9. Watch for neurologic toxicity (from quinine infusion) like muscular twitching, delirium, confusion, convulsion, and coma.
10. Evaluate the degree of anemia.
11. Watch for any signs especially abnormal bleeding.
12. Consider severe malaria as medical emergency that requires close monitoring of vital signs.
Treatment and Medications:
- Artemether-lumefantrine (Therapy only, commercial names Coartem and Riamet)
- Artesunate-amodiaquine (Therapy only)
- Artesunate-mefloquine (Therapy only)
- Artesunate-Sulfadoxine/pyrimethamine (Therapy only)
- Atovaquone-proguanil, trade name Malarone (Therapy and prophylaxis)
- Quinine (Therapy only)
- Chloroquine (Therapy and prophylaxis; usefulness now reduced due to resistance)
- Cotrifazid (Therapy and prophylaxis)
- Doxycycline (Therapy and prophylaxis)
- Mefloquine, trade name Lariam (Therapy and prophylaxis)
- Primaquine (Therapy in P. vivax and P. ovale only; not for prophylaxis)
- Proguanil (Prophylaxis only)
- Sulfadoxine-pyrimethamine (Therapy; prophylaxis for semi-immune pregnant women in endemic countries as “Intermittent Preventive Treatment” – IPT)
- Hydroxychloroquine, trade name Plaquenil (Therapy and prophylaxis)
Prevention and Control:
- Malaria cases should be reported.
- A thorough screening of all infected persons from mosquitoes is important.
- Mosquito breeding places must be destroyed.
- Homes should be sprayed with effective insecticides which have residual actions on the walls.
- Mosquito nets should be used especially when in infected areas.
- Insect repellents must be applied to the exposed portion of the body.
- People living in malaria-infested areas should not donate blood for at least three years.
- Blood donors should be properly screened.
Handbook of Common Communicable and Infectious Diseases 2006 Ed