Symptoms of malaria

Last updated: Thursday, December 11, 2008 Print

The first symptoms are usually very similar to ‘flu – aches and pains, fever, headache and so on. After a few days, the typical paroxysms may occur – chills, followed firstly by a high fever for a few hours, and then by profuse sweating. Between these paroxysms, the patient may feel well, depending on the type of malaria that has been contracted. Some forms of malaria are more severe than others, and the time between the paroxysms differs, depending on the type of malaria. Malaria should be suspected in anybody with these sorts of symptoms who has been to a malaria area.

Plasmodium vivax, ovale and malariae

The incubation period (the time between being bitten by the mosquito and developing symptoms) is variable – usually between 2 and 3 weeks. However, in some cases it may take months for the disease to manifest itself. The initial symptoms are often similar to those of influenza:

an intermittent mild fever
headache
muscle aches and chills
a general feeling of illness (malaise).

After a few days (three to five) the typical malarial paroxysms start. These are usually characterised by chills, followed by fever (up to 40 degrees Celsius), and then sweating. The paroxysms normally last about 8 to 10 hours. In between paroxysms patients often feel remarkably well. In vivax and ovale malaria the paroxysms typically recur every 48 hours, while in malariae malaria, the paroxysms recur every 72 hours. The paroxysms occur at about the same time that the red blood cells burst and release more parasites, and this explains the 48 or 72 hour cycle (see previous section “The parasite”). Eventually, the body will eliminate the parasites from the blood, and the paroxysms will get less and less severe and disappear.

Plasmodium falciparum

Symptoms usually begin 10 to 35 days after a mosquito injects the parasite into a person. Again, there are initial “prodromal” symptoms, followed by the malarial paroxysms. However, unlike the other forms of malaria, the paroxysms are not usually as regular, and patients often have a fever between paroxysms.

Although P. falciparum also causes rupture of the red cells every 48 hours, the timing is not as well co-ordinated as with the other forms of malaria, hence the less well delineated paroxysms. In addition, there are usually more parasites in the blood with falciparum malaria than with the other forms, which is one of the reasons that falciparum malaria is more severe than the other forms.

Malaria caused by Plasmodium falciparum is the most severe form of malaria. The most important, and potentially life threatening complication is cerebral malaria. Symptoms of cerebral malaria include: