Incubation period

Symptoms of malaria may take around seven days to develop after a bite from an infected mosquito. This is known as the incubation period or the time between being infected and when symptoms start. Usual incubation period for malaria is around 10 to 15 days. Some cases of malaria may take longer to develop.

Patients with Plasmodium falciparum infection present in the first month or within the first six months of infection. Plasmodium vivax or Plasmodium ovale infections may present later than 6 months after exposure, and sometimes after years.

Initial symptoms

Initially the symptoms are similar to a bout of flu, hepatitis or gastroenteritis.

High fever of above 38C (over 100.4F) that comes in bouts. The fever may come every 48 to 72 hours when the red blood cells laden with the parasites burst into the blood stream. The fever may also occur in four to eight hour cycles. Classically (but less frequently seen clinically) the attacks occur every second day with the “tertian” parasites (Plasmodium falciparum, Plasmodium vivax, and Plasmodium ovale) and every third day with the “quartan” parasite (Plasmodium malariae).

Fever is accompanied by sweating, chills and shaking. Patient feels cold at first with shivering that lasts for up to an hour. This then turns into a fever that lasts for two-to-six hours, accompanied by severe sweating.

There are three stages in classical malaria. These are not seen always. The stages are:

• a cold stage with shivering
• a hot stage with fever, headaches, vomiting
• a sweating stage with intense sweating.

Other initial symptoms include;

• Severe headache
• Severe vomiting and diarrhea may be seen in some cases.
• There may be muscle pain and a general feeling of being unwell.
• On examination there may be features of an enlarged liver and spleen, jaundice (yellowing of the whites of the eyes, urine and nail beds) and pain over the abdomen.

Complications of malaria

The most serious type of malaria is caused by the Plasmodium falciparum parasite. Those with Plasmodium falciparum malaria may develop several complications. The symptoms of a more complicated form of malaria include:-

• Difficulty in breathing
• Convulsions or seizures
• Loss of derangement of consciousness
• Bleeding tendencies
• Severe fall in blood glucose
• Severe anemia
• Kidney failure
• Shock of cardiovascular collapse with severe fall in blood pressure and stoppage of urine formation
• Acute respiratory distress syndrome
• Multi-organ failure