When symptoms appear
Malaria can begin with flu-like symptoms. In the early stages, infection from P. falciparum is similar to infection from P. vivax, P. malariae, and P. ovale. You may have no symptoms or symptoms that are less severe if you are partially immune to malaria.
The time from the initial malaria infection until symptoms appear (incubation period) typically ranges from:2
- 9 to 14 days for Plasmodium (P.) falciparum.
- 12 to 18 days for P. vivax and P. ovale.
- 18 to 40 days for P. malariae.
- 11 to 12 days for P. knowlesi.
Symptoms can appear in 7 days. And the time between exposure and signs of illness may sometimes be as long as 8 to 10 months with P. vivax and P. ovale.
The incubation period may be longer if you are taking medicine to prevent infection (chemoprophylaxis) or because you have some immunity due to previous infections.
Variation in symptoms
In regions where malaria is present, people who get infected many times may have the disease but have few or no symptoms.3 Also, how bad malaria symptoms are can vary depending on your general health, what kind of malaria parasite you have, and whether you still have your spleen.
Common symptoms of malaria
In the early stages, malaria symptoms are sometimes similar to those of many other infections caused by bacteria, viruses, or parasites. Symptoms may include:
- Nausea and vomiting.
Symptoms may appear in cycles. The time between episodes of fever and other symptoms varies with the specific parasite you are infected with. Episodes of symptoms may occur:
- Every 24 hours if you are infected with P. knowlesi.
- Every 48 hours if you are infected with P. vivax or P. ovale.
- Every 72 hours if you are infected with P. malariae.
P. falciparum does not usually cause a regular, cyclic fever.
The cyclic pattern of malaria symptoms is due to the life cycle of malaria parasites as they develop, reproduce, and are released from the red blood cells and liver cells in the human body. This cycle of symptoms is also one of the major signs that you are infected with malaria.
Other common symptoms of malaria
Other common symptoms of malaria include:
- Dry (nonproductive) cough.
- Muscle or back pain or both.
- Enlarged spleen.
In rare cases, malaria can lead to impaired function of the brain or spinal cord, seizures, or loss of consciousness.
Infection with the P. falciparum parasite is usually more serious and may become life-threatening.
There are other conditions with symptoms similar to a malaria infection. It is important that you see your doctor to find out the cause of your symptoms.