Malaria is a mosquito-borne infectious disease affecting humans and other animals caused by parasitic protozoans (a group of single-celled microorganisms)
Malaria is a serious disease that causes a high fever and chills. You can get it from a bite by an infected mosquito. Malaria is rare in the United States. It is most often found in Africa, Southern Asia, Central America, and South America.
Malaria is caused by a bite from a mosquito infected with parasites. In very rare cases, people can get malaria if they come into contact with infected blood. You cannot get malaria just by being near a person who has the disease.
Malaria – Symptoms
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.
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.
Other common symptoms of malaria
Other common symptoms of malaria include:
Dry (nonproductive) cough.
Muscle or back pain or both.
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.
Malaria – What Happens
When you’re bitten by a malaria-infected mosquito, the parasites that cause malaria are released into your blood and infect your liver cells. The parasite reproduces in the liver cells, which then burst open. This allows thousands of new parasites to enter the bloodstream and infect red blood cells. The parasites reproduce again in the blood cells, kill the blood cells, and then move to other uninfected blood cells.
After the early stages, life-threatening complications may develop rapidly with P. falciparum and P. knowlesi. If the infected person is not treated, serious complications or death can occur.
But you may recover in a week to a month (or longer) after being infected with P. vivax, P. malariae, or P. ovale, even without treatment.
Malaria can be a very serious disease for a pregnant woman and her developing fetus, for people without a spleen, and for young children. Medicine choices are limited for a pregnant woman or a child. Infection with P. falciparum can lead to death for a pregnant woman and her fetus. For these reasons, a pregnant woman should not travel to an area where she could get P. falciparum malaria.
Malaria – Exams and Tests
Doctors use thick and thin blood smears to find out whether malaria-causing parasites are in your blood. These tests should be done if you have been in a region where malaria is present, you were exposed to mosquitoes, and you have flu-like symptoms.
A blood smear is prepared from a blood sample.
If the first blood smear does not show the presence of malaria parasites but your doctor suspects malaria, you should have a repeat test every 8 to 12 hours for 36 hours.
During treatment, doctors use blood smears to see whether the number of malaria parasites in the blood is decreasing.
A blood test that can diagnose malaria rapidly also is available. If this rapid test indicates a person has malaria, the results are usually confirmed with a blood smear.
Other useful tests that may be done include:
Liver function tests, to check for liver damage.
Complete blood count (CBC), to check for anemia or evidence of other possible infections. Anemia sometimes develops in people with malaria, because the parasites damage red blood cells.
A blood glucose test, to measure the amount of a type of sugar, called glucose, in your blood.