There are a variety of different test to diagnose malaria, including blood tests for initial diagnosis and molecular, serology, and drug resistance tests for further diagnosis and treatment planning. The goal of these tests is to look for parasites or anti-bodies in the blood. Malaria is an infectious disease that is caused by an organism from the Plasmodium genus. It is delivered via the bite of a mosquito, and is found mostly in tropical areas of the world.
Malaria can take years to show symptoms, as the parasite that causes it can incubate anywhere from weeks to years in the liver. Eventually, the parasite multiplies in the red blood cells, typically causing symptoms that include fever, headache, and the classic indication of malaria, alternating chills and fever every two to three days. Other symptoms include joint pain, vomiting, anemia, and hemoglobin in the blood. In more severe cases, convulsions can occur.
One of the most reliable and economic malaria tests is a blood test using thick or thin films of the blood that can detect the presence of a malarial parasite. The films are placed under a microscope and examined by an experienced microscopist. Using thick film allows for a high volume of blood to be examined, whereas the thinner film allows for more detailed examination. Both are usually used.
In some areas, there is no access to a microscope. In this case, a test known as a Rapid Diagnostic Test (RDT) can be performed. A drop of blood is drawn using a finger stick, and is then placed on a sensitive dipstick. The dipstick then indicates by a color change if malarial parasites are present. A drawback to the RDT is that it cannot detect how many parasites there are, and can also be more expensive than a blood film test. The advantage is that is doesn’t require either training or a microscope to perform.
Another type of malaria test is molecular diagnosis. It tests for the nucleic acids that are produced by the parasite using something called polymerase chain reaction (PCR). It is a very sensitive test, but it is very specialized and requires special equipment. Normally it is used after a diagnosis of malaria to further clarify which species of the parasite is causing the disease. This allows for the proper medication to be prescribed.
There are two other malaria tests called serology and drug resistance. Neither is useful for initial diagnosis, however. Serology detects anti-bodies to malarial parasites, which is only effective to detect past infection. Drug resistance tests are used to determine what type of drug will best kill a particular malarial parasite.