How Malaria Is Diagnosed

Malaria is a highly prevalent infection, affecting over 200 million people worldwide per year. However, its diagnosis can be delayed because:

• Its vague, flu-like symptoms may initially appear to be signs of a mild, self-limited viral infection for several days.
• The prolonged incubation period means that if you have had exposure to malaria through a mosquito bite, you would not experience symptoms for several weeks or months, often after exposure to a tropical climate and its mosquitos is forgotten.

Several clinical signs are characteristic of malaria, and when these signs occur, reliable diagnostic tests can confirm whether you have an infection caused by the parasite.

Self-Check/At-Home Testing

You can learn to recognize early signs of malaria so that you can get yourself or your loved ones tested to see if you have the infection.

History of a Mosquito Bite

If you have had mosquito bites in a geographic region where malaria infection occurs, this raises your chance of becoming infected.

Flu-Like Illness

Malaria is a flu-like illness, with a combination of symptoms that can include fevers, fatigue, headaches, muscle aches, stomach upset, vomiting, and diarrhea.

Cycles of Fever, Chills, Sweats, and Shaking 

Malaria is often recognized because of a cyclic fever pattern. You might experience alternating fevers and chills with cycles that can last anywhere from 10 to 35 hours.

Labs and Tests 

There are several blood tests that can aid in the diagnosis of malaria. The parasite typically lives inside the red blood cells of the body. Some tests can identify the organism itself, while other tests can detect chemicals that signal the presence of the organism inside your body.

Complete Blood Count and Chemistry Profile 

A complete blood count test and electrolyte levels can identify some of the consequences of malaria, such as inflammation, anemia, and kidney failure.

Microscopic Examination

A blood smear is a method of visualizing a blood sample, which is placed on a slide and inspected under a microscope. The parasite is recognizable when the blood sample is stained with a special dye, a Giemsa stain.

If you have a negative blood smear in which the parasite is not identified, this does not necessarily mean that you do not have the infection.

Rapid Antigen-Detection Tests

A test that can identify the presence of the parasite quickly, a rapid antigen-detection test has some advantages and some disadvantages. It does not require an expert to stain and examine a microscopic sample, but it is costly and considered less accurate than a microscopic examination.

Polymerase Chain Reaction (PCR)

PCR can detect the presence of the malaria parasite’s genetic material in a blood sample taken from an infected person. It is considered a highly sensitive test, but results may take several days. However, this test is not readily available and is primarily used for research purposes. The test requires a specialized laboratory facility and is more costly than other standard blood tests for malaria.

Malaria Doctor Discussion Guide

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Imaging

Blood tests are the only definitive tests for malaria because the parasite infects red blood cells, which cannot be seen in imaging studies. However, imaging can provide supportive evidence of infection.

Brain CT or Brain MRI 

In some circumstances, such as with cerebral malaria—a serious complication in which malaria spreads to the brain—non-invasive tests such as brain CT or MRI can be helpful. In those cases, imaging of the brain can show the presence of brain swelling, as well as areas of small hemorrhages and strokes, for which follow-up treatment strategies can be administered. These imaging tests will not be specific enough to diagnose malaria by themselves.

Differential Diagnosis

There are several other conditions that share some of the clinical signs of malaria. Often, diagnostic tests are required to differentiate between these conditions and malaria.

Respiratory Viruses

Like malaria, influenza virus and other common viral infections can cause any combination of fevers, chills, stomach upset, nausea, vomiting, coughing, and shortness of breath. The difference is that malaria has a specific medical treatment that does not cure viral infections.

Most of the time, if you have an influenza infection or an infection with another virus, you are likely to receive medication only for the symptoms, not the virus. Medical treatments that treat the influenza virus itself do not help improve or cure malaria.

Sepsis 

Sepsis is a life-threatening condition caused by the body's exaggerated response to infection. It is characterized by cardiovascular collapse, causing several symptoms that are similar to those of complicated malaria infections, such as a high fever, chills, and sweats. Severe malaria can lead to organ failure and is one of the infections that is considered a cause of sepsis.

Meningitis or Encephalitis 

Infection involving the brain (encephalitis) or the covering that surrounds the brain (meningitis) can cause seizures, weakness, vision changes, and loss of consciousness. Cerebral malaria, like meningitis and encephalitis, is a serious infection that can cause permanent neurological damage.

Each of these infections needs to be medically treated with its own targeted therapy to control and eliminate the cause of the infection.

Dengue Fever

Dengue is also an infection transmitted by a mosquito, and, like malaria, it causes fevers, headaches, and muscle aches. A big difference between this infection and malaria is that dengue is often associated with a rash, while malaria is not. The dengue virus requires a different medical treatment than that of the malaria parasite.

Enteric Fever (Typhoid Fever)

Enteric fever is an infection caused by bacteria that is transmitted through food or human contact, not by mosquitos. Several symptoms are similar to those of malaria, including fevers, chills, fatigue, stomach upset, vomiting, and diarrhea.

Enteric fever is diagnosed via blood and stool testing and causes anemia and liver abnormalities on laboratory examination. Malaria is diagnosed by visualization of the malaria parasite on a microscopic blood smear. The infectious cause is different, and the infections require different medical treatment.

Sickle Cell Anemia Crisis

Malaria and a sickle cell anemia crisis share a few characteristics, including blood clots in tiny blood vessels and rupture of red blood cells. A blood smear can differentiate between the conditions.

Sickle cell anemia crisis and malaria are treated differently, with malaria requiring anti-parasite medication and sickle cell crisis requiring blood transfusion and possibly administration of oxygen.