Malaria, a potentially fatal disease, is caused by a parasite known as Plasmodium. Anopheles mosquito acts as a carrier for this parasite and it is transmitted to humans through bite of anopheles female mosquitoes. There are more than 400 plus species of Anopheles, but there are 5 known species that cause malaria in humans and amongst these there are 4 species that are concerning to humans. These are P. falciparum, P. vivax, P. ovale and P. malariae. The 5th species is P. knowlesi. By far, P. falciparum is the most deadly parasite amongst them, which is most prevalent in the African subcontinent and is responsible for around 91% deaths all around the world. P. vivax and P. ovale are usually found outside the African subcontinent.
What Are The Signs And Symptoms Of Malaria?
Malaria, an acute febrile disease, typically presents with “flu-like symptoms” such as fever and chills, body aches, malaise (a general feeling of illness), fatigue and headache. After the onset of initial symptoms, it progresses into paroxysm of high fever and chills along with profuse sweating. The severity of symptoms mostly depends on the species of plasmodium that has caused the illness.
The symptoms of malaria caused by Plasmodium vivax, Plasmodium ovale and Plasmodium malariae are typically milder than their counterpart Plasmodium falciparum, which causes severe life-threatening complications if left untreated and can eventually lead to death. In P. vivax, P. ovale and P. malariae, the incubation period is around 2 to 3 weeks and may even take up to months to manifest their symptoms when in dormant stage. The initial symptoms of malaria are malaise, an intermittent fever with chills, headache and body aches.
There can also be following associated symptoms of nausea and vomiting, diarrhea, fatigue, abdominal pain and blood in stools. The initial symptoms will be followed by paroxysms of high grade fever (around 104 degree Fahrenheit) with chills, profuse sweating (diaphoresis) and on rare occasions delirium. Between these paroxysms there will be intervals where the patient feels good without any symptoms. The paroxysmal symptoms correspond to the release of more parasites into the blood stream due to destruction of infected red blood cells.
It typically takes about 48 hours (2 days) to release increased parasites in to the bloodstream in P. vivax and P. ovale and takes about 72 hours (3 days) in P. malariae infection that coincide with the paroxysmal symptoms. Eventually, the body clears the parasites from the blood and the paroxysms become less and less severe until they subside. The symptoms do subside even in untreated cases within a month, but may also recur. There have been known cases of relapses in P. vivax and P. ovale that corresponds to the inactive liver stages occasionally releasing parasites into the bloodstream causing recurrence of infection.
The symptoms caused by Plasmodium falciparum are usually severe and can be fatal. The incubation period of P. falciparum is around 10 to 14 days. The symptoms are also the same with high grade fever, severe headache, chills, diaphoresis, along with anemia, dark colored urine, drowsiness, delirium, confusion, convulsions and can even lead to coma in cerebral malaria (in this swelling of brain blood vessels also may occur), which is the most life threatening complication of malaria and could be fatal in infants, pregnant women and also travelers to high risk areas (basically who have less immunity to the infection).
In P. falciparum too, there are paroxysmal symptoms that coincide with the destruction of red blood cells and release of parasites (around 48 hours) into the bloodstream. However, in P. falciparum the paroxysms are not so well defined and also there are increased numbers of parasite released into the bloodstream, which increase the severity of the infection with P. falciparum.
The other complications of P. falciparum malaria may include:
- Organ failure mainly kidney, liver or spleen.
- Anemia due to destruction of large amount of red blood cells.
- Pulmonary edema: It causes fluid accumulation in the lungs that causes respiratory distress making it hard to breathe. However, this is a rare complication.
- Hypoglycemia: Low blood sugar (this may happen in other forms of malaria too).
Untreated P. falciparum malaria can be fatal and one should see a doctor when one notices the above signs and symptoms even if they have been treated prophylactically.
- World Health Organization (WHO) – Malaria: https://www.who.int/news-room/questions-and-answers/item/malaria
- Centers for Disease Control and Prevention (CDC) – Malaria: https://www.cdc.gov/malaria/about/index.html
- Mayo Clinic – Malaria:https://www.mayoclinic.org/diseases-conditions/malaria/symptoms-causes/syc-20351184
- MedlinePlus – Malaria:https://medlineplus.gov/malaria.html