Malaria is a potentially fatal disease caused by an infection with Plasmodium parasites. In most cases, the disease is transmitted through the bite of an infected female Anopheles mosquito. Symptoms may include fever, chills, joint pain, shivering, vomiting, anemia, and diarrhea, which can appear months, or even years, after initially contracting the infection. Preventive measures are those that would prevent mosquito bites. DEET and other insect repellents, covering one's bed with mosquito-netting in the tropics, wearing long sleeves and other measures to prevent mosquitoes from having access to bare skin all prevent infection. Malaria is treated with medications; when treatment is started early enough, the disease can be cured.
Coined from the Italian for 'bad air', malaria was originally thought to be caused by exposure to swampy air. When the relationship between the mosquito population and the transmission of malaria was finally recognized, controlling the spread of malaria became much easier.
Malaria is a leading cause of death and disease worldwide, especially in developing countries. Each year, an estimated 300 to 500 million cases occur, and more than 1 million people die of the disease annually. Although malaria can be a fatal disease, in many cases, death can be prevented with proper and prompt treatment.
Almost unknown in the US and Europe, malaria is more prevalent in tropical climates, where children and pregnant women are more at risk.
Malaria is diagnosed through microscopic examination of the blood cells. Once a patient is diagnosed, a variety of drugs can be helpful. Quinine, distilled from the bark of a South American tree, the cinchona, was an early drug that both treated and protected against contracting malaria. It is still used against variants of malaria that have developed immunity to more modern drugs. It is of historical interest that quinine is the 'tonic' ingredient in tonic water. This helps to explain the popularity of gin and tonic drinks in the tropics.
Sickle cell anemia, a genetic blood disease, is a caused by a mutation that evolved in humans living in high malaria risk areas. A person who inherits the mutation from 'carrier' parents will have sickle cell anemia, a chronic disease that periodically flares up and causes bouts of extreme pain. Those who only receive one copy of the mutated gene, however, have an increased resistance to malaria. The resistance to malaria for some outweighed the painful disease in others, and the mutation prospered in high malaria zones in the tropics.
The cause of malaria is an infection with a malaria parasite. There are several types of malaria parasites, each belonging to the genus Plasmodium.
Malaria parasites (Plasmodium) are tiny organisms that can only be seen under a microscope. There are more than 100 species of Plasmodium, which can infect many animal species, including:
Reptiles
Birds
Various mammals.
Only four species of Plasmodium infect humans in nature. These four types of Plasmodium include:
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae.
While an infection with a Plasmodium parasite actually causes malaria, there is another important species in malaria transmission. This is the Anopheles mosquito. Anopheles mosquitoes are important because they actually transmit Plasmodium to humans through a bite. No other types of mosquitoes are known to transmit malaria.
Mosquito transmission cycle:
Uninfected mosquito. A mosquito becomes infected by feeding on a person who has malaria.
Transmission of parasite. If you're the next person this mosquito bites, it can transmit malaria parasites to you.
In the liver. The parasites then travel to your liver — where they can lie dormant for as long as a year.
Into the bloodstream. When the parasites mature, they leave the liver and infect your red blood cells. This is when people typically develop malaria symptoms.
On to the next person. If an uninfected mosquito bites you at this point in the cycle, it will become infected with your malaria parasites and can spread them to the next person it bites.
Less commonly, malaria transmission may occur through contact with infected blood, such as:
A blood transfusion
An organ transplant
From mother to undborn child in "congenital malaria"
By sharing needles used to inject drugs.
In these cases, the cause of malaria is still a Plasmodium parasite; but how the parasite spreads differs.
Malaria causes a wide variety of symptoms, ranging from absent or very mild symptoms to severe disease, and even death. Malaria disease can be categorized as uncomplicated or severe (complicated). In general, malaria is a curable disease if diagnosed and treated promptly and correctly.
The symptoms of malaria can occur between a week and month after exposure to the parasites which cause malaria, and in people who take antimalarial drugs, the symptoms may be suppressed, appearing even later. Recognizing the symptoms of malaria and getting treatment early can prevent damage caused by the disease, and provide the patient with information which can be used to manage malarial attacks in the future and prevent reinfection.
Several different forms of malaria can appear, but all are usually characterized by an early stage in which the patient experiences chills and trembling, with some children developing seizures. After the so-called "cold phase" is over, symptoms of malaria can include shivering, fever, loss of appetite, headache, nausea, vomiting, aches and pains, low blood pressure, dry cough, jaundice, sweating, fatigue, and enlargement of the liver or spleen. The symptoms of malaria are often described as "flu-like."
It is a good idea to seek medical treatment when the symptoms of malaria are identified. A doctor can determine which parasite is responsible for the patient's illness, and prescribe an appropriate medication. Many malaria parasites are resistant to a broad spectrum of drugs, which means that the patient will need follow up to confirm that the infection has been resolved. When caught early, patients may be cured completely, but patients can also develop persistent long-term infections which never resolve, plunging the patient into malaria attacks periodically.
If left untreated, malaria may result in a wide variety of symptoms, ranging from very mild symptoms to severe disease, such as kidney failure, seizures, fluid in the lungs, coma, and even death.
An acute malarial attack can last several hours, and in patients with severe malaria, they may be unable to function because the symptoms of malaria are so extreme. Other patients experience low grade symptoms which cause discomfort, but not total disability. During attacks, antimalarial drugs can be used to suppress the symptoms and keeping the patient more comfortable, and patients with a history of malaria can take such drugs to prevent re-infection and to minimize symptoms when they do develop a bout of malaria.
Malaria is treated with a class of drugs which are known, unsurprisingly, as antimalarials. Antimalarial drugs are designed to attack the parasites which cause malaria, preventing them from spreading while also killing them off so that they cannot continue causing infection. The success of treatment varies, depending on what strain of malaria the patient has, whether or not the malaria is drug resistant, and whether or not the patient is able to complete the course of drugs needed to treat the malaria.
Unfortunately, these drugs can be very expensive, which makes them difficult to access for many residents of regions in which malaria is endemic.
This mosquito-borne infection has been plaguing people for centuries, until the discovery of quinine allowed doctors to treat patients afflicted with the disease. However, quinine-resistant strains of malaria were quick to develop, forcing researchers to work on new classes of drugs to treat malaria. This battle between researchers and parasites continues to this day: several drug companies are constantly researching new treatments for malaria.
If a patient has what is known as uncomplicated malaria, he or she can be treated as an outpatient, ideally within 24 hours of the emergence of symptoms. The patient's blood will be tested to determine the strain causing the infection, and then an appropriate oral medication for malaria will be prescribed. Doctors must take the patient's medical history into account, along with any other drugs the patient might be taking, before deciding which antimalarial to use.
In the case of patients with severe malaria, hospitalization is required, and drugs are delivered intravenously or via suppository. Some drugs used to treat malaria include: Fansidar, Malarone, Lariam, quinine, quinine sulfate, chloroquine, doxycycline, primaquine, and artemisin derivatives. In some cases, a combination of antimalarials will be used in case the patient's malaria is drug resistant. The cost of these drug treatments varies, and this is another consideration in malaria treatment, as it is important for patients to finish taking their malaria drugs, otherwise, they could develop drug-resistant malaria.
The best way to treat malaria, of course, is to prevent it. Prophylactic drugs are strongly recommended for people who live or travel in areas where malaria is endemic, but unfortunately many people in developing nations cannot afford prophylactic drug courses. Some charity organizations provide such drugs for free to communities in the developing world, but it is difficult to get full coverage in areas like sub-Saharan Africa and Southeast Asia. The risk of malaria can also be reduced by using mosquito netting to cover beds, screening windows, and using bug repellent on the body and clothes to keep mosquitoes and other insects away.
Especially in areas where malaria is a recurrent problem, people should take every possible precaution to prevent infection.