What is Malaria?

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QUESTION

What is it?

ANSWER

I have copied the below answer from an earlier question also asking what malaria is:

Malaria is a disease caused by parasites of the genus Plasmodium. Transmitted by mosquitoes, there are several different kinds of malaria distributed throughout the tropical and sub-tropical regions of the world, causing somewhere between 300-500 million cases of disease each year, and as many as 1 million deaths. In fact, malaria is one of the biggest killers of children under the age of five in sub-Saharan Africa, one of the regions of the world where the burden from malaria is the highest. Malaria is usually an acute disease, manifesting itself with severe fever, chills, headache and often nausea as well. Some types of malaria can have relapsing episodes over a time period of many years.

Having said this, malaria is easily preventable, through avoiding mosquito bites by wearing appropriate clothing and sleeping under insecticide-treated bednets, or through taking preventative medication (called prophylaxis). Malaria is also treatable once symptoms appear, through ingesting safe, effective and relatively cheap drugs. With such control measures at hand, you may ask why malaria is still such a huge problem in our world; the answer is that delivering control strategies and treatment to populations most at risk is difficult, and often countries with high malaria burdens don’t have efficient and effective health systems in place to coordinate control efforts.

International non-governmental organisations such as the World Health Organisation, as well as a multitude of non-profit organisations such as the Malaria Consortium and Malaria No More, work tirelessly to bring malaria control and treatment to the places that need it most, with the aim to eradicate malaria as a disease of public health importance.

What does malaria cause?

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QUESTION:

What does malaria cause?

ANSWER:

Malaria is a disease. It is caused by tiny single-celled parasites called Plasmodium, which are transmitted through the bite of infected Anopheles mosquitoes. There are many symptoms that occur as a result of infection with malaria, namely fever, chills, headaches and nausea, among others. Malaria can be a very serious disease, especially if not treated promptly, and so when spending time in malaria-infection areas (such as many areas of low to moderate elevation in the tropics and sub-tropics) precautions should be taken to avoid mosquito bites and thus infection. If a person finds themselves suffering from some of the above symptoms after being in a malaria transmission region, it is crucially important they get diagnosed straight away; if they do indeed have malaria, then they can be given treatment to facilitate a quick and safe recovery.

Causes of malaria, treatment with drugs and emerging resistance

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QUESTION:

What is malaria and what causes it besides bacteria? What is the name of the causal agent for malaria, which drug is used to cure it and how do the pathogens become resistant to the drugs?

ANSWER:

There are many questions in there! Malaria is actually caused by a single-celled animal, called a protozoan; it’s not a bacterial disease. There are different species of these protozoans, which form a genus called Plasmodium; the different species cause different types of malaria, for example Plasmodium falciparum, the most deadly and severe form, and Plasmodium vivax, which is widespread throughout the world but is a less acute infection. These different forms of malaria are each treated with different medications, depending on what is most effective and available; P. vivax, for example, can be treated with chloroquine, whereas in many places, P. falciparum has become resistant to this drug. In areas where resistance to chloroquine has emerged, other drugs are used; in Africa, artemisinin-based combination therapies (ACTs) are commonly used against chloroquine-resistant P. falciparum. Other drugs used to treat malaria include quinine compounds such as quinine sulphate, mefloquine, sulfadoxine-pyrimethamine and medications combining proguanil with atovaquone (marketed as Malarone).

The emergence of resistance to these drugs is a worrying phenomenon with respect to malaria; it is such a widespread and deadly disease, that the consequences of failed treatment are very high. Resistance can be caused by many factors, at the level of the drug, the human host, the mosquito host and also the malaria parasite itself. For example, poor drug compliance during treatment can lead to a failure to clear an infection completely, allowing the remaining parasites, which were less susceptible to the drug, to survive and reproduce. With successive generations, natural selection will lead to the evolution of strains of malaria parasites which are firmly resistant to that drug. The same process occurs when mass drug administration programmes, for example in areas of high malaria endemicity, give people sub-therapeutic doses of medication (in other words, doses of the drug that are too low to kill the parasite). Another problem is when people are not checked for their infection status after having been treated for malaria; if treatment fails for some reason, they will still have parasites in their blood, and should be treated again to ensure that all the malaria has been killed. If this doesn’t happen, the parasites can carry on reproducing, as in the processes described above. For these reasons, it is crucially important for people to be given accurate doses of medication, to ensure that they complete the full course of treatment, and that once treatment has been completed, they are accurately tested as negative for the malaria parasite. Finally, there are factors related to the affinity of the malaria parasite to its vector mosquito hosts which can lead to the emergence of drug resistant strains. For example, it has been shown that strains of malaria which are resistant to chloroquine are better able to survive and reproduce inside their mosquito hosts, leading to a greater population size of resistant parasites compared to drug-susceptible ones. It is for these reasons that malaria treatment and control programmes are now being very careful with the ways in which they administer drugs and monitor infections, in order to limit any further reisstance developing; similarly, pharmaceutical and biochemical researchers are constantly on the look-out for new compounds or methods of killing malaria parasites, which can be developed into new forms of treatment.