How to Prevent Malaria

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QUESTION

How to prevent malaria?

ANSWER

Despite its wide geographic range and potentially severe consequences, there are actually several effective strategies for controlling malaria, many of which have been successful of reducing the burden of the disease, and especially the number of deaths, in various regions.

The first step towards control is prevention. This has largely been achieved through the distribution of long-lasting insecticide treated bednets, which prevent people from being bitten by infected mosquitoes as they sleep at night. While this has drastically reduced the number of cases of malaria in some settings, and particularly in certain high risk groups such as children under five and pregnant women, some worrying new data just was published which suggested that in high transmission zones, bednets may actually exacerbate re-infection rates for older children and adults, and lead to insecticide resistance in mosquitoes. As such, while bednets clearly are still a key prevention strategy, their effect should be closely monitored.

Secondly, there is diagnosis and treatment. These go hand in hand, as they usually require the availability of health services or health professionals. If malaria infections are rapidly and accurately diagnosed, appropriate treatment can be swiftly given, preventing the progression of the disease and allowing the patient to recover. Appropriate administration of medication, as well as adherence to the full course of the drugs, can also help to prevent drug-resistance from emerging.

Finally, there are on-going research initiatives looking to find new ways to tackle malaria. For example, many scientists are involved in the search for a malaria vaccine, which, if safe, effective, and sufficiently cheap, could transform the way we think about fighting malaria. Similarly, due to the unfortunate circumstance of ever-increasing drug-resistance, particularly in Plasmodium falciparum, new types of medication are constantly being tested and trialled. The combination of all these efforts has managed to reduce the mortality of malaria greatly over the past few years; the aim now, espoused by organisations such as Malaria No More, is to get to a point where deaths from malaria are eliminated by the year 2015.

 

Pathophysiology of Malaria

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QUESTION

What is the pathophysiology of malaria?

ANSWER

Malaria causes disease through a number of pathways, which depend to a certain extent on the species. Malaria is caused by a single-celled parasite of the genus Plasmodium; there are five species which infect humans, being Plasmodium falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi.

All these species are introduced into the human blood stream through the bite of an infected mosquito; the life stage of malaria at this point is called a “sporozoite”, and they pass first to the liver, where they undergo an initial stage of replication (called “exo-erythrocytic replication”), before passing back into the blood and invading red blood cells (called “erythrocytes”, hence this is the “erythrocytic” part of the cycle). The malaria parasites that invade red blood cells are known as merozoites, and within the cell they replicate again, bursting out once they have completed a set number of divisions. It is this periodic rupturing of the red blood cells that causes most of the symptoms associated with malaria, as the host’s immune system responds to the waste products produced by the malaria parasites and the debris from the destroyed red blood cells. Different species of malaria rupture the red blood cells at different intervals, which leads to the diagnostic cycles of fever which characterise malaria; P. vivax, for example, tends to produce cycles of fever every two days, whereas P. malaria produces fever every three.

In addition, Plasmodium falciparum produces unique pathological effects, due to its manipulation of the host’s physiology. When it infects red blood cells, it makes them stick to the walls of tiny blood vessels deep within major organs, such as the kidneys, lungs, heart and brain. This is called “sequestration”, and results in reduced blood flow to these organs, causing the severe clinical symptoms associated with this infection, such as cerebral malaria.

More details on the exact biochemical mechanisms for sequestration and its effect on the pathology of the infection can be found on the Tulane University website.

 

Does all malaria kill without treatment?

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QUESTION:

Does all malaria kill without treatment?

ANSWER:

No. There are five main species of malaria which infect humans: Plasmodium falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi. Of these, P. falciparum is the most deadly, and can often cause death if left untreated.

The other four may also result in death, but more rarely, and usually only in high risk individuals, such as young children, pregnant women and people with weakened immune systems. Given the seriousness of the symptoms and the possibility of death in all cases, it is very important to seek medical advice if you suspect you have malaria. Once given accurate diagnosis of which type of malaria you have, you can be given appropriate treatment.

Malaria and Blood Cells

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QUESTION

What effect does malaria have on blood cells?

ANSWER

Malaria survives by invading red blood cells (erythrocytes), then replicating within them several times (the exact number and timing of replication depends on the species of malaria), then, once done with replication, bursts from inside the red blood cells, destroying it in the process. As such, malaria infection decreases the number of red blood cells in a patient’s blood, which can lead to anaemia. Moreover, the most severe species of malaria, Plasmodium falciparum, forces red blood cells to stick to the insides of tiny blood vessels deep within major organs such as the kidneys and even brain. This process is called sequestration.

Infection with malaria is also often associated with a decrease in the overall number of white blood cells, but elevated numbers of monocytes can sometimes be observed.

Symptoms of Malaria

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QUESTION

What are the symptoms of malaria?

ANSWER

The symptoms of malaria include fever and flu-like illness, including shaking chills, headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhea may also occur. Malaria may cause anemia and jaundice (yellow coloring of the skin and eyes) because of the loss of red blood cells. Infection with one type of malaria, Plasmodium falciparum, if not promptly treated, may cause kidney failure, seizures, mental confusion, coma, and death. Since the early symptoms of malaria are very similar to many other conditions, including flu and the common cold, if you live in a malaria area it is important not to ignore these symptoms but to seek medical help and have a blood test to check for malaria early on. 

Treatment for Malaria

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QUESTION:

What is the main medicine to cure malaria and about safety precautions?

ANSWER:

There are a number of medicines used to treat malaria. Traditionally, chloroquine has been the first line drug of choice for uncomplicated, non-resistant malaria. However, several types of malaria, and most notably Plasmodium falciparum, the most severe and deadly kind, has become resistant to chloroquine in many places. In some parts of south-east Asia, Plasmodium vivax has also begun to show worrying signs of chloroquine resistance. In such settings, where resistance to chloroquine is suspected, the first line medications for uncomplicated cases are artemisinin-based combination therapies (ACTs), such as Coartem.

The World Health Organization has recommended that artemisinin only be given in combination with another drug to prevent malaria also becoming resistant to this therapy as well. Cases of malaria which have progressed beyond the grasp of that treatable with oral medication as described above (so-called “complicated” cases, most common with P. falciparum infection) are usually given intravenous quinine as a first-line response.

All of these treatments have been rigorously tested in strictly controlled clinical and field trials, and while they may have side effects, they are generally mild and in most cases, the patient will be given the dose without prior testing for reaction to the drug. One exception is with primaquine, which is sometimes used as a preventative medication against malaria and can also be used to treat the liver stages of P. vivax and P. ovale. Primaquine is known to cause severe haemolysis in people with G6DP deficiency, and so people with a high statistical probability of having this condition (for example due to family history or ethnicity) should be tested prior to being given primaquine.

Drugs for Malaria

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QUESTION

What drugs are used in the treatment of malaria?

ANSWER

There are a number of medicines used to treat malaria. Traditionally, chloroquine has been the first line drug of choice for uncomplicated, non-resistant malaria. However, several types of malaria, and most notably Plasmodium falciparum, the most severe and deadly kind, has become resistant to chloroquine in many places. In some parts of south-east Asia, Plasmodium vivax has also begun to show worrying signs of chloroquine resistance. In such settings, where resistance to chloroquine is suspected, the first line medications for uncomplicated cases are artemisinin-based combination therapies (ACTs), such as Coartem.

The World Health Organization has recommended that artemisinin only be given in combination with another drug to prevent malaria also becoming resistant to this therapy as well. Cases of malaria which have progressed beyond the grasp of that treatable with oral medication as described above (so-called “complicated” cases, most common with P. falciparum infection) are usually given intravenous quinine as a first-line response.

All of these treatments have been rigorously tested in strictly controlled clinical and field trials, and while they may have side effects, they are generally mild and in most cases, the patient will be given the dose without prior testing for reaction to the drug. One exception is with primaquine, which is sometimes used as a preventative medication against malaria and can also be used to treat the liver stages of P. vivax and P. ovale. Primaquine is known to cause severe haemolysis in people with G6DP deficiency, and so people with a high statistical probability of having this condition (for example due to family history or ethnicity) should be tested prior to being given primaquine.

 

RTS,S Malaria Vaccine

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QUESTION:

What information can you provide on this vaccine candidate?

ANSWER:

RTS,S is a vaccine candidate against Plasmodium falciparum malaria which works by encouraging the host’s body to produce antibodies and T cells which diminish the malaria parasite’s ability to survive and reproduce in the liver.

Produced by GlaxoSmithKline, RTS,S is the first vaccine candidate against Plasmodium falciparum that has reached advanced (Phase III) clinical field trials on a large scale. It was developed way back in 1987, and had successive trials in the United States in 1992 and then in Africa in 1998. In 2001, GSK and the Malaria Vaccine Initiative at PATH went into a public-private partnership, with grant money from the Bill and Melinda Gates Foundation, to develop the vaccine for use in children and infants in sub-Saharan Africa.

The Phase III trials are currently underway in a number of African countries; if all goes to plan, the vaccine will be submitted for regulation by drug authorities as early as 2012. This information, and more, can be found courtesy of the Malaria Vaccine Initiative website: http://www.malariavaccine.org/index.php.

ARCEVA for malaria

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QUESTION:

Is ARCEVA a good vaccine for malaria?

ANSWER:

ARCEVA isn’t a vaccine for malaria, but it is a brand name of one type of medication used to treat the disease. It belongs to the group of drugs called artemisinin-based combination therapies (ACTs), which are recommended by the World Health Organisation to treat uncomplicated malaria caused by Plasmodium falciparum, the most dangerous form of malaria. ARCEVA specifically contains artemether combined with lumefantrine. It is very important to know that there is no effective vaccine against malaria that is currently available; many scientists and researchers are vigorously hunting for such a vaccine, knowing that this would radically decrease the number of cases of malaria worldwide.

Symptoms of Malaria

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QUESTION:

SYMPTOMS OF MALARIA?

ANSWER:

The symptoms of malaria include fever and flu-like illness, including shaking chills, headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhea may also occur. Malaria may cause anemia and jaundice (yellow coloring of the skin and eyes) because of the loss of red blood cells. Infection with one type of malaria, Plasmodium falciparum, if not promptly treated, may cause kidney failure, seizures, mental confusion, coma, and death.