Prevention of Malaria

by

QUESTION

How do I prevent malaria?

ANSWER

There are a number of ways to prevent malaria. These can be placed into two categories: medication and vector protection.

For medication, there are drugs you can take to prevent the malaria parasite from developing after someone is bitten by an infected mosquito. These drugs are known as “chemoprophylaxis”. There are several different kinds, such as doxycycline, mefloquine (marketed as Lariam), atovaquone-proguanil (marketed as Malarone) and chloroquine – the type you use depends on the type of malaria present in the area. For example, in much of Africa and India, malaria is resistant to chloroquine, so this cannot be used as a prophylactic. In parts of Thailand, resistance to mefloquine has emerged. However, if the appropriate type of prophylaxis is used, it is very effective against malaria. The problem is that these drugs have not been tested for long-term use, can be expensive and may have side-effects. Therefore they are of limited use for people who live in areas where malaria is endemic, and are more appropriate for travellers who are in malarial areas for short amounts of time. However, anti-malarial medication may be used in a very specific way for people at particularly high-risk for malaria, such as pregnant women and young children. In these cases, the high-risk individuals receive a dose or series of doses of malaria medication in order to prevent malaria. This form of prevention is known as intermittent preventive therapy (IPT).

Vector prevention involves protecting oneself against getting bitten by mosquitoes. This can involve wearing long-sleeved clothing in the evenings and at night, when malaria mosquitoes are most active, or wearing insect repellent on exposed skin. Indoor residual spraying, whereby repellent and insecticides are sprayed inside the house, can also be used to bring down the number of mosquitoes. Another very effective technique for preventing malaria is to sleep under a long-lasting insecticide-treated bednet. The mesh acts as a barrier against the mosquitoes, and the insecticide impregnated in the mesh further repells the mosquitoes and prevents them from biting through the mesh.

Malaria Prevention

by

QUESTION

what is the prevention of malaria?

ANSWER

There are many ways in which to prevent malaria. I’ll break them down into three categories: 1) medical prevention, 2) protection from getting mosquito bites and 3) vector control.

1) Medical prevention

Malaria can be prevented using certain medications. Taking drugs to prevent a disease is known as “chemoprophylaxis”, and so these drugs are often referred to as “malaria prophylactics”. There are several different types of malaria prophylactic: the most common ones are chloroquine, a mix of atovaquone and proguanil (marketed as Malarone), mefloquine (marketed as Lariam) and doxycycline. The mode of taking these medications vary (Lariam is taken once a week, for example, whereas the others are usually taken once every day), and they also have different restrictions and side effects. Chloroquine is not effective in areas where local forms of malaria have become resistant, for example, and Lariam is not recommended for people with a history of mental instability, as it is known to cause hallucinations and otherwise impair consciousness. Here on Malaria.com, we are actually currently running a survey on side effects of malaria prophylactic drugs, so if you have ever taken medication to prevent malaria, please take the survey: Malaria Medication Side-effects Survey: Treatment and Prophylaxis

It is worth noting that these drugs have not been tested for long term use, plus they can be expensive if taken for an extended period of time. As such, they may not be appropriate for people living in endemic areas for malaria. However, medication can be useful for preventing malaria in high risk groups, even when they are living in a malaria endemic area. One example is the use of intermittent preventive treatment (IPT) for preventing malaria infection in pregnant women, infants and young children. For more information on this, please see the review article written by Dr Felicia Lester for this website: http://www.malaria.com/research/malaria-pregnancy-preventive-treatment

2) Protection from getting mosquito bites

This section links in with the more general vector control strategies, which will be discussed below. Since malaria is transmitted through the bite of infected mosquitoes, preventing mosquito bites is a very effective way of reducing malaria incidence. One of the most popular methods for personal protection, especially in areas where malaria is endemic, is through sleeping under a mosquito bednet. The mesh prevents mosquitoes from being able to fly close to the person sleeping; however, if there are holes in the net, or the person skin is pressed directly against the mesh, the mosquito may still be able to bite them. This is where insecticide-treated bednets come in – they are impregnated with mosquito repellents to stop mosquitoes from biting through the mesh or passing through holes. Newly developed long-lasting insecticide treated bednets (LLINs) are even more effective, in that they don’t require “re-dipping” to maintain the level of repellent in the fibres, and so can protect a person for several years without losing efficacy. These LLINs have been instrumental in reducing cases of severe and fatal malaria, especially among pregnant women and young children, who are often targeted by bednet distributors.

Other methods for preventing mosquito bites include wearing long-sleeved clothing and personal application of mosquito repellent, particular those containing a percentage of DEET, which is a very effective insecticide. These measures should be especially taken in the evening, early morning and at night, which is when the Anopheles mosquitoes that carry malaria are most active.

3) Vector control

Finally, malaria can be prevented from reducing numbers of mosquitoes directly. Some methods target the adult mosquitoes; one such initiative is indoor residual spraying (IRS), whereby the inside of a house is sprayed with an insecticide to kill mosquitoes. Twelve different insecticides are approved by the World Health Organisation for this purpose, though pyrethroids are among the most popular, as they can be used on a variety of surfaces, do not leave a visible stain and can also protect against other insect pests, such as bedbugs.

Other methods for vector control focus on other parts of the mosquito lifecycle. Mosquito larvae require stagnant freshwater for their development, so some projects have worked to eliminate standing water sources, such as unnecessary ditches and puddles, which reduces the amount of habitat available for mosquitoes to lay their eggs and sustain larvae. Other programmes have spread insecticides directly in stagnant water to kill the larvae, or sought to introduce fish or other aquatic organisms, such as copepods, which consume mosquito eggs and larvae. This latter biological control approach is popular because it can also supply an area with fish for local consumption, and doesn’t contaminate water sources with chemicals.

Antimalarial Drug Therapeutic Life

by

QUESTION

Why do some antimalarial drugs have long therapeutic life while others have short therapeutic lives?

ANSWER

Different anti-malarial drugs target slightly different aspects of the malaria Plasmodium parasite, and so are made with different chemical structures.

The differences in therapeutic life across different malaria drugs has to do with the specific pharmacokinetic properties of the chemical compounds from which the drugs are made. Even drugs designed around the same principal chemical compound can persist for different amounts of time in the human body, depending on the other chemicals with which the active compound is bound. The length of time it takes for a chemical compound to halve in concentration, or for its pharmacological effect to reduce by half, in the human blood stream is known as its “half life.”

For example, the common anti-malarial drug chloroquine has a half life of about 10 days, and is based on a chemical compound called 4-aminoquinoline. However, another drug also based on 4-aminoquinoline, called amodioquine, has a half life of only 10 hours.

Proguanil (combined with atovaquone in the drug Malarone) is dihydrofolate reductase inhibitor with a half life of about 16 hours, while mefloquine (sold as Lariam), is made from quinoline methanol and has a half life ranging from 10-40 days. These differences in length of therapeutic action also affect the efficacy of the compounds against malaria at various stages in its progression, and can also be implicated in the propensity to resistance developing to the drug in the malaria parasite.

How is Malaria Treated

by

QUESTION

How is malaria treated?

ANSWER

This answer is copied from an earlier question about the various available cures for malaria.

Malaria can be cured with a number of different medications, depending on then type of malaria and how far the disease has been progressed.

For standard, non-complicated Plasmodium falciparum malaria, the World Health Organisation recommends use of artemisinin-based combination therapies (ACTs), such as Coartem. This is due to increasing levels of resistance to chloroquine in many parts of the world. Indeed, even though chloroquine is still used in many places as first-line treatment against P. vivax, P. malariae, P. ovale and P. knowlesi uncomplicated malaria, there is some evidence that resistance to this treatment is also emerging, for example in P. vivax in parts of south-east Asia.

In cases where malaria infection has progressed to a stage where oral administration of medication is not possible, or where cerebral symptoms are suspected, the usual treatment option is intravenous quinine.

In addition, P. vivax and P. ovale malaria parasites are able to produce forms (called hypnozoites) which can become dormant in liver hepatocyte cells after the blood stages of the infection have been cleared. These dormant forms can become reactivated weeks or even months or years after the initial infection, which is called a “relapse” of the infection. One drug, called primaquine, is able to kill these liver stages, and so patients with either of these types of malaria should also discuss the possibility of taking primaquine.

Apart from these first-line treatments, there are other medications which are used against malaria, both prophylactically as well as for treatment. These include orally-administered quinine, pyrimethamine, mefloquine, proguanil, atovaquone and sulfonamides.

 

Medicines to Prevent Malaria?

by

QUESTION

Which medicines are used to prevent malaria?

ANSWER

There are a number of drugs used to prevent malaria infection, known as malaria prophylactic medication. These vary in terms of how they are taken, how long they are taken for, how much they cost and the typical side effects people experience while they are taking them. In addition, some are recommended more highly for certain types of malaria or certain regions of the world, due primarily to the emergence of resistance in certain areas.

The most common forms of malaria prophylaxis used are doxycycline, atovaquone/proguanil (sold under the brand name Malarone), chloroquine (sold as Aralen) and mefloquine (sold as Lariam). More information on these, on other types of prophylaxis and malaria prevention in general can be found on our Malaria Prevention page.

How is Malaria Cured?

by

QUESTION

How is malaria cured?

ANSWER

Malaria can be cured with a number of different medications, depending on then type of malaria and how far the disease has been progressed.

For standard, non-complicated Plasmodium falciparum malaria, the World Health Organisation recommends use of artemisinin-based combination therapies (ACTs), such as Coartem. This is due to increasing levels of resistance to chloroquine in many parts of the world. Indeed, even though chloroquine is still used in many places as first-line treatment against P. vivax, P. malariae, P. ovale and P. knowlesi uncomplicated malaria, there is some evidence that resistance to this treatment is also emerging, for example in P. vivax in parts of south-east Asia.

In cases where malaria infection has progressed to a stage where oral administration of medication is not possible, or where cerebral symptoms are suspected, the usual treatment option is intravenous quinine.

In addition, P. vivax and P. ovale malaria parasites are able to produce forms (called hypnozoites) which can become dormant in liver hepatocyte cells after the blood stages of the infection have been cleared. These dormant forms can become reactivated weeks or even months or years after the initial infection, which is called a “relapse” of the infection. One drug, called primaquine, is able to kill these liver stages, and so patients with either of these types of malaria should also discuss the possibility of taking primaquine.

Apart from these first-line treatments, there are other medications which are used against malaria, both prophylactically as well as for treatment. These include orally-administered quinine, pyrimethamine, mefloquine, proguanil, atovaquone and sulfonamides.

For more information, see the WHO recommendations for malaria treatment.

Anti-Malarial Tablets for Kenya

by

QUESTION

Which are the best tablets to take against malaria in Kenya?
Is there a malaria vaccination?

ANSWER

I’ll answer your second question first—no, there does not yet exist a commercially available malaria vaccine. Currently, one promising vaccine candidate is undergoing Phase 3 clinical trials in children in sub-Saharan Africa; recently published preliminary findings suggest that it provides roughly 50% protection against malaria.

As for which tablets you should take, there are a number of options, and choosing between them is basically a matter of personal preference. The three main kinds recommended for sub-Saharan Africa are doxycycline, atovaquone/proguanil combination (sold under the brand name Malarone) and mefloquine (sold as Lariam). These three differ in how you take them (usually once a day for doxycycline and Malarone and once a week for Lariam), how expensive they are (doxycycline is the cheapest, Malarone the most expensive) and the side effects you might experience (sun sensitivity is a big problem for some people on doxycycline, some people report hallucinations on Lariam, whereas Malarone usually has the fewest severe side effects).

If you’re not sure what’s best for you, you can always talk it over with your doctor when asking for the prescription, and they might have recommendations, based on their knowledge of your health and specific requirements.

It is worth noting that levels of chloroquine resistance are very high in sub-Saharan Africa, and so chloroquine is not recommended as a prophylactic when travelling to this region.

Malaria prophylaxis

by

QUESTION:

What name brand medicine should you take if you are traveling to area where malaria is present?

ANSWER:

That depends on a few factors, such as where exactly you are going, whether you have had bad experiences with any malaria preventative drugs (prophylactics) in the past, and how much money you want to spend! Common brand names of malaria prophylactic drugs include Lariam (generic name mefloquine) and Malarone (a combination of atovaquone and proguanil). Doxycycline is also a popular antimalarial, which is often sold under its generic name.

Causes of malaria, treatment with drugs and emerging resistance

by

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.

Malaria effects on body’s digestive system

by

QUESTION:

How does Malaria affect the digestive system?

ANSWER:

Malaria does not usually affect the digestive system directly, although nausea and abdominal pain can be symptoms of the disease, usually due to the high fevers caused by the infection. Having said that, some of the drugs given as treatment or prevention of malaria are also known to have gastrointestinal side effects; both chloroquine and proguanil (one of the active ingredients in Malarone) are known to cause nausea and abdominal pain as common side effects, and both can also sometimes (in rare cases) result in gastrointestinal bleeding. It is recommended that these medications be taken with food, to reduce the likelihood of experiences any such side effects.