Prevention of Malaria

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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.

Lariam Side Effects

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QUESTION

My son is playing tennis in Rwanda, Africa. He feels terrible and I suspect it may be the Lariam. He has a fever and has been seeing stuff like snakes, etc. I am very worried as there is no doctor nearby. Is there anything to do to help him? The last Lariam he took was on Saturday.

ANSWER

Certainly Lariam is associated with some severe side effects, which include hallucinations such as that which you describe. Unfortunately, the best way to deal with the side effects of Lariam is to stop taking the drug.

If your son decides to do this, I strongly suggest he looks into taking a different malaria prophylactic for the remainder of his trip in Rwanda—doxycycline is readily available from most pharmacies in the region and is very modestly priced. Your son will probably need to take one tablet (100mg) every day (if he is under 8 years old the dosing is slightly different) and should be continued for 4 weeks after he leaves the malarial area. Side effects to look out for include severe sun sensitivity, so he should be diligent with sun block if he starts taking doxycycline.

A more expensive alternative is Malarone, which is also harder to find in Africa, but which has milder side effects and only needs to be taken for a week after returning home.

We are always very interested in our readers’ experiences with malaria preventative drugs and treatment, and we actually have a survey about malaria prophylaxis up on our home page at the moment&mdsh;please have your son take our Malaria Survey when he gets a chance.

Malaria Prevention

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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.

Repellent for Malaria Mosquitos

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QUESTION

My daughter is leaving for Africa for 5 weeks on a mission trip. Is there a repellent that can be used to ward off these infected mosquitos? Also what can she do to stay safe and protected?

ANSWER

There is no way of warding off only those mosquitoes that are infected with malaria. However, insect repellents which contain DEET (10% or higher) are the most effective against the species of Anopheles mosquito that carry malaria.

From personal experience, I can tell you that “natural” insect repellants that do not contain DEET are just not as effective against these mosquitoes. Your daughter can also spray her clothing with permethrin, which repells insects, and she should wear long-sleeved clothing in the evenings, early mornings and at night, when the malaria mosquitoes are most active. She should also try to sleep every night under a long-lasting insecticide treated bednet, which drastically reduces the number of bites.

In addition, your daughter should look into taking anti-malarial preventative medication, known as malaria prophylaxis. There are a number of different types; the two most commonly recommended for Africa are doxycycline (cheap, effective, but can cause sun sensitivity and so people taking it must be vigilant about using sun block! It also needs to be taken for four weeks after leaving the malarial area) and atovaquone-proguanil (sold as Malarone—this is effective, and has very few side effects, but is often very expensive. It only needs to be taken for a week after returning home), both of which are taken as a daily pill with food.

Antimalarial Drug Therapeutic Life

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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.

Malaria Symptoms, Cures, and Prevention

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QUESTION

What is malaria cure, prevention, symptom and course?

ANSWER

I am not sure what you mean by “course” – however, links to information on malaria treatment, prevention and symptoms can be found on the main page of our website. For your convenience, I have provided them here:

As for malaria treatment, I have copied here an earlier answer in response to a question about malaria cures:

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.

 

Which Anti Malarial for South-East Asia?

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QUESTION

We are in our 70s and will be on a cruise from Siem Reap to Ho Chi Minh. Which anti malarial would be most effective for these areas?

ANSWER

The main thing to consider when travelling to south-east Asia is that there are areas where some of the malaria is resistant to mefloquine (commonly sold as Lariam), and therefore this drug is not appropriate as an anti-malarial in these regions.

Chloroquine resistance is also rife throughout the region, although this drug is rarely used as a malaria prophylactic drug. However, apart from this, the choice of anti-malarial depends to a large extent on personal preferences.

The two main types recommended by the CDC for travel to south-east Asia are atovaquone-proguanil (marketed commonly as Malarone) and doxycycline. The former is associated with very few side effects, is taken once a day, and needs to be taken for a week after returning from the malarial area. However it is also very pricey! Doxycycline, on the other hand, is very cheap, but many people experience high sun sensitivity which can lead to severe sun burn if sufficient care is not taken. It also has to be taken for a full four weeks after returning from the malarial area.

Blood Test After Child’s Malaria Exposure

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QUESTION

Our 2 year old son was exposed and bitten about 10 times on Friday, 21st of Ocober in Malindi, Kenya. This was our last day in Kenya after 3 days on the coast preceded by 4 in Masai Mara. On October 28, our son started vomiting. This lasted a day. He did not have a fever at the time. The doctor diagnosed him with rota virus. Our 2 year old took his last dose of Malarone on the same day the vomiting started.

We believe he did not keep it down. Since the doctor visit our son has developed a cough and has had a low constant 38 C fever for a day and a half. Given the risk of a small child to malaria, is there any reason we should not request a blood test for Malaria?

ANSWER

Generally speaking, coughing is not a common symptom of malaria, and fever more usually comes in cycles, so the clinical presentation suggests that your son may be suffering from another illness.

However, as you say, small children are particularly at risk from malaria, so I would say it is worth getting a blood test for malaria, to be on the safe side. It only requires fingerprick blood, and the results can be available very quickly.

It is also important to remember that Malarone (including Malarone Paediatric, the version marketing for children over 11kg in weight) should be taken for 7 days AFTER leaving a malarial area, to prevent latent stages of malaria developing into a full infection.

With small children, other preventative measures are also especially important, such as sleeping under an insecticide-treated bednet, wearing long sleeved clothing in the evenings and early mornings and using insect repellent on exposed skin.