Mefloquine

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QUESTION

My son, 7 years old, took Mefloquine course for malaria prevention last year. We are travelling to INdia again this year. Does he and myself need to repeat the anti-malaria pills again this year?

ANSWER

Yes. You need to take anti-malarial preventative medication every time you go back to a malarial area. It is also important to continue taking the drug for the required amount of time before and after returning from your trip—in the case of mefloquine, you need to start taking it two weeks before you depart for the malarial area, and then continue you taking it for 4 weeks after you get back. This ensures that if you are exposed to malaria at the beginning or end of your trip, you are still adequately protected.

If you have some time, we at Malaria.com would be very grateful if you would take a minute or two to answer our malaria survey that we are conducting about our readers’ experiences with anti-malarials, and particularly their side effects.

P.vivax Malaria Treatment

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QUESTION

Which drug should be given to a p.vivax malaria patient with deficient glucose 6-phosphate for prevention of relapse?

ANSWER

Unfortunately, primaquine is the only drug that is known to kill the latent liver stages of P. vivax and P. ovale. Since it can induce haemolysis in people with G6DP deficiency, this drug is usually not recommended for people with this deficiency. However, there are actually gradations of severity of G6DP deficiency, and so in some cases, primaquine at therapeutic doses may be tolerated by people with only mild G6DP deficiency, if they are carefully monitored for anaemia throughout the process. This may be preferable to no treatment, since no other known medication can prevent relapse.

Is Malaria Contagious?

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QUESTION

Is malaria contagious?

ANSWER

Malaria cannot be transmitted directly between people via normal circumstances, so it is not contagious in the same way flu or the common cold is contagious. It also cannot be sexually transmitted.

In most cases, malaria can only be transmitted via the bite of an infected mosquito, so unless those mosquitoes are present, it cannot be transmitted. Because infectious stages of the parasite are present in the blood, in some cases malaria can be transmitted via blood transfusion (if the blood is not properly treated or screened), via organ transfer, or from a mother to her foetus, either via the placenta or during childbirth (this is called “congenital malaria”). However, compared to the amount of transmission which occurs via mosquito, these cases are relatively rare, and the vast majority of the time, malaria is not directly transmitted between people.

Recurrent Malaria

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QUESTION

can malaria represent itself after 50 years?

ANSWER

There are two types of malaria which can lay dormant for long periods of time, though I don’t personally know of more than a handful of cases where the relapse was a matter of decades after the initial infection. These two types are P. vivax and P. ovale, so if you know you were infected with one of these types a number of years ago, it is possible that you could experience a relapse many years later, though as mentioned above, it is rare for the time lapse to be as long as 50 years.

Malaria Treatments

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QUESTION

What are the of different types of antimalaria drugs?

ANSWER

Most drugs used in treatment are active against the parasite forms in the blood (the form that causes disease) and include:

  • chloroquine
  • atovaquone-proguanil (Malarone®)
  • artemether-lumefantrine (Coartem®)
  • artesunate-pyronaridine (Pyramax®)
  • dihydroartemisinin-piperaquine (Duo-Cotecxin®)
  • mefloquine (Lariam®)
  • quinine (given intravenously, this is recommended first-line treatment for severe, complicated malaria)
  • quinidine
  • doxycycline (used in combination with quinine)
  • clindamycin (used in combination with quinine)

All of the treatments above which combine an artemisinin-derivative (such as artemether, artesunate or dihydroartemisinin) in combination with another anti-malarial are called the artemisinin-based combination therapies (ACTs) and are collectively recommended by the World Health Organisation as the first line medication against uncomplicated malaria.

In addition, primaquine is active against the dormant parasite liver forms (hypnozoites) and prevents relapses. Primaquine should not be taken by pregnant women or by people who are deficient in G6PD (glucose-6-phosphate dehydrogenase). Patients should not take primaquine until a screening test has excluded G6PD deficiency.

Treatment and Management of Malaria Parasite

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QUESTION

What are the treatments and management of malaria?

ANSWER

Treatment is actually part of the strategy for managing malaria, so I will come back to that later. The other main ways in which malaria is controlled is through prevention, diagnosis (followed by treatment if necessary) and education.

1) Prevention:

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 travelers 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 repels the mosquitoes and prevents them from biting through the mesh.

2) Diagnosis

Diagnosis is considered a crucial step in controlling malaria, since it ensures that people are receiving correct medication, whether for malaria or for another condition which is causing their symptoms. Currently, the most commonly observed form of diagnosis is through microscopy of thick and thin blood films, which can be stained if necessary. These should be read by a qualified technician to determine both the species of malaria infection and the intensity of parasitaemia (number of parasites in the blood).

More recently, other methods for diagnosis have emerged. These include the use of rapid diagnostic tests (RDTs) which utilize a drop of blood applied to a reagent strip which very quickly reacts to show whether the patient is infected with malaria. While considered generally more sensitive than blood films, some RDTs don’t test for all types of malaria parasite, and many require that the reagents be kept cold in order for the test to be effective, which can be a problem in some developing countries.

Perhaps the most sensitive test for malaria is through PCR, which can theoretically detect a single malaria parasite in a drop of blood, and also determine the species. However, measures of infection intensity require an alternative form of PCR, called real-time PCR, which can be technologically challenging. All forms of PCR require a lot of expensive equipment and reagents, trained technicians and take several hours to run.

3) Treatment

Malaria treatment can be determined based on the diagnostic results, as well as other factors, such as:

  • The area where the infection was acquired and its drug-resistance status
  • The clinical status of the patient
  • Any accompanying illness or condition
  • Pregnancy
  • Drug allergies, or other medications taken by the patient

Most uncomplicated (i.e. not severe) cases of P. falciparum can be treated with oral medication, such as artemisinin-based combination therapies (ACTs). Artemisinin is given in combination with another anti-malarial drug in order to prevent resistance from developing in the parasite. Patients who have complicated (severe) P. falciparum malaria or who cannot take oral medications should be given the treatment by continuous intravenous infusion, with quinine recommended by WHO as the first-line treatment.

Other drugs, which are used in some settings, are considered second-line or alternative forms of treatment. These include:

  • chloroquine (very rarely used for P. falciparum, due to widespread resistance)
  • atovaquone-proguanil (Malarone®)
  • mefloquine (Lariam®)
  • quinine
  • quinidine
  • doxycycline (used in combination with quinine)
  • clindamycin (used in combination with quinine)

In addition, primaquine is active against the dormant parasite liver forms (hypnozoites) and prevents relapses, for patients with P. vivax or P. ovale malaria. Primaquine should not be taken by pregnant women or by people who are deficient in G6PD (glucose-6-phosphate dehydrogenase). Patients should not take primaquine until a screening test has excluded G6PD deficiency.

4) Education

Through education, people living in at-risk areas for malaria transmission can learn about ways to prevent the disease (see above), as well as what to do if they suspect they are infected (i.e. seek diagnosis). Similarly, education is important for travellers visiting malarial areas, so they know the best ways in which to avoid being infected.

Malaria Prevention

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QUESTION

What is malaria and the preventive measures?

ANSWER

Malaria is a disease caused by single-celled parasites of the genus Plasmodium. There are currently five species which cause disease in humans, and while each is slightly different, they all act in basically the same way, and cause similar symptoms. Of the five, the most dangerous is Plasmodium falciparum, which can lead to death in a matter of days if not treated promptly.

In terms of prevention, the same basic methods are used to prevent all types of 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 travelers 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 repels the mosquitoes and prevents them from biting through the mesh.

Malaria Prophylaxis in Ghana, Africa

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QUESTION

My husband will be traveling to Ghana soon. We have Mefloquine and Primaquine. Which one do you think is best for prophylaxis in Ghana? He also has Fansidar, but we understand it’s best not to use this for prophylaxis. Thank you for your help!

ANSWER

There are positives and negatives associated with both of these medications. Mefloquine is recommended for travelers in Ghana (whereas the Centers for Disease Control does not explicitly recommend primaquine for this area, since primaquine is particularly effective against Plasmodium vivax malaria, which is almost completely absent from West Africa), and only has to be taken once a week (primaquine must be taken daily).

A disadvantage with mefloquine is that you must start taking it 2 weeks before your trip, whereas primaquine can be started as little as 1-2 days before travel; mefloquine is also not recommended for people with a history of psychiatric or mental problems, as it can cause severe side effects. Even healthy individuals often report disturbing dreams or increased agression/anxiety while taking mefloquine. However, one major disadvantage to primaquine is that you must be tested for G6DP deficiency prior to taking it – your husband may have already done this, prior to being prescribed the drug. People with G6DP deficiency should not take primaquine.

Overall, the decision comes down to personal preference, though from a disease perspective, mefloquine would probably be the better choice for travel to Ghana, given the higher prevalence of P. falciparum malaria in this region, as opposed to P. vivax. Other options to consider would be atovaquone-proguanil (Malarone – expensive, taken daily, but very effective and very well tolerated by most people, with very low side effects) or doxycycline (very cheap, taken daily, is an antibiotic so can prevent some other infections but often results in sun sensitivity, which can be a problem in the tropics). Both of these can be started 1-2 days before arriving in the malarial area.

After you come back, I would be very grateful if you could take our malaria medication side effects survey, as we are very interested in hearing from our readers what their experiences with malaria prophylaxis and treatment have been.

Persistent Antibodies to Malaria?

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QUESTION

I had malaria as child, more than 30 years ago. It was successfully treated with no relapse. I have since travelled to malaria- endemic countries, but the last time was over 3 years ago. No symptoms. I recently donated blood and routine screening has detected malaria antibodies. How long do the antibodies persist?

ANSWER

Based on your experience, I would say at least three years! While I doubt your antibodies would persist since your infection as a child, it is more likely that in your more recent trips to malarial areas you have been re-exposed to the parasite, but for whatever reason, the infection didn’t progress into a full-blown episode of malaria. This could well be due to some residual immunity from childhood, or you just received a light enough infection that your general immune system was able to fight off. Either way, this would have produced new antibodies against malaria, which were picked up by the blood screen.

The length of time antibodies persist is important information in the control of malaria, since serological tests (which detect antibodies) can be used for screening of populations in low-transmission environments, but their efficacy is reduced in locations where people have been treated for malaria but their antibodies persist. Also, understanding how antibodies are created and maintained in the body is necessary for gaining an appreciation of how preventive measures, such as bednets, might potentially leave populations more vulnerable to malaria later on, through lack of acquired immunity.