Who Discovered Malaria?

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QUESTION

Who discovered malaria?

ANSWER

People have known about malaria for thousands of years—the first record of it comes from 2700 BCE, in an ancient Chinese medical text. Other ancient peoples, such as the Egyptians, Greeks and Romans, also knew the symptoms associated with malaria. But it wasn’t until the 19th century that the causes of malaria were understood. In 1880, a French physician named Charles Louis Alphonse Laveran first saw the parasites that cause malaria in the blood of a patient. By 1886, Camillo Golgi, an Italian physiologist, had observed that there were at least two separate types of malaria, which produced different length cycles of fever during the clinical presentation. These two forms were later called Plasmodium vivax and Plasmodium malariae. It wasn’t until more than a decade later, in 1897/1898, that the method of transmission of malaria was first understood – Ronald Ross, a British army doctor, showed that malaria could be passed from a human patient to a mosquito vector, and also between infected hosts using mosquitoes. He won the Nobel Prize for medicine for his work in 1902.

Since then, research on malaria has expanded exponentially, with particular attention giving to understanding ways in which the parasite can be therapeutically halted, thus leading to the discovery of new malaria medications.

Does Malaria Still Exist?

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QUESTION

does malaria still exist?

ANSWER

Yes, malaria still exists, and is responsible for 250 million cases of illness every year, of which about 700,000 result in death. So it is a very serious global health problem!

Some countries, such as the United States, have managed to successfully eliminate malaria through a combination of vector control strategies (i.e. spraying for mosquitoes, reducing the presence of water bodies where mosquitoes breed, etc) and better health infrastructure for diagnosis and treatment. This strategy has also been successful in other settings, such as the Mediterranean and much of the Middle East, as well as even in some high transmission tropical settings such as Malaysia (particularly in urban areas).

The widespread distribution of long-lasting insecticide treated bednets has further assisted in malaria prevention in high transmission areas. However, much of the rest of the world is still struggling to control malaria, though the number of deaths is dropping every year, and some organisations hope to reduce malaria mortality to zero by the year 2015.

If you have taken medications for malaria, please help Malaria.com by taking our Malaria Survey. Thank you!

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.

Why is Malaria Dangerous?

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QUESTION

How does Malaria become so dangerous?

ANSWER

Malaria in humans can be caused by a number of different parasites – the most dangerous, and the one which is responsible for over 90% of the worldwide deaths from malaria, is Plasmodium falciparum.

The reason that P. falciparum is so dangerous is because it affects the behaviour of red blood cells. Red blood cells that are infected with P. falciparum become “sticky”, and as they pass through the the small blood vessels inside the body’s organs, they become stuck – this process is known as “sequestration”. As the number of red blood cells stuck inside the small blood vessels increases, blood flow to the organ is reduced, which can result in further complications. When sequestration occurs inside the blood vessels in the brain, the result is what is clinically recognised as cerebral malaria – complications can include impaired consciousness, coma and even death.

If diagnosed and treated promptly, most cases of P. falciparum can be resolved quickly and without complications, using oral medication. However, the parasite can reproduce very quickly, meaning that cases can become more serious within days and even hours. As such, if P. falciparum infection is suspected, and particularly in high-risk individuals such as young children, pregnant women and immunocompromised individuals, diagnosis should be sought immediately so that appropriate treatment can be delivered.

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.

Causes of Malaria

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QUESTION

What is malaria usually caused by?

ANSWER

Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells. Usually, people get malaria by being bitten by an infective female Anopheles mosquito. Only Anopheles mosquitoes can transmit malaria and they must have been infected through a previous blood meal taken on an infected person. When a mosquito bites an infected person, a small amount of blood is taken in which contains microscopic malaria parasites. About 1 week later, when the mosquito takes its next blood meal, these parasites mix with the mosquito’s saliva and are injected into the person being bitten.

If you have ever taken anti-malaria medication, please take this brief Malaria Survey.

Number of Malaria Infections Per Mosquito

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QUESTION

How many people get malaria by one mosquito?

ANSWER

That is a very interesting question—the answer is that is varies between regions, and also depends on the type of mosquito. It was often believed that female mosquitoes (which feed on blood—males only feed on nectar) required a single blood meal in order to lay eggs and reproduce, and so would feed approximately once per week, infecting a single host each blood meal. However, recent evidence has shown that in many locations, Anopheles mosquitoes will actually take multiple blood meals on a single night, thus potentially being able to infect several hosts per gonotrophic (reproductive) cycle. Even more interestingly, in some studies it appears that mosquitoes infected with Plasmodium are more likely then uninfected mosquitoes to take multiple blood meals, thus suggesting that the parasite is in some way manipulating the feeding behaviour of the vector mosquito in order to facilitate its own transmission!

If you have taken medications for malaria, please help Malaria.com by taking our Malaria Survey. Thank you!

Where is Malaria Found?

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QUESTION

Where is malaria found?

ANSWER

Malaria is found throughout the world’s tropical and sub-tropical areas, and mainly in Central and South America, Africa, Asia and the Indo-Pacific region. It is most common in tropical regions, where transmission occurs year-round; in sub-tropical and temperate areas, transmission may only occur during seasons that have appropriate climatic conditions. This includes sufficiently high temperature and water availability for the growth and development of the mosquito, which transmits the disease. The map below shows the estimated risk for malaria across the world, courtesy of the World Health Organisation.

To search an up-to-date malaria map by country, please visit the CDC Malaria Map application.

global malaria risk

Map of estimated malaria risk (2010 data). Courtesy of WHO (http://www.who.int/en/)

Malaria Recurrence

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QUESTION

My friend suffers malaria due to plasmodium falsciparum at least every two weeks. It has been treated with coartem, artequine, artesunate+fansida, quinine/quinimax since 2004 without any relief at all. It returns a week or two later and lab tests attest to same. What else should be done?

ANSWER

It is rare for someone living in an endemic area to suffer so regularly from malaria—usually after repeated exposure the body builds up a certain level of immunity which prevents mild attacks developing into serious illness. Also, P. falciparum is not resistant to Coartem, so something else is probably going on. 

The first thing to make sure is that your friend complies fully with the medication they are given, and completes the full course of drugs. If they stop taking the pills before the full course is completed, the malaria parasite might be reduced enough for symptoms to subside and for the parasite to be undetectable in blood tests, but is still there in low numbers and so can bounce back after your friend stops taking the pills, resulting in a new bout of disease. This process is called recrudescence, and can be prevented by ensuring that the full course of medication is taken, so that ALL the malaria parasites in the blood are killed.

Otherwise, it is clear that your friend needs to take more preventative measures against contracting malaria. These include sleeping under a long-lasting insecticide-treated bednet, spraying the inside of the house with insecticides to prevent malaria mosquitoes from persisting inside and wearing long-sleeved clothing and insect repellent in the evenings and at night, when mosquitoes are biting most actively.

Your friend may also want to look into taking malaria prophylaxis (preventative medication) at times of the year when they are most at risk from infection, or if they know they will be undertaking activities that leave them vulnerable to mosquito bites (i.e. working outdoors at night for a period of time). Some anti-malarial prophylactic drugs, such as doxycycline, are readily available in most malarial countries at a very good price. However, they cannot be taken indefinitely, so for people living in endemic areas, other preventative measures should be considered first.

How Does One Contract Malaria?

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QUESTION

How to get malaria?

ANSWER

Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells. Usually, people get malaria by being bitten by an infective female Anopheles mosquito. Only Anopheles mosquitoes can transmit malaria and they must have been infected through a previous blood meal taken on an infected person. When a mosquito bites an infected person, a small amount of blood is taken in which contains microscopic malaria parasites. About 1 week later, when the mosquito takes its next blood meal, these parasites mix with the mosquito’s saliva and are injected into the person being bitten.

Because the malaria parasite is found in red blood cells of an infected person, malaria can also be transmitted through blood transfusion, organ transplant, or the shared use of needles or syringes contaminated with blood. Malaria may also be transmitted from a mother to her unborn infant before or during delivery (“congenital” malaria).

If you have taken medications for malaria, please help Malaria.com by taking our Malaria Medication Side-effects Survey: Treatment and Prophylaxis. Thank you!