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!

Diagnosing Malaria

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QUESTION

Where in Malaysia (Kuala Lumpur) can I diagnose malaria? Is it possible within 24 hours?

ANSWER

Given that malaria is endemic in Malaysia (though not usually found in Kuala Lumpar) you should be able to get a malaria test at most clinics or hospitals. The most common test is a thick and thin blood film, read under the microscope by a qualified technician—in some places, clinics are also using rapid diagnostic tests (RDTs). Both of these methods are rapid to prepare and analyse—microscopy may take a couple of hours, depending on the business of the medical staff, whereas an RDT should be ready in about half an hour. In some areas, you can also buy RDTs over the counter at a pharmacy for self-testing.

Malaria Transmission Through Sexual Contact

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QUESTION

Can i get malaria if i have sex with someone that has malaria?

ANSWER

No. Malaria cannot be sexually transmitted. In virtually all cases, malaria is transmitted through the bite of an infected mosquito, of the genus Anopheles. The mosquito passes the malaria parasite (there are several species which cause malaria in humans, all of the genus Plasmodium) through its saliva when it feeds on blood. Only female mosquitoes feed on blood, and so only females transmit malaria. The mosquito picks up malaria also by feeding on blood, this time from someone who already has the infection.

The only other ways to get infected with malaria are through blood transfusion, organ transplant and via the placenta during pregnancy (“congenital” malaria), and these are all very rare, particularly as blood and organ donors are now usually screened for malaria infection prior to transfusion or transplant.

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

Mosquitoes and AIDS

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QUESTION

Can mosquito cause AIDS, and why?

ANSWER

No, HIV (the virus that causes AIDS) cannot be transmitted via mosquitoes. When the virus was first discovered, there was a fear that it could be transmitted via the blood ingested by mosquitoes as they feed between humans. However, it was shown very quickly that the virus was too unstable to survive within the mosquito, and so transmission of HIV is limited to direct transfer of blood, semen, vaginal fluid and breast milk, for example during sharing of intravenous needles, unprotected sexual activity and childbirth.

Post Malaria Auto-Immune Disease

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QUESTION

I contracted P. Malariae while on a Humanitarian trip in El Salvador in 1996, despite taking the Doxycycline prophylaxis. The diagnosis was difficult, as my fever never broke 100 deg F. A sample of my blood was eventually sent to the CDC to confirm the suspicions of my Dr, who just couldn’t prove the dx by smear. The titer came back positive 1. Now to my question. Have you come across any cases of post-malarial auto-immune disorders or cluster-type syndromes?

About a year and a half. After my initial infection, I developed severe hand joint pain that progressed to much of the rest of my body. At the time, RNP/anti-RNP tests were positive, with elevated sed rates, but negative ANA & RF tests. Now those tests are all “wnl,” but I have some form of “agressive osteoarthritis,” DDD, Spinal stenosis/osteophytes/spinalolisthesis w/nerve damage, and the catch all “Fibromyalgia” along with it’s cluster symptoms.

I would be so very, very grateful if you could point me in the right direction of a study, more information, a Dr who has experience with tropical diseases, or any other information that might net me some answers. I am so tired of being tired and in pain. I shouldn’t need knee replacements and 2 discectomies with a double lumbar fusion at 44. Sadly, I’ve already had one in my neck & may need more. I feel like my life was stolen by a mosquito—the deadliest creature on Earth.

ANSWER

I do not believe there is any relationship between the malaria and these symptoms or with any autoimmune diseases.  Although it sounds like your P. malariae infection was a bit difficult to diagnose it is very easy to treat.  There is no known drug resistance and so any of the recommended treatment courses should have cured you of the infection.  If you subsequently developed an autoimmune disease, it is most likely just a coincidence.  Untreated P. malariae infections can become chronic and result in late complications such as renal failure but that is not the case here.

Malaria Test for Infant

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QUESTION

What can I do if my infant (6-12 months) gets malaria and how can I tell if they have it?

ANSWER

Your infant can easily be diagnosed by a blood test, so visit a clinic, doctor or hospital immediately. The diagnosis will either be done by looking at a thick and thin blood film under a microscope, or by a rapid diagnostic test.

It is important that a blood test is done in addition to a clinical diagnosis—the symptoms of malaria are very similar to many other infections but the treatment may vary. If found to be positive for malaria, the doctor will recommend appropriate treatment and dosage for the type of malaria they have and their weight/age.

If you live in a malarial area, it is also important to take measures to prevent malaria, such as having your child sleep under a long-lasting insecticide treated bednet, and perhaps spraying your rooms in the evening with insecticides to reduce the number of mosquitoes.