Where did malaria start in Africa?

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QUESTION

Where did malaria start in Africa?

ANSWER

Malaria has been present in Africa for tens of thousands of years; given this ancient history, it is very difficult to know exactly where it first entered the continent. Also, there are several different types of malaria in Africa, which have likely had different histories, and malaria researchers continually unearth new evidence regarding the origins of these different species.

For example, it has long been thought that Plasmodium falciparum, the most deadly form of malaria, emerged somewhere in the western Congo Basin in Central Africa. Originally, it was thought to have crossed over into humans from a closely related species found in chimpanzees, but recent research, published only in 2010, has suggested that a new species, found in gorillas, is actually the closer relative.

Plasmodium vivax, the most geographically widespread species of malaria that infects humans, has less clear origins. Many of its closely related species occur in south-east Asia, which leads some researchers to suggest this is where it emerged, passing into Africa as humans and their livestock moved across Asia towards the Middle East and North Africa, or possibly via  migration through Madagascar. However, other researchers argue that the high prevalence of certain genetic mutations which protect against Plasmodium vivax malaria found in populations in Africa and of African descent, and particularly West Africa, is evidence that P. vivax actually originated on this continent.

How long do I need to carry a Malaria Risk Card

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QUESTION

Hello, 13 months ago I worked in Nigeria, Africa for a period of 6 weeks. During which time I took Malarone tables daily. I think I was only bitten once or twice when there – but have never had Malaria. I currently carry a Malaria Risk Card in my wallet. At the time I was told I could potentially contract Malaria up to a period of 2 years after exposure – is this correct, or can I now remove the Risk Cards from my wallet?

ANSWER

If you never had malaria while you were in Nigeria, then you certainly would not still be at risk from it now. The only case in which you might still be at risk is if you had been diagnosed with either Plasmdodium ovale or P. vivax (two of the five forms of malaria that infect humans) – these can cause relapses months or even years after initial infection.

However, as I said above, since you did not have malaria at all, this does not apply to you. It is true that malaria has a latent phase, and so can sometimes only start to cause symptoms after someone returns home from a malarial area, but this period is usually one or two weeks, and certainly not months or years!

Transmission of Malaria

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QUESTION

Why can the malaria parasite be transmitted from mosquito to human, but not from human to human (via blood)?

ANSWER

This is a very good question, and actually, malaria can be transmitted via human blood directly to another person, but this occurs relatively rarely!

It has to do with the life cycle of the malaria parasite. When a mosquito bites a human host, it injects sporozoites from its salivary glands into the blood. This life stage first migrates to the liver, where it undergoes a cycle of multiplication, before entering the blood stream. Here, in the so-called “erythrocytic” portion of the life cycle, the parasite reproduces a series of times in red blood blood, before finally forming gametocytes, which are required to be ingested by a mosquito vector during another blood meal for the life cycle to be continued. As such, when blood is passed between people, they would have to pass infected red blood cells, and not gametocytes (which are not infective to humans, only to mosquitoes) in order for the other person to become infected.

As such, when a person who is infected with malaria donates blood, there is a chance that they might pass on some red blood cells which are infected with mature trophozoites or schizonts; these could then go on to infect more red blood cells in the person who received the blood. However, in most countries, blood is screened for malaria, and in fact, in many places, people who might have been exposed to malaria are not allowed to donate whole blood, only plasma (in which the red blood cells have been removed, and therefore there is no risk of transmission). Given the high levels of malaria prevalence in some endemic countries, however, preventing people from donating blood who are positive for malaria may result in too little blood being collected; in these cases, other strategies, such as treating donors or closely monitoring patients post-transfusion, may prove to be a better strategy.

malaria life cycle schematic CDC

Schematic of the malaria life cycle, courtesy of CDC (www.cdc.gov)

Annual Blood Examination Rate in Bengal

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QUESTION

What is the annual blood examination rate in West Bengal?

ANSWER

The annual blood examination rate (ABER) is a measure of the level of diagnostic monitoring activity. Data from 2007 suggested the ABER in West Bengal was around 5%, which is well below the level of 10% which is recommended for active surveillance and is the target of the National Vector Borne Disease Control Programme.

However, within West Bengal there is variation in the ABER both geographically and temporally. One study showed that in Naxalbari block in Darjeeling district, ABER in 2003 and 2004 was as low as 3.5%. The region experienced a malaria outbreak in late 2005, and the average ABER for this year soared as high as 16%; however, from January to May of 2005, before the transmission season and the outbreak, the ABER was only 0.5%! This means that monitoring efforts at the start of the outbreak were probably insufficient to detect the emergence of the outbreak and therefore delayed the process of responding to the emerging disease threat. Maintaining sufficient levels of malaria surveillance monitoring is particularly important in West Bengal, since this state is one of the major endemic centres for malaria in India, contribution about 11% of all malaria cases and about 6% of all cases of Plasmodium falciparum.

Lasting Headaches and Malaria

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QUESTION

I had malaria in July of 2011, returned to the U.S. in August, and had an occurrence of P. falciparum a little more than a month later. It was quickly treated, but I continue to get headaches. They occur about daily, and exercise induces a very severe headache. Is this a common lasting symptom of malaria?

ANSWER

Once successfully treated, malaria almost never has recurring or lasting side effects, nor are lasting headaches a known side effect of treatment with ACTs (artemisinin-based combination therapies, which is the recommended first-line treatment against P. falciparum). If your headaches are made worse through exertion, you should talk to your doctor about making sure they are not a symptom of a more serious condition.

How is Malaria Treated

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QUESTION

How is malaria treated today?

ANSWER

Several different medications exist which are used for the treatment of malaria. The exact drug and method of treatment depends somewhat on the type of malaria the patient is infected with.

In most cases of non-complicated (i.e. when the patient is stable and conscious) malaria, the World Health Organisation recommends an orally-administered (in the form of solid pills) artemisinin-based combination therapy (ACT), such as Coartem (a combination of artemether and lumefantrine). Other types of medication include atovaquone-proguanil (Malarone) and sulfadoxine-pyrimethamine (Fansidar). In some locations, where chloroquine-resistance is not a problem, chloroquine can also be used as a treatment. For complicated malaria, where the patient is in a more severe state, intravenously administered quinine is usually the first-line treatment.

If diagnosed early and the patient is given appropriate medication, virtually all cases of uncomplicated malaria can be effectively treated.

Chloroquine side-effects

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QUESTION

For about two years in the early ’90s I indulged in self-prescription of chloroquine because then, I lived in a mosquito infested environment which made me suffer constant malarial attacks. Could this be why I now suffer from severe pains around my pelvis and down my thighs to one of my knées? I make this guess as a layman because recently, following a malarial attack, I took a non-chloroquine anti-malarial and discovered that the drug also provided me with temporary relief from those pains.

ANSWER

I have not found any information that suggests pelvic/leg pain could be one such effect. In fact, the only conclusive data is on irreversible retinal damage, which is a known consequence of long-term or high dosage chloroquine use. If you have experienced difficulty reading or other visual problems, it may be worth getting screened.

Since your symptoms improved with taking another anti-malarial, it may be that you have some other infection or illness which responds to the anti-malarial drugs (which are known to be effective against other diseases – for example, artemisinin can be used to treat schistosomiasis, a parasitic worm infection). This is something you should discuss with your doctor, as chronic pelvic pain can have a variety of causes and is often misdiagnosed.

Malaria from Dominican Republic?

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QUESTION

Hi i just came back from the Dominican Republic. I started to have a mild fever, chills, muscle pains, a headache, and a cough. Today the fever and chills are gone but my cough and headache have gotten worse. It hurts my head a lot when I cough, I feel a lot of pressure in my head. Can you please tell me why my head hurts so much.  Is this a symptom of malaria? hope to hear from you guys soon thanks!

ANSWER

Headaches can be caused by many things – they are usually classified as primary (tension headaches, migraines or cluster headaches), secondary (as a side effect to some other illness or syndrome, which can very commonly be an infection or response to an allergen) and neuralgia and “other” headaches (neuralgia is inflamed nerves). Malaria, as a serious infection, can cause secondary headaches, while other symptoms include fever (usually in cycles of 2 or 3 days), chills, nausea and aches. However, these symptoms are also consistent with a wide range of other illnesses, including influenza and other common diseases. Malaria symptoms will only appear at least one week after being bitten – if you have started feeling symptoms sooner than this, then you probably don’t have malaria.

Malaria is present in the Dominican Republic, with highest transmission risk in the western part of the country, near the Haitian border. The cities of Santiago and Santo Domingo are considered very low risk for malaria. It is actually recommended that all travellers to the DR take anti-malarial medication (called prophylaxis), to protect against malaria infection. If you were taking prophylaxis, then the risk of getting malaria is very low. However, if you were visiting areas outside of these cities, were not taking anti-malaria medication and it has been at least a week since you were bitten by mosquitoes while there, it may be worth going to your doctor or a hospital to have a malaria test. If you are diagnosed with the disease, then your doctor can quickly prescribe you effective treatment, which should clear up the infection in a matter of days. The type of malaria in the Dominican Republic (Plasmodium falciparum) can be dangerous if left untreated, though in this area, it responds readily to several different drugs, including chloroquine, so treatment will be uncomplicated.

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

Late Malaria Confirmation

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QUESTION

I was given a field diagnosis of malaria 1 1/2years ago and was treated. Can I still get a blood test to confirm if I truly had malaria?

ANSWER

That’s a very interesting question, and the answer is: it depends. Since you were treated, you will no longer have the parasites in your blood stream, and so you cannot use a traditional blood film, looked at under a microscrope, which is the standard diagnostic method in many places.

However, there are other blood tests which look for the presence of antibodies against specific malaria proteins. These antibodies can remain in the blood for a long time after the malaria infection – probably months, but perhaps even years, though the exact length of time may vary from person to person, as well as between antibodies. If you wanted, you could inquire in your hospital whether it would be possible to get a serology test for malaria (serology tests look for antibodies) – if they tell you the brand they use then you could also contact the manufacturer to ask if they have done tests on the length of time the antibodies stay in the blood.

Cure for Malaria

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QUESTION

Is there a cure for Malaria?

ANSWER

Yes. Several different medications exist which are used for the treatment of malaria. The exact drug and method of treatment depends somewhat on the type of malaria the patient is infected with. In most cases of non-complicated (i.e. when the patient is stable and conscious) malaria, the World Health Organisation recommends an orally-administered (in the form of solid pills) artemisinin-based combination therapy (ACT), such as Coartem (a combination of artemether and lumefantrine). Other types of medication include atovaquone-proguanil (Malarone) and sulfadoxine-pyrimethamine (Fansidar). In some locations, where chloroquine-resistance is not a problem, chloroquine can also be used as a treatment. For complicated malaria, where the patient is in a more severe state, intravenously administered quinine is usually the first-line treatment.

If diagnosed early and the patient is given appropriate medication, virtually all cases of uncomplicated malaria can be effectively treated.