What is the malaria antigen test?

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QUESTION:

How does the malaria antigen test work? After how many days presence of malaria can antigens be detected in the blood ? Is it posible to detect antigens on the first day of fever ?

ANSWER:

The malaria antigen test works by detecting antigens in the blood which are released by the parasite. The antigens are usually LDH (lactate dehydrogenase) or HRP2 (Histidine-rich protein 2). If the test is in RDT (rapid diagnostic test) format, there is an antibody against one of the parasite antigens stuck onto the test strip. A tiny drop of blood (usually from a fingerprick) is placed in a well at one end of the test, and covered with a test buffer solution; as the patient’s blood migrates up the test strip, the parasite antigen will be captured by this antibody. The parasite antigen is then bound by another antibody which is coupled to colloidal gold, which will show up as a positive band on the test.

Detection of the malaria antigen in the blood depends on the sensitivity of the test and the parasitaemia (number of parasites) in the blood. If the parasitaemia is high enough it should be possible to detect antigen on the first day of fever.

Is Malaria Deadly?

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QUESTION:

Can malaria come back, and is it deadly?
ANSWER:

In some cases, and if not treated properly, malaria can come back. One example of when malaria comes back is when the infection is not completely cleared from the blood, for example if the full course of treatment is not taken. This is more common with Plasmodium falciparum malaria, as it can multiply rapidly in the blood. This characteristic makes it the most dangerous form of malaria, and if left untreated, is can often be deadly.

Other forms of malaria come back through different methods; for example, Plasmodium falciparum and Plasmodium ovale, have forms of the parasite that can sequester in the liver and remain dormant for long periods of time, even years. Once these liver stages return to the blood and start multiplying again, the patient will get a recurrence of malaria symptoms. It is possible to treat these liver stages, through taking specific medication; for this reason, it is crucial that if you suspect you might have malaria, you are diagnosed accurately to ensure that you receive the correct forms of medication to prevent the malaria coming back in any way.

Malaria untreatable?

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QUESTION:

I just want to find out what can cause malaria to be untreatable because have been injected (13) times and no changes. What can cause it, and i need a drug name that can take care it.

ANSWER:

Treatment for malaria is very rarely in the form of an injection, so I suspect you are not being treated appropriately. Malaria is caused by being bitten by a mosquito infected with parasites called Plasmodium, which enter your blood stream as the mosquito drinks your blood. If you have the symptoms of malaria, and live in an area where malaria is found, it is very important that you get diagnosed before you are treated. Many other diseases have similar symptoms to malaria, and so unless you know for sure what disease you have, you might not get the correct medication. Moreover, some forms of malaria require different drugs to others, which is another reason why accurate diagnosis is crucial.  You can find more information here on Malaria Prevention and Treatment. If you have or suspect you have a malaria, you should consult your physician.

 

Causes of malaria

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QUESTION:

What are the causes of malaria?

ANSWER:

Malaria is caused by parasites of the genus Plasmodium. These are single-celled animals known as protozoans (from the Greek ‘protos’ and ‘zoia’ which together mean ‘first animal’) and they are transmitted via mosquitoes that feed on blood; the parasites need both mosquito and human hosts to complete their life cycle (see below a graphic of the complete life cycle, courtesy of CDC). In the process of reproducing, the malaria parasites destroy human red blood cells, which is what causes the clinical symptoms of disease that the patient experiences, such as fever, headaches and nausea.

Malaria life cycle CDC

Generalized malaria life cycle (courtesy of CDC: www.cdc.gov)

There are four main species of Plasmodium that infect humans: P. falciparum, P. vivax, P. malariae and P. ovale. P. falciparum causes the most severe manifestations of the disease and is responsible for the majority of human deaths from malaria. There is a fifth type of malaria, P. knowlesi, which usually infects macaque monkeys but has been known to pass into humans as well.

For more on this, please see Christina Faust’s excellent blog post about her research.

Causes of Malaria

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QUESTION:

What causes malaria?

ANSWER:

Malaria is a disease caused by a parasitic single-celled animal known as Plasmodium. There are different species of Plasmodium, which cause different kinds of malaria. The main types which infect humans are P. falciparum, P. vivax, P. ovale and P. malariae. The parasite is transmitted by certain species of mosquito; the parasite lives in the human blood stream and so goes in to the mosquito when the insect feeds. When the same individual mosquito then feeds on another person, it transmits parasites into a new host.

The symptoms of malaria are caused by the actions that the parasite undertakes while in the human host. For example, part of its reproductive cycle involves invading and then multiplying inside red blood cells. Once several cycles of reproduction have occurred, the new parasites burst out of the red blood cell, destroying it. The cycles are times so that all the new parasites burst out of the red blood cells at the same time; this coordinated destruction of the red blood cells, either every 24, 48 or 72 hours, depending on the malaria species, causes the one day, two day or three day cycles of fevers and chills that characterise malaria infection episodes.

Can malaria come back?

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QUESTION:

If you had malaria once, can it return for a second time without being in a malaria area?

ANSWER:

Yes. There are several ways in which malaria can come back without being re-infected again. The blood forms of the parasites can sometimes persist at low numbers, so that the patient no longer has any symptoms; if these blood forms begin to reproduce again, the patient will once again begin to feel sick and have malaria symptoms. This is known as ‘recrudescence’ and can occur as quickly as within the same year as the initial infection but also as long as fifty years later, depending on the type of malaria! Treating the infection thoroughly, and being tested for parasites after treatment, is one way to avoid recrudescence.

The other way in which malaria can come back is through ‘recurrence’, which is when the malaria parasite enters a dormant phase which resides in the liver. Again, the patient will feel no symptoms while the malaria is dormant, but once these liver stages change into the blood stages and reproduce, symptoms will reoccur. This form of relapse only occurs with Plasmodium vivax and P. ovale infections, and can be prevented through taking an additional form of medication, called primequine, at the same time as the normal malaria drugs when diagnosed. This extra medicine kills the liver forms of malaria and thus prevents recurrence. For more details on this, please see the comments I made, on behalf of Dr Etty Villanueva, on the post ‘Malaria Symptoms and Causes’, published on the 22nd of February, 2011.

How serious is malaria as a disease?

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QUESTION:

(In conclusion to an earlier question regarding the seriousness of the disease and the way it is likely to affect population vigour if not controlled) –  What can the community, the government, individuals (school children, parent, and teachers) do to improve the situation?

ANSWER:

The best way to improve the impact that malaria has upon populations afflicted by malaria is to prevent the disease in the first place.

At a community level, this can be done through the use of long-lasting insecticide treated bednets, which have been shown to be extremely effective in preventing exposure to malaria-carrying mosquitoes. The nets are furthermore cheap and easy to use; the problem is distributing them, and ensuring that the highest-risk groups of people (pregnant women and children under 5 years old) have priority access to the bednets.

In some places, bednets are given out for free at antenatal clinics to target pregnant women; in other places, bednets have been sold at subsidised prices as a way of maintaining the sustainability of the delivery program.

For more information about bednet distribution and the debate surrounding whether they should be free or paid for, please see the post “Malaria – Free Bednets?”

These high risk groups may also benefit from intermittent preventive therapy (IPT) whereby individuals are given treatment for malaria at set intervals, to reduce the risk of suffering from a full-on malaria infection. More information on IPT can be seen in the comments to the question “Reduce risk of P. falciparum.”

If bednet coverage is not thorough an thus prevention not complete, the next stage in reducing the burden of the disease on endemic communities is through accurate, effective diagnosis followed by appropriate treatment. This requires a functional and efficient health services system as well as a well developed transportation network, to ensure that people are encouraged to seek assistance at a clinic or hospital if they develop malaria symptoms, and that they can easily and quickly reach these facilities.

Advanced health systems and transportation networks are the goal of many developing countries, and many regions in the world have made huge amounts of progress in these areas recently. However, momentum must be maintained, and governments throughout the regions of the world where malaria continues to be a huge public health burden need to continue their efforts to strengthen the availability of malaria diagnostics and treatment, in order to remove malaria as an obstacle to people’s well-being and development.

Treatment for malaria in Africa

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QUESTION:

What is the treatment for malaria in Africa?

ANSWER:

The appropriate form of treatment for malaria, regardless of where you are, depends on the type of malaria you have. This can be determined through diagnosis; each of the main malaria parasites that ordinarily infect humans (P. falciparum, P. vivax, P. malariae and P. ovale) looks slightly different under the microscope, although you have to be well trained to tell them apart! Rapid diagnostic tests (RDTs) can also sometimes distinguish between malaria species, although many RDTs only test for P. falciparum, he most acute, severe and deadly of the species.

In much of Africa, P. falciparum is the most common and dangerous form of the disease. In some places, it can be treated with chloroquine, though in many places the parasite has developed resistance to this drug, so other treatment is necessary.

The most common drugs given in areas with known chloroquine-resistant strains of P. falciparum are ACTs (artemisinin-based combined therapies). There are some parts of Africa where other forms of malaria, such as P. ovale and P. vivax, can also occur – it is important to know whether a patient is infected with these species as they require an additional form of treatment, the drug primequine, in order to kill dormant liver stages that characterise these species and can lead to a relapse of infection months or even years after the initial exposure.

EDITORIAL – Reflections on World Malaria Day 2011

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How far have we come in the last four years?

Four years ago, it was estimated that a child died every 30 seconds from malaria, and that more than a million people each year were killed by this devastating and debilitating disease. Four years ago, the malaria advocacy partnership Roll Back Malaria organized the first World Malaria Day, and published the Global Malaria Action Plan (GMAP), which set comprehensive goals for the control of malaria world-wide, with the ultimate aim to eradicate malaria completely. [Read more…]

How Many Deaths Result from Malaria?

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QUESTION:

Can you tell me, how many deaths result from malaria till today?

ANSWER

A lot! I think it is impossible to get an exact number, or even a decent guess – data on malaria deaths even in modern times are estimates at the best of times, and we have no way of knowing how many people were exposed to and/or died of malaria in ancient times.

Current estimates as to the annual number of deaths from malaria vary depending on which source you look at, but most agree that somewhere around 1 million people die every year from being infected with malaria. Of course, that number would have been lower in the past when total population numbers were also lower.

However, I think it would be fair to say that probably hundreds of millions of people have, over the course of history, died from being infected with malaria. More to the point, malaria continues to be a huge public health burden on huge portions of the world’s population, and disproportionately on the world’s poorest people, which makes it a top priority for disease advocacy, research and control initiatives.