Malaria In Africa

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QUESTION

What factors cause Africans to get this disease?

ANSWER

The highest number of malaria cases every year occur in Africa, not because of anything specifically due to the people living there (in fact, they may be better protected against malaria than most—I will come onto this later) but because malaria transmission is very high in many parts of sub-Saharan Africa and sufficient preventative measures are still lacking in some places.

Malaria transmission requires specific environmental criteria, such as sufficient temperature and rainfall. These conditions are met in many countries in Africa, and unlike some other parts of the world, temperatures are suitable year-round for the development of the Anopheles mosquitoes that act as the vector for mosquito, meaning that in some places, transmission can occur throughout the year. In addition, many people do not take appropriate preventative measures against malaria; in some cases, this is due to a lack of means to buy items such as insecticide-treated bednets, and in other cases people have not been educated about the dangers of malaria or how to prevent it, so they do not know what preventative measures they should be undertaking.

Organisations such as the World Health Organisation, the US Agency for International Development, the Global Fund, the Roll Back Malaria consortium and Malaria No More are working to improve both access to preventative measures, such as bednets and indoor residual spraying, while also educating people about the need for prevention and also what to do if they suspect themselves or a family member has malaria. These efforts have already reduced the burden of malaria in Africa; the number of deaths is dropping every year, and they hope to have eliminated deaths from malaria altogether by the year 2015.

I mentioned that Africans may be better protected against malaria naturally—scientists have noted that populations living in areas with high levels of malaria have some genetic protection against infection. One example of this is the Duffy antigen. People who are negative for this gene seem to be protected against Plasmodium vivax and P. knowlesi malaria (it was originally thought they were resistant to infection, but more recent evidence from Kenya suggests in fact they still get infected, but do not get as sick). Another is the gene for sickle cell anaemia; despite causing highly debilitating and even lethal anaemia if both copies of the gene are inherited, a single copy of the gene confers strong resistance against malaria. Both of these genetic traits are highly prevalent in African populations.

In addition, early exposure to malaria results in the acquisition of immunity to infection. This, over time, Africans who survive childhood malaria go on to be less susceptible as adults. The exception to this are pregnant women; in order to support the growing foetus, a pregnant women’s immune system becomes much weaker (otherwise there is a risk of the immune system rejecting the foetus). As such, even if she had high levels of acquired immunity to malaria prior to her pregnancy, once pregnant she becomes much more susceptible. This is particularly true for a woman’s first pregnancy.

Malaria Transmission and Deaths in the United States

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QUESTION

How do you get malaria? How does malaria come to the United States? How many people have died from malaria?

ANSWER

Malaria is caused by infection with single-celled parasites called Plasmodium. There are five different species which infect humans; of these, Plasmodium falciparum is the most deadly. The Plasmodium parasites are transmitted to humans through the bite of an infected female Anopheles mosquito; when these mosquitoes bite a human, they transfer some of the parasites in their saliva.

After undergoing one set of multiplications in the liver, the malaria parasites are released into the blood, where they repeatedly infect and destroy red blood cells, multiplying in the process. These cycles of infection and destruction of red blood cells cause the cyclical fever that is characteristic of malaria. Eventually, the parasite produces new types of cells, called gametocytes; if the patient is then bitten by another mosquito, the mosquito can take up gametocytes as well as blood when it feeds, and the cycle continues.

Malaria used to be relatively common in the United States, though usually only occurring during the summer months and restricted to the warm, wet south-eastern region. However, a concerted control campaign in the 1940s, focusing mainly on vector control (i.e. killing mosquito and reducing their opportunities for breeding) swiftly led to the eradication of malaria from the US.

Nowadays, virtually all malaria cases in the US are imported from abroad, whereby people get infected when traveling to other countries, but are only diagnosed as having malaria when they return home. There are about 1,000 cases of malaria reported each year in the US, and most of these were actually caught outside the US. Very rarely, an Anopheles mosquito will bite one of these travelers once they have returned from abroad, and therefore have the potential to transmit malaria within the US. However, due to a strong public health network and good access to malaria diagnosis and treatment, these events rarely lead to more than a handful of cases before they are quickly treated and transmission eliminated again.

The World Health Organisation estimates that last year, approximately 700,000 people died of malaria. Of these, 90% were in sub-Saharan Africa, and the vast majority were children under the age of 5.

Dangerous

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QUESTION

Why malaria so dangerous?

ANSWER

Malaria can be dangerous for a number of different reasons, some of which relate to each other. First of all, there are five different types of malaria that infect humans, and each varies in terms of its severity and potential for severe consequences. Even within these types, the severity of the disease caused (termed “virulence” by scientists and doctors), can even vary by strain or geography. Generally, the most dangerous form of malaria is caused by Plasmodium falciparum. One reason why this species of malaria is so dangerous is that is replicates very quickly in the blood. This means that infection levels can build up very quickly; if a person infected with P. falciparum does not get diagnosed and treated within a few days of feeling sick, the infection can progress to a point where the disease becomes very severe. This rapid accumulation of infection is also observed with P. knowlesi, a much rarer form of malaria found in south-east Asia. The parasites of P. knowlesi have a 24-hour reproductive cycle in the blood, the quickest for any type of malaria that infects humans. However, P. falciparum also has other characteristics which make it even more dangerous, and which do not occur with P. knowlesi. For example, when P. falciparum infects red blood cells, it causes their shape to change, and makes them “sticky”. This stickiness causes the red blood cells to become lodged in the blood vessels leading in to major organs, in a process known as sequestration. Sequestration creates blockages of these blood vessels, reducing blood flow and resulting in oxygen deprivation. When this process occurs in the blood vessels in the brain, the outcome is known as cerebral malaria, characterised by impaired consciousness, coma and even death. It is this pathology which is associated with most cases of severe malaria, and causes the most number of deaths.

However, if treated promptly with the correct drugs, even P. falciparum malaria is usually easily controlled. Therefore, one of the additional reasons why malaria is so dangerous is that in many places, and particularly sub-Saharan Africa, people do not have access to medication, or not the right types of medication. Many strains of P. falciparum have become resistant to chloroquine, once the first line treatment for malaria, and so this drugs is now ineffective in many cases. Instead, the World Health Organisation recommends now that artemisinin-based combination therapies (ACTs, such as Coartem) should be given as first-line treatment against all uncomplicated malaria, to prevent additional resistance from developing.

Do malarial drugs engender joint pains?

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QUESTION

I am now over 50 and I lived all my life in Africa during which time I have had a considerable incidences of malarial attacks. Each time I took any anti-malarial drug I experienced some side-effects including blurred vision, fatigue and joint pains. The pains especially have since become a permanent part of me and even severe enough to hamper my mobility. Does my condition sound to have any relationship with the several quantity and varieties of anti malarial drugs that I took almost all my life?

ANSWER

There are no known long-term side effects to taking modern anti-malarial drugs. However it could be that you have had a reaction or allergy to the specific kind of anti-malarials you have used in the past. For example, quinine sulphate is associated with joint pain in rare cases. However, in Africa these days, the World Health Organisation recommends only the use of artemisinin-based combination therapies (ACTs, such as Coartem) as the first-line treatment for malaria. The side effects of ACTs tend to be mild, and limited to nausea, dizziness and vomiting. As far as I am aware, joint pain and blurred vision have not been reported as side effects.

We at Malaria.com are very interested in hearing people’s experiences with antimalarial medication, so we would be very grateful if you would take the time to complete a survey on malaria treatment which we are running on the website. Thank you!

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.

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.

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/)

How Many People Have Died from Malaria?

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QUESTION

How many people have died from this disease today? (2011)

ANSWER

Estimates for the number of annual deaths from malaria vary, and are not very accurate since they depend heavily on the quality of reporting. Since the majority of people who die from malaria are in sub-Saharan Africa, and often far from decent health facilities, it can sometimes be difficult to determine whether someone died of malaria or some other cause. The latest data available are for 2010 (2011’s statistics will be published some time in 2012): World Health Organisation estimated that last year approximately 655,000 people died from malaria, which was a decrease of 39,000 from 2009 and a drop of 25% from 2000. It is expected that the number of deaths will continue to fall in 2011. Organisations such as Malaria No More are dedicated to ending all deaths from malaria by the year 2015.

If you have ever taken anti-malaria medication, please take Malaria.com’s brief Malaria Medication Side-effects Survey: Treatment and Prophylaxis.

Malaria Prevention

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QUESTION

what is the prevention of malaria?

ANSWER

There are many ways in which to prevent malaria. I’ll break them down into three categories: 1) medical prevention, 2) protection from getting mosquito bites and 3) vector control.

1) Medical prevention

Malaria can be prevented using certain medications. Taking drugs to prevent a disease is known as “chemoprophylaxis”, and so these drugs are often referred to as “malaria prophylactics”. There are several different types of malaria prophylactic: the most common ones are chloroquine, a mix of atovaquone and proguanil (marketed as Malarone), mefloquine (marketed as Lariam) and doxycycline. The mode of taking these medications vary (Lariam is taken once a week, for example, whereas the others are usually taken once every day), and they also have different restrictions and side effects. Chloroquine is not effective in areas where local forms of malaria have become resistant, for example, and Lariam is not recommended for people with a history of mental instability, as it is known to cause hallucinations and otherwise impair consciousness. Here on Malaria.com, we are actually currently running a survey on side effects of malaria prophylactic drugs, so if you have ever taken medication to prevent malaria, please take the survey: Malaria Medication Side-effects Survey: Treatment and Prophylaxis

It is worth noting that these drugs have not been tested for long term use, plus they can be expensive if taken for an extended period of time. As such, they may not be appropriate for people living in endemic areas for malaria. However, medication can be useful for preventing malaria in high risk groups, even when they are living in a malaria endemic area. One example is the use of intermittent preventive treatment (IPT) for preventing malaria infection in pregnant women, infants and young children. For more information on this, please see the review article written by Dr Felicia Lester for this website: http://www.malaria.com/research/malaria-pregnancy-preventive-treatment

2) Protection from getting mosquito bites

This section links in with the more general vector control strategies, which will be discussed below. Since malaria is transmitted through the bite of infected mosquitoes, preventing mosquito bites is a very effective way of reducing malaria incidence. One of the most popular methods for personal protection, especially in areas where malaria is endemic, is through sleeping under a mosquito bednet. The mesh prevents mosquitoes from being able to fly close to the person sleeping; however, if there are holes in the net, or the person skin is pressed directly against the mesh, the mosquito may still be able to bite them. This is where insecticide-treated bednets come in – they are impregnated with mosquito repellents to stop mosquitoes from biting through the mesh or passing through holes. Newly developed long-lasting insecticide treated bednets (LLINs) are even more effective, in that they don’t require “re-dipping” to maintain the level of repellent in the fibres, and so can protect a person for several years without losing efficacy. These LLINs have been instrumental in reducing cases of severe and fatal malaria, especially among pregnant women and young children, who are often targeted by bednet distributors.

Other methods for preventing mosquito bites include wearing long-sleeved clothing and personal application of mosquito repellent, particular those containing a percentage of DEET, which is a very effective insecticide. These measures should be especially taken in the evening, early morning and at night, which is when the Anopheles mosquitoes that carry malaria are most active.

3) Vector control

Finally, malaria can be prevented from reducing numbers of mosquitoes directly. Some methods target the adult mosquitoes; one such initiative is indoor residual spraying (IRS), whereby the inside of a house is sprayed with an insecticide to kill mosquitoes. Twelve different insecticides are approved by the World Health Organisation for this purpose, though pyrethroids are among the most popular, as they can be used on a variety of surfaces, do not leave a visible stain and can also protect against other insect pests, such as bedbugs.

Other methods for vector control focus on other parts of the mosquito lifecycle. Mosquito larvae require stagnant freshwater for their development, so some projects have worked to eliminate standing water sources, such as unnecessary ditches and puddles, which reduces the amount of habitat available for mosquitoes to lay their eggs and sustain larvae. Other programmes have spread insecticides directly in stagnant water to kill the larvae, or sought to introduce fish or other aquatic organisms, such as copepods, which consume mosquito eggs and larvae. This latter biological control approach is popular because it can also supply an area with fish for local consumption, and doesn’t contaminate water sources with chemicals.

What is Malaria?

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QUESTION

What is Malaria?

ANSWER

Malaria is a disease caused by parasites of the genus Plasmodium. Transmitted by mosquitoes, there are several different kinds of malaria distributed throughout the tropical and sub-tropical regions of the world, causing somewhere between 300-500 million cases of disease each year, and as many as 1 million deaths. In fact, malaria is one of the biggest killers of children under the age of five in sub-Saharan Africa, one of the regions of the world where the burden from malaria is the highest. Malaria is usually an acute disease, manifesting itself with severe fever, chills, headache and often nausea as well. Some types of malaria can have relapsing episodes over a time period of many years.

Having said this, malaria is easily preventable, through avoiding mosquito bites by wearing appropriate clothing and sleeping under insecticide-treated bednets, or through taking preventative medication (called prophylaxis). Malaria is also treatable once symptoms appear, through ingesting safe, effective and relatively cheap drugs. With such control measures at hand, you may ask why malaria is still such a huge problem in our world; the answer is that delivering control strategies and treatment to populations most at risk is difficult, and often countries with high malaria burdens don’t have efficient and effective health systems in place to coordinate control efforts.

International non-governmental organisations such as the World Health Organisation, as well as a multitude of non-profit organisations such as the Malaria Consortium and Malaria No More, work tirelessly to bring malaria control and treatment to the places that need it most, with the aim to eradicate malaria as a disease of public health importance.