World Malaria Day, 25th April 2016

Featured, Health 2016-04-27

It’s World Malaria Day! Today is an international campaign day dedicated to raising awareness of one of the most prevalent and deadly parasitic diseases on the planet.

 

Malaria is one of the leading causes of child deaths in Africa. Symptoms include high fevers, chills and muscle pains, and often occur in cycles. Occasionally the malaria parasites can cause extreme forms that affect the brain, lungs, heart or kidney. Malarial deaths are often caused by the development of secondary health issues that may not have occurred had the person not contracted malaria in the first place. These include anaemia, an enlarged spleen or other nutrition-deficiency-related indicators.

 

It is thought that around half of the world’s population lives in areas that are at risk of malaria transmission and that 91% of malarial deaths in 2010 occurred in Africa. The map below highlights the areas where malaria transmission occurs throughout, only in some parts or does not occur in the region at all.

malaria world map

Source: http://www.cdc.gov/malaria/malaria_worldwide/impact.html

 

What Happens on World Malaria Day?

The purpose of World Malaria Day is to encourage activities across various platforms, demonstrating global support for communities affected by the disease and to researchers who are helping to bring new treatments and preventative measures to those affected. Events are being held across the world, including the World Malaria Day Reception in Washington DC and various workshops on malaria, as well as free malaria testing at hospitals in countries such as Uganda. If you are not attending any events then you can get involved on social media by using the hashtags #EndMalaria and #WorldMalariaDay.

 

Each World Malaria Day focuses around a theme. Previous years have included themes such as ‘Malaria – a disease without borders’, ‘Counting malaria out’ and for the past two years: ‘Invest in the future: defeat malaria’. This year the focus of the day will be ‘End malaria for good’. This campaign seems to bear an element of finality compared to previous years, and this could be due to the significant decrease in malaria deaths by 60% since 2000. This statistic has given many people real hope of seeing an end to malaria – is the elimination and eradication of this disease finally on the horizon?

 

The Basics: The Parasite

Now you know a bit about World Malaria Day, let’s explore the basics of the disease. Malaria is a single-celled microorganism from the genus Plasmodium. There are five species within this genus that can infect humans: P. falciparum, P. vivax, P. ovale, P.malariae and P. knowlesi. The most virulent and dangerous of these species is P. falciparum. The World Health Organisation reports that 91%[1] of malarial deaths is from P. falciparum infections. Milder forms of malaria are usually caused by the P. vivax, P. ovale and P. malariae species, hence death tolls from these infections are typically lower. The P. knowlesi strain is not strictly a threat to humans[2] as it is mainly infects only long-tailed and pig-tailed macaques – being transferred to humans when this bush meat is consumed.

 

The Basics: The Vector

Malaria is a mosquito-borne disease. The mosquito acts as a carrier, or vector, that allows the parasite to infect humans. The genus of mosquito that carries the malaria parasite is known as the Anopheles mosquito. There are a huge number of species within this genus that act as malaria vectors, see the map below[3]. It is the female insect that carries the parasite and transmits Plasmodium to a human host in its saliva. It’s specifically the female mosquito that transmits the disease because they require a blood meal to help with the production of a clutch of eggs.

malaria map 2

Source: http://www.cdc.gov/malaria/about/biology/mosquitoes/map.html

 

The Basics: Malaria Lifecycle

As the mosquito penetrates the skin of a human to take a blood meal, it injects saliva to aid feeding, and this saliva contains the malaria parasite. The malaria parasite migrates through the bloodstream of the human to the liver. It infects liver cells and multiplies within the cells. P. vivax and P. ovale are able to lie dormant within the cells of the liver and cause relapses weeks or years later. Eventually, the liver cells rupture and malaria parasites are released into the bloodstream to infect red blood cells (also known as erythrocytes). They can then enter one of two stages: the Erythrocytic Cycle or the Sexual Erythrocytic Cycle.

 

The Erythrocytic Cycle is when the parasites multiply within the red blood cell and rupture to release even more parasites into the blood stream, allowing infection of even more red blood cells. The Sexual Erythrocytic Cycle is when the parasites differentiate into male or female gametes within the red blood cells. It is these gamete-containing cells that are taken up by a mosquito during feeding. Within the mosquito the parasite gametes form zygotes, and eventually infective malaria parasites form within the mosquito’s midgut. The parasite then migrates to the mosquito’s salivary glands, ready to be injected into another human host.

 

erythrocyte cycle

Source: http://www.cdc.gov/malaria/about/biology/

 

The Basics: Vector Control and Treatment

Vector control has played a big part in helping to reduce the number of infections and deaths from malaria. One of the most effective tools in vector control so far has been the implementation of insecticide-treated bed nets. These act as a physical and chemical barrier between humans and the malaria-carrying mosquitoes. These bed nets are designed to last for up to 3 years before they will need to be replaced, to ensure that they maintain a steady defence against the insects. According to the WHO, between 2000 and 2015 over a billion insecticide-treated nets[4] were delivered to communities in need. This has meant that from 2000-2015, the number of children under the age of 5 living in sub-Saharan Africa and sleeping under bed nets has increased from 2% to 68%! Having said this, the number of other age groups sleeping under these nets has fallen below that of the children under 5. This is because, in 2013, it was found that only around 29% of households that had access to bed nets had enough to protect all members of that household. Additionally, mosquitos developing insecticide resistance is becoming an ever-increasing problem, contributing to the difficulties faced when tackling this disease.

 

Malaria is an entirely preventable and treatable disease. The drugs given to treat the disease have to be meticulously researched and specifically designed to combat weaknesses of the parasite. Therefore, the WHO recommends[5] therapies that use a combination of mechanisms to attack the parasite; these are usually artemisinin-based combination therapies (ACTs). The WHO recommends 5 different ACTs, with these being the most effective anti-malarial treatments on the market today. The therapy administered will be based on results of studies conducted in the patient’s local area that assessed the strain of Plasmodium falciparum parasite in that region. Due to the combination of drug actions within these therapies, it means that resistance to the drugs from the parasites is very slow. However, much like insecticide resistance, this is also a real issue in the fight against malaria.

 

It seems like, so far, real progress has been made towards the elimination of malaria. One of the most powerful ways to help fight malaria is by sharing knowledge of the disease through scientific research and educating those affected by the disease. This is why World Malaria Day is such an important tool for raising awareness of the disease. It is a global effort to share resources and focus on the future goals of malaria elimination.

 

What will you be doing for World Malaria Day?

 

Why not show your support using the hashtags #WorldMalariaDay and #EndMalaria

 

References

[1] http://apps.who.int/iris/bitstream/10665/43939/1/9789241563697_eng.pdf

[2] http://cid.oxfordjournals.org/content/46/2/172.full

[3] http://www.cdc.gov/malaria/about/biology/mosquitoes/map.html

[4] http://www.who.int/malaria/areas/vector_control/core_methods/en/

[5] http://www.who.int/malaria/areas/treatment/overview/en/

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