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✍🏻 Madeline Park | MBiol Biology student at the Uni of Leeds & NHS Lab Assistant in Haemotology
Why is malaria a disease of poverty? 🏚️
In 2021, Malaria caused approximately 247 million cases and 619,000 deaths making it a leading cause of illness and death.
The disease is caused by tiny infective organisms called plasmodium parasites, which are carried by female Anopheles mosquitos.
Malaria can then only be contracted in areas such as South America, Asia and Africa where the mosquitoes are present. If diagnosed and treated early malaria can be cured, making it one of the most preventable diseases.
Unfortunately, many areas of Africa and South America are remote and many locals in these areas live in extreme poverty, so it can be difficult to access the healthcare facilities needed to effectively treat the disease. For this reason, malaria has been named as a disease of poverty.
What is malaria caused by? 🪰
Malaria is caused by plasmodium parasites.
Plasmodium parasites can be thought of as little bugs which are carried in the digestive tract of the Anopheles mosquitos, such as the stomach and saliva.
Overall there are 100 plasmodium parasites which can cause infections in many animal species like reptiles, birds and mammals. However, there are only 4 plasmodium species which are able to infect humans and these are:
Plasmodium falciparium
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Of these 4 species, Plasmodium falciparium causes the deadliest malaria infections and Plasmodium vivax causes the highest number of malaria infections each year.
What is the lifecycle of malaria? 🔁
The lifecycle of malaria parasites is complex, and alters slightly depending on the plasmodium species.
In general, when an infected mosquito bites a human the parasites enter the bloodstream and travel down towards the liver where they are able to multiply and mature.
Once the parasites leave the liver they then enter the red blood cells. Red blood cells are the component of our bloodstream (or blood) which carries oxygen from the lungs around the body.
When a mosquito then feeds on this infected person it takes in these parasites and stores them in their stomach and saliva.
After a couple of weeks, this mosquito will feed on another person and start a new infection.
What are the symptoms of malaria? 🌡️
The symptoms of malaria are a result of the loss of red blood cells, due to them bursting when full of parasite.
Anaemia
Yellowing of the skin or whites of the eyes
Fatigue
Headaches
Fever
Chills nausea
Muscle pains
Furthermore, when an infection becomes severe, red blood cells become larger and less mobile. These red blood cells then become stuck in blood vessels around major organs leading to clogs and organ failure; this ultimately is what leads to death.
How can malaria be prevented? 👖
The easiest way to help prevent malaria is by stopping mosquitos from feeding on you.
This can be done by using mosquito repellents and covering up arms and legs in the evening when mosquitos are most active. Sleeping under mosquito nets soaked in insecticides will also prevent mosquitos from biting during the night time. Furthermore, when travelling to areas impacted by malaria antimalaria tablets are often prescribed to provide increased protection against malaria.
Surprisingly, in a Spanish study, there was a group of mosquitos which were unable to store Plasmodium falciparum malaria parasites in their guts. It was then found that these mosquitos were carrying a bacteria in their stomachs called TC1.
Further work found that the bacteria can reduce the number of malaria parasites in the mosquito's gut by a staggering 73%. The reduced amount of malaria parasites in the mosquito’s gut will reduce the likelihood of passing malaria parasites into humans during a bite, overall decreasing malaria transmission. Now further studies are being done to look at the feasibility of exploiting this bacteria, or the properties of the bacteria, to limit the transmission of malaria parasites to humans and greatly reduce the number of yearly infections and subsequent deaths.
Has a vaccine been developed to prevent malaria? 💉
Developing a vaccine for malaria has proven to be a great challenge due to the multiple life forms the parasite goes through within the human body such as the sporozoite, merozoites and gametocytes.
Vaccines work by exposing the body to small proteins found on the surface of an infective agent, called antigens. Once exposed to these proteins the body is able to remember and learn how to remove the infective agent from the body in order to prevent future infections.
A new malaria vaccine called Mosquirix has been developed, this vaccine targets proteins found on the sporozoites before they enter the liver. It has recently been announced that 12 African countries will receive 18 million doses of the Mosquiriox vaccine in an attempt to prevent the number of infections and deaths caused each year.
Although the Mosquirox vaccine is a huge milestone in malaria prevention, there is still some work to be done. Mosquiriox is not nearly as effective as other mainstream vaccines such as the COVID-19 vaccine. This is because of the parasite's complex lifecycle. Although, it is hoped that mosquirix will promote the development of more effective vaccines. It is hoped that an effective vaccine could lead to the eradication of malaria altogether; for example, before the smallpox vaccine the smallpox disease claimed the lives of millions of people a year, but now the last known case was in 1978.
How have some people developed resistance to malaria? ⛨
In areas such as Sub-Saharan Africa, where malaria is very common, people have evolved traits which naturally make them less likely to develop a malaria infection.
These traits include sickle cell anaemia and the lack of a structure on the outside of the red blood cell called the Duffy allele. Sickle cell anaemia generates red blood cells which are more elongated than normal, the cell then carries less oxygen. With less oxygen, the plasmodium parasites struggle to survive and grow therefore giving the body more time to fight back and prevent an infection.
The lack of a Duffy antigen can prevent P.vivax merozoites from entering red blood cells, this is because it is the presence of a Duffy antigen that allows P.vivax merozoites to attach and penetrate the red blood cells. If the parasite cannot enter then the lifecycle is broken and stops an infection.
How is malaria treated? 💊
If malaria is diagnosed by healthcare professionals early then immediate treatment with antimalarials, such as chloroquine, will decrease the number of parasites living in body and a full recovery can be made.
Antimalaria drugs work by killing the plasmodium parasites present in red blood cells. Each drug works in a slightly different way. For example, the drug Artemether prevents parasites from being able to reproduce, so the amount of parasites does not increase and an infection is not formed.
Quinidine however prevents the parasite from being able to absorb nutrients causing the parasite to starve to death. The most common antimalaria is chloroquine but it is unknown how this drug works.
What is the future of malaria treatment? 🔮
Malaria is on of the leading causes of death, dispite the fact that early detection and treatment of the disease allows a successful recovery.
Increased investment in providing healthcare facilities to areas such as Sub-Saharan Africa could vastly reduce the number of yearly deaths from malaria.
Furthermore, new scientific discoveries such as a bacteria which reduces the transmission of malaria from mosquitos to humans and the development of a malaria vaccine would assist in the reduction of malaria infections and deaths.
More investment into healthcare facilities along with further development of better malaria vaccines along with the exploitation of the TC1 bacteria to reduce transmission could lead to the eradication of malaria worldwide.
Written by: Madeline Park (Content Writer)
Edited by: Grace Pountney (Founder and Director)
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