How Does One Contract Malaria?

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QUESTION

How to get malaria?

ANSWER

Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells. Usually, people get malaria by being bitten by an infective female Anopheles mosquito. Only Anopheles mosquitoes can transmit malaria and they must have been infected through a previous blood meal taken on an infected person. When a mosquito bites an infected person, a small amount of blood is taken in which contains microscopic malaria parasites. About 1 week later, when the mosquito takes its next blood meal, these parasites mix with the mosquito’s saliva and are injected into the person being bitten.

Because the malaria parasite is found in red blood cells of an infected person, malaria can also be transmitted through blood transfusion, organ transplant, or the shared use of needles or syringes contaminated with blood. Malaria may also be transmitted from a mother to her unborn infant before or during delivery (“congenital” malaria).

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

Mosquitoes and AIDS

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QUESTION

Can mosquito cause AIDS, and why?

ANSWER

No, HIV (the virus that causes AIDS) cannot be transmitted via mosquitoes. When the virus was first discovered, there was a fear that it could be transmitted via the blood ingested by mosquitoes as they feed between humans. However, it was shown very quickly that the virus was too unstable to survive within the mosquito, and so transmission of HIV is limited to direct transfer of blood, semen, vaginal fluid and breast milk, for example during sharing of intravenous needles, unprotected sexual activity and childbirth.

What are Gametocytes?

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QUESTION

What are Gametocytes?

ANSWER

Gametocytes are the sexually reproductive form of the malaria parasite. They circulate in the blood of the human/mammal host and are picked up by the mosquito when it takes a blood meal.

Inside the mosquito, the gametocytes undergo sexual reproduction in the mosquito midgut, producing oocysts which attach to the midgut wall and produce sporozoites, which are the stage that are infective to humans when the mosquito takes another blood meal (the sporozoites are passed into the blood via the saliva of the mosquito).

How to get malaria?

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QUESTION

How do we get malaria?

ANSWER

Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells. Usually, people get malaria by being bitten by an infective female Anopheles mosquito. Only Anopheles mosquitoes can transmit malaria and they must have been infected through a previous blood meal taken on an infected person. When a mosquito bites an infected person, a small amount of blood is taken in which contains microscopic malaria parasites. About 1 week later, when the mosquito takes its next blood meal, these parasites mix with the mosquito’s saliva and are injected into the person being bitten.

Because the malaria parasite is found in red blood cells of an infected person, malaria can also be transmitted through blood transfusion, organ transplant, or the shared use of needles or syringes contaminated with blood. Malaria may also be transmitted from a mother to her unborn infant before or during delivery (“congenital” malaria).

Causes of Malaria

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QUESTION

What causes malaria?

ANSWER

Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells.

Usually, people get malaria by being bitten by an infective female Anopheles mosquito. Only Anopheles mosquitoes can transmit malaria and they must have been infected through a previous blood meal taken on an infected person. When a mosquito bites an infected person, a small amount of blood is taken in which contains microscopic malaria parasites. About 1 week later, when the mosquito takes its next blood meal, these parasites mix with the mosquito’s saliva and are injected into the person being bitten.

Because the malaria parasite is found in red blood cells of an infected person, malaria can also be transmitted through blood transfusion, organ transplant, or the shared use of needles or syringes contaminated with blood. Malaria may also be transmitted from a mother to her unborn infant before or during delivery (“congenital” malaria).

 


 

How to Control Malaria

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QUESTION

Suggestions to control malaria?

ANSWER

This answer is copied from an earlier question asking about strategies for controlling malaria in Africa. The methods below are being used by many health ministries, international agencies and non-governmental organisations to combat malaria all over the world (and not just in Africa).

Currently, malaria control is based on a combination of prevention, education, research and treatment. In more detail:

Prevention: This is arguably one of the keys to sustainably reducing malaria burdens and even eliminating infections. Central to this goal has been the distribution of long-lasting insecticide treated bednets, which prevent people from being bitten by infected mosquitoes while they sleep at night. Unfortunately, some recent research has just been published which suggests that bednets might be contributing to insecticide resistance in mosquitoes, as well as increased rates of malaria in adults due to decreasing natural immunity. As such, it may be that more research is needed in order to determine the most effective and efficient ways of using bednets to prevent malaria infection, particularly in high-risk groups like young children and pregnant women. Another arm of prevention is reducing the number of mosquitoes in an area (called vector control), and thus preventing transmission from occurring at all – this can be achieved through insecticide spraying but also filling in the stagnant pools of water that mosquitoes lay their eggs in. Vector control was highly successful in reducing malaria transmission in the United States and Mediterranean in the years after World War II.

Education: Through education, people living in at-risk areas for malaria transmission can learn about ways to prevent the disease, as well as what to do if they suspect they are infected. Similarly, education is important for travellers visiting malarial areas, so they know the best ways in which to avoid being infected.

Research: Understanding the distribution, factors affecting transmission and the development of new strategies for control and treatment is going to be crucial in the fight against malaria, and particularly in high-burden areas such as Africa. Similarly, scientists are busily looking for new compounds to treat malaria, as well as the ever-elusive malaria vaccine. If such a vaccine could be developed, it would be a huge step forward in the fight against malaria; recently, a study was published which reported the results of the first Phase 3 clinical trial of a malaria vaccine, in African children. The vaccine appeared to confer approximately a 50% level of protection against malaria; while this is a start, it perhaps did not live up to many people’s hopes of a new method for controlling malaria.

Treatment: Hand in hand with treatment comes diagnosis; if a person can have their infection easily, accurately and cheaply diagnosed, then they will be able to access effective treatment more rapidly, thus improving their chances of a swift recovery. As such, countries in Africa are working hard to provide health systems capable of local diagnosis and availability of treatment, so that people don’t have to travel far to have their infections cured.

Taken together, these four strategies are having some success even in the world’s poorest and most malaria-endemic regions, especially in decreasing the number of malaria deaths. Decreasing the overall number of infections will be yet a greater challenge, but one which the world, especially through commitment to the Millenium Development Goals, is dedicated to overcoming.

 

 

History of Fighting Malaria

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QUESTION

What are some examples of attempts of fighting this disease that happened in the past?

ANSWER

The battle against malaria has been going on, in one form or another, for literally thousands of years. The ancient Chinese mention the symptoms of the disease in a medical scroll as early as 2700 BCE – even more remarkably, a herb called Artemesia has been used in traditional Chinese medicine for more than 2000 years to treat malaria, and compounds extracted from that same herb are the basis for some of the most effective modern medications, known as artemisinin-based combination therapies (ACTs). Indigenous tribes in the Americas also had traditional medicines to treat malaria; having conquered the New World, the Spanish learned of a bark, from the Cinchona tree, which could cure malaria. Quinine, extracted from this same tree bark, is still used today to treat malaria.

However, back then the causes of malaria were not known—it wasn’t until the late 19th century that a more complete understanding of malaria would emerge. The first key development in this process was the observation of the parasites that cause malaria in a patient’s blood, which was first done by Charles Louis Alphonse Laveran in 1880.

A few years later, in 1897, a British army doctor called Ronald Ross discovered that the parasite was transmitted via the bite of infected mosquitoes, of the genus Anopheles. This latter finding allowed for the emergence of the first programmes for malaria control, which focused on vector control, through insecticide use and elimination of water bodies used by the mosquito larvae. An early example of the success of this approach came in the building of the Panama Canal; started in 1906, progress was initially slow, due to the enormous proportion of workers who fell ill from yellow fever and malaria. With vector control, the number of cases plummeted, and the canal was finally opened in 1914.

While prophylactic quinine had also been part of the control strategy during the building of the Panama Canal, it played a much more secondary role to vector control. Using similar strategies, focusing primarily on killing adult mosquitoes through insecticide spraying (mainly DDT), the United States of America successfully eliminated malaria from its shores in the early 1950s. Prior to this, transmission had occurred across most of the south-east of the country.

In the last 50 years, access to early diagnosis and effective treatment have gained a more prominent role among many malaria control strategies, although prevention is still seen as crucial. Many developing countries, where malaria is still rife, have set up national control programmes, which seek to ensure that all communities have access to adequate care and information about malaria prevention.

A key tool in the prevention arsenal has been the long-lasting insecticide treated bednet; sleeping underneath one prevents bites from the mosquitoes that carry malaria, which are most active in the evenings and at night, especially in children and pregnant women, who are among the people most at risk from infection. Bednet distribution has been a major focus of many malaria campaigns, and very successful in many places; in 2008, for example, bednet coverage was estimated at over 80% of the at-risk population in Djibouti, Mali, Ethiopia and Sao Tome and Principe.

How does malaria enter the body?

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QUESTION:

What is the portal of entry for malaria?

ANSWER:

Malaria enters its human hosts via the bite of mosquitoes of the genus Anopheles. The malaria parasites are present in the mosquitoes saliva, and enter into the human bloodstream when the mosquito bites to take a blood meal.

Once in the human body, the malaria parasite then undergoes a number of different life stages, involving reproduction in the liver as well as inside red blood cells. Once the malaria parasite has undergone reproduction in the red blood cells, the new parasites burst out and back into the blood stream, where they can be ingested by another mosquito biting again. Inside the mosquito, the malaria parasites undergo more reproduction and life stage changes, until they are ready to be transferred into a human host again, via another bite. In this way, the cycle continues.

Malaria Infection Possibilities?

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QUESTION:

How can malaria affect somebody if you far from mosquitoes?

ANSWER:

It is extremely unlikely for you to become infected with malaria unless you are bitten by an infected mosquito. In rare caces, there have been reports of people contracting malaria through blood transfusions, but in most places, blood donors with a history of malaria are not allowed to donate whole blood, and only plasma, thus preventing transmission through this route.

Discovery of Mosquito Causing Malaria

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QUESTION:

Who found that malaria was caused by a mosquito?

ANSWER:

The man who first discovered that malaria was transmitted by mosquitoes was a British Army doctor called Ronald Ross. Working in India in 1897-1898, Ross demonstrated how malaria parasites could be transmitted first between a patient and a mosquito, and then between hosts via mosquitoes (this latter work was done using birds). Ronald Ross was honoured with the Nobel Prize in 1902 for his discoveries.