Discovery of Malaria

by

QUESTION

Who was the discoverer of malaria?

ANSWER

Malaria has been known to humans since ancient times, though what exactly caused it and how it was transmitted was not known. The parasite which causes malaria, from the genus Plasmodium, was first observed in the blood of a patient who had died from the disease by Charles Louis Alphonse Laveran, a French physician working in Algeria. This was in 1880; a few years later, in 1897-1898, a British army doctor called Ronald Ross showed that malaria could be transmitted via the bite of a mosquito. Both doctors eventually received the Nobel Prize for their discoveries.

Life Cycle of Malaria

by

QUESTION

What is the life cycle of malaria?

ANSWER

Malaria is caused by a single celled organism in the genus Plasmodium. Five species of Plasmodium infect humans, but all follow a very similar life cycle, including two separate cycles of asexual reproduction in the human host (one in the liver, called the exo-erythrocytic cycle, and one in the blood, and specifically inside red blood cells, known as the erythrocytic cycle) and a sexual reproductive stage inside the mosquito definitive host (usually called the “vector”). A schematic of the full life cycle is below, courtesy of the CDC (www.cdc.gov).

You may also view a video of malaria life cycle.

malaria life cycle CDC

Schematic of the malaria life cycle, courtesy of CDC (www.cdc.gov)

Structure and Size of Malaria Mosquito

by

QUESTION

What is the structure and size of the mosquito?

ANSWER

The mosquitoes that transmit human malaria belong to the genus Anopheles. As such, they follow the general body plan structure of a flying insect—three segments (head, thorax and abdomen), three pairs of legs and two pairs of wings. Anopheles females have modified mouthparts that allow them to feed on blood, by inserting a specialized proboscis into the skin; male Anopheles feed on nectar and so do not possess the same type of mouthparts.

The size of the adult mosquito varies on factors such as the exact species, the larval environment and food availability, but the length of the body is rarely greater than 16mm and the total weight is usually less than 2.5 milligrams.

Is Malaria Incurable?

by

QUESTION

is malaria incurable?

ANSWER

No. Malaria can usually be very easily treated, if diagnosed early and if appropriate medication is given promptly.

The World Health Organization recommends artemisinin-based combination therapies (ACTs) as the first line treatment against uncomplicated malaria; intravenous quinine is usually the first-line recommended treatment for severe, complicated malaria.

Classification of Malaria Parasite

by

QUESTION

What is the classification of malaria?

ANSWER

Malaria is caused by a single celled protist of the genus Plasmodium. This genus is part of a Phylum of single-celled protist organisms called Apicomplexa.

The Apicomplexans mostly posses an organ called an apicoplast, which is part of an apical structure designed to aid entry into a host cell. The Apicomplexa is split into two Classes, of which Plasmodium belongs to the Aconoidasida (lacking a structure called a conoid, which is like a set of microtubules), and then to the Order Haemosporidia, which contains parasites which invade red blood cells. Within this Order, Plasmodium belongs to the Family Plasmodiidae, which all share numerous characteristics, including asexual reproduction in a vertebrate host and sexual reproduction in a definitive host (a mosquito, in the case of the Plasmodium species that infect all mammals, including humans).

In the case of human malarias, the definitive host is often referred to as the vector. The family contains about twelve genera, of which one is Plasmodium, which itself is now often divided up into numerous sub-genera, and then again into hundreds of different species, of which five infect humans (P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi).

Malaria Hosts

by

QUESTION

Which are malaria hosts and how does malaria have an effect on one of them?

ANSWER

The parasite which causes malaria (called Plasmodium) requires two different hosts—a vertebrate intermediate host, such as a human, and an insect definitive host, also known as the vector. For the types of malaria which infect humans and other mammals, the vector is always a mosquito of the genus Anopheles.

However, there are other types of malaria which infect birds and reptiles, and these can use other genera of mosquito as their vectors, and some parasites closely related to Plasmodium can even use sandflies and other types of insects as their vectors too.

In humans, malaria usually causes disease, characterized by high fever, chills, aches and nausea. However, the presentation of symptoms and their severity depends on a number of factors, such as the type of Plasmodium (P. falciparum is the most dangerous to humans), the immune status of the host and the infective dose received from the vector.

Many mammals are also susceptible to malaria, such as macaque monkeys, and with them as well the effect of the parasite depends on a number of factors. For example, for macaques in south-east Asia, many will be co-infected with several different types of malaria simultaneously, though none appear to cause disease. However, if macaques from other parts of tje world, such as the Himalayas, are experimentally infected with these same types of malaria, they will get sick and possibly even die. As such, evolutionary history also plays a part in terms of how severe malaria will be in a particular host.

For the insect vector, infection with malaria parasites does not appear to have a strong deleterious effect, though some studies have shown reduced survival in mosquitoes infected with malaria. Also, changes in behavior have been observed. For example, some studies have shown that mosquitoes which are infected with malaria are more likely to continue seeking for food (i.e. through biting a host) even if they have recently fed than mosquitoes which are uninfected, or infected with non-transmissable life stages of malaria. This suggests that in some way the malaria parasite is manipulating the vector’s behavior in order to increase its own chances of being passed on to a new host.

Causes of Malaria

by

QUESTION

What are the causes of 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).

Classification of Malaria

by

QUESTION

Classification of malaria

ANSWER

Malaria is caused by a single celled protist of the genus Plasmodium. This genus is part of a Phylum of single-celled protist organisms called Apicomplexa.

The Apicomplexans mostly posses an organ called an apicoplast, which is part of an apical structure designed to aid entry into a host cell. The Apicomplexa is split into two Classes, of which Plasmodium belongs to the Aconoidasida (lacking a structure called a conoid, which is like a set of microtubules), and then to the Order Haemosporidia, which contains parasites which invade red blood cells. Within this Order, Plasmodium belongs to the Family Plasmodiidae, which all share numerous characteristics, including asexual reproduction in a vertebrate host and sexual reproduction in a definitive host (a mosquito, in the case of the Plasmodium species that infect all mammals, including humans).

In the case of human malarias, the definitive host is often referred to as the vector. The family contains about twelve genera, of which one is Plasmodium, which itself is now often divided up into numerous sub-genera, and then again into hundreds of different species, of which five infect humans (P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi).

Malaria Transmission

by

QUESTION

How is malaria transmitted?

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).

Malaria Origins

by

QUESTION

What is the origin of malaria?

ANSWER

Malaria is caused by a single-celled parasite of the genus Plasmodium. There are five difference species of Plasmodium which infect humans – these all likely evolved from various different species of Plasmodium which infect other primates, such as gorillas (for P. falciparum) and macaques (P. vivax, P. knowlesi, possibly other types as well). This happened many thousands of years ago; humans have been plagued by malaria since before records began. In fact, the first recorded mention of the symptoms of malaria come from ancient China, in a manuscript dated to 2700 years before the common era, or almost 5000 years ago.

However, understanding that malaria was caused by a microscopic parasite, which is transmitted by mosquitoes, occurred much more recently; the Plasmodium parasite was first observed in the blood of a person who died from malaria in 1880 by the French physician Charles Louis Alphonse Laveran. A few years later, in 1897/1898, a British physician, Ronald Ross, demonstrated that the parasite could be transmitted between hosts via the bite of an infected mosquito. Both physicians eventually won Nobel Prizes for their work.