Malaria Drug Binding Site

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QUESTION

What is malaria, and drug binding site?

ANSWER

Malaria is caused by a single-celled protozoan parasite of the genus Plasmodium. Five kinds of Plasmodium are known to infect people: P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi.

There is no one drug binding site with respect to malaria: different anti-malarial drugs have different modes of action, and not all are well described. I will briefly outline the proposed mechanism of action of two of the most common types of anti-malarials: artemisinin (and derivatives) and chloroquine (quinine is thought to act similarly to chloroquine).

Artemisinin is thought to have anti-malarial properties by virtue of possessing an endoperoxide moiety, or double oxygen bridge (-Carbon-Oxygen-Oxygen-Carbon). In the presence of intracellular free ion, this moiety is converted by a chemical reaction to “free radicals”, atoms with unpaired electrons which are highly reactive. The free radicals act as alkylating agents and induce cell death, but only those that are already pathologically crippled, for example due to malaria infection. Another hypothesis is that the free radicals directly damage the malaria parasite.

Chloroquine is thought to act by causing buildup of the toxic by-product of hemoglobin metabolism, heme – the malaria parasite usually converts heme to hemozoin, a non-toxic crystal, and stores it in the digestive vacuole. When chloroquine diffuses into an infected red blood cell, it reacts with heme to “cap” it, preventing further conversion into hemozoin. Moreover, chloroquine also converts hemozoin into a highly toxic substance called the FP-Chloroquine complex. This build-up of toxicity leads to breakdown of the cell membrane, and eventual cell death and autodigestion.

Malaria and Ross River Fever

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QUESTION

Is malaria similar to Ross river Fever which is common in Australia? If you have Ross River and get bitten by a mosquito can the mosquito pass it on to some one else.

ANSWER

Ross River fever is similar to malaria in that both are transmitted by mosquitoes. However, Ross River fever is caused by a virus, whereas malaria is caused by a protozoan (single-celled) parasite. Also, the type of mosquitoes they use are different. Malaria can only be transmitted by mosquitoes of the genus Anopheles, whereas the Ross River fever virus is usually transmitted by Aedes or Culex mosquitoes.

Another difference is that Ross River virus also infects lots of other mammals, with kangaroos and wallabies key reservoir species in the wild, whereas the species of malaria which infect humans are more or less limited to us (though there have been cases of human malaria infecting closely related animals, such as gorillas and chimpanzees).

As for your other question, as far as I know there is no reason why a mosquito infected with Ross River virus couldn’t bite multiple humans or other mammals, and thus transmit the disease to several new hosts.

Plasmodium

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QUESTION

Is Plasmodium a bacteria. Why?

ANSWER

No, Plasmodium is actually a protozoan—that is, a single-celled organism that is usually microscopic and belongs to the Domain Eukaryota (which also includes all plants and animals, but excludes bacteria and archaea). More specifically, Plasmodium belongs to the Apicomplexa group of protozoans, which are characterised as being parasites of animals, and possessing several unique characteristics, such as an apical complex structure used for invading host cells, and from which the group derives its name.

Protozoans differ from bacteria in terms of evolutionary history as well as a number of key characteristics. For example, protozoans, like all eukaryotes, possess a membrane-bound nucleus and organelles, neither of which are seen in bacteria. Bacteria, moreover, can produce their own food (they are autotrophic), whereas protozoans tend to be heterotrophic and rely on other organisms for food.

Who introduced malaria in which century?

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QUESTION

Who introduced malaria in which century, how does it cause malaria and what is the virus’ name?

ANSWER

Malaria wasn’t introduced; it has been evolving alongside humans for thousands, if not millions of years. The first known mention of malaria by humans is in an ancient Chinese medical text, from 2700 BCE (before common era). Other ancient people, such as the Romans and the Greeks, knew the symptoms of malaria and described it in writing.

Malaria is actually not caused by a virus, but a single-celled animal called a protozoan. The genus name of the protozoans that cause malaria is Plasmodium, and there are five main species that infect humans: P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi.

The malaria parasites cause the disease by entering into red blood cells and multiplying; when they have reproduced, they burst out of the red blood cell, destroying it. The patient’s blood is therefore rapidly full of malaria parasites, their waste products, plus bits of destroyed red blood cell; this produces an extreme immune reaction which causes many of the symptoms of malaria. In infection with P. falciparum, the most deadly and severe kind, infection with the parasite causes red blood cells to sequester in tiny red blood cells within major organs, causing reduced oxygen flow and complications. When this occurs in the brain, the result is cerebral malaria, which can result in convulsions and even a coma.