How did Malaria Evolve?

A new study, from the University of Pennsylvania School of Medicine, reveals how the connection between chimpanzee and human genomes (the similarities in our DNA) may help answer this question. By analyzing the genomes of parasites that infect chimpanzees, scientists are able to understand how human-infecting malaria parasites may have evolved many years ago.

 

Chimpanzees and humans share evolutionary history, linking the evolution of malaria between our species.

Cerebral Malaria: When it Goes Too Far

Malaria is diagnosed by looking for parasites in a drop of blood smeared on a slide under a microscope.

When I woke up in the middle of the night and proceeded to throw up every thirty minutes on the the minute, developing a high-grade fever and severe dehydration, it took no more than a finger prick and a look at the blood smear under a microscope to see the parasites in my blood. The diagnosis ranges from 1-5, 5 being the most severe and meaning that there were 5 parasites seen on the slide from a single drop of blood. Within 5 hours of showing symptoms, I had a blood smear, revealing level five. Immediately, I was given an IV to administer high dose anti-malaria drugs, anti-nausea, fever reducers and pain medicine. I was in good hands, and recovered fully in less than a week.

Rise in Immunity Spurs International Concern

"Malaria is still a devastating disease, with nearly 250 million cases and more than one million deaths every year. Mosquitoes have developed resistance to existing insecticides and there is evidence of emerging resistance by the parasite to the drugs used to treat the disease.”-Professor Steve Ward, Deputy Director, of LSTM reports

RTS,S Has a Fighting Chance to Become Malaria Vaccine

Underlying Factors

 Malaria is a complex disease, and therefore poses several challenges for the development of a vaccine. It is important to note that the most prevalent species of the parasite (there are four known to cause malaria in humans), Plasmodium falciparum is the main focus of vaccine efforts at this point. The malaria parasite is a protozoan, which is more biologically complex than bacteria or viruses. It also creates a complicated array of potential vaccine targets. The three most promising vaccines and their modes of action are detailed below, including an analysis of which of the three is has the highest potential to become a widely used vaccine to prevent malaria from P. falciparum. A malaria vaccine would reduce the number of severe malaria cases and deaths, and by ensuring preventability would be an important step towards eradication of the disease. There are currently three vaccines in various stages of development, and, based on efficacy testing and other supporting evidence, it has been determined that RTS,S is the vaccine that will succeed over other candidates.

What is malaria?

Malaria is a disease that of the blood that is treatable but fatal if left untreated. Close to half the world's population is at risk of contracting the disease. There are many different malaria parasites. The most common type is called plasmodium falciparum, and it is transmitted by the female Anopheles mosquito. The mechanism of action is a parasite that requires both human and mosquito hosts to complete its life cycle. This life cycle begins when an infected mosquito bites a person, transferring the Plasmodium parasites, in the form of sporozoites, carried in the mosquito's saliva. Sporozoites then enter the human's liver cells. After a few days, the sporozoites become merozoites and penetrate the red blood cells (RBC). They then divide and, usually every 48 or 72 hours, break out of the cells, which lyses the RBC and allows some of the merozoites to infect other RBC and therefore spread throughout the body.

Not all of the merozoites infect more RBC, however. Some form gametocytes. These are critical, because they are picked up by the bite of an anopheles mosquito. The life cycle of the parasite is now continued inside of the mosquito. Gametocytes divide via meiosis to form the male and female gametes, which undergo fertilization. The zygote forms a cyst on the wall of the mosquito's gut and releases thousands of sporozoites. They migrate to the mosquito's salivary glands, ready to infect again.

Prevention a key component of combatting malaria. More to come on this topic.