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Plasmodium falciparum is a unicellular protozoan parasite of humans, and the deadliest species of Plasmodium that causes malaria in humans. The parasite is transmitted through the bite of a female Anopheles mosquito and causes the disease's most dangerous form, falciparum malaria. It is responsible for around 50% of all malaria cases. P. falciparum is therefore regarded as the deadliest parasite in humans. It is also associated with the development of blood cancer (Burkitt's lymphoma) and is classified as a Group 2A (probable) carcinogen. The species originated from the malarial parasite Laverania found in gorillas, around 10,000 years ago. Alphonse Laveran was the first to identify the parasite in 1880, and named it Oscillaria malariae. Ronald Ross discovered its transmission by mosquito in 1897. Giovanni Battista Grassi elucidated the complete transmission from a female anopheline mosquito to humans in 1898. In 1897, William H. Welch created the name Plasmodium falciparum, which ICZN formally adopted in 1954. P. falciparum assumes several different forms during its life cycle. The human-infective stage are sporozoites from the salivary gland of a mosquito. The sporozoites grow and multiply in the liver to become merozoites. These merozoites invade the erythrocytes (red blood cells) to form trophozoites, schizonts and gametocytes, during which the symptoms of malaria are produced. In the mosquito, the gametocytes undergo sexual reproduction to a zygote, which turns into ookinete. Ookinete forms oocytes from which sporozoites are formed. In 2022, some 249 million cases of malaria worldwide resulted in an estimated 608000 deaths, with 80 percent being 5 years old or less. Nearly all malarial deaths are caused by P. falciparum, and 95% of such cases occur in Africa. In Sub-Saharan Africa, almost 100% of cases were due to P. falciparum, whereas in most other malarial countries, other, less virulent plasmodial species predominate. History Falciparum malaria was familiar to the ancient Greeks, who gave the general name πυρετός (pyretós) "fever". Hippocrates (c. 460–370 BCE) gave several descriptions on tertian fever and quartan fever. It was prevalent throughout the ancient Egyptian and Roman civilizations. It was the Romans who named the disease "malaria"—mala for bad, and aria for air, as they believed that the disease was spread by contaminated air, or miasma. Discovery A German physician, Johann Friedrich Meckel, must have been the first to see P. falciparum but without knowing what it was. In 1847, he reported the presence of black pigment granules from the blood and spleen of a patient who died of malaria. The French Army physician Charles Louis Alphonse Laveran, while working at Bône Hospital (now Annaba in Algeria), correctly identified the parasite as a causative pathogen of malaria in 1880. He presented his discovery before the French Academy of Medicine in Paris, and published it in The Lancet in 1881. He gave it the scientific name Oscillaria malariae. However, his discovery was received with skepticism, mainly because by that time, leading physicians such as Theodor Albrecht Edwin Klebs and Corrado Tommasi-Crudeli claimed that they had discovered a bacterium (which they called Bacillus malariae) as the pathogen of malaria. Laveran's discovery was only widely accepted after five years when Camillo Golgi confirmed the parasite using better microscopes and staining techniques. Laveran was awarded the Nobel Prize in Physiology or Medicine in 1907 for his work. In 1900, the Italian zoologist Giovanni Battista Grassi categorized Plasmodium species based on the timing of fever in the patient; malignant tertian malaria was caused by Laverania malariae (now P. falciparum), benign tertian malaria by Haemamoeba vivax (now P. vivax), and quartan malaria by Haemamoeba malariae (now P. malariae). The British physician Patrick Manson formulated the mosquito-malaria theory in 1894; until that time, malarial parasites were believed to be spread in air as miasma, a Greek word for pollution. His colleague Ronald Ross of the Indian Medical Service validated the theory while working in India. Ross discovered in 1897 that malarial parasites lived in certain mosquitoes. The next year, he demonstrated that a malarial parasite of birds could be transmitted by mosquitoes from one bird to another. Around the same time, Grassi demonstrated that P. falciparum was transmitted in humans only by female anopheline mosquito (in his case Anopheles claviger). Ross, Manson and Grassi were nominated for the Nobel Prize in Physiology or Medicine in 1902. Under controversial circumstances, only Ross was selected for the award. There was a long debate on the taxonomy. It was only in 1954 the International Commission on Zoological Nomenclature officially approved the binominal Plasmodium falciparum. The valid genus Plasmodium was created by two Italian physicians Ettore Marchiafava and Angelo Celli in 1885. The Greek word plasma means "mould" or "form"; oeidēs meaning "to see" or "to know." The species name was introduced by an American physician William Henry Welch in 1897. It is derived from the Latin falx, meaning "sickle" and parum meaning "like or equal to another". Origin and evolution P. falciparum is now generally accepted to have evolved from Laverania (a subgenus of Plasmodium found in apes) species present in gorilla in Western Africa. Genetic diversity indicates that the human protozoan emerged around 10,000 years ago. The closest relative of P. falciparum is P. praefalciparum, a parasite of gorillas, as supported by mitochondrial, apicoplastic and nuclear DNA sequences. These two species are closely related to the chimpanzee parasite P. reichenowi, which was previously thought to be the closest relative of P. falciparum. P. falciparum was also once thought to originate from a parasite of birds. Levels of genetic polymorphism are extremely low within the P. falciparum genome compared to that of closely related, ape infecting species of Plasmodium (including P. praefalciparum). This suggests that the origin of P. falciparum in humans is recent, as a single P. praefalciparum strain became capable of infecting humans. The genetic information of P. falciparum has signaled a recent expansion that coincides with the agricultural revolution. It is likely that the development of extensive agriculture increased mosquito population densities by giving rise to more breeding sites, which may have triggered the evolution and expansion of P. falciparum. Structure P. falciparum does not have a fixed structure but undergoes continuous change during the course of its life cycle. A sporozoite is spindle-shaped and 10–15 μm long. In the liver it grows into an ovoid schizont of 30–70 μm in diameter. Each schizont produces merozoites, each of which is roughly 1.5 μm in length and 1 μm in diameter. In the erythrocyte the merozoite form a ring-like structure, becoming a trophozoite. A trophozoite fe.... Discover the Mk Grassi popular books. Find the top 100 most popular Mk Grassi books.