Laveran's discovery of the malaria parasite

Posted to Bône in Algeria in 1878, the French army physician Alphonse Laveran found that many of his patients had malarial fevers of a kind he had seen only in rare, mild forms in France. At necropsies on patients who had died of malignant fever he studied melanaemia, the black pigment in malarial blood, which others had described without settling its cause.

In fresh blood he noticed pigmented spherical bodies that moved like amoebae, clear spots inside red cells, and crescent-shaped pigmented forms, and he began to suspect parasites. Then, in 1880 at the military hospital in Constantine, he saw thread-like filaments resembling flagella moving rapidly at the edges of the pigmented bodies in a patient's blood, pushing aside neighboring red cells. After that, he later wrote, he had no more doubt that they were parasites.

He reported to the Academy of Medicine and the Academy of Sciences between 1880 and 1882 and published a monograph in Paris in 1881. It met with much skepticism. In 1879 Klebs and Tommasi-Crudeli had described a Bacillus malariae in the soil and water of malarial districts, and many Italian workers had confirmed it. Laveran's organism looked like no known microbe, and blood examination in 1880 was crude. In 1882 he went to Rome and, at the San Spirito hospital, found the same parasites in patients infected in the Roman Campagna.

Confirmations slowly accumulated, and by 1889 the parasite had been found in most malarial regions; that year the Academy of Sciences awarded him the Bréant Prize. Having failed to find the parasite in air, water or soil, Laveran proposed in 1884 that it lived in mosquitoes, a role Ronald Ross later demonstrated. Laveran received the Nobel Prize in 1907 for his work on protozoa as causes of disease.