Juan Carlos Finlay Barré

Cuban physician and researcher of diseases such as cholera and yellow fever. Discoverer of the Aedes aegypti mosquito as the agent transmitting yellow fever, which earned him international recognition.

Son of a Scotsman and French mother, he was born in Santa María del Puerto Príncipe, the current city of Camagüey, and is considered the most universal of Cuban scientists.

His first name was Juan Carlos, but he signed "Carlos J.". His father was Dr. Edward Finlay y Wilson, an English physician, native of Hull, Yorkshire county, and his mother, Marie de Barrés de Molard Tardy de Montravel, of French origin, native of the island of Trinidad.

He completed primary and secondary studies in France and Germany, and began studying medicine at the Lycée of Rouen, in France, where his father had previously studied. A severe attack of typhoid fever forced him to return to Havana, where, after recovering, academic authorities denied him the ability to continue his studies. This led him to transfer to Jefferson Medical College in Philadelphia, where he graduated in 1855 with an excellent record.

In December of that year he requested to take a revalidation exam at the Real y Literaria Universidad de San Gerónimo de La Habana (University of Havana) in order to practice medicine in Cuba, but the prejudices of colonial authorities and the stammer that remained as a consequence of his illness dashed that aspiration.

He encountered great obstacles to practicing in his native country, and his father managed to persuade him to travel with him to Lima, Peru, in order to recover from the setback and improve his expression in the Spanish language, so that, after a year, he could request a new revalidation exam. On the second occasion he obtained excellent results, and with them he achieved authorization to practice his profession in Cuba on March 15, 1857.

Once graduated in his country, he dedicated himself to providing assistance primarily to patients with eye diseases, although he focused his greatest interest on the investigation of certain affections, especially cholera and yellow fever. After many setbacks in the search, experimentation, and reasoning, he came to consider the Aedes aegypti mosquito as the agent transmitting yellow fever, and publicly presented the results of his studies for the first time at the International Sanitary Conference held in Washington in February 1881.

Without mentioning the insect, he declared there three conditions for the spread of the disease: the previous existence of a case in a certain period of evolution, the presence of someone apt to be infected, and the presence of an independent agent of the disease and the patient, but indispensable for transmitting it from the sick subject to another healthy one.

Months later he had equipped himself with experimental data that allowed him to draft his work The mosquito hypothetically considered as agent of transmission of yellow fever, which he presented on August 14, 1881 before the Real Academia de Ciencias Médicas, Físicas y Naturales de La Habana. This time, the argumentation and conclusions were definitive, as Finlay did not refer to the mere presence of an agent, but affirmed that the conditions for the spread of the disease were the existence of a yellow fever patient in whose capillaries the mosquito would drive its lancets and saturate them with virulent particles, and the prolongation of the insect's life from the moment it bit the patient until the moment it bit another subject who should reproduce the disease—a subject apt to contract it.

That contribution, based on experimental evidence, served, more than for the demonstration of a theory, to become the cornerstone of a doctrine: the Finlayan doctrine of disease transmission from human to human through the intermediary of blood-sucking agents. With this it was well demonstrated that the discovery of the scientific theory of the propagation of infectious-contagious diseases and their mode of transmission was original and exclusive to Finlay.

He was the first to undertake research in human beings and reproduce mild cases of the disease without risk to life. The fact of being able to establish in a rigorous manner an experimental verification of the reproduction of the disease gave scientific character to Finlay's theory of contagion, whose observations and experimental works on yellow fever inoculation enabled his recognition of it as a nosological entity.

The fact that this doctrine could be applied by extension to all organic beings conferred upon it the character of biological discovery. That important announcement was initially received with reservation and misunderstanding, as it constituted a discontinuity in the scientific thought of the time; an abrupt leap and qualitatively different from the level of knowledge of the era. However, later it served as a stimulus to research into the modes of transmission of other diseases; it fostered interdisciplinary studies between physicians and biologists; it substantially modified the postulates of preventive medicine and public hygiene, and contributed, along with the discoveries of Pasteur and Koch, to laying the foundations for the eradication of contagious diseases through induced immunology, vaccination, and vector control; in addition to leading to the creation of a new science: medical entomology.

On the other hand, with campaigns against yellow fever based on Finlayan postulates, sanitation was achieved in countries with endemic foci or that suffered frequent epidemics. Even in the present era, its application represents the best means to eradicate and control contagious diseases, save millions of human lives, and promote economic and social development.

Finlay also made great contributions to disciplines such as entomology, virology, and ophthalmology, as well as actions in the treatment of ailments such as leprosy, filariasis, cancer, tetanus, malaria, and tuberculosis, all included in his vast output as an author of articles.

In this regard, between 1864 and 1912 he published a total of 264 works in different types of documents; of these, 187 articles on 32 topics in Cuban and foreign journals, which evidences, in addition to his spirit of dedication to research, the vast knowledge he possessed.

As for the subjects dealt with in his works, the numerical predominance was for those referring to the history, etiology, prophylaxis, and treatment of yellow fever and other aspects related to it (127). To those works he added nine others, which he dedicated respectively to ophthalmopathies and cholera. To the metaxenic theory of disease transmission by biological vectors, which emerged several decades ahead of the pace of scientific development of his time, more than 50% of the literature generated by Finlay is owed, precisely, to the subject of yellow fever.

Among the eleven Cuban journals in which articles with his signature appeared, the Anales de la Academia de Ciencias stands out, on whose pages are treasured, among others, his first article, published in 1864, in which he studied the first case of exophthalmic goiter detected in Cuba; his demonstration of the aquatic origin of cholera, which positioned him as one of the first to reach that conclusion anywhere in the world; the contribution in which he addressed, for the first time in Cuba, the theoretical problems concerning research methodology; the first reports in America on filariasis in animals and in human beings, and the work resulting from his studies on yellow fever.

For his great contribution to freeing mankind from the terrible ravages of yellow fever and for the possibility he provided to eradicate other diseases, Dr. Carlos J. Finlay has been considered a benefactor of humanity.

When the Republic of Cuba was established on May 20, 1902, the Department of Sanitation was created, and he was appointed its first director, and from there he performed a commendable task in the highest health administration of the Island, until his retirement to private life in 1909.

Six years later, on August 19, 1915, he died at the age of 82 years. His remains have rested since that date in the Necrópolis Cristóbal Colón of the Cuban capital.

On several occasions between 1905 and 1915, the year of his death on August 19, he was nominated for the Nobel Prize in Medicine, the only Cuban who has so far been proposed for such a precious award on an individual basis. He also received important decorations, among them the Mery Kingsley medal, the highest distinction conferred by the School of Tropical Medicine of Liverpool, Great Britain, and the insignia of the Legion of Honor, granted by the Government of France.

Source: EnCaribe.org