Early life and education
Finlay was born Juan Carlos Finlay y de Barrés in
Puerto Príncipe (now Camagüey),
Cuba to Scottish-born Dr. Edward (Eduardo) Finlay and French-born Elisa (Isabel) de Barrés.
At that time Cuba was part of the Kingdom of
Spain. He reversed the order of his given names to "Carlos Juan" later in his life. His father was a physician who had fought alongside
Simón Bolívar, and his family owned a coffee plantation in
Alquízar. He attended school in France in 1844, but was forced to return to Cuba after two years because he contracted
After recovering, he returned to Europe in 1848, but became stuck in England for another two years due to political turmoil, and after arriving in France to continue his education, he contracted
typhoid fever and again returned to Cuba.
Because the University of Havana would not recognize his European academic credits, he enrolled at
Jefferson Medical College in
Philadelphia, Pennsylvania, which did not require prerequisites. Here Finlay met
John Kearsley Mitchell, a proponent of the
germ theory of disease, and his son
Silas Weir Mitchell, who supervised his studies. He graduated from Jefferson Medical College in 1855.
He then returned to
Havana and set up an ophthalmology practice in 1857, and then studied in
Paris from 1860-61. In October 1865 he married Adela Shine, a native of the
Island of Trinidad. They would have three sons, Charles, George and Frank.
Finlay's work, carried out during the 1870s, finally came to prominence in 1900. He was the first to theorize, in 1881, that a mosquito was a carrier, now known as a disease
vector, of the organism causing
yellow fever: a mosquito that bites a victim of the disease could subsequently bite and thereby infect a healthy person.
 He presented this theory at the 1881
International Sanitary Conference, where it was well received. A year later Finlay identified a mosquito of the
Aedes as the organism transmitting yellow fever.
 His theory was followed by the recommendation to control the mosquito population as a way to control the spread of the disease.
El Obelisco, Finlay's memorial in Havana
His hypothesis and exhaustive proofs were confirmed nearly twenty years later by the
Walter Reed Commission of 1900. Finlay went on to become the chief health officer of Cuba from 1902 to 1909. Although Dr. Reed received much of the credit in history books for "beating" yellow fever, Reed himself credited Dr. Finlay with the discovery of the yellow fever vector, and thus how it might be controlled. Dr. Reed often cited Finlay's papers in his own articles and gave him credit for the discovery in his personal correspondence.
The Finlay Medical History Museum in 2016
In the words of General
Leonard Wood, a physician and
U.S. military governor of Cuba in 1900: "The confirmation of Dr. Finlay's doctrine is the greatest step forward made in medical science since
Jenner's discovery of the vaccination [for
This discovery helped
William C. Gorgas reduce the incidence and prevalence of mosquito-borne diseases in
Panama during the American campaign, from 1903 onwards, to construct the
Panama Canal. Prior to this, about 10% of the workforce had died each year from
malaria and yellow fever.
On Cuba Street in downtown Old Havana, the Revolutionary Government in 1962 founded a medical history museum in honor of Carlos J. Finlay.
In the municipality of
Marianao, now within the city of
Havana, there is a monument in the shape of a syringe, honoring Dr. Finlay and usually referred to as El Obelisco (The Obelisk). Finlay was also commemorated on a 1981 Cuban stamp.
 A statue commemorating Dr. Finlay is located on the bayfront in
Panama City, near the canal he helped make possible. The
Carlos J. Finlay Prize for Microbiology is named in his honor.
Finlay was a member of Havana's Royal Academy of Medical, Physical and Natural Sciences. He was fluent in
English and could read
Latin. His interests were widespread and he wrote articles on subjects as varied as
plant diseases.His main interest, however, was yellow fever, and he was the author of 40 articles on this disease. His theory that an intermediary host was responsible for the spread of the disease was treated with ridicule for years. A humane man, he often took on patients who could not afford medical care. As a result of his work, Finlay was nominated seven times for the
Nobel Prize in Physiology or Medicine, although he was never awarded the prize.
 He received the National Order of the
Legion of Honour of France in 1908.
"History Museum of the Medical Sciences ' Carlos J. Finlay', created by the Revolutionary Government in eternal homage to the men who contributed to the advance of the sciences in Cuba. National Commission of the Academy of Sciences of the Republic of Cuba. Havana, 13 June 1962."
Finlay died from a
stroke, caused by severe brain seizures, at his house in Havana on August 20, 1915.