Understanding Yellow Fever

In February 1881, Cuban physician Carlos Finlay presented his conclusions at the International Sanitary Conference in Washington, D.C., identifying fertilized female Aedes aegypti mosquitoes as the transmitters of yellow fever. His proposal received more sarcasm than attention. Later that year, in Havana, he presented experimental evidence to  support  his conclusions, but they still failed to gain acceptance.

At the time, Cuba was fighting for its independence from Spain. After the Spanish-American War, U.S. troops remained on the island, where yellow fever continued to claim the lives of many soldiers. Believing the disease was transmitted through direct contact, the U.S. Army established the Yellow Fever Commission under Major Walter Reed. Reed himself believed yellow fever was inhaled and even advised a friend traveling to Cuba to place cotton plugs in his nostrils.

Dr. Jesse Lazear, the only member of the commission with experience in mosquito research, had begun cultivating mosquito larvae from Carlos Finlay's laboratory. While investigating Finlay’s conclusions, Lazear allowed himself to be bitten by an infected mosquito; as a result, he contracted yellow fever and died in 1900. The tragedy brought renewed attention to Finlay's work, and the commission ultimately confirmed what Finlay had known for nearly twenty years: that yellow fever was transmitted by the Aedes aegypti mosquito.

Documenting Indigenous Medicine

Spanish physician Francisco Hernández, based in Mexico from 1571 to 1577, led the first scientific study of Indigenous medicinal plants and their therapeutic uses in the Americas.

From the earliest years following the discovery of the Americas, Latin America provided Europe with an extraordinary wealth of medicinal plants and food resources. These were undoubtedly the reasons that led King Philip II of Spain to launch the first scientific exploration of the region. It was at this moment when Francisco Hernández,  physician,  pharmacist, and  naturalist entered the scene. Francisco Hernández studied Medicine at the University of Alcalá de Henares, and was appointed Protomédico de las Indias (Chief Physician of the Indies) by the king, who commissioned him  to prepare a complete and well-documented account of the medicine and healing resources of all the Americas.

On his first expedition to the New World, Hernández traveled with a team of physicians, botanists, and Indigenous artists throughout Mesoamerica, documenting more than 5,000 plants used in Nahua medicine. During this remarkable expedition, Hernández spent several days in Gran Canaria, where he wrote a book—now lost—on the island's flora. He then arrived in Santo Domingo, where he wrote another book on Haitian plants. He did the same in Cuba, spending several days in Havana before finally reaching Veracruz. After beginning his scientific work and recovering from a serious illness, Hernández set out to explore Mexico’s territory.

In 1574, after four years of travel and research, Hernández settled at the Royal Hospital of San José de los Naturales in Mexico City. There, he compiled his findings and tested the effectiveness of the knowledge he had collected by prescribing Nahua medicinal plants to the hospital's patients.

Hernández's extraordinary work in preserving, systematizing, and validating the vast body of herbal knowledge of the Mesoamerican civilizations laid the foundations of modern ethnobotany and pharmacology.

Defeating Leprosy

Venezuelan physician Dr. Jacinto Convit worked with a team of researchers at the Biomedical Institute of Venezuela to develop a pioneering therapeutic vaccine for leprosy, one of humanity's oldest and most feared diseases.

He studied medicine at the Central University of Venezuela (UCV) and, from an early age, showed a strong interest in social medicine. Early in his career, he worked at the Cabo Blanco leprosarium, located in what is now La Guaira State. There, while caring directly for isolated and marginalized patients, he came to understand not only the disease itself but also the human suffering and social stigma experienced by those affected.

In 1980, Convit and his team developed the world’s first therapeutic vaccine against leprosy by combining heat-killed Mycobacterium leprae with the BCG vaccine. His work led to a historic transformation in the treatment of the disease. He replaced compulsory isolation in leprosaria with outpatient, patient-centered care, making Venezuela the first country in the world to officially close its leprosy colonies. This model was later adapted to combat other endemic diseases, including leishmaniasis and onchocerciasis, bringing about a structural shift in Venezuela's public health policy. Just as importantly, it helped reduce the stigma surrounding leprosy, marking a milestone in global public health.

Convit’s scientific contributions extended well beyond leprosy. Applying the same immunological principles, he developed an effective immunotherapy for localized cutaneous leishmaniasis (LCL) in 1986.

In 1988, he was nominated for the Nobel Prize in Medicine. Although his scientific achievements earned him international recognition, he once remarked, “Winning the Nobel Prize doesn't keep me awake at night. Finding a cure for cancer does.”

At the age of 100, Dr. Convit published his final scientific paper on breast cancer. He passed away in May 2014 at the age of 101, leaving behind a legacy of scientific innovation, compassion, and humanitarian service.

References

Finlay, el Cubano burlado: Lo ignoraron durante 20 años hasta que un “mártir” estadounidense murió picado por un mosquito
https://www.clarin.com/internacional/finlay-cubano-burlado-ignoraron-20-anos-martir-estadounidense-murio-picado-mosquito_0_oUS3uPFAd2.html

La expedición de Francisco Hernández
https://www.doaks.org/resources/online-exhibits/epidemics/las-epidemias-en-espanol/herbarios-mesoamericanos/expedicion-francisco-hernandez

1571, Francisco Hernández
https://www.cervantesvirtual.com/portales/exploradores_y_viajeros_espana_y_nuevo_mundo/francisco_hernandez/

Una silueta del doctor Francisco Hernández
https://www.revistacienciasunam.com/es/178-revistas/revista-ciencias-29/1661-una-silueta-del-doctor-francisco-hernández.html

Dr. Jacinto Convit
https://www.paho.org/es/heroes-salud-publica/dr-jacinto-convit#:~:text=Convit%20trabaj%C3%B3%20con%20un%20grupo,la%20historia%20de%20la%20humanidad.

Trabajo Especial: Jacinto Convit: Héroe de la salud pública
https://unc.edu.ve/index.php/trabajo-especial-jacinto-convit-heroe-de-la-salud-publica/