Cover of La Higiene magazine, with a caricature of Dr. Juan N. Dávalos, on the occasion of his famous campaign against glanders.

For a man like Hart, a faithful lover of history, talking about the diverse origins of Cubans was always a recurring theme. He recalled with pleasure that his friend, the writer Alejo Carpentier, used to tell him, "Armando, we Cubans come from everywhere, but we all come down from ships." To Hart this was not an exaggeration on the part of Alejo, for in his own family, the norm was invariably followed. The memories of those "Don Quixotes" looking for new horizons always moved his imagination, to the point that he was able to describe their genealogy in detail and recalled every significant date of the family. Of course, the noble story of the outstanding Cuban scientist Juan Nicolás Dávalos y Betancourt, Armando's maternal grandfather, was one of his favorite topics of conversation.

His grandfather Juan Nicolás was born on November 6, 1857, in Sabanilla del Encomendador, in the current municipality of Juan Gualberto Gómez, in Matanzas. He graduated with a Bachelor of Arts degree in 1879 and then studied medicine at the universities of Havana and Madrid. He also studied at the Institut Pasteur in France, in other European countries and in the United States, with the aim of broadening his knowledge and acquiring the necessary practical culture of the laboratory. In 1899, he obtained the degree of Doctor of Medicine at the University of Havana. Among his most notorious works as an outstanding scientific figure, his work at the Histobacteriological Laboratory and Institute of Anti-Rabies Vaccination in Havana, which had been created in 1887 by Dr. Juan Santos Fernández, stands out. In that center he worked alongside a plethora of illustrious scientists, among which Dr. Carlos J. Finlay stands out.

Grandfather Juan Nicolás was an eminent bacteriologist and a forerunner of bacteriology in our country, a branch in which he made notable discoveries. In the testimonies that have been preserved about him, it is noted that it was not only his talent for scientific research that left an imperishable mark on contact with him, but also his ethics and moral structure, as well as his integral discipline. Because he was a man of unresolute intellectual and scientific honesty and of great investigative audacity, in a field as complex as that of bacteriological sciences.

He devoted himself entirely to his investigative work. Journalist Víctor Muñoz said of him in the press of the time, "he is the wise man who dreams of bacteria." The historian César Rodríguez Expósito, in the biography in which he paid tribute to him, entitled "Dr. Juan N. Dávalos: the wise man who dreams of bacteria",[1] spoke of his character and stressed that in the face of the dangers of his work he was not afraid and maintained an imperturbable serenity, as well as his enthusiasm for research. for one of his favorite principles was to "work for science, which is to work for the progress of the Fatherland."

In 1894, by means of a modified method and in the company of his colleague, Dr. Enrique Acosta, grandfather Juan, obtained his greatest scientific triumph related to obtaining the first Cuban anti-diphtheria serum, of which they were its introducers and producers in the country; following the technique of the French scientist Emile Roux, but adapted to the climatological conditions of Cuba and with such good results that its creator himself recognized it. That is why Cuba became the first country in the Americas to apply the serum against diphtheria. That was a great achievement that saved many diphtheria patients from death and also managed to reduce mortality, especially in the child population. Juan Nicolás was dedicated to actively promoting the treatment of microbial diseases through medicinal serums or serotherapy.

Very important for the country was the research he carried out to isolate the germ of glanders, "whose epidemics in human beings were caused by the massive stabling of equine cattle within the city". Grandfather was also able to isolate and identify dissimilar pathogenic microorganisms and obtained serum against tetanus and typhoid fever. His studies extended to malaria, yellow fever, leprosy, among other diseases. He lived in the heat of trying to find a vaccine, a serum, some agent that could counteract the virulence of the infections.

On January 27, 1895, when he was only 38 years old, his application for admission to the Royal Academy of Medical, Physical and Natural Sciences of Havana was accepted, in which with his work "Serotherapy" he was elected Numerary Member, in a solemn session. He joined the newly inaugurated Laboratory (Biological, Chemical and Bacteriological) of the Island of Cuba in 1902 and when Dr. Finlay assumed the National Head of Cuban Health, grandfather Juan was appointed head of the Bacteriology Section. From that moment on, he began to work with the eminent scientist in the fight against childhood tetanus and tuberculosis.

In the Annals of the Royal Academy, and in several national and foreign scientific journals, we find several dozen of his outstanding texts published, among which we can mention for their great value: "Serotherapy or treatment of microbial diseases by blood serum" and "Avian diphtheria on the Island of Cuba", which appeared in the Annals of the Royal Academy of Medical Sciences. Physics and Natives of Havana. [2]

Dr. Juan Nicolás was an authentic Cuban scientist and a dedicated doctor, who dedicated his entire life to study. Thanks to his consecrated vocation for science and the culture he possessed, the laudable results he obtained were put at the service of his country. For him there was only his work for the human cause in its purest sense. A generous spirit like his was marked by genuine humility, born of talent, imagination and ethics with the indelible stamp of his selfless work.

While doing his research, he accidentally inoculated himself with the rabies virus during the autopsy of a rabbit, which was also contaminated with the germs of tuberculosis, tetanus and typhoid fever. He was so devoted to his work that he received these infections as something absolutely natural. The sequelae of all these diseases contributed to his early death, which occurred on December 4, 1910, still in the fullness of his scientific and professional possibilities. He was buried in his house at Lamparilla 34 and buried in the pantheon that had just been built at that time by the Academy of Sciences in the Colón Cemetery.

The work of grandfather Juan Nicolás transcended the time in which he lived and Cuban microbiologists today remember him as part of his sacred memory; Because his studies were nourished not only by his encouraging force for the future, but also by his extraordinary capacity to create culture. Evoking his scientific stature and his legacy, which is an intrinsic part of our historical memory, allows us Cubans to explain to the world who we are.

Juan Nicolás.

[1] Cuadernos de Historia de la Salud Pública no. 35. Havana: Editorial Ciencias Médicas; 1967.

[2] Volume 36, 1899-1900, pp. 273-281, and in Volume 40, 1907, pp. 303-325, respectively.