A pioneering microbiologist whose work transformed public health and established modern virology in Chile
During the summers of 1955 to 1960, a microscopic ghost haunted Chilean homes. Summer polio epidemics paralyzed the child population, sowing profound fear among families who, terrified, read about the ravages of this relentless disease in magazines like "Ercilla" and "Vea" 1 .
The terrifying image of iron lungs—those impressive metal armor encapsulating children deprived of movement—invaded the collective imagination, imported from the pages of the North American magazine "Life" to the most remote province of Chiloé 1 .
In this climate of fear and hopelessness, a scientific figure would emerge to change the course of Chilean medical history: Dr. Guillermo Contreras Da Silva, a man whose work not only aborted the last great polio epidemic in Santiago but forever transformed the practice of microbiology in Chile. His legacy, forged between Santiago and New Haven, between the Bacteriological Institute and the University of Chile, represents one of the brightest chapters in 20th century Chilean public health 1 .
Before Dr. Contreras's intervention, polio epidemics were a recurring summer terror in Chile, with hundreds of children affected annually and many left with permanent paralysis.
Graduated as a physician-surgeon from the University of Chile School of Medicine and joined the Virology section of the Bacteriological Institute under Dr. Raúl Palacios 1 .
At Yale, Contreras worked on classifying Coxsackie viruses using pioneering serological methods, acquiring expertise in the most advanced techniques for studying enteroviruses 2 .
This training would prove fundamental for the future of Chilean virology, bringing cutting-edge research methodologies back to his home country.
The culminating moment in Dr. Contreras's career came in 1961, when his laboratory played a crucial role in implementing the first mass vaccination with the Sabin vaccine in Chile 1 2 . This campaign, directed by Drs. José M. Borgoño and Manuel Zúñiga, would constitute one of the greatest triumphs of Chilean public health 1 .
The visit of Albert Sabin to Chile and the subsequent introduction of his oral attenuated vaccine marked a turning point in the fight against polio 1 .
Dr. Contreras's laboratory not only provided the scientific evidence that supported the Ministry of Health's decision to adopt this vaccine but also performed the virological follow-up of the immunization program, characterizing the behavior of vaccine viruses in the child population 1 .
Sabin Vaccine Introduction
Year of the first mass vaccination campaign in Chile
Oral attenuated vaccine chosen over injectable alternative for easier administration and broader coverage.
The 1961-62 campaign drastically aborted the last polio epidemic in Santiago, preventing hundreds of cases.
This success laid the groundwork for the total eradication of this disease in Chile 1 .
Dr. Contreras's pioneering work included one of the first systematic studies on the traffic of polioviruses—both wild and vaccine strains—in the child population of Santiago. His experiment represented a comprehensive approach to understanding enterovirus epidemiology in the Chilean context 1 .
The experimental design incorporated multiple components:
The findings of Dr. Contreras and his group revealed for the first time in Chile detailed patterns about the simultaneous circulation of multiple enteroviruses and their potential for interference with vaccine viruses 1 .
They identified the presence and circulation of Echo and Coxsackie viruses in the Chilean child population, laying the groundwork for understanding the viral ecosystem in which anti-polio vaccination would have to operate 1 .
These studies allowed characterization of the immune response of Chilean children to the different components of the Sabin vaccine, identifying variations in the immunogenicity of vaccine strains under local conditions 1 .
The virological revolution driven by Dr. Contreras depended on the implementation of techniques and reagents previously unavailable in Chile. His laboratory represented the introduction of molecular and cellular virology to the country, with all the tools that this implied.
| Reagent/Medium/Material | Function in Virological Research | Specific Application in Dr. Contreras's Laboratory |
|---|---|---|
| Cell culture media | Maintain living cells to propagate viruses | Culture of poliovirus from clinical samples |
| Fetal bovine serum | Provide growth factors for cells | Nutrition of cell lines for viral cultures |
| Trypsin | Dissociate tissues and adherent cells | Subculture of cell lines maintained in the laboratory |
| Specific antisera | Identify and classify viruses through neutralization | Differentiation of poliovirus serotypes and other enteroviruses |
| Tissue culture systems | Provide substrate for viral replication | Detection of polio virus from fecal samples |
Beyond his concrete contributions to virology, Dr. Contreras introduced three fundamental concepts that would transform microbiological practice in Chile 1 :
Under his influence, Chilean microbiology transitioned from a descriptive, medically oriented discipline to an independent science capable of generating autonomous knowledge about the biological aspects of microorganisms 1 .
Contreras insisted that microbiological results should be measured and analyzed with mathematical and statistical methods, incorporating quantitative rigor to a traditionally qualitative discipline 1 .
He demonstrated how a basic science like microbiology could have immediate practical applications in public health, directly benefiting society 1 .
"I often say that when you can measure and express in numbers what you are describing, you know something. If what you're talking about cannot be measured or expressed in numbers, knowledge about it is generally scarce and unsatisfactory."
The transfer of Dr. Contreras's activities from the Bacteriological Institute to the University of Chile in 1962 produced a dramatic and modernizing change in the teaching of virology and microbiology in the Schools of Medicine and Sciences of this institution 1 .
There, together with collaborators like Adela Olhbaum, Romilio Espejo, Carmen Grado, and others, he laid the foundations for what would become the Virology Program of the Institute of Biomedical Sciences 6 .
Dr. Contreras's influence extended beyond Chilean borders. In 1968-69 he obtained a Guggenheim Fellowship that allowed him to work in the Department of Cell Biology at the Albert Einstein College of Medicine in New York 1 2 .
Subsequently, in 1975, he moved to the Wistar Institute in Philadelphia, and from 1976 until his retirement in 1991, he served as head of the Division of Viral Products of the Bureau of Biologics in Ottawa, Canada 1 2 .
His collaborative approach fostered fruitful interactions with other biological disciplines and health professionals, as demonstrated by his collaboration with bacteriologist Beatriz Gilabert in the study of bacterial and viral pathogens in infants with diarrhea 5 .
Dr. Guillermo Contreras Da Silva passed away in Canada in November 2003, a victim of Alzheimer's disease, but his legacy endures in every successful vaccination campaign, in every microbiology laboratory that integrates quantitative approaches, and in the scientific independence that the discipline enjoys in Chile 1 .
His professional life embodies the social transcendence of basic science—demonstrating how specialized training in world excellence centers, when combined with vision and social commitment, can radically transform a nation's public health. From those terrifying summers of the 1950s, when polio ran rampant, to the successful implementation of a vaccine that would change the destiny of thousands of Chilean children, Dr. Contreras represents the transformative power of scientific knowledge applied with rigor and passion.
"Dr. Contreras and his group transformed the teaching and character of microbiology in Chile from a descriptively medically oriented discipline into an autonomous, quantitative, and experimental science."
This scientific epitaph describes not only an academic contribution but a paradigm shift that continues to bear fruit in 21st century Chilean microbiology.