Study of the Oral Microbiome of Chronically Homeless Adults

Abstract (English)

This project began during the COVID-19 pandemic, when the National Autonomous University of Mexico (UNAM) launched the PAPIIT project "COVID-19 and Homeless Populations in Mexico City." As part of this initiative, we offered homeless persons COVID-19 vaccinations and antibody and antigen testing.
Surprisingly, despite their vulnerable conditions—lack of shelter, poor nutrition, sleep deprivation, minimal hygiene, chronic substance use, and no healthcare access—only two of over 300 participants tested positive for COVID-19. This unexpected finding led us to hypothesize that their microbiome might serve as a protective immunological barrier.
The human microbiome—microorganisms like bacteria, fungi, and viruses living in or on the body—is shaped by diet, hygiene, environment, and lifestyle. Given the distinctive conditions faced by homeless individuals, we suspected their oral microbiome would show unique features. Scientific evidence increasingly supports a strong connection between the microbiome and immune function, reinforcing our hypothesis.
To explore this, we conducted ethnographic research to understand participants' daily lives and collected anthropometric data (height, weight, BMI, grip strength). In collaboration with the Sequencing Lab at the Mexican Social Security Institute (IMSS), we analyzed bacterial DNA from saliva samples to examine microbial diversity, abundance, and interaction networks.
Currently, the human microbiome is seen as a promising, equitable approach to disease prevention and treatment. However, studies on the microbiome of people experiencing homelessness are virtually nonexistent. This gap highlights the novelty and importance of our work and its potential within anthropological research.
Our research offers a unique perspective on how extreme environmental conditions might shape the microbiome and influence immune resilience. Its value lies in both its subject and its interdisciplinary approach—merging social anthropology with cutting-edge microbiological science. Our findings were recently published and will be presented in this proposal.