While most research to date has focused on single pathogen transmission dynamics, in reality multiple pathogens spread concurrently within and among host populations. In addition to the pathogen community, the microbiome has an important role in the outcome of infections through host and pathogen interactions. By examining the respiratory pathogen and microbial diversity within hosts over time we can begin to understand their consequences on host health and disease transmission. The goal of this study was to understand the causes of CIRD (canine infectious respiratory disease) by identifying pathogen presence and abundance in symptomatic infections compared to asymptomatic hosts. We also investigated whether there is a difference between the microbiomes of healthy individuals and those presenting clinical symptoms. To answer these questions, we collected nasal swab samples from canines at the Oregon Humane Society rehoming center over a two-week period to quantify the respiratory pathogen community and microbiome diversity of each host through nanoscale PCR diagnostic techniques and 16S gene sequencing.
Results/Conclusions
Of the nine pathogens detected in the diagnostic pathogen panel, Mycoplasma cynos load was significantly associated with symptomatic infections. We found no difference in the amount of total shedding and the number of pathogens being shed between asymptomatic and symptomatic dogs suggesting asymptomatic infections contribute to disease transmission. Moderate shedding was observed in three pathogens, Bordetella bronchiseptica, Canine parainfluenza virus (CPIV), and Canine adenovirus (CAV), despite being vaccinated against. High total pathogen shedding had lower evenness in samples suggesting only one pathogen was dominating high shedding infections and pathogen facilitation of coinfection was unlikely. Over time, we saw only symptomatic dogs continued to shed CAV and Bordetella bronchiseptica. We also saw differences in where pathogens were coming from as dogs were transferred into the system from other rehoming centers. Microbiome analysis showed differences in the microbial communities of symptomatic and asymptomatic hosts. Our results demonstrate complex interactions and dynamics exist within the respiratory pathogen community and microbiome that together determine the health outcome of the host. Elucidating the causes and consequences of the pathogen community and microbiome diversity will be necessary in the field of disease ecology to understand patterns of disease transmission over space and time.