Genetic structure of Mycoplasma ovipneumoniae informs pathogen spillover dynamics between domestic and wild Caprinae in the western United States

Pauline L Kamath,Paul C Cross,Thomas E Besser,Kezia Manlove,E Frances Cassirer

doi:10.1038/s41598-019-51444-x

Abstract

Spillover diseases have significant consequences for human and animal health, as well as wildlife conservation. We examined spillover and transmission of the pneumonia-associated bacterium Mycoplasma ovipneumoniae in domestic sheep, domestic goats, bighorn sheep, and mountain goats across the western United States using 594 isolates, collected from 1984 to 2017. Our results indicate high genetic diversity of M. ovipneumoniae strains within domestic sheep, whereas only one or a few strains tend to circulate in most populations of bighorn sheep or mountain goats. These data suggest domestic sheep are a reservoir, while the few spillovers to bighorn sheep and mountain goats can persist for extended periods. Domestic goat strains form a distinct clade from those in domestic sheep, and strains from both clades are found in bighorn sheep. The genetic structure of domestic sheep strains could not be explained by geography, whereas some strains are spatially clustered and shared among proximate bighorn sheep populations, supporting pathogen establishment and spread following spillover. These data suggest that the ability to predict M. ovipneumoniae spillover into wildlife populations may remain a challenge given the high strain diversity in domestic sheep and need for more comprehensive pathogen surveillance.

Highlights

Disease management at the interface between wildlife and livestock is crucial for animal health and conservation, but remains a logistical and scientific challenge[1]
We investigated the genetic relationships of the respiratory pathogen, Mycoplasma ovipneumoniae, among domestic and wild sheep and goats across the western United States to elucidate pathogen transmission dynamics
We examined the strain diversity and phylogeographic structure of M. ovipneumoniae in domestic and wild Caprinae hosts affected by bronchopneumonia across the western United States (Fig. 1)

Summary

Introduction

Disease management at the interface between wildlife and livestock is crucial for animal health and conservation, but remains a logistical and scientific challenge[1]. We investigated the genetic relationships of the respiratory pathogen, Mycoplasma ovipneumoniae, among domestic and wild sheep and goats across the western United States to elucidate pathogen transmission dynamics. A variety of factors, including behavior[24,25,26], herd density[27,28], and social structure[29] may influence the risk of pathogen exposure and transmission in wild sheep populations. The primary mechanism by which some of these factors likely influence pathogen spillover and transmission risk is through alterations in the spatial overlap, and contact rates, of wild and domestic hosts[28] to reduce this risk, federal and state natural resource agencies have implemented policies focused on the spatial separation of wild sheep and domestic Caprinae[30]

Methods

Results

Discussion

Conclusion