Chronic pathogen carriage is one mechanism that allows diseases to persist in populations. We hypothesized that persistent or recurrent pneumonia in bighorn sheep (Ovis canadensis) populations may be caused by chronic carriers of Mycoplasma ovipneumoniae (Mo). Our experimental approach allowed us to address a conservation need while investigating the role of chronic carriage in disease persistence.
We tested our hypothesis in two bighorn sheep populations in South Dakota, USA. We identified and removed Mo chronic carriers from the Custer State Park (treatment) population. Simultaneously, we identified carriers but did not remove them from the Rapid City population (control). We predicted removal would result in decreased pneumonia, mortality, and Mo prevalence. Both population ranges had similar habitat and predator communities but were sufficiently isolated to preclude intermixing.
We classified chronic carriers as adults that consistently tested positive for Mo carriage over a 20‐month sampling period (n = 2 in the treatment population; n = 2 in control population).
We failed to detect Mo or pneumonia in the treatment population after chronic carrier removal, while both remained in the control. Mortality hazard for lambs was reduced by 72% in the treatment population relative to the control (CI = 36%, 91%). There was also a 41% reduction in adult mortality hazard attributable to the treatment, although this was not statistically significant (CI = 82% reduction, 34% increase).
Synthesis and Applications: These results support the hypothesis that Mo is a primary causative agent of persistent or recurrent respiratory disease in bighorn sheep populations and can be maintained by a few chronic carriers. Our findings provide direction for future research and management actions aimed at controlling pneumonia in wild sheep and may apply to other diseases.
Zoonotic disease risk is greatly influenced by cultural practices and belief systems. Yet, few studies have integrated traditional ecological knowledge and ontology with western ways of knowing to better understand potential zoonoses. Here, we integrate molecular phylogenetics, histopathology, and ethnography to characterize a filarial nematode found within the abdominal cavity of spider monkeys (Ateles paniscus). The filarid is recognized as ‘spider monkey cotton’ by indigenous Waiwai in the Konashen Community Owned Conservation Area, Guyana. Ethnographic data revealed that the Waiwai perceive of ‘spider monkey cotton’ as a normal characteristic within the ‘spider monkey person.’ Further, the Waiwai indicated that ‘cotton’ was ubiquitous with spider monkeys and is not understood to be infectious nor zoonotic. This distinction is in contrast to other internal parasites found within spider monkeys that the Waiwai know to cause disease in both monkeys and humans. Our morphological and molecular characterization support the classification of the filarid as Dipetalonema caudispina, a minimally studied and seemingly non-zoonotic parasite, consistent with Waiwai beliefs. Thus, our findings allow us to establish commensurability between scientific knowledge and indigenous ontology. More broadly, this work highlights the importance of integrating multiple knowledge systems and leveraging advanced genomics to better understand and prevent emerging zoonotic diseases.
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