In an ambitious effort to understand disease exposure in pumas, bobcats and domestic cats across the United States, FELIDAE project investigators recently published a study in the journal Ecological Applications.
How does disease spread in large predators across an ecosystem? How does the structure of a landscape impact disease spread? And how does wildlife management affect the spread of disease? The FELIDAE (Feline Ecology: Landscapes, Infectious Disease, And Epidemics) research project seeks to shed light on these questions. Our mission is to understand the ecology of infectious diseases in wild and domestic felids to inform policies that minimize disease outbreaks in wildlife, domestic animals, and humans.
Current Project: NSF-EID Puma Research
In 2014, the NSF Ecology of Infectious Disease Program (NSF-EID 1413925) awarded a five year grant to principal investigators at Colorado State University, the University of Minnesota, the University of Tasmania, and the University of California, Davis. The research teams are led by Sue VandeWoude (Colorado State – Microbiology, Immunology, and Pathology), Kevin Crooks (Colorado State – Fish, Wildlife, and Conservation Biology), Chris Funk (Colorado State – Biology), Meggan Craft (Minnesota – Veterinary Population Medicine), Scott Carver (Tasmania – Wildlife Ecology), and Holly Ernest (University of Wyoming – Wildlife Genomics and Disease Ecology. The aim of this project is to study how landscape structure and management interventions interact to influence disease spread in heterogeneous landscapes.
At the heart of this project is the apex predator Puma concolor, a large cat in the family Felidae that is better known by a host of different names, including puma, cougar, mountain lion, catamount, and panther. By focusing on the spread of two contact-dependent pathogens – Feline Immunodeficiency Virus (FIV) and Feline Foamy Virus (FFV) – we will build innovative network models capable of predicting disease transmission. We will then test these models by analyzing viral samples taken from pumas in geographically distinct populations. In so doing, we will be helping to protect one of the most iconic predators in the Americas, while also contributing to a body of knowledge that may one day limit the spread of disease between wildlife, domestic animals, and humans alike.
In 2007, the NSF Ecology of Infectious Disease Program (NSF-EID 0723676) awarded a five year grant to principal investigators at Colorado State University, led by Sue VandeWoude (Microbiology, Immunology, and Pathology) and Kevin Crooks (Fish, Wildlife, and Conservation Biology), to study the effects of urban fragmentation and landscape connectivity on disease prevalence and transmission in North American felids. The project focused on puma (Felis concolor), bobcat (Lynx rufus), and domestic cats (Felis cattus) occurring in divergent ecosystems in California, Colorado, and Florida.
The primary objectives of this project were to:
- Assess the relationship between habitat fragmentation and prevalence of viral, bacterial, and parasitic pathogens
- Use transmission dynamics of selected disease agents as markers of connectivity in fragmented populations
- Evaluate the effect of urbanization on the incidence of cross-species disease transmission.
The FELIDAE Project builds upon several key ideas from wildlife management and disease ecology. These ideas include:
- The use of apex predators as critical focal species for landscape and disease ecology studies. Apex predators like the puma are particularly useful research subjects for evaluating the effect of human disturbances on a landscape. This is because such predators, in addition to facing targeted persecution by humans, typically have wide ranges, low densities, slow population growth, and fastidious resource requirements, making them especially sensitive to changes in a landscape. Because of their extensive ranges, predators can also be important vectors for a variety of diseases, some of which may infect human beings or domestic animals. For this reason, accurate prediction of disease spread in apex predators is highly desirable. However, basic disease models typically require data on such parameters as population size and contact rates. Such data are notoriously difficult to collect for wildlife in general, and even more so for secretive and widely-dispersed predators. To overcome these limitations, we have outlined a novel approach that uses molecular and statistical tools to accurately model pathogen spread in such species.
- The value of landscape genomics to study ecology of infectious disease. Landscape genomics is a discipline that draws upon landscape ecology, statistics, and genetics to test and predict gene flow throughout a landscape. Prior work by our research group has demonstrated that genetic relationships between various bobcat pathogens can reveal patterns of disease transmission among hosts.
- The value of network modeling to study the ecology of infectious disease. Movement patterns affect the rate of contact between individuals, and are therefore key drivers in the spread of contact-dependent infectious diseases. Network modeling, which represents animals as nodes and connections between animals as edges, has provided critical insights into the spread of infectious disease. For example, prior work by our research group suggests that “network distance” better represents the rate of contact between animals than does simple physical distance in a heterogeneous landscape.
- Use of non-pathogenic, chronic, contact-dependent microparasites to estimate host contact. A deeper understanding of “who infects whom” is a central theme in contemporary disease ecology and epidemiology. A chief limitation in these fields, however, has been the challenge of accurately measuring contacts and transmission events between individuals. Microparasites (e.g. viruses) that cause chronic, non-pathogenic infections are valuable tools for overcoming this difficulty. RNA viruses are well-suited as markers of host contact because their rapid mutation rate results in unique genetic signatures that can be compared between individuals. Retroviruses, RNA viruses that replicate by way of a DNA intermediate, are especially useful because they cause persistent infections detectable in the blood cells of infected animals. Our project focuses on various retroviruses, including Feline Immunodeficiency Virus (FIV) and Feline Foamy Virus (FFV), that vary in prevalence, mode of transmission, mutation rate, and virulence.
- Impact of management actions on disease dynamics. Management interventions that influence the demographic characteristics of an animal population, including sex ratio and age structure, can alter the spread of infectious disease. We will compare three different management scenarios that represent unique opportunities to study such interventions in apex predator populations. These scenarios are: (1) population supplementation in the highly endangered Florida panther; (2) intensive, large-scale harvesting of a rural population of Colorado pumas; and (3) steady-state management of urban pumas along the Colorado Front Range and in coastal southern California. These different interventions can be used as experimental tools to evaluate how demographic factors influence disease spread.
Outcomes from the FELIDAE Project include:
- Over 70 abstracts at national and international scientific meetings
- Over 30 collaborators from over 20 academic, state, federal, and non-profit organizations
- Over 30 grants to supplement research
- Over 20 refereed papers in a diversity of scientific journals
- Training of 3 graduate students, including 1 female, and 3 post-doctoral fellows
- Support of 3 additional post-doctoral fellows, 8 graduate students, 7 veterinary students, and 7 undergraduate students
- Outreach efforts, including public seminars and an ongoing K-12 education project
- Articles in multiple international, national, and local media outlets
The FELIDAE project has successfully created an extensive database on puma disease ecology. In a prior NSF-EID project (EF-0723676), we amassed nearly 350 puma blood samples from six locations in three different states. This database contains data on host demographic information, including sex, age, capture location, and sample date, along with a disease profile of each animal for 12 pathogens, including FIV and FFV.
We have also described urban impacts on disease exposure in felids that vary significantly by location and pathogen. For example, our previous work has shown that major freeways in southern California limit bobcat gene flow, but not that of FIV. In contrast, the city of Los Angeles acts as a complete barrier to both host gene flow and pathogen transmission. These results suggest that landscape structure might be critical for understanding pathogen transmission in puma and other wide-ranging species.
We have also shown that host demographic factors, such as sex and age, are important predictors of pathogen exposure, particularly for directly transmitted agents like FIV and FFV. The fact that demographic factors are not always consistent predictors between different sites suggests that pathogen transmission is further contextualized by landscape characteristics.
Significantly, we have also made significant strides toward characterizing puma FIV and FFV. Our researchers have developed well-established protocols for FIV and FFV seroanalysis, as well as for highly efficient PCR amplification of nearly full-length FIV genomes. This allows us to perform detailed phylogenetic comparisons between isolates from different study populations.