Ecology of infectious disease in people, primates, and domestic animals

red colobusPeople, wildlife, and domestic animals around the world are intereacting in new ways as environments change around them. For over 16 years, The Kibale EcoHealth Project has studied the non-human primates, people, and domestic animals of Kibale National Park, Uganda, as a case study of this phenomenon. Kibale is a protected tropical forest known for its exceptional diversity of primates. We focus on "interface" habitats in and near the national park, where human-wildlife conflict and contact occur in a region that is a hot spot for disease emergence. We study how environmental changes alter cross-species disease transmission and how KEP logothese alterations impact human and animal health. We train international students and work with governmental organizations and NGOs to translate our scientific results into effective‚ targeted policy.

Discovering novel pathogens

Only a fraction of the world's pathogens are known. We use metagenomics and other methods to "hunt" for viruses, bacteria, and other disease-causing agents. We study systems where epidemiological data indicate that a "mystery bug" might be causing a health-related issue. However, we also examine healthy populatons in ecological settings where diseases are likely to occur, to identify "pre-emergent" microbes. Our studies to date have revealed fascinating new pathogens, from divergent simian hemorrhagic fever viruses in wild monkeys, to unknown tapeworms in captive apes, to viruses of bald eagles across the USA. Our goal is to understand how pathogens in nature form communities, interact with their hosts, and impact human and animal health.

Discovering novel transmission pathways

Even if the world's pathogens were completely cataloged, this information would not be sufficient to inform public health. We complement our studies of pathogen discovery with approaches from the social sciences that we have dubbed "pathway discovery." Pathways are the routes that microbes traverse as they travel from their natural reservoirs to new hosts and new environments. To discover and characterize transmission pathways, and ultimately to disrupt them, we use methods from the social sciences, including quantitative approaches such as social network analysis and qualitative approaches such as ethnography. By mixing methods, we hope to define and distill the myriad ways that microbes can move across complex landscapes, among hosts, and over time – whether those microbes are known, novel, or not yet evolved.

Disease, society, and evolution

Disease has played a major, but under-appreciated, role in shaping our species. We study animal populations and their infectious diseases as model systems for human biological and societal evolution. For example, we study "sickness behaviors" to understand how infection shapes primate social dynamics. We study groups of primates forced into new environments and confronting new pathogens as epidemiological surrogates for modern-day displaced human populations. We study non-primate species (e.g. birds, fish) to understand "deep" relationships between infection and social evolution. We have evolved with our pathogens, and they have evolved with us – the outcomes of this co-evolution yield fundamental insights into the human condition.

Epidemiology of emerging arboviruses

birdArboviruses (viruses vectored by arthropods) are emerging at acclerated rates worldwide. Dengue virus, chikungunya virus, Zika virus, West Nile virus, and yellow fever virus are but a few examples. We study arboviruses both because they are important and as a model for rapidly emerging diseaes. Arboviruses are paticularly problematic in urban settings. For example, West Nile virus in the United States emerges in a predictable cycle known as “amplification.” When the virus amplifies sufficiently in avian hosts and mosquito vectors‚ it “spills over” into humans. Our research shows how fine-scale ecological processes spark local transmission foci for West Nile virus and other arboviruses‚ and how these foci coalesce into larger patterns of amplification. Our goal is to elucidate the fundamental ecological mechanisms that drive the transmission and evolution of arboviruses in diverse ecological settings.

Diseases of domestication

Pigs Agricultural intensification has led to an explosion of new infections. The resulting diseases threaten human wellbeing, even if they are not zoonotic. For example, porcine reproductive and respiratory syndrome virus (PRRSV‚ distantly related to coronaviruses such as SARS) is the world's most economically damaging pathogen of domestic pigs and threatens global food security. We study how evolving viruses like PRRSV transmit in demographically well characterized domestic animal populations, and how their rapid evolution helps them evade host immunity and resist our best efforts to control them. Viruses of domestic animals are useful model systems for understanding the epidemiology‚ ecology‚ and evolution of emerging pathogens in general. They also illustrates how the domestication of animals – a milestone in human evolution – carried with it costs as well as benefits.

Diseases of conservation

We study health and disease in wildlife to improve conservation and natural resources management. Infection can have dire conseqeunces for the ecosystem services on which the world relies. A rapildly changing global environment necessitates that we pay greater attention to wildlife disease than ever before, even if those diseases do not infect people. Below are some examples of important wildlife diseases that we are currently studyng.

  • Freshwater mussels (family Unionida) are among the most beautiful, biodiverse, and underappreciated animal taxa. They are also critical providers of ecosystem services such as water purification, substrate stabilization, and food and habitat provision for other wildlife. Unfortunately, freshwater mussel populatipons around the world are suffering catastrphic mass mortality events. We are collaborating with the US Fish and Wildllife Service, the US Geological Survey and others to understand the proximate and ultimate causes of mussel die-offs around the world.
  • Bonefish (Albula spp) are a coveted near-shore marine sport fish that depend on delicate mangrove ecosystems. Healthy bonefish populations can support local economies and can justify conserving coastal habitats. Unfortunately, bonefish populatipons are in decline, especially in the Florida Keys. We are collaborating with the Bonefish & Tarpon Trust, the Fisheries Conservation Foundation, and others to understand the health-related causes of bonefish declines.
  • Viral hemorrhagic septicemia virus (VHSV, family Rhabdoviridae) is an invasive pathogen that threatens the health and sustainability of North America's fisheries. We are using novel epidemiological and diagnostic tools to manage the emergence and spread of VHSV. This project is a collaboration between UW-Madison, the Wisconsin Department of Natural Resources, and the University of Wisconsin Sea Grant Institute.
  • White-nose syndrome is an emerging fungal disease that threatens bat populations across North America. In collaboration with the USGS National Wildlife Health Center, we are studying the pathogenesis of the fungus (Pseudogymnoascus destructans) and how it persists and spreads in cave ecosystems.
  • Other projects in our lab include studies of the health consequences of bushmeat hunting in Nigeria, infectious causes of health declines in polar bears, penguins, primates, and birds, and other intriguing epidemiological and clinical challenges that come our way.