Round Tables

Monday,October 23

9:30 – 10:30 am

Overcoming Immune Evasion by Rabies Virus – chaired by Dr. Zhen F. Fu (60 min)

Summary: The hallmark of rabies is the almost 100% mortality because there is currently no effective treatment for clinical rabies. Although various approaches have been attempted, the success has been limited. One possible reason is that once the virus invades the central nervous system (CNS), it evades immune surveillance. In order to develop effective therapeutics for clinical rabies, it is necessary to clear the virus from the CNS. It has been known for some time that virus neutralizing antibodies (VNA) are capable of clearing rabies virus from the CNS. However, VNA are not detected in the CNS of most rabies patients even at the time of death. This is because first, most patients never develop VNA. Even if VNA develop in the periphery, they might not cross the blood-brain barrier (BBB) to reach the CNS. Thus to clear rabies virus, VNA have to be developed and BBB permeability has to be enhanced. Recombinant viruses have been used to stimulate VNA production and enhance BBB permeability. VNA can also be administered directly into the CNS. All of these have been shown to be capable of clearing rabies virus from the CNS in experimental animals.

Agenda and Speakers:

  1. Overview of therapeutics for clinical rabies: successes and failures (8 min) Dr. Charles Rupprecht, Wistar institute

  2. The blood-brain barrier and potential therapeutic targets (8 min) Dr. Alan C. Jackson, University of Manitoba

  3. Live viruses used for virus clearance and possible therapy (8 min) Dr. Ashley Banyard, Animal and Plant Health Agency, UK

  4. Direct administration of VNA into the CNS can clear rabies virus from the CNS (8 min), Dr. Zhen F. Fu, University of Georgia.

Discussion (28 min)

Tuesday, October 24

8:00 – 9:30 am

Best Practice Utilization of Post-exposure Rabies Prophylaxis – chaired by Dr. Charles E Rupprecht (90 min)

Summary: Although great regional progress has occurred over the past three decades, rabies prevention and control activities in the Americas are less than homogeneous. This roundtable session will explore different approaches to human and animal rabies management throughout the Americas. The basis for these differences stem from a variety of ecological, economic and cultural circumstances. For instance, surveillance criteria and activities vary. Reservoirs are diverse. Epidemiological patterns are complex, from the Arctic to the Neotropics. Canine rabies virus transmission has been eliminated in many countries, but not all. Vampire rabies is a major issue for parts of the region, whereas rabies perpetuation among insectivorous bats impacts others. Using salient local examples, widespread historical experiences, professional ingenuity and audience participation, the panel will provide an engaging experience within the backdrop of current PAHO/WHO recommendations.

Agenda and Speakers

  1. Wisdom with WHO – Dr. Bernadette Abela-Ridder

  2. Current conundrums in Canada – Dr. C. Filejski

  3. Unresolved understatements in the USA – Dr. C.E. Rupprecht

  4. Medical maelstroms in Mexico – Drs. V. Gutierrez / B. Contreras

  5. Biomedical bedevilment in Brazil -Dr. E. Pacheco de Caldas

Wednesday, October 25

9:00 – 10:30 am

Management of Skunk Rabies in North America – chaired by Drs. A. Gilbert and R. Chipman (90 min)

Summary: Striped skunks (Mephitis mephitis) are an important spillover host for raccoon and Arctic fox rabies virus variants, which have been or are currently circulating eastern North America. In addition, striped skunks are the primary host of at least four rabies virus variants circulating in North America (NCSK, SCSK, CASK, MXSK), although spotted skunks (Spilogale gracilis), hog-nosed skunks (Conepatus leuconotus) and hooded skunks (Mephitis macroura) may also be important regional hosts. Although spillover infections to domestic animals and other wildlife, as well as human exposure burden, are lower in areas where skunk rabies virus variants circulate compared to levels associated with other meso-carnivore variants, the vast territories affected by skunk rabies and enzootic persistence of skunk rabies circulation over the past half-century present challenges for management and control.

Limited tools and strategies currently exist for skunk rabies management in North America. Historically, toxicants have been used to reduce local skunk populations in an attempt to reduce rabies incidence, but these methods are now illegal in many areas, lack broad social acceptance, and their effects were transient. Trap-vaccinate-release (TVR) strategies have been successful at controlling skunk rabies in limited areas, but TVR quickly becomes intractable at larger geographic scales. Since the late 1990s, oral rabies vaccination (ORV) has been used to manage rabies in red foxes, raccoons, and striped skunks in eastern North America. Frequent cross species transmission of raccoon variant into skunks in the eastern US as well as a lack of understanding of the implications for raccoon rabies elimination and potential for a host shift of raccoon variant into skunks, present management challenges. Moreover, field applications of ORV targeting skunks to date have shown less than promising results at economically sustainable bait densities. Recent field trials with RABORAL V-RG and ONRAB in skunks in the US are in progress or recently completed that may, along with skunk rabies control programs in Ontario, provide some direction for future steps. This session is designed to discuss and debate the myriad of questions and challenges we face for effective ORV-based management of rabies in skunks in North America.

Agenda and Speakers:

Background (20 min)

    1. Skunk ecology (10 mins) (Dr. Tad Theimer)

    2. History of skunk rabies and control efforts in North America (10 mins) (Dr. Margo Pybus)

Skunk Rabies Management with ORV (20 min)

    1. ONRAB field studies targeting skunks in Canada (10 min) (Tore Buchanan)

    2. ONRAB field trials using standard density applications in the US – WV, NY/VT/NH, with focus on skunk results; plus WV ONRAB high density field trial and skunk ecology study (10 min) (Rich Chipman)

ORV Bait Product Development (20 min)

    1. Oral rabies vaccine bait development for Raboral V-RG (10 min) (Dr. Joanne Maki, Merial, Inc.)

    2. Oral rabies vaccine bait development for ONRAB (10 min) (Alex Beath, Artemis Technologies, Inc.)

Summary and Discussion (30 min)

    1. Key factors for improving skunk rabies management (10 min) (Dr. Charles Rupprecht)

    2. Discussions and identification of research gaps (20 min)- all

Thursday, October 26

8:00 – 9:30 am

Rabies Ecology in the Warming Arctic: – chaired by Drs. P. Leighton and E. Rees (90 min)

Summary: Arctic fox rabies is one of the most important wildlife diseases for public health in the Arctic. This lethal disease is endemic in the Arctic ecosystem, maintained by transmission within arctic (Vulpes lagopus) and red fox (Vulpes vulpes) populations. Transmission to humans occurs primarily through contact with infected foxes, or from domestic dogs that have become infected by rabid foxes.

The disease persists in the primary reservoir species, arctic foxes, despite having a population density lower than would be predicted to maintain this disease in red fox populations further south. Disease dynamics are potentially driven by multiple and interacting aspects of arctic and red fox ecology. The current climate warming adds an additional layer of complexity by: 1) altering fox habitat quality through weather and surface ice/snow conditions, 2) reducing lemming habitat quality, and consequently the punctual abundance of this food resource for foxes, 3) enabling red foxes to expand their range further northwards and overlap more densely and expansively with arctic foxes, and 4) facilitating growth and number of northern communities through increasing economic activities.

It is not known how climate-inducted factors will in turn influence rabies dynamics and rabies management in northern communities. This session focuses on discussing what is known, addressing knowledge gaps, and strategies for moving forward for managing public health risk to northern communities.

Agenda and Speakers:

Context (30 min)

  1. Introduction to roundtable discussion (5 min) (Drs. Erin Rees and Patrick Leighton)

  2. Arctic fox rabies ecology (5 mins) (Dr. Karsten Hueffer) (U. Alaska)

  3. Insights from phylogenetics (5 mins) (Dr. Christine Fehlner-Gardiner) (CFIA)

  4. Wild card of natural immunity (5 mins) (Dr. Stacey Elmore) (USDA)

  5. Climate warming and changes to rabies dynamics (5 mins) (Dr. Audrey Simon) (U. Montreal)

  6. Dogs and rabies management (5 mins) (Dr. Catherine Filejski)

Discussion (60 min)

  1. Identification of research gaps

  2. Key factors for improving management