Challenges to controlling rabies in skunk populations using oral rabies vaccination: A review.

Controlling rabies in skunk populations is an important public health concern in many parts of the United States due to the potential for skunk rabies outbreaks in urban centres and the possible role for skunks in raccoon rabies variant circulation. Oral rabies vaccination (ORV) programmes have supported wildlife rabies control efforts globally but using ORV to control rabies in skunk populations has proven more challenging than with other target species, like foxes, coyotes and raccoons. A review of published studies found that some ORV constructs are immunogenic in skunks and protect against virulent rabies virus challenges, especially when delivered by direct installation into the oral cavity. However, in field ORV programmes using currently available vaccine-bait formats and distribution methods targeting other rabies reservoir species, skunks often fail to seroconvert. Field effectiveness of ORV in skunks appears to be limited by poor bait uptake or inadequate ingestion of vaccine rather than from poor vaccine efficacy. Observations of captive skunks revealed vaccine spillage when handling and biting into baits such that modification of bait formats might improve field effectiveness. In addition, a dose-response relationship between bait distribution density and post-baiting seroconversion among skunks was observed across the limited number of field studies. Additional research is needed to identify opportunities to modify ORV baits and distribution strategies to improve the viability of ORV as a rabies control strategy in skunks.

Public Health Implications of Changing Rodent Importation Patterns - United States, 1999-2013.

The United States imports a large volume of live wild and domestic animal species; these animals pose a demonstrated risk for introduction of zoonotic diseases. Rodents are imported for multiple purposes, including scientific research, zoo exhibits and the pet trade. Current U.S. public health regulatory restrictions specific to rodent importation pertain only to those of African origin. To understand the impacts of these regulations and the potential public health risks of international rodent trade to the United States, we evaluated live rodent import records during 1999-2013 by shipment volume and geographic origin, source (e.g. wild-caught versus captive- or commercially bred), intended purpose and rodent taxonomy. Live rodent imports increased from 2737 animals during 1999 to 173 761 animals during 2013. Increases in both the number and size of shipments contributed to this trend. The proportion of wild-captured imports declined from 75% during 1999 to <1% during 2013. Nearly all shipments during these years were imported for commercial purposes. Imports from Europe and other countries in North America experienced notable increases in volume. Gerbils and hamsters arriving from Europe and chinchillas, guinea pigs and hamsters arriving from other countries in North America were predominant taxa underlying this trend. After 2003, African-origin imports became sporadic events under the federal permit process. These patterns suggest development of large-scale captive rodent breeding markets abroad for commercial sale in the United States. While the shift from wild-captured imports alleviates many conservation concerns and risks for novel disease emergence, such consolidated sourcing might elevate exposure risks for zoonotic diseases associated with high-density rodent breeding (e.g. lymphocytic choriomeningitis or salmonellosis). A responsive border health system must periodically re-evaluate importation regulations in conjunction with key stakeholders to ensure a balance between the economic benefits of rodent trade against the potential public health risks.

Impact of Rabies Vaccination History on Attainment of an Adequate Antibody Titre Among Dogs Tested for International Travel Certification, Israel - 2010-2014.

Rabies is endemic in wildlife or domestic carnivore populations globally. Infection of domestic dogs is of particular concern in many areas. In regions where domestic animals are at risk of exposure to rabies virus, dogs should be routinely vaccinated against rabies to protect both pet and human populations. Many countries require demonstration of an adequate level of serum rabies neutralizing antibodies to permit entry of dogs during international travel. We analysed rabies titres of dogs seeking travel certification in Israel to assess demographic and vaccine history factors associated with antibody titres below the acceptable threshold for travel certification. Having received only one previous rabies vaccination and a longer duration since the most recent vaccination was received were primary risk factors for not achieving an adequate rabies virus neutralizing antibody titre for travel certification. These risk factors had stronger effects in younger animals, but were consistent for dogs of all ages. In particular, these findings reiterate the importance of administering at least two rabies vaccinations (the primo vaccination and subsequent booster) to ensure population-level protection against rabies in dogs globally.

Community survey of rabies knowledge and exposure to bats in homes - Sumter County, South Carolina, USA.

Subsequent to a human rabies death in Sumter County, South Carolina, we assessed the frequency of exposures to bats in homes and citizens' rabies knowledge. A self-administered survey was mailed to 6033 randomly selected Sumter County addresses. The survey inquired about household exposures to bats and respondents' rabies knowledge. Surveys were returned by mail for descriptive analysis. Of 597 respondents, 3.5% (21/597) reported having bats living in (2.8% or 17/597) or entering their homes (2.5% or 15/597) during 2010-2012. Respondents generally understood that mammals transmit rabies virus through bites, but were less aware of the severity of rabies illness and modern post-exposure vaccine administration. Respondents were unsure about how to exclude bats from homes and ranked highly both healthcare and non-healthcare entities as preferred resources for obtaining assistance with bat-related concerns. We found potential for human exposures to bats in Sumter County households and gaps in citizen knowledge of rabies and bat exclusion. Public health officials should engage non-healthcare partners in assistance disseminating rabies educational materials and for providing appropriate referral for persons potentially exposed to bats.

Dogs Entering the United States from Rabies-Endemic Countries, 2011-2012.

International dog imports pose a risk because of the potential movement of disease agents, including the canine rabies virus variant which has been eliminated from the United States since 2007. US regulations require a rabies vaccination certificate for dogs arriving from rabies-endemic countries, but permit the importation of dogs that have not been adequately immunized against rabies, provided that the dogs are confined under conditions that restrict their contact with humans and other animals until they have been immunized. CDC Form 75.37, 'Notice to Owners and Importers of Dogs', explains the confinement requirements and serves as a binding confinement agreement with the importer. In this evaluation, we describe the characteristics of unimmunized dogs imported into the United States over a 1-year period based upon dog confinement agreements recorded at the Centers for Disease Control and Prevention (CDC) quarantine stations. Confinement agreements were issued for nearly 2800 unimmunized dogs that entered the United States during 1 June 2011-31 May 2012, the majority of which travelled to the United States by air and without any seasonal pattern in import volume. Over 60% of these animals were puppies <3 months of age and included a wide variety of breeds. The dogs arrived from 81 countries, with the majority arriving from North America or Europe. Dogs placed on confinement agreements had final destinations in 49 states. California, New York, Texas, Washington and Florida received the largest number of dogs on confinement agreements. These results (which do not reflect human travel or US dog ownership data) suggest that a large portion of unimmunized dogs arrive from rabies-endemic countries for commercial, shelter and rescue purposes. Further evaluation and key stakeholder involvement are needed to assess whether the current dog importation regulations are an adequate compromise between the benefits and risks of dog importation.

Prevention and control of rabies in an age of global travel: a review of travel- and trade-associated rabies events--United States, 1986-2012.

Rabies prevention and control efforts have been successful in reducing or eliminating virus circulation regionally through vaccination of specific reservoir populations. A notable example of this success is the elimination of canine rabies virus variant from the United States and many other countries. However, increased international travel and trade can pose risks for rapid, long-distance movements of ill or infected persons or animals. Such travel and trade can result in human exposures to rabies virus during travel or transit and could contribute to the re-introduction of canine rabies variant or transmission of other viral variants among animal host populations. We present a review of travel- and trade-associated rabies events that highlight international public health obligations and collaborative opportunities for rabies prevention and control in an age of global travel. Rabies is a fatal disease that warrants proactive coordination among international public health and travel industry partners (such as travel agents, tour companies and airlines) to protect human lives and to prevent the movement of viral variants among host populations.