Transmission and Epidemiology of Bluetongue and Epizootic Hemorrhagic Disease in North America: Current Perspectives, Research Gaps, and Future Directions.

Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) are arthropod-transmitted viruses in the genus Orbivirus of the family Reoviridae. These viruses infect a variety of domestic and wild ruminant hosts, although the susceptibility to clinical disease associated with BTV or EHDV infection varies greatly among host species, as well as between individuals of the same species. Since their initial detection in North America during the 1950s, these viruses have circulated in endemic and epidemic patterns, with occasional incursions to more northern latitudes. In recent years, changes in the pattern of BTV and EHDV infection and disease have forced the scientific community to revisit some fundamental areas related to the epidemiology of these diseases, specifically in relation to virus-vector-host interactions and environmental factors that have potentially enabled the observed changes. The aim of this review is to identify research and surveillance gaps that obscure our understanding of BT and EHD in North America.

Seasonal and interseasonal dynamics of bluetongue virus infection of dairy cattle and Culicoides sonorensis midges in northern California--implications for virus overwintering in temperate zones.

Bluetongue virus (BTV) is the cause of an economically important arboviral disease of domestic and wild ruminants. The occurrence of BTV infection of livestock is distinctly seasonal in temperate regions of the world, thus we determined the dynamics of BTV infection (using BTV-specific real time reverse transcriptase polymerase chain reaction) among sentinel cattle and vector Culicoides sonorensis (C. sonorensis) midges on a dairy farm in northern California throughout both the seasonal and interseasonal (overwintering) periods of BTV activity from August 2012 until March 2014. The data confirmed widespread infection of both sentinel cattle and vector midges during the August-November period of seasonal BTV transmission, however BTV infection of parous female midges captured in traps set during daylight hours also was detected in February of both 2013 and 2014, during the interseasonal period. The finding of BTV-infected vector midges during mid-winter suggests that BTV may overwinter in northern California by infection of long-lived female C. sonorensis midges that were infected during the prior seasonal period of virus transmission, and reemerged sporadically during the overwintering period; however the data do not definitively preclude other potential mechanisms of BTV overwintering that are also discussed.

The evolution of One Health: a decade of progress and challenges for the future.

The One Health concept is gathering momentum and, over the next 12 months, Veterinary Record will be publishing a series of articles to help encourage that process. Written by specialists in a range of fields, the articles will consider the meaning of One Health, the interactions between animal and human health and how a collaborative and interdisciplinary approach could help to solve emerging global problems. To set the scene, Paul Gibbs outlines the recent history of One Health, discusses current challenges and muses on what the future might hold.

Prevalence of and exposure factors for seropositivity to H3N8 canine influenza virus in dogs with influenza-like illness in the United States.

OBJECTIVE: To estimate the seroprevalence of antibodies against H3N8 canine influenza virus (CIV) in a population of US dogs with influenza-like illness (ILI) and to identify factors associated with seropositivity. DESIGN: Cross-sectional study. ANIMALS: 1,268 pet and shelter dogs with ILI in 42 states. PROCEDURES: Serum samples collected from dogs from 2005 through June 2009 were tested for H3N8 CIV antibodies with a hemagglutination inhibition assay. Intrinsic factors (age, breed, and sex), extrinsic factors (dogs housed in a shelter facility, boarding kennel, or other setting), and geographic region (southwest, west, Midwest, southeast, and northeast) were compared between seropositive and seronegative dogs to identify variables associated with seropositivity. RESULTS: Most (750/1,268 [59%]) dogs in the study were from Colorado, Florida, or New York. The overall seroprevalence of antibodies against H3N8 CIV was 49% (618/1,268 dogs; 95% confidence interval, 46% to 51%). The annual prevalence of H3N8 CIV seropositivity increased from 2005 (44%) to 2006 (53%) and 2007 (62%), then decreased in 2008 (38%) and 2009 (15%). The likelihood of H3N8 CIV seropositivity was associated with geographic region (southeast during 2005, west and northeast during 2006 and 2007, and northeast during 2008) and exposure setting (dogs housed in a shelter facility or boarding kennel during 2005 and 2006). CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study suggested there is a need for continued surveillance for H3N8 CIV infection in dogs in the United States and that personnel in communal dog-housing facilities should formulate, implement, and evaluate biosecurity protocols to reduce the risk of CIV transmission among dogs.

The historical, present, and future role of veterinarians in One Health.

The renewed interest in the concept of One Health has occurred as a result of the increased emergence of zoonotic infectious diseases over the past decade. The subsequent impacts of these diseases on human, livestock, and wildlife health, as well as the economic effects, have given international health organizations and national governments a greater appreciation of the importance of collaborative efforts in solving health problems. The One Health concept is not new, but under its umbrella, a new generation of veterinarians, physicians, ecologists, biologists, and social scientists is shaping the concept in novel ways. This has led to increased support for One Health initiatives to control disease by international agencies, national governments, and nongovernmental organizations as well as a growing emphasis on One Health concepts in training the veterinary workforce. Veterinary schools are reorganizing veterinary education to better teach students the precepts of One Health. This chapter explores the evolution and application of the One Health concept from the perspective of the veterinarian. The veterinary profession is positioned to be a strong advocate and leader of One Health. Veterinarians have a long history of involvement with One Health activities, and this involvement has adjusted and shifted with the changing needs of society. A new area of work for veterinarians is ecosystem health, which is becoming more relevant as a result of the impact that the ever-increasing human population is having on the environment that supports them.

Diagnostic performance of the canine influenza A virus subtype H3N8 hemagglutination inhibition assay.

Canine Influenza A virus subtype H3N8 (H3N8 CIV) was recognized in 2004 as a novel respiratory pathogen for dogs. To date, infections have been diagnosed in thousands of dogs in 38 U.S. states. Diagnostic techniques such as reverse transcription polymerase chain reaction (RT-PCR) and virus isolation may yield false-negative results if samples are collected after virus shedding has ceased. Therefore, serology is often necessary to confirm diagnosis. The hemagglutination inhibition (HI) assay is the test of choice for serological diagnosis of influenza infections in animals. However, discrepancies exist between diagnostic laboratories and research groups in some of the test parameters for the H3N8 CIV HI assay and the cutoff antibody titer for seropositivity. The objectives of the current study were 1) to assess the diagnostic performance of a H3N8 CIV HI assay using field sera from canine infectious respiratory disease outbreaks and 2) to evaluate the effect of test parameter variations on test performance, including the use of different red blood cell (RBC) species, serum treatment methods, and virus isolates. Based on a receiver operating characteristic analysis using serum microneutralization assay titers as the gold standard, the H3N8 CIV HI assay described in the present study is highly sensitive (99.6%) and specific (94.6%) when the cutoff antibody titer for seropositivity is 32. Evaluation of parameter variations determined that the sensitivity and specificity of the H3N8 CIV HI assay depend on serum pretreatment with a receptor-destroying enzyme or periodate, use of 0.5% turkey or chicken RBCs, and use of antigenically well-matched H3N8 virus strains.

One Health and the neglected zoonoses: turning rhetoric into reality.

Successful adoption of a One Health approach could have far-reaching impacts on poverty alleviation, health and food security, particularly in developing countries through integrated control of neglected zoonoses. However, the practical implementation of this approach presents many challenges. Anna Okello and colleagues argue that, for effective implementation, lessons learned and 'best practice' must be led by national and regional stakeholders drawn from a variety of disciplines. High-profile regional and international institutions can play an important role in the global governance of One Health by encouraging individual countries to devise appropriate tailored solutions that are workable within their own context.

Equine and canine influenza: a review of current events.

In the past decade, the pandemics of highly pathogenic avian influenza H5N1 and the novel H1N1 influenza have both illustrated the potential of influenza viruses to rapidly emerge and spread widely in animals and people. Since both of these viruses are zoonotic, these pandemics have been the driving force behind a renewed commitment by the medical and veterinary professions to practice One World, One Health for the control of infectious diseases. The discovery in 2004 that an equine origin H3N8 influenza virus was the cause of an extensive epidemic of respiratory disease in dogs in the USA came as a surprise; at that time dogs were thought to be refractory to infection with influenza viruses. In 2007, a second emerging canine influenza was confirmed in Korea, but this time the causal virus was an H3N2 avian influenza virus. This review focuses on recent events associated with equine and canine influenza viruses. While these viruses do not appear to be zoonotic, the close association between humans and dogs, and to a lesser extent horses, demands that we develop better surveillance and control strategies for emerging diseases in companion animals within the context of One World, One Health.

One World - One Health' and the global challenge of epidemic diseases of viral aetiology.

'One World - One Health' is an exciting movement to encourage wildlife, domestic animal and human health professionals to work collectively to address the world's most challenging health concerns. It is broad in scope and truly multidisciplinary. This particular commentary on 'One World - One Health' is focused on ways in which individuals are forging closer collaboration and action to meet the global threat of emerging diseases caused by viruses, with particular attention being paid to those diseases that are zoonotic.

A global perspective on recent epidemics: are there lessons for the Caribbean region in the coming decade?

The paper reviews the changing global landscape of infectious diseases and outlines the history and epidemiology of selected recent epidemics that have relevance to human and animal health in the Caribbean area; specifically, West Nile encephalitis, bovine spongiform encephalopathy, foot-and-mouth disease, avian and canine influenza, classical swine fever and bluetongue. While it is not possible to predict which new diseases will emerge over the next 10 years to affect the Caribbean countries, one can identify trends. It is safe to say that new diseases will emerge. The region has an excellent record of disease prevention and eradication, but this should not be a justification for celebration and relaxation. Various factors continue to place the Caribbean at risk, ranging from the increased volume of trade and tourism in the region through to global warming. Diseases originating elsewhere in the world could easily involve the region.

A global perspective on recent epidemics: are there lessons for the Caribbean region in the coming decade?

The paper reviews the changing global landscape of infectious diseases and outlines the history and epidemiology of selected recent epidemics that have relevance to human and animal health in the Caribbean area; specifically, West Nile encephalitis, bovine spongiform encephalopathy, foot-and-mouth disease, avian and canine influenza, classical swine fever and bluetongue. While it is not possible to predict which new diseases will emerge over the next 10 years to affect the Caribbean countries, one can identify trends. It is safe to say that new diseases will emerge. The region has an excellent record of disease prevention and eradication, but this should not be a justification for celebration and relaxation. Various factors continue to place the Caribbean at risk, ranging from the increased volume of trade and tourism in the region through to global warming. Diseases originating elsewhere in the world could easily involve the region.

In vitro development and characterization of a manatee bronchial cell line.

In the present study, culture conditions that promote the growth and differentiation of manatee respiratory tract epithelial cells toward a mucociliary phenotype were determined. Characterization of a manatee-specific cell line enables investigators to conduct in vitro testing where live-animal experimentation is not possible. Cell cultures were established from both explants and enzymatically dissociated cells that were isolated from manatee bronchial tissue. To modulate their differentiation, bronchial epithelial cells were grown on Transwell collagen membranes either submerged or at an air-liquid interface. Growth on a collagen membrane at an air-liquid interface and medium supplemented with retinoic acid was required to promote a mucociliary phenotype. When cells were grown in submerged cultures without retinoic acid, they appeared more squamous and were not ciliated. Intracellular keratin proteins were detected in both submerged and interface cultures. Cultured manatee bronchial epithelial cells will facilitate future studies to investigate their potential role in pulmonary disease associated with brevetoxicosis after exposure to the red-tide organism, Karenia brevis.

Educational preparedness of veterinarians for foreign animal diseases.

Veterinary medical education in FADs has been and will continue to be critically important if veterinarians are expected to fulfill the profession's primary obligations to society--those of protecting our animals' health, conserving our animal resources, and promoting public health. It is imperative that curricula and instruction in veterinary schools and colleges provide the depth and breadth of knowledge and understanding necessary to prepare all veterinarians, including those in private practice, for their key role in defending against FADs. Development and implementation of governmental and military programs to diagnose, prevent, control, and eradicate FADs will require a dedicated cadre of public sector veterinarians who have a solid educational foundation in FADs and understand the contemporary issues and global challenges we face. Animal-related industries, associations, and organizations will increasingly rely on well-educated veterinarians to help guide them in ways that will protect animals, clientele, consumers, and trading partners from effects of FADs. Agencies and organizations concerned with conservation of animal resources will require veterinary expertise necessary to prevent FADs in a multitude of animal species, including marine animals, wildlife, endangered species, zoologic specimens, and important genetic lines as well as our domestic companion and livestock species. Species affected by FADs also include human beings for those disease agents with zoonotic potential; thus, veterinary education also plays a key role in public health.

Bluetongue epidemiology in the Caribbean region: serological and entomological evidence from a pilot study in Barbados

Variations in the percentages of lambs seroconverting to bluetongue viruses was seen between sites and years in Barbados. Transmission at some sites was nearly absent whereas all lambs at one site became seropositive. The agar gel immunodiffusion test for bluetongue gave consistent results in series of serum samples from 112 of 121 sentinel lambs. Collections of biting midges in association with sheep yielded six species. Culicoides insignis Lutz, C. pusillus Lutz, C. phlebotomus (Williston), C. furens (Poey), C. jamaicensis Edwards and C. trilineatus Fox. The first two species comprised 92 percent of those caught during a sentinel lamb study and were the predominant species trapped for virus isolation. No viruses were recovered from 5517 C. insignis, 614 C. pusillus, three C. trilineatus and two C. furens placed into pools during two brief intensive trapping operations. (AU)

Bluetongue epidemiology in the Caribbean region: serological and entomological findings from a pilot sentinel system in Trinidad and Tobago

When monitored by the agar gel immunodiffusion test for antibody to bluetongue viruses, a sentinel flock of twenty-five lambs remained seropositive through the year, whereas in a sentinel herd of twenty calves only two individuals seroconverted and these became negative again within 2 months. A light trap operated with the calf herd yielded high numbers of culicoides insignis Lutz (over 18,000 per trap night) along with C. filariferus Hoffman, C. pusillus Lutz, C. leopoldi Ortiz, C. foxi Ortiz, C. limai Barretto, C. diabolicus Hoffman and C. guyanensis Floch and Abonnenc. Culicoides were trapped at the sheep station which had housed the lambs 3 years following the sentinel study. No virus was isolated from pools of C. insignis, C. filariferus and C. pusillus. Six outer species were collected in insufficient numbers to warrant attempted virus isolations. (AU)