Coronaviruses (CoVs) produce a wide spectrum of disease syndromes in different mammalian and avian host species. These viruses are well-recognized for their ability to change tissue tropism, to hurdle the interspecies barriers and to adapt ecological variations. It is predicted that the inherent genetic diversity of CoVs caused by accumulation of point mutations and high frequency of homologous recombination is the principal determinant of these competences. Several CoVs (e.g. Severe acute respiratory syndrome-CoV, Middle East respiratory syndrome-CoV) have been recorded to cross the interspecies barrier, inducing different disease conditions in variable animal hosts. Bovine CoV (BCoV) is a primary cause of gastroenteritis and respiratory disease in cattle calves, winter dysentery in lactating cows and shipping fever pneumonia in feedlot cattle. Although it has long been known as a restrictive cattle pathogen, CoVs that are closely related to BCoV have been recognized in dogs, humans and in other ruminant species. Biologic, antigenic and genetic analyses of the so-called ‘bovine-like CoVs’ proposed classification of these viruses as host-range variants rather than distinct virus species. In this review, the different bovine-like CoVs that have been identified in domesticated ruminants (water buffalo, sheep, goat, dromedary camel, llama and alpaca) and wild ruminants (deer, wild cattle, antelopes, giraffes and wild goats) are discussed in terms of epidemiology, transmission and virus characteristics. The presented data denote the importance of these viruses in the persistence of BCoV in nature, spread to new geographical zones, and continuous emergence of disease epidemics in cattle farms.

The Pacific oyster Crassostrea gigas contributes significantly to global aquaculture; however, C. gigas culture has been affected by ostreid herpesvirus-1 (OsHV-1) and variants. The dynamics of how the virus maintains itself at culture sites is unclear and the role of carriers, reservoirs or hosts is unknown. Both wild and cultured mussels Mytilus spp. (Mytilus edulis, Mytilus galloprovincialis and hybrids) are commonly found at C. gigas culture sites. The objective of this study was to investigate if Mytilus spp. can harbour the virus and if viral transmission can occur between mussels and oysters. Mytilus spp. living at oyster trestles, 400–500 m higher up the shore from the trestles and up to 26 km at non-culture sites were screened for OsHV-1 and variants by all the World Organization for Animal Health (OIE) recommended diagnostic methods including polymerase chain reaction (PCR), quantitative PCR (qPCR), histology, in situ hybridization and confirmation using direct sequencing. The particular primers that target OsHV-1 and variants, including OsHV-1 microVar (μVar), were used in the PCR and qPCR. OsHV-1 μVar was detected in wild Mytilus spp. at C. gigas culture sites and more significantly the virus was detected in mussels at non-culture sites. Cohabitation of exposed wild mussels and naïve C. gigas resulted in viral transmission after 14 days, under an elevated temperature regime. These results indicate that mussels can harbour OsHV-1 μVar; however, the impact of OsHV-1 μVar on Mytilus spp. requires further investigation.

Syngamid strongylids of the genus Mammomonogamus undoubtedly belong among the least known nematodes with apparent zoonotic potential and the real diversity of the genus remains hard to evaluate without extensive molecular data. Eggs of Mammomonogamus sp. are frequently found in feces of African forest elephants (Loxodonta cyclotis) and western lowland gorillas (Gorilla gorilla gorilla) in Dzanga-Sangha Protected Areas. Using sedimentation-based coproscopic techniques, we found the eggs of Mammomonogamus in 19·7% elephant and 54·1% gorilla fecal samples with 8–55 and 1–24 eggs per gram of fecal sediment for elephants and gorillas, respectively. We used a combination of light microscopy, scanning electron microscopy and analysis of cytochrome c oxidase subunit I (cox1) and a partial sequence of 18S rDNA isolated from single eggs to test the hypothesis of possible Mammomonogamus conspecificity in gorillas and elephants. Whereas 18S rDNA sequences were identical in both gorillas and elephants, we distinguished seven different haplotypes within the cox1. Two haplotypes were found in both gorillas and elephants suggesting sharing of Mammomonogamus. Assignment of the parasite to M. loxodontis is proposed. Provided sequences represent the first genomic data on Mammomonogamus spp.

Avian influenza viruses have become endemic in land-based domestic poultry and have crossed species barriers. Turkeys are an important host in influenza virus ecology because they are susceptible to infection with these viruses and are often involved in inter species transmission. Several previous studies reveal that waterfowl-origin influenza viruses can be more easily transmitted to domestic turkeys than to chickens. Studies indicate turkeys to be better hosts for low pathogenic avian influenza viruses isolated from commercial poultry operations and live bird markets in comparison to chickens. Moreover, turkeys require low, 50% infectious-dose titres from wild bird as well as poultry adapted viruses, suggesting their high susceptibility for infection following a low dose exposure. Additionally, interspecies transmission of swine influenza viruses to turkeys occurs frequently, thus turkeys may be considered as a bridge species between poultry and wildlife. These findings suggest that turkeys can be easily infected with influenza viruses of different origins and highlight the potential role of turkeys in the transmission and maintenance of influenza viruses between premises.

Rotavirus (RV) infection causes acute infantile diarrhoea in humans and animals and remains a major concern for vaccine development. The close proximity of humans to animals may foster cross-species infection resulting in the emergence of novel/unusual strains by genetic reassortment. In this study, we characterized 500 diarrhoeal samples for group A rotaviruses (RVA) from children (n = 290), piglets (n = 95) and calves (n = 115) in Northeast India during 2012–2013. The data showed that 142/500 (28·4%) faecal samples were positive for RVA with the highest level of infection detected in piglets (57/142, 40·1%) followed by children (51/142, 35·9%) and calves (34/142, 23·9%). Sequence-based G- and P-typing showed G1P[8] (25%) and G1P[7] (35%) were the prevailing genotypes in both humans and animals. Single cases of unusual genotypes, i.e. G9P[8], G5P[8] in humans and G1P[13], G1P[23] and G3P[7] in animals were also identified. Cluster analyses of the sequences showed regional strains were genetically closer to their homologous strains. However, human G5P[8] and porcine G1P[8] strains showed homology to heterologous hosts of their prototype strains. The subsequent global spread of unusual RV strains may result in their establishment over time, presenting challenges to future vaccine evaluation programmes. More studies on emerging genotypes are required to elucidate how RVA strains evolve post-vaccination. This study supports the need for continuous surveillance of RVA infections after detecting from diverse hosts in a common setting.

Aquatic wild birds are often carriers of low-pathogenic avian influenza viruses (LPAIVs). If H5 and H7 LPAIVs are transmitted to poultry and have the opportunity to circulate, a highly pathogenic AIV may arise. Contact with aquatic wild birds is one of the most important ways in which these LPAIVs can be introduced into poultry flocks. In this study, the transmissibility of a duck-originated H5 LPAIV between ducks and chickens was analysed in a series of animal experiments, using different transmission routes. Results indicate that the outcome of virus intake by chickens exposed to infectious ducks depends on the way the virus is presented. Faecally contaminated drinking water proved to be the most efficient route by which the virus can be transmitted to chickens. The results from this study also suggest that some duck-originated H5 LPAIVs may be introduced to poultry but do not have the potential to become established in poultry populations.

Influenza A viruses are enveloped viruses belonging to the family Orthomyxoviridae that encompasses four more genera: Influenza B, Influenza C, Isavirus and Thogotovirus. Type A viruses belong to the only genus that is highly infectious to a variety of mammalian and avian species. They are divided into subtypes based on two surface glycoproteins, the hemagglutinin (HA) and neuraminidase (NA). So far, 16 HA and 9 NA subtypes have been identified worldwide, making a possible combination of 144 subtypes between both proteins. Generally, individual viruses are host-specific, however, interspecies transmission of influenza A viruses is not uncommon. All of the HA and NA subtypes have been isolated from wild birds; however, infections in humans and other mammalian species are limited to a few subtypes. The replication of individual influenza A virus in a specific host is dependent on many factors including, viral proteins, host system and environmental conditions. In this review, the key findings that contribute to the transmission of influenza A viruses amongst different species are summarized.

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.