A review of recent unexpected animal disease events in Japan and Korea and the follow-up action taken

Epidemiology of African Swine Fever and Its Risk in Nepal

African swine fever (ASF) is a highly contagious viral infection of domestic and wild pigs with high mortality. First reported in East Africa in the early 1900s, ASF was largely controlled in domestic pigs in many countries. However, in recent years ASF outbreaks have been reported in several countries in Europe and Asia. The occurrence of ASF in China, the largest pork producer in the world, in 2018 and in India, the country that surrounds and shares open borders with Nepal, has increased the risk of ASF transmission to Nepal. Lately, the pork industry has been growing in Nepal, overcoming traditional religious and cultural biases against it. However, the emergence of viral infections such as ASF could severely affect the industry’s growth and sustainability. Because there are no effective vaccines available to prevent ASF, the government should focus on preventing entry of the virus through strict quarantine measures at the borders, controls on illegal trade, and effective management practices, including biosecurity measures.

Agroterrorism targeting livestock: a review with a focus on early detection systems

Agroterrorism targeting livestock can be described as the intentional introduction of an animal disease agent against livestock with the purpose of causing economic damage, disrupting socioeconomic stability of a country, and creating panic and distress. This type of terrorism can be alluring to terrorists because animal disease agents are easily available. This review addresses the vulnerabilities of the livestock industry to agroterrorism. However, we also show that early detection systems have recently been developed for agroterrorism and deliberate spread of animal pathogens in livestock, including an agroterrorism intelligence cycle, syndromic surveillance programs, and computer-based clinical decision support systems that can be used for early detection of notifiable animal diseases. The development of DIVA-vaccines in the past 10 to 15 years has created, in principle, an excellent response instrument to counter intentional animal disease outbreaks. These developments have made our animal agriculture less vulnerable to agroterrorism. But we cannot relax; there are still many challenges, in particular with respect to integration of first line of defense, law enforcement, and early detection systems for animal diseases.

The challenges of classical swine fever control: modified live and E2 subunit vaccines

Classical swine fever (CSF) is an economically important, highly contagious disease of swine worldwide. CSF is caused by classical swine fever virus (CSFV), and domestic pigs and wild boars are its only natural hosts. The two main strategies used to control CSF epidemic are systematic prophylactic vaccination and a non-vaccination stamping-out policy. This review compares the protective efficacy of the routinely used modified live vaccine (MLV) and E2 subunit vaccines and summarizes the factors that influence the efficacy of the vaccines and the challenges that both vaccines face to CSF control. Although MLV provide earlier and more complete protection than E2 subunit vaccines, it has the drawback of not allowing differentiation between infected and vaccinated animals (DIVA). The marker vaccine of E2 protein with companion discriminatory test to detect antibodies against E(rns) allows DIVA and is a promising strategy for future control and eradication of CSF. Maternal derived antibody (MDA) is the critical factor in impairing the efficacy of both MLV and E2 subunit vaccines, so the well-designed vaccination programs of sows and piglets should be considered together. Because of the antigen variation among various genotypes of CSFV, antibodies raised by either MLV or subunit vaccine neutralize genotypically homologous strains better than heterologous ones. However, although this is not a major concern for MLV as the induced immune responses can protect pigs against the challenge of various genotypes of CSFVs, it is critical for E2 subunit vaccines. It is thus necessary to evaluate whether the E2 subunit vaccine can completely protect against the current prevalent strains in the field. An ideal new generation of vaccine should be able to maintain the high protective efficiency of MLV and overcome the problem of antigenic variations while allowing for DIVA.

Influenza type A virus: an outstandingly protean pathogen and a potent modular weapon

A remarkable debate recently arose on a global scale, about bioethics, biohazard, bioweaponry and bioterrorism issues related to scientific research concerning the induced transition of the highly lethal H5N1 avian flu virus from a non-pandemic to a tentatively pandemic strain, which might fall into malevolent hands. Appreciable ecogenetic complexity marks the main attributes of influenza type A viruses, namely infectivity, virulence, antigenicity, transmissibility, host range, endemicity, and epidemicity. They all shape, conjunctively, the outstanding protean nature of this pathogen, hence the modularity of the latter as a potent weapon. The present analysis inquires into those attributes, so as to profile and gauge threat, usability, impact and coping, particularly that the dimension of genetic engineering of this virus largely amplifies its potential. Within that context, various human interventions and misuses, including human experimental infections, undesirable vaccinations, as well as unauthorized and unskillful operations, led to bad corollaries and are also discussed in the present study. Altogether, a variety of interrelated properties underlying the complicatedness of and menaces posed by influenza A virus as a grave medical challenge, a dually explorable pathogen, and a modular biological warfare agent, are thereby illuminated, alongside with their scientific, strategic and practical implications.

Education of veterinary medical and other public health providers: linking interventions with health outcomes

A systematic literature review was performed to summarize the nature, implementation, outcomes, and long-term impacts of previously instituted interventions and programs aimed at educating veterinary public health providers. A logic model was developed to direct the literature search strategy, provide a framework for evaluating the relationship between veterinary public health professional education and their associated population health outcomes, and guide future training development and recommendations for the education of veterinary health professionals. Our literature review indicates that there is a relative lack of published literature that connects veterinary public health educational interventions to population health outcomes. Reasons for the lack of evidence to connect educational programs and population health outcomes include the evaluation of outcomes on a short-term rather than intermediate- or long-term basis, a lack of experimental studies, and infrequent grounding in population health or educational theory. Future intervention recommendations as suggested in the reviewed articles are also summarized.

An epidemiological analysis of the foot-and-mouth disease epidemic in Miyazaki, Japan, 2010

An epidemic of foot-and-mouth disease occurred in Miyazaki, Japan, beginning in late March 2010. Here, we document the descriptive epidemiological features and investigate the between-farm transmission dynamics. As of 10 July 2010, a total of 292 infected premises have been confirmed with a cumulative incidence for cattle and pig herds of 8.5% and 36.4%, respectively, for the whole of Miyazaki prefecture. Pig herds were more likely to be infected than cattle herds (odds ratio = 4.3 [95% confidence interval (CI): 3.2, 5.7]). Modelling analysis suggested that the relative susceptibility of a cattle herd is 4.2 times greater than a typical pig herd (95% CI: 3.9, 4.5), while the relative infectiousness of a pig herd is estimated to be 8.0 times higher than a cattle herd (95% CI: 5.0, 13.6). The epidemic peak occurred around mid-May, after which the incidence started to decline and the effective reproduction numbers from late May were mostly less than unity, although a vaccination programme in late May could have masked symptoms in infected animals. The infected premises were geographically confined to limited areas in Miyazaki, but sporadic long-distance transmissions were seen within the prefecture. Given that multiple outbreaks in Far East Asian countries have occurred since early 2010, continued monitoring and surveillance is deemed essential.

African swine fever: how can global spread be prevented?

African swine fever (ASF) is a devastating haemorrhagic fever of pigs with mortality rates approaching 100 per cent. It causes major economic losses, threatens food security and limits pig production in affected countries. ASF is caused by a large DNA virus, African swine fever virus (ASFV). There is no vaccine against ASFV and this limits the options for disease control. ASF has been confined mainly to sub-Saharan Africa, where it is maintained in a sylvatic cycle and/or among domestic pigs. Wildlife hosts include wild suids and arthropod vectors. The relatively small numbers of incursions to other continents have proven to be very difficult to eradicate. Thus, ASF remained endemic in the Iberian peninsula until the mid-1990s following its introductions in 1957 and 1960 and the disease has remained endemic in Sardinia since its introduction in 1982. ASF has continued to spread within Africa to previously uninfected countries, including recently the Indian Ocean islands of Madagascar and Mauritius. Given the continued occurrence of ASF in sub-Saharan Africa and increasing global movements of people and products, it is not surprising that further transcontinental transmission has occurred. The introduction of ASF to Georgia in the Caucasus in 2007 and dissemination to neighbouring countries emphasizes the global threat posed by ASF and further increases the risks to other countries. We review the mechanisms by which ASFV is maintained within wildlife and domestic pig populations and how it can be transmitted. We then consider the risks for global spread of ASFV and discuss possibilities of how disease can be prevented.

Pathogenicity and transmission studies of H5N2 parrot avian influenza virus of Mexican lineage in different poultry species

In 2004, a low pathogenic H5N2 influenza virus (A/parrot/CA/6032/04) was identified in a psittacine bird for the first time in the United States. Sequence and phylogenetic analysis of the hemagglutinin gene grouped the parrot isolate under the Mexican lineage H5N2 viruses (subgroup B) with highest similarity to recent chicken-origin isolates from Guatemala. Antigenic analysis further confirmed the close relatedness of the parrot isolate to Mexican lineage viruses, the highest cross-reactivity being demonstrated to Guatemala isolates. In vivo studies of the parrot isolate in chickens, ducks and turkeys showed that the virus, though did not cause any clinical signs, could replicate to high titers in these birds and efficiently transmit to contact control cage mates. The possibility that the parrot harboring the virus was introduced into the United States as a result of illegal trade across the border provides additional concern for the movement of foreign animal diseases from neighboring countries. Considering the potential threat of the virus to domestic poultry, efforts should be continued to prevent the entry and spread of influenza viruses by imposing effective surveillance and monitoring measures.