A Review of OIE Country Status Recovery Using Vaccinate-to-Live Versus Vaccinate-to-Die Foot-and-Mouth Disease Response Policies I: Benefits of Higher Potency Vaccines and Associated NSP DIVA Test Systems in Post-Outbreak Surveillance.

To rapidly return to trade, countries with OIE status, FMD-free country where vaccination is not practised, have destroyed emergency vaccinated animals, raising ethical concerns with respect to social values, the environment, animal welfare and global food security. This two-part review explores whether science could support eligibility to return to previous OIE status in 3 months irrespective of vaccinate-to-live or vaccinate-to-die policies. Here, we examine the benefits of higher potency (≥ 6 PD50 ), high-purity vaccines formulated from antigen banks for emergency use, their efficacy and performance in differentiating infected from vaccinated animals (DIVA) assays for post-outbreak surveillance. From an intensive programme of research, we conclude that high-quality, higher potency vaccines are proven to reduce FMD virus (FMDV) subclinical circulation and the risk of carriers. Broader coverage than predicted by serology suggests the potential to hold a few 'key' vaccine strains improving logistics and reducing the financial burden of antigen banks. The OIE should adopt formal definitions for emergency vaccination and emergency vaccines. In terms of supportive tools, we consider that the lack of OIE recognition of DIVA tests other than those of PANAFTOSA in cattle is a shortcoming. There is need for research on maternal antibody interference with DIVA tests and on the use of such tests to establish whether greater purification of vaccines improves performance. We consider that alignment of waiting periods for vaccinate-to-live and vaccinate-to-die in OIE Code Article 8.5.9 1 b. and c. is feasible until an acceptable level of statistical certainty for surveillance or target probability of freedom is established to substantiate the absence of FMDV infection or circulation. It is surveillance intensity rather than waiting periods that establishes the risk of residual FMDV. EU Directive 2003/85/EC implicitly recognizes this, permitting derogation of the OIE waiting periods.

A Review of OIE Country Status Recovery Using Vaccinate-to-Live Versus Vaccinate-to-Die Foot-and-Mouth Disease Response Policies II: Waiting Periods After Emergency Vaccination in FMD Free Countries.

For countries with OIE status, FMD free country where vaccination is not practised, vaccinate-to-live policies have a significant economic disincentive as the trade restriction waiting period is double that of vaccinate-to-die policies. The disposal of healthy vaccinated animals strictly for the purpose of regaining markets with debatable scientific justification is a global concern. The feasibility of aligning the waiting periods to facilitate vaccinate-to-live is explored. The first article of this two-part review (Barnett et al., 2015) explored the qualities of higher potency Foot-and-Mouth Disease (FMD) vaccines, performance of differentiating infected from vaccinated animals (DIVA) diagnostic assays particularly in vaccinates and carriers, as well as aspects of current limitations of post-outbreak surveillance. Here, the history behind the OIE waiting periods for FMD free status is reviewed as well as whether the risk of vaccinated animals and their subsequent products differ appreciably at 3 versus 6 months. It is concluded that alignment is feasible for vaccinate-to-live using higher potency FMD vaccines within the current OIE waiting period framework of 3 and 6 months blocks of time. These waiting periods reflect precedence, historical practicalities and considered expert opinion rather than a specific scientific rationale. The future lies in updated epidemiological and diagnostic technology to establish an acceptable level of statistical certainty for surveillance or target probability of freedom of FMDV (infection or circulation) not time restricted waiting periods. The OIE Terrestrial Code limits trade from a FMD free country where vaccination is not practiced to animal products and live non-vaccinated animals. The risk of FMDV in products derived from higher potency vaccinated animals is appreciably less than for countries with infected FMD status or even from a FMD free country where vaccination is practised for which the Code has Articles with guidelines for safe trade with time restrictions of 3 months or less. All these presume that key requirements in the implementation of emergency vaccination including appropriate vaccine match, vaccine application, susceptible population coverage, etc. are addressed.

A review of bovine anaplasmosis.

Bovine anaplasmosis, caused by Anaplasma marginale, is an infectious but non-contagious disease. It is spread through tick bites or by the mechanical transfer of fresh blood from infected to susceptible cattle from biting flies or by blood-contaminated fomites including needles, ear tagging, dehorning and castration equipment. Transplacental transmission of A. marginale may contribute to the epidemiology of bovine anaplasmosis in some regions. Bovine anaplasmosis occurs in tropical and subtropical regions worldwide. Cattle of all ages are susceptible to infection with A. marginale, but the severity of disease increases with age. Once cattle of any age become infected with A. marginale, they remain persistently infected carriers for life. Diagnosis of bovine anaplasmosis can be made by demonstration of A. marginale on stained blood smears from clinically infected animals during the acute phase of the disease, but it is not reliable for detecting infection in pre-symptomatic or carrier animals. In these instances, the infection is generally diagnosed by serologic demonstration of antibodies with confirmation by molecular detection methods. The susceptibility of wild ruminants to infection by A. marginale and the role of wild ruminants in the epidemiology of bovine anaplasmosis are incompletely known owing to lack of published research, lack of validation of diagnostic tests for these species and cross-reaction of Anaplasma spp. antibodies in serologic tests. Control measures for bovine anaplasmosis vary with geographical location and include maintenance of Anaplasma-free herds, vector control, administration of antibiotics and vaccination.

Surveillance for avian influenza virus subtypes H5 and H7 in chickens and turkeys farmed commercially in New Zealand.

AIM: To determine the status of avian influenza (AI) virus sub-types H5 and H7 of New Zealand's commercial chicken and turkey farms. METHODS: A cross-sectional serological survey, stratified by production sector, used a sample frame defined by those farms registered with the Poultry Industry Association of New Zealand (PIANZ) or the Egg Producers Federation of New Zealand (EPF). Sectors included were chicken broiler, caged/barn layer, free-range layer, pullet rearer and turkey broiler. The survey used a between- and within-farm design prevalence of 5% (95% confidence for chickens, 99% confidence for turkeys) and 30% (95% confidence), respectively, of AI virus subtypes H5 and H7. The epidemiological unit was the farm for the free-range layer sector, and the individual shed/barn for the other sectors. Serum samples were screened using a commercial generic influenza A indirect ELISA; positive samples were subjected to haemagglutination-inhibition (HI) testing for AI virus subtypes H5 and H7. A comprehensive investigation, that included widespread serological and antigenic screening, was carried out on all farms identified with serum reactors to either the H5 or H7 virus subtype. RESULTS: A total of 4,180 blood samples from 167 chicken and 10 turkey farms were collected and tested using ELISA. Positive ELISA results were returned from 26 farms, comprising 10 caged/barn layer, 14 free-range layer and two turkey (shed-raised) broiler farms. HI testing of ELISA-positive sera for the H7 subtype virus identified no positive sera in any sector. Reactors to the H5 subtype virus were limited to three free-range layer chicken farms; each farm returned a single serum reactor. Follow-up investigations on these free-range farms identified evidence of historic exposure to the H5 subtype virus on one farm, and concluded that the serum reactors identified in the initial sampling round on the other two farms were non-specific (false-positive) reactions. CONCLUSIONS: The survey found no evidence of active infection with notifiable AI viruses, and provided evidence of absence of exposure to AI virus subtypes H5 and H7 in the chicken broiler, caged/barn layer, turkey broiler and pullet-rearer sectors at a between- and within-farm prevalence of 5% and 30%, respectively, with 95% confidence. The results established commercial free-range layer farms as a risk sector for exposure to notifiable AI virus.

Toward a global foot and mouth disease vaccine bank network.

A network of foot and mouth (FMD) vaccine banks has been initiated with the support of vaccine bank managers and technical advisors that participated in a workshop held at the Institute for Animal Health, Pirbright, in the United Kingdom in April 2006. Terms of Reference that provide guidance for coordinated activities are under consultation. Practical and economic benefits can be realised from collaboration, which will be achieved through mutually acceptable mechanisms for the exchange of information and materials relevant to vaccine banks and their management. If administrative and technical hurdles can be overcome, the network has the potential to contribute significantly to the improved control of FMD worldwide. A 'global' and interactive vaccine bank association could be created by agreeing a system of resource sharing that could orchestrate additional emergency cover with vaccine or antigen from the reserves of network members.