The spatio-temporal dynamics of a post-vaccination resurgence of rabies in foxes and emergency vaccination planning

We used a simulation model to study the spatio-temporal dynamics of a potential rabies outbreak in an immunized fox population after the termination of a long-term, large-scale vaccination program with two campaigns per year one in spring and one in autumn. The 'worst-case' scenario of rabies resurgence occurs if rabies has persisted at a low prevalence despite control and has remained undetected by a customary surveillance program or if infected individuals invade to the control area. Even if the termination of a vaccination program entails such a risk of a subsequent new outbreak, prolonged vaccination of a wild host population is expensive and the declining cost-benefit ratio over time eventually makes it uneconomic. Based on the knowledge of the spatio-temporal dynamics of a potential new outbreak gained from our modelling study, we suggest "terminating but observing" to be an appropriate strategy. Simulating the decline of population immunity without revaccination, we found that a new outbreak of rabies should be detected by customary surveillance programs within two years after the termination of the control. The time until detection does not depend on whether vaccination was terminated within the fourth, fifth or sixth years of repeated biannual campaigns. But it is faster if the program was completed with an autumn campaign (because next-year dispersal then occurs after a noticeable decrease in population immunity). Finally, if a rabid fox is detected after terminating vaccination, we determine a rule for defining a circular hazard area based on the simulated spatial spread of rabies. The radius of this area should be increased with the time since the last vaccination campaign. The trade-off between the number of foxes potentially missed by the emergency treatment and the cost for the emergency measures in an enlarged hazard area was found.     

Sylvatic rabies in Italy: epidemiology

Epidemiological data on sylvatic rabies in Italy, during 10 years, from 1977 to 1986 are reported. This rabies epizootic expanded to all the alpine arch from Trieste to Aosta, can be divided in five different outbreaks. The good knowledge of the infected alpine area helped us in the identification of rabies outbreaks and in rabies struggle and prevention. Data from the literature on the relationship: landscape/fox/density/fox hunting/rabies have been confirmed and contributed to disease eradication. In a ten year epizootic, no human cases of rabies have been reported thanks to continuing health education and pre/post infection vaccination of persons at risk. The systemic vaccination of dogs and grazing animals and the severe struggle to stray dogs and cats reduced rabies of domestic animals to 1/10 as compared with the other European countries. Hunter's education together with valuable rewards made possible a good monitoring of sylvatic rabies diagnostic and rabies eradication after the first wave of rabies. In order to eradicate the last two rabies outbreaks, oral fox vaccination, using attenuated live vaccine, has been carried out with immediate efficacious results.     

Rabies and brucellosis immunization status and adverse reactions to rabies vaccines in veterinary students.

Rabies pre-immunization has been recommended for high risk professions, including veterinarians. Cell-cultured rabies vaccines have considerably reduced the risk of post-vaccination neurological reactions found in earlier vaccines. However, some adverse reactions have been reported with Human Diploid Cell Vaccines. 329 French veterinary students were surveyed about their rabies and brucellosis vaccination status, the occurrence of adverse reactions to rabies vaccine, and their antibody titer monitoring practices. Questions also were asked to determine if mandatory rabies pre-exposure immunization upon entry to veterinary school motivated students to maintain their rabies pre-exposure vaccination. The overall vaccination rate was 98.5% for rabies and 17% for brucellosis. 19% of the rabies vaccinated students reported some form of adverse reaction, whatever the vaccine brand used, but not experienced systemic allergic reaction. Adverse reactions were twice more frequent in female than male students and were more frequent after primary series than revaccination series (Relative Risk = 1.76). Despite the mild reactions encountered, rabies pre-exposure vaccination has been well-accepted by French veterinary students. In contrast, vaccination against brucellosis was not as well-accepted for prophylaxis.     

Rabies-free status of Switzerland following 30 years of rabies in foxes

The European fox rabies epizootic starting in 1939 at the eastern border of Poland reached Switzerland on March 3, 1967. Rabies spread over large parts of the country until 1977, the year it caused three human deaths. In 1978 the first field trial world-wide for the oral immunization of foxes against rabies was conducted in Switzerland. Initially, the expansion of the vaccination area led to a rapid reduction in rabies cases. However, the 1990s were characterized by a recrudescence of rabies in spite of regular oral immunization of foxes. The last endemic case of rabies was diagnosed in 1996 after an adaptation of the vaccination strategy. A total of 17,109 rabies cases, of which 73% in foxes and 14% in domestic animals were diagnosed, leading to an estimated number of some 25,000 postexposure treatments in humans. To eliminate rabies, a total of 2.8 million baits containing a modified live virus were distributed--mostly by hand--in the field.     

Evaluation of Mass Vaccination Campaign Coverage Against Rabies in Dogs in Tunisia

In Tunisia, rabies continues to be considered as a serious public health concern. Very costly mass vaccination of dogs against rabies and expensive post‐exposure prophylaxis are prerequisites to maintain a low level of human rabies cases. In Tunisia, the implementation of mass vaccination campaigns at the national level has undoubtedly contributed to the drop of rabies endemicity, but the overall outcome is rather suboptimal. In this investigation, we wanted to estimate the extent of the vaccination coverage in dogs in three Governorates (Manouba, Kassrine and Mednine), by collecting data through questionnaires and interviews relevant to 1470 owned dogs. When the campaign is correctly applied, as in Manouba, almost all the targeted dog population can be reached by parenteral vaccination and an almost elimination of the disease can be evidenced. However, in Kasserine and especially in Medenine, where the vaccination coverage is lower than 31%, a reservoir for the disease can be maintained. To match the official figures of vaccination coverage, we should update the statistics of the size of dog population which seems to be bigger than what is assumed. In addition, we wanted to assess the level of involvement of the local population with the vaccination campaigns by marking vaccinated dogs with necklaces and establishing later on the vaccination coverage accordingly. The highest levels of vaccination coverage can be reached in the rural regions. Therefore, the low vaccination coverage in rural areas, reported at the national level, is more attributable to the lack of human and financial resources to reach remote regions. We think that rabies control programmes in Tunisia can be successful if vaccination coverage can reach 70% in all parts of the country. The achieved vaccination coverage should be estimated after random visits in many parts of the country and by checking valid vaccination certificates.     

Factors associated with the success of rabies vaccination of dogs in Sweden

Background

United Kingdom, Ireland, Malta and Sweden maintain their national provisions for a transitional period regarding rules concerning rabies vaccination and individual serological test for rabies neutralizing antibodies. The purpose of vaccinating dogs against rabies is to establish pre-exposure immunity and protect individual animals from contracting rabies.The aim of the study was to investigate factors associated with reaching the internationally accepted threshold antibody titre of 0.5 IU/mL after rabies vaccination of dogs.

Methods

The study was a prospective single cohort study including 6,789 samples from Swedish dogs vaccinated with commercially available vaccines in Sweden, and the dog''s antibody responses were determined by the OIE approved FAVN test. Information on potential risk factors; breed, age, gender, date of vaccination, vaccine label and the number of vaccinations, was collected for each dog. Associations between the dependent variable, serological response ≥ 0.5 IU/mL or < 0.5 IU/mL and each of the potential risk factors were investigated using logistic regression analysis.

Results

Of 6,789 vaccinated dogs, 6,241 (91.9%) had an approved test result of ≥ 0.5 IU/mL. The results of the multivariable logistic regression analysis showed that vaccinating with vaccine B reduced the risk of having antibody titres of < 0.5 IU/mL by 0.2 times compared with vaccination using vaccine A. Breed size was found significant as an interaction with number of vaccinations and age at vaccination as an interaction with day of antibody testing after last vaccination. In summary, larger breeds were at higher risk of having antibody titres of < 0.5 IU/mL but if vaccinated twice this risk was reduced. Moreover, there were a increased risk for dogs < 6 months of age and > 5 years of age to have antibody titres of < 0.5 IU/mL, but this was affected by number of days from vaccination till testing.

Conclusions

The probability of success of rabies vaccinations of dogs depends on type of vaccine used, number of rabies vaccinations, the breed size of the dog, age at vaccination, and number of days after vaccination when the antibody titres are tested. The need for a booster vaccination regimen is recommended for larger breeds of dog.     

Mathematic model for the population biology of rabies in raccoons in the mid-Atlantic states

A series of coupled differential equations was used to model the temporal dynamics of rabies in raccoons in the mid-Atlantic region of the United States. The model takes explicit account of the development of natural immunity to rabies and was used to evaluate culling and vaccination elimination strategies. For habitats typical of the mid-Atlantic states, and given the assumptions of the model, it was estimated that elimination of rabies in raccoons by culling may involve the annual removal of over 32% of the raccoon population or the yearly vaccination of up to 99% of the susceptible fraction. Assuming a constant marginal cost for both culling and vaccination, the model suggests that, whatever the actual cost of each method, the cheapest strategy will always involve either culling or vaccination alone. A combined strategy of culling and vaccination will be cheaper than culling alone only when the per capita cost of vaccination is around one-fifth or less the per capita cost of culling.     

Oral vaccination against rabies and the behavioural ecology of the red fox (Vulpes vulpes)

As a result of oral vaccination of foxes (Vulpes vulpes) against rabies, this virus disease has almost been completely eradicated from West- and Central Europe. In most countries, vaccine baits were distributed twice a year: during spring (March to May) and autumn (September to October). This strategy has shown to be able to control and eventually eradicate rabies. However, it remains to be clarified if this is the most cost-effective strategy. Astonishingly, the behavioural ecology of the target species, the red fox, did receive only limited attention selecting the periods when baits should be distributed. Considering the behavioural ecology and rabies epidemiology of foxes, territory owners seem to play a key role in the spread and maintenance of rabies. Thus, oral vaccination campaigns should be targeted primarily at these animals. It is suggested that the optimal timing for bait distribution in Europe is late autumn (November) or early winter (December), depending on the prevailing climatic conditions. Additional campaigns, when financially feasible, can be implemented in order to maintain a high vaccination coverage during the remaining year. Furthermore, different baiting strategies can be selected in case of re-infection or persistent residual foci.     

The economic implications of sylvatic rabies eradication in Italy

After more than 10 years of absence, sylvatic rabies re‐appeared in Italy in 2008. To prevent disease spread, three oral rabies vaccination (ORV) campaigns targeting red foxes were performed through manual distribution of vaccine baits between January and September 2009. As these campaigns proved unsuccessful, at the end of December 2009, baits started being distributed using helicopters, allowing uniform coverage of larger areas in a shorter time period. From winter 2009 to autumn 2016, a total of 15 ORV campaigns (four emergency, four regular and seven preventive ORV) were implemented through aerial distribution of baits. In this study, we assessed the costs of the aerial ORV campaigns, which were aimed at eradicating the disease and reobtaining the rabies‐free status. Cumulative costs per km² were estimated at €59.45 during emergency campaigns and ranged between €51.94 and €65.67 in the regular vaccinations. The main portion of costs for ORV programmes were related to baits supply and distribution: €49.24 (82.83%) in emergency campaigns and from €40.33 to € 43.35 in regular ORVs (71.97% and 66.02%, respectively). At the end of each ORV campaign, the efficacy of vaccination activities was estimated by assessing the proportion of foxes testing positive for tetracycline biomarker in jawbone, indicating bait intake. Results revealed that the proportion of foxes that ingested baits varied between 70.97% and 95.51%. Statistical analysis indicated that reducing the density of dropped baits could potentially lead to a cost‐saving of 22.81%, still maintaining a satisfactory level of bait intake by the fox population.     

Consideration of different outbreak conditions in the evaluation of preventive culling and emergency vaccination to control foot and mouth disease epidemics

In recent foot and mouth disease outbreaks, many healthy animals have been culled to prevent disease transmission. Emergency vaccination is discussed as an alternative to culling of unaffected animals. A spatial and temporal Monte–Carlo simulation model was used to compare preventive culling and emergency vaccination. Different outbreaks are described using additional influence factors such as airborne spread, farm density, type of index-case farm and delay until establishment of the control strategies. The fewest farms were infected establishing a combined strategy including a 1 km preventive culling and 1–10 km emergency vaccination zone around each outbreak farm. Taking the number of culled and vaccinated farms into account, vaccination around the first diagnosed farm combined with the baseline strategy (culling of outbreak farms, protection and surveillance zone, contact tracing) is to be preferred. In the present study, emergency vaccination was an effective control strategy especially in densely populated regions.     

上海市犬只狂犬病认定免疫点主要管理做法分析

强化犬只狂犬病免疫工作是从源头控制狂犬病的最有效措施。近年来,上海市按照《上海市养犬管理条例》的要求,通过严把免疫资质准入、规范内部管理、落实疫情报告责任、推进免疫质量考核等举措,使犬只狂犬病认定免疫点的布局日趋合理,文明服务更加规范,这已成为上海市民犬只狂犬病免疫的主渠道,免疫数量和质量逐年提升,构筑了良好的免疫屏障。今后在犬只狂犬病认定免疫点管理方面,上海市应强化疫苗源头管理,加大非法免疫惩处力度,合理认定免疫点整体布局,规范引导免疫行为和内部运行。     

The potential of oral vaccines for disease control in wildlife species

Numerous infectious diseases caused by bacteria or viruses persist in developed and developing countries due to ongoing transmission among wildlife reservoir species. Such diseases become the target of control and management programmes in cases where they represent a threat to public health (for example rabies, sylvatic plague, Lyme disease), or livestock production (for example bovine tuberculosis, brucellosis, pseudorabies), or where they threaten the survival of endangered animal populations. In the majority of cases, lethal control operations are neither economically feasible nor publicly supported as a practical means for disease management. Prophylactic vaccination has emerged over the last 15 years as an alternative control strategy for wildlife diseases, mainly driven by the success of widescale oral rabies vaccination programmes for meso-carnivores in North America and Northern Europe. Different methods have been trialled for the effective delivery of wildlife vaccines in the field, however oral vaccination remains the most widely used approach. Successful implementation of an oral wildlife vaccine is dependent on a combination of three components: an efficacious immunogen, a suitable delivery vehicle, and a species-specific bait. This review outlines the major wildlife disease problems for which oral vaccination is currently under consideration as a disease management tool, and also focuses on the technological challenges that face wildlife vaccine development. The major conclusion is that attenuated or recombinant live microbes represent the most widely-used vaccines that can be delivered by the oral route; this in turn places major emphasis on effective delivery systems (to maintain vaccine viability), and on selective baiting systems, as the keys to wildlife vaccine success. Oral vaccination is a valuable adjunct or alternative strategy to culling for the control of diseases which persist in wildlife reservoirs.     

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.     

Rabies oral vaccination of foxes during the summer with the VRG vaccine bait

The vaccination of foxes by distributing vaccine baits in the environment was initiated in France in 1986. Two campaigns per year were carried out: one in the spring and one in the autumn. After the spring campaigns, only 22-52% of fox cubs consumed vaccine baits compared to 75% of the adults and 70-80% of the adults or fox cubs after autumn campaigns. In order to reduce the period of time during which fox cubs do not have access to baits and are not immunised, a vaccination campaign was organised during the summer of 1992 over a contaminated area of 25,748 km2 where vaccines had never previously been given. Vaccine bait stability was assessed during the same summer in the field and their appetence tested on captive foxes. The efficacy of the campaign was evaluated by the relative decrease in rabies incidence and the rate of bait uptake by foxes compared to those from neighbouring areas vaccinated for the first time with the same vaccine during the spring or autumn. Summer vaccination significantly increased (P < 0.01) bait uptake by fox cubs (71%) compared with spring vaccination (39%), but no significant difference was observed for adult foxes. Moreover, the decrease in rabies incidence, measured during the 6-month period following the campaigns was less pronounced after summer vaccination (49% decrease) than when the first vaccination was carried out during the spring or autumn (79 and 72% decrease, respectively). Three campaigns led to an apparent elimination of rabies when the first campaign was performed in the spring or autumn, but only to a 76% decrease in rabies incidence density index when the first campaign was performed during the summer. The high thermostability of the Raboral VRG bait permits its use during the summer for an emergency campaign. For routine vaccination plans, however, the classical calendar of spring and autumn vaccination campaigns should continue to be preferred.     

Rabies Vaccination: Higher Failure Rates in Imported Dogs than in those Vaccinated in Italy

The current European Union (EU) legislation decrees that pets entering the EU from a rabies‐infected third country have to obtain a satisfactory virus‐neutralizing antibody level, while those moving within the EU require only rabies vaccination as the risk of moving a rabid pet within the EU is considered negligible. A number of factors driving individual variations in dog vaccine response have been previously reported, including a high rate of vaccine failure in puppies, especially those subject to commercial transport. A total of 21 001 observations collected from dogs (2006–2012) vaccinated in compliance with the current EU regulations were statistically analysed to assess the effect of different risk factors related to rabies vaccine efficacy. Within this framework, we were able to compare the vaccination failure rate in a group of dogs entering the Italian border from EU and non‐EU countries to those vaccinated in Italy prior to international travel. Our analysis identified that cross‐breeds and two breed categories showed high vaccine success rates, while Beagles and Boxers were the least likely to show a successful response to vaccination (88.82% and 90.32%, respectively). Our analysis revealed diverse performances among the commercially available vaccines, in terms of serological peak windows, and marked differences according to geographical area. Of note, we found a higher vaccine failure rate in imported dogs (13.15%) than in those vaccinated in Italy (5.89%). Our findings suggest that the choice of vaccine may influence the likelihood of an animal achieving a protective serological level and that time from vaccination to sampling should be considered when interpreting serological results. A higher vaccine failure in imported compared to Italian dogs highlights the key role that border controls still have in assessing the full compliance of pet movements with EU legislation to minimize the risk of rabies being reintroduced into a disease‐free area.     

Rabies vaccination compliance following introduction of the triennial vaccination interval--the Texas experience

In 2003 the Texas Board of Health approved a modification to the Texas Administrative Code that permitted pet owners to have their dogs (Canis familiaris) and cats (Felis catus) vaccinated against rabies every 3 years, provided a triennial vaccine was used. The change had been opposed by hundreds in the veterinary community, some concerned that its implementation would be followed by a decrease in rabies vaccination rates. To determine if this decrease had occurred, rabies vaccination rates for 4 years before and after migration to the 3-year vaccination interval were examined. Data for dogs and cats, ≥ 4 months of age, were collected from the Texas Department of Health Rabies Incident Report database. Each animal's record included its current rabies vaccination status. The number of animals that were currently vaccinated against rabies was tallied and the percent vaccinated was calculated. From 1999 through 2002, 46% of dogs were vaccinated against rabies. From 2004 through 2007, 56% of dogs were vaccinated against rabies. From 1999 to 2002, 18% of cats were vaccinated against rabies. From 2004 to 2007, 30% of cats were vaccinated against rabies. There has been a significant increase in the numbers of dogs (P < 0.001), and cats (P < 0.001), vaccinated against rabies since the introduction of the triennial vaccination interval. This observational study documents the positive changes in rabies vaccination rates following migration from a 1-year to 3-year vaccination interval.     

Terrestrial rabies control in the European Union: Historical achievements and challenges ahead

Due to the implementation of oral rabies vaccination (ORV) programmes, the European Union (EU) is becoming progressively free of red fox (Vulpes vulpes)-mediated rabies. Over the past three decades, the incidence of rabies had decreased substantially and vast areas of Western and Central Europe have been freed from rabies using this method of controlling an infectious disease in wildlife. Since rabies control is a top priority in the EU, the disease is expected to be eliminated from the animal source in the near future. While responsible authorities may consider the mission of eliminating fox rabies from the EU almost accomplished, there are still issues to be dealt with and challenges to be met that have not yet been in the focus of attention, but could jeopardise the ultimate goal. Among them are increasing illegal movements of animals, maintaining funding support for vaccination campaigns, devising alternative vaccine strategies in neighbouring Eastern European countries and the expanding distribution range of several potential rabies reservoir species in Europe.     

Incidence of adverse events in ferrets vaccinated with distemper or rabies vaccine: 143 cases (1995-2001)

OBJECTIVE: To determine the incidence of adverse events in ferrets vaccinated with a modified-live avian cell culture canine distemper virus vaccine licensed for use in ferrets, an inactivated rabies vaccine licensed for use in ferrets, or both. DESIGN: Retrospective study. ANIMALS: 143 ferrets. PROCEDURE: Medical records were reviewed to identify ferrets that had an adverse event after vaccination. RESULTS: Adverse events developed within 25 minutes after vaccination in 13 ferrets. One ferret developed an adverse event after receiving a distemper and a rabies vaccine simultaneously and developed a second adverse event the following year after receiving the rabies vaccine alone. Therefore, a total of 14 adverse events were identified. All adverse events were an anaphylactic reaction characterized by generalized hyperemia, hypersalivation, and vomiting. Ten of the 14 anaphylactic reactions occurred after ferrets received both vaccines, 3 occurred after ferrets received the distemper vaccine alone, and 1 occurred after a ferret received the rabies vaccine alone. Incidences of adverse events after administration of both vaccines, the distemper vaccine alone, and the rabies vaccine alone were 5.6, 5.9, and 5.6%, respectively. Ferrets that had an anaphylactic reaction were significantly older at the time of vaccination than were ferrets that did not. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that there may be a high incidence of anaphylactic reactions after vaccination of domestic ferrets. Ferrets should be observed for at least 25 minutes after vaccination, and veterinarians who vaccinate ferrets should be prepared to treat anaphylactic reactions.     

Postexposure rabies prophylaxis protocol for domestic animals and epidemiologic characteristics of rabies vaccination failures in Texas: 1995-1999

OBJECTIVE: To determine whether postexposure rabies prophylaxis (PEP) in domestic animals, as mandated by the state of Texas, has continued to be effective and to evaluate PEP and preexposure rabies vaccination failures from 1995 through 1999. DESIGN: Retrospective study. ANIMALS: 830 unvaccinated domestic animals (621 dogs, 78 horses, 71 cats, and 60 cattle) that received PEP and 4 animals (3 dogs and 1 horse) that had preexposure rabies vaccination failure. PROCEDURE: Zoonotic incident case reports from 1995 through 1999 were reviewed for information regarding unvaccinated domestic animals that received PEP according to state protocol after exposure to a rabid animal; reports were also reviewed for information regarding preexposure rabies vaccination failures. The PEP recommendations were to immediately vaccinate the animal against rabies, isolate the animal for 90 days, and administer booster vaccinations during the third and eighth weeks of the isolation period. Rabies vaccines used in the PEP protocol were administered via the route prescribed by the USDA. RESULTS: From 1995 through 1999, 830 animals received PEP; 4 failures were recorded. Additionally, 4 preexposure rabies vaccination failures were recorded. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study indicate that an effective PEP protocol for unvaccinated domestic animals exposed to rabies includes immediate vaccination against rabies, a strict isolation period of 90 days, and administration of booster vaccinations during the third and eighth weeks of the isolation period. This PEP schedule has proven to be effective for control of rabies in domestic animals.     

Importation of dogs into the United States: risks from rabies and other zoonotic diseases

The importation of dogs into the United States poses a risk for the introduction of rabies and other zoonotic diseases. Federal regulations (42 CFR 71.51) currently require proof of valid rabies vaccination for imported dogs, but allow the importation of some unvaccinated dogs, including dogs less than 3 months of age, provided certain requirements for confinement are met until the dog is vaccinated. Although there are no accurate surveillance data on the number of dogs imported each year, it is estimated based on extrapolated data that over 287,000 dogs were imported into the United States during 2006. Of these, approximately 25% were either too young to be vaccinated or lacked proof of valid rabies vaccination. Import trends suggest that an increasing number of unvaccinated puppies are being imported into the United States, many through commercial resale or rescue operations. Since 2004, foreign canine rabies virus variants have been documented in at least two imported puppies. Federal regulations are currently being reviewed by the Centers for Disease Control and Prevention to determine if they can be updated to address current import trends and disease risks, such as requiring a health screen and valid rabies vaccinations for all dogs prior to entry.