Who's Better At Biosecurity?
There are a lot of recommendations out there for establishing or improving sound infection control practices on horse farms, many of which can be found on this very blog. Some refer to such practices as "biosecurity," but what's done on horse farms compared to the often very strict biosecurity protocols at facilities such as swine or poultry operations (e.g. all-in all-out management, closed barns, shower in) is very different, so we prefer to call it an infection control program, rather than "biosecurity." Regardless, one of the biggest challenges with regard to infection control, in almost any setting, is getting people to comply with all the various policies and recommendations. Unfortunately, it's not enough to just tell people what needs to be done (that'd be too easy!) - knowledge by itself usually won't change people's behaviour. They also need to be motivated to change their behaviour, for example by the potential for a positive reward (e.g. they get to take their horses to shows) or the potential to avoid a negative outcome (e.g. their horses don't get sick). Furthermore, individuals need to really believe they are capable (physically and mentally) of performing the required tasks - if they don't think they can do it or be effective at it, they're unlikely to try. In reality, getting people to change their behaviour to adopt sound infection control practices can be quite complex.
A study soon to be published in Preventative Veterinary Medicine (Schemann et al. in press) looked at some of the factors that affect horse owners' biosecurity practices and perceptions. The study was performed in Australia one year after the devastating equine influenza outbreak that occurred in 2007, using an online questionnaire to which 759 horse owners responded. Each owner's biosecurity compliance was rated as low (30%), medium (20%) or high (50%) based on how often they reported using 16 different infection control measures.
Factors that were associated with low compliance or poor biosecurity practices included people who:
- were younger in age
- had two or more children
- were not involved with horses commercially
- had no long-term business impact from the 2007 equine flu outbreak
- were not fearful of a future outbreak of equine flu in Australia
- thought their current hygiene and access control practices were not very effective in protecting their horses
Now, studies based on surveys of this kind always need to be taken with a grain of salt, as the study population itself was difficult to define and the information was all self-reported by owners, which can lead to confounding and misclassification bias. Nonetheless, the results are still interesting and on the whole are consistent with behaviour theory. Those whose income and livelihood were not dependent on the horse industry, and those who were not fearful of another outbreak, would be less motivated to put the effort into infection control measures. Furthermore, those who felt that what they were doing already wasn't really effective (for whatever reason) would be less motivated to try harder because they can't see the benefit. It's quite possible (as the authors speculate) that having two or more children results in less compliance with infection control simply due to the time constraints associated with having kids. Lack of time to properly perform infection control procedures is a major barrier to compliance, even in human hospitals, particularly with understaffing issues. The lower compliance among young people is also common to studies looking at protective behaviour in human health, possibly because young people have a sense of certain degree of invulnerability that results in riskier behaviour overall.
When it comes to infection control, the old adage "a chain is only as strong as its weakest link" is very important to remember. Although 50% of the horse owners in this study reported having high biosecurity compliance, the 30% with low compliance could ruin all their efforts should another outbreak occur, by contributing to the transmission and propagation of the disease on their own farms as well as to others. Hopefully this study will help the horse industry and government identify specific groups (i.e. young people, those not financially dependent on horses) at which educational and motivational campaigns can be targeted in the future.
World Rabies Day
While it's not really an occasion to celebrate, September 28 was World Rabies Day. Rabies has been a problem for millennia, and it's not going away any time soon. This viral disease, which is almost invariably fatal, kills 50 000 - 70 000 people per year. Some countries have astounding rates of rabies cases, such as India where ~20 000 people die of the disease every year. Internationally, most human rabies infections are caused by dogs, but wildlife are the main source in some regions (such as Canada and the US) . Basically all rabies infections are preventable with proper access to good medical care and rabies post-exposure prophylaxis, but sadly the thousands of people who die do not receive treatment.
Is rabies controllable? Yes. With measures to reduce rabies in wild and stray animals, pet vaccination, public education measures, good access to medical care, adequate rabies vaccine supplies and adequately trained healthcare personnel, the incidence of rabies can be dramatically decreased. However, these measures require time, money, effort and political will, and those are limitations in some areas.
Can rabies be eradicated? That's a tough question. Eradicating a disease that can be found in many wild animal species internationally is extremely difficult. It's hard to envision complete eradication of this virus, as was done for smallpox (a human-only disease) and rinderpest (a cattle-only disease). Both those diseases had the advantage of only being found in one species, making control and eradication much more feasible. However, while we might not be able to eradicate rabies, it's certain that tens of thousands of lives could be saved every year with good rabies control programs.
More information about rabies can be found in on the Worms & Germs Resource page.
Canine flu in Texas
An outbreak of canine influenza is occurring in San Antonio, TX, as this virus continues its strange and unpredictable movement through the North American dog population. In an article published on a local San Antonio news website, Dr. Michele Wright, a San Antonio veterinarian, reports 20 confirmed and 70 suspected cases over the past month. It's not clear whether these are all from her clinic, nor is there any information about possible sources of the virus or the severity of disease. Dr. Wright also states that the virus has been identified in Austin and Dallas.
It's not particularly surprising that canine flu has been found in Texas. It's now been identified in at least 38 US states, as well as one Canadian province. An outbreak is not particularly surprising either in this case, because when a virus reaches a new area, it can easily cause widespread disease since it encounters a population of animals that don't have any pre-existing immunity (i.e. antibodies) against it.
What's strange about canine flu is how it has spread across North America. When it was first identified in Florida greyhounds in 2004, it seemed like it was going to spread widely across the dog population. It spread quickly at greyhound tracks and in clusters in Florida and in other states, but it's subsequent spread across the continent was quite patchy - it caused only localized outbreaks in different states, instead of the catastrophic continent-wide epidemic that was anticipated. Whether this relates to the amount and type of direct contact between dogs (e.g. dogs are only infectious for a short period of time and an infected dog has to meet a susceptible dog during that time to continue transmission of the virus, otherwise it dies out), specific aspects of the virus in dogs (e.g. how long it is shed) or lack of recognition of disease in some areas (e.g. mild disease that doesn't get diagnosed) is unclear.
We've been looking for canine flu in Ontario for a few years now, with no "success" (that is, we haven't found it yet).
Are we flu-free at the moment? Probably not. I suspect it's lurking out there, but it's possible that it really hasn't made it to Ontario - yet.
If it's not here now, will it make it here eventually? Almost certainly. It's taking longer than I expected but all it takes is one infected dog entering the country. With the amount of cross-border dog movement, it's probably inevitable.
What about vaccination for canine flu? It comes down to risk of exposure and risk aversion. If flu is in the area, vaccination is a good idea. If flu is in adjacent areas, it's also a good idea. If flu isn't recognized in the area, it's a matter of how much risk people are willing to take and thinking about higher risk situations, as described below.
What about vaccination in Ontario, or other places where the virus doesn't seem to be present? It's hard to say when to recommend canine flu vaccination. Certainly, vaccination of dogs traveling to areas where canine flu is or has been present is a good idea. Vaccination of dogs that engage in high risk activities such as going to shows or kennels is also prudent, since these are the places where we may see the firsts outbreaks if/when canine flu makes it here. Vaccination of low-risk dogs in the province is probably not necessary at the moment (unless people are very risk averse and don't want to take any chances).
Why vaccinate? It's just "the flu"... This is an attitude that the human public health field battles all the time. Most people who get human influenza (humans can't get the dog version of the virus) feel crappy for a few days and get over it. The perception that it's only and always a mild disease keeps some people from getting vaccinated. However, thousands of people die from flu complications, particularly the very young and elderly individuals. Vaccinating everyone helps reduce the chance that these high-risk people will get sick. Also, while rare, serious (including fatal) infections can occur in otherwise healthy people. In dogs, there's probably actually more indication to vaccinate if there is a realistic risk of exposure. Canine flu can cause classical flu-like disease, akin to the typical human case. However, severe (often fatal) pneumonia can also occur in otherwise healthy dogs. High rates of severe disease were reported initially when canine flu was first identified. It seems like severe disease rates have dropped, but it's still a concern. I wouldn't be surprised if severe disease is more common in dogs with canine flu than in people with human flu.
Whether or not to vaccinate is a discussion dog owners should have with their veterinarian, considering the risk of exposure, risk of severe illness and risk aversion. At the same time, people in areas where flu has not been identified need to be on the lookout for it, to ensure that it gets diagnosed promptly if it emerges, and that information gets communicated to veterinarians and the dog-owning public so that appropriate responses can be made.
Another EHV-1 Equine Hospital Quarantine
Once again, an equine hospital is under quarantine because of equine herpesvirus type 1 (EHV-1). There have been a number of such incidents this year, highlighting both the increasing concern with this important pathogen and perhaps more transparency and willingness on the part of hospitals to take aggressive infection control measures when it is detected.
The latest incident involves the University of Tennessee Equine Hospital. The entire situation is related to identification of EHV-1 infection in one horse that was admitted on September 15 and euthanized a few hours later because of severe and progressive neurological disease. The next day, the Tennessee state veterinarian implemented a seven-day quarantine, while the hospital voluntarily implemented a 14-day quarantine. Seven days is pretty short and if you're concerned enough that you think quarantine is needed - if it's going to be done at all, it should be done right (i.e. for longer than a week).
At last report, there was no evidence of transmission to other horses. Presumably university personnel are closely watching horses in the hospital and are hopefully in contact with people who had horses they after the EHV-1 horse was admitted but before quarantine was implemented.
The need for facility closure or quarantine is always something of debate. EHV-1 should be a containable problem with prompt recognition of affected horses, proper isolation facilities and compliance with infection control procedures. Identifying infectious horses is a key aspect, as they are not always screaming "I have EHV!" when you see them. If a horse with EHV isn't identified as a potentially infectious animal and isolated from the start, the risk of transmission goes up. In this case, it was stated that the horse was kept in a "separate area of the equine hospital." It's not clear whether this was in an isolation unit or not. If it was admitted directly to isolation and was handled with appropriate protocols, the risk of other horses being infected should be very low. Given the time frame involved (it was only in the hospital for a few hours), even if it was in the main hospital, the likelihood of transmission to other horses is probably still relatively low, but it's certainly possible.
From a disease control standpoint, it's much better to be overly aggressive at the start while you are sorting out what's going on rather than sitting back and hoping for the best. While this often results in negative publicity, it's better than ending up with an outbreak which results in even worse publicity, as well as more sick animals.
EPM Testing
Equine protozoal myeloencephalitis (EPM) is a frustrating disease. It's been referred to as one of the most overdiagnosed, underdiagnosed and misdiagnosed equine diseases - an apt description. In some areas, every horse (particularly every racehorse) that has any real or perceived abnormality (such as not running fast enough) gets treated, usually without any attempt to make a true diagnosis. Most of these animals don't have EPM, but some might, along with horses displaying a range of sometimes vague neurological signs. When an effort is made to really establish a diagnosis, unfortunately it's not straightforward, which leads to more confusion about the disease and how to manage it.
The Animal Health Diagnostic Center at Cornell University have released a document on EPM testing and diagnosis. This document discusses when and why to test, along with important information about the available, recommended tests. It's a nice, comprehensive overview of the subject and worth a look for equine veterinarians as well as horse owners wondering whether their horse may have this enigmatic disease.
Classroom pets...Things to consider
Having pets in school classrooms is a somewhat controversial subject. For every good point that's raised (e.g. promoting empathy, entertainment, learning about animals and their care) there are bad points (e.g. poor environment for the pet, rough handing, disorganized or absent medical care, disease transmission, fear, allergies, distraction). Some organizations have developed detailed guidelines for using animals in classrooms, but animals are often in classrooms with little consideration of the issues. Little is known about what happens with these pets. We tried to do a survey of teachers from some school boards a few years ago and only ended up getting about two responses out of hundreds of eligible teacher participants (the overall lack of support from board administration didn't really help get the survey out and get teachers interested either, but that's another story). So, we really don't have a good idea of the types of animal contact that occur in classrooms or the problems that result, but we know from various case reports that complications like infections can and do occur.
PetSmart and the Pet Care Trust have a "Pets in the Classroom" program where kindergarten to grade six teachers can get support for having a pet in the classroom. Their release outlines a few of their perceived benefits, and some of the complexities of having pets in classrooms. Their points are in italics, with some comments from me.
Hamsters make fun classroom pets because they are active and teach children the importance of schedules and responsibilities.
- Yes and no. They can be entertaining, but they can also be distracting. You have to differentiate something that's a novelty from something that is being used as part of the educational curriculum. Hamsters can be injured with rough handling by young children and close supervision is required. They may also bite when handled, especially when handled by young kids who don't know what they are doing. Plans to take care of the hamster over holidays and the summer are needed, and are often not considered in advance. The disease risks of hamsters are relatively low, but not non-existent. Having nocturnal animals in a busy daytime setting is also questionable ethically.
Guinea Pigs are easily handled and encourage children to follow a regimented routine.
- They are similar to hamsters in their benefits and risk, but their larger size makes them more robust and less prone to handling injury. They are probably one of the better mammals to have in a classroom, but still require good organization, planning and practices.
Fish are a great way to illustrate basic chemistry and biology principles while students follow regularly scheduled water changes.
- Fish can be great classroom animals. There are ways to incorporate them into the curriculum, from behaviour to animal care to feeding to water quality and environmental concerns. They need some care, with regular feeding and proper water maintenance, but with basic supervision and planning, the risks to the animals and people are minimal and they can be of benefit educationally.
Bearded Dragons depend on their environment for heating and cooling and are a great way to teach about geography and the environment.
- Bearded dragons (see image) are great little reptiles with a lot of personality. However, they have specific requirements for care and feeding, something that cannot be easily fulfilled in a lot of classrooms. Also, being reptiles, they are high risk for Salmonella shedding. In a low risk household, it's not a big deal with basic hygiene practices. However, in a classroom with lots of kids, perhaps limited enforcement of hygiene, and kids eating in the area where the reptile is, the risks get higher. General guidelines are that children less than five years of age and people with compromised immune systems should not have contact with reptiles. This means they should not be in kindergarten classrooms or rooms where such students may spend time. More complicated is the issue of immunocompromised individuals. I'm not convinced that teachers always know when one of their students is immunocompromised, and what happens if there's an established pet and a student becomes immunocompromised? Bottom line: Reptiles shouldn't be in classrooms.
Leopard Geckos are docile in nature and teach children about different nocturnal behaviors.
- These are interesting little critters, but not good classroom pets, like other reptiles, for the reasons outlined above. Nocturnal pets may not be great for classrooms either since the daytime activity and disruption may be harmful to them in the long term.
Certain pets can be good additions to certain classrooms, with some logical planning and common sense, but poor planning and bad animal choices can be harmful to students and animals. School boards should be proactive and develop or adopt sound protocols for classroom pets.
Equine Infectious Neurological Disease Update: Ontario
The latest update on equine infecious neurological diseases in Ontario (Eastern equine encephalitis (EEE), West Nile virus (WNV), rabies and neuropathic equine herpevirus type 1 (EHV-1)) is available from the Ontario Ministry of Agriculture, Food and Rural Affairs.
There aren't a lot of surprises, and it's good to see the numbers of cases have remained relatively low. Most notably, there have been three EEE and five WNV cases confirmed, from different regions of the province. This shows that these diseases are still occurring in Ontario horses, albeit at a very low rate.
You always have to consider the limitations of surveillance data like this. To make the list, a horse has to get infected, get sick enough for someone to notice, a veterinarian has to be called and proper samples have to be taken for diagnostic testing. There's certainly no guarantee that this happens in all instances, and it's reasonable to assume that a few more cases of these diseases have occurred in Ontario this year.
In Ontario, August and September tend to be the months of highest activity for EEE and WNV, and as we move into cooler weather (and decreased mosquito activity) the risk of EEE and WNV will start to plummet. I wouldn't be surprised if the numbers increase slightly by the time the final tally is made, but there are no indications that we have major disease activity at the moment.
Surveillance data such as this, including total numbers of cases in the province and an indication of areas where case occur, are important for horse owners and veterinarians to consider when determining their vaccination programs.
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Equine Biosecurity Risk Calculator
After an extensive development and review process, an Equine Biosecurity Risk Calculator (click here) is now available online on the Equine Guelph website. This joint venture of Equine Guelph and Colorado State University, with support from the AAEP Foundation and Vetoquinol, is designed to offer practical advice on equine infectious disease risk and control.
While no one can really give an exact number regarding "risk" of infectious diseases on any particular equine facility, it is possible to identify areas in need of improvement. That's what this "calculator" is designed to do. Horse owners can complete the online questionnaire and get a general assessment of risk, plus detailed information about areas of concern. The calculator is free to use and no identifying information is collected.
Every horse owner should try this and see what areas are identified that could be improved. While facilities are quite variable in their application of infection control practices, I've yet to encounter a "perfect" facility - undoubtedly everyone will get at least a few ideas to consider to help reduce the risk of infectious disease in their animals.
MRSA from foal to girl
A case report highlighted by TheHorse.com and presented at the ASM/ESCMID MRSA conference in Washington DC last week described a horse-associated methicillin-resistant Staphylococcus aureus (MRSA) infection in Dutch girl.
The girl, a 16-year-old with a severe neuromuscular disease who was wheelchair-bound and on a ventilator, developed an infection following an insect bite. When the infection didn't respond to initial treatment, a sample was taken for culture and MRSA was identified. The girl didn't have any known risk factors for MRSA infection but had had close contact with a foal. The Friesian foal had been at a veterinary hospital prior to the girl's infection. It had a wound infection that was successfully treated with antibiotics, but no culture was taken at the time. The foal was considered a possible source of the MRSA, particularly since the strain that was recovered was ST398, which is widely found in livestock and which is regularly seen in horses in the Netherlands. After the girl's infection was identified, the foal was tested and was also found to be carrying MRSA. The girl's infection was successfully treated and the foal eliminated MRSA carriage without treatment (which is expected in horses because long-term carriage of MRSA seems to be rare to non-existent in this species).
The source of the infection could not be definitively proven, but given the fact that the horse was at a facility that regularly sees MRSA cases, that the strain involved is typically associated with livestock, and that the girl had no other livestock contact, it's a reasonable to assume it came from the foal.
We've known for a few years that MRSA is an issue in horses, and that it can be passed between horses and people - in both directions. Equine veterinarians and horse owners have abnormally high MRSA carriage rates. MRSA carriers are people who have MRSA living in or on them (most often in the nose) without any signs of infection. Most carriers never have a problem, but disease can develop in some situations. The incidence of human MRSA infections transmitted from horses is low, although it's almost certain that many horse-associated MRSA infections are not reported because the link with horses isn't made or people don't mention the horse contact. TheHorse.com article is incorrect in stating that this is only the third case of horse-to-human MRSA infection, since we've already published two such reports, one of which included multiple cases. Regardless, it's an uncommon problem but it is probably also under-recognized. Horse owners shouldn't panic about MRSA, but they should realize that MRSA is circulating in the horse population and that by nature of their frequent and close contact with horses, they are at higher risk for MRSA carriage, and likely also infection.
More information about MRSA in horses can be found on the Worms & Germs Resources - Horses page.
Safe Sex For Horses
The recent (or, I guess, not so recent, since it seems to have been lingering in the background for a while) contagious equine metritis (CEM) outbreak in the US was a good demonstration of the potential impact venereally transmitted diseases can have on the horse industry. Concerns about such things are greatest in breeds that only allow live cover, since an individual stallion may be exposed to a large number of mares every year, and with the mobile nature of the horse population, it's possible for one infected horse to disseminate an infection widely across or between countries.
While CEM is probably the highest profile venereal disease in horses, it's not the only one. Other pathogens like equine arteritis virus and equine herpesvirus type-3 (equine coital exanthema virus) are also of concern, along with various opportunistic bacteria.
Proper management and infection control practices can greatly reduce, but not eliminate, the risk of sexually transmitted infections in horses. Unfortunately, such practices aren't always used. Sometimes it's because of lack of consideration or laziness. Sometimes it's because of lack of awareness. To help improve awareness and make it easier for people to take appropriate precautions, the American Association of Equine Practitioners (AAEP) has recently released Biosecurity Guidelines for Control of Venereally Transmitted Diseases. It's an excellent resource for veterinarians and horse owners, and should be part of the infection control program for anyone breeding horses.
Economic Impact Of Aussie Horse Flu
A huge equine influenza virus outbreak occurred in Australia in 2007 - a classic example of what can happen when a virus gets into an area where it's never been before. There were huge numbers of affected horses and a massive disruption to the industry due to quarantines and other control measures.
A special edition of the Australian Veterinary Journal (July 2011) includes a series of papers covering different aspects of this outbreak. In one paper (Smyth et al) the authors look at the economic consequences and tried to determine the financial costs of the outbreak. Such estimates are always tough to make and can never be 100% accurate, but they can give a general idea of the scope and impact of an outbreak. Not surprisingly, the costs were pretty astounding.
Australian Government
A series of measures were implemented to assist individuals and organization that were impacted. The total cost of those packages was over $263 million AusD.
State/Territory Governments
New South Wales and Queensland were most seriously affected, but all states and territories were impacted. These governments provided support in addition to the federal funds. For example, Queensland allocated over $27 million to various efforts, while New South Wales contributed more than $46 million.
Racing and Wagering Western Australia
This is the government body that regulates racing in Western Australia. The outbreak cost this agency around $500 000, a figure that does not include lost employee time and approximately $15 million in lost wagering revenue. Some of this was recovered through insurance, but it's now unlikely that they will be able to get further insurance to cover outbreaks.
Harness Racing Industry
It's always hard to figure out the true costs to an industry after a major disaster because the trickle down effect goes so far, affecting people who provide support and services (e.g. hay suppliers) to various businesses that are affected directly because people in those groups don't have money to spend. The total identifiable costs were calculated to be over $23 million, about half of which was to owners and trainers. The authors acknowledge the true costs were probably much higher.
Inquiry
A large inquiry was commissioned after the outbreak. This cost over $5 million.
Animal Health Australia
This group coordinated the emergency response and had to divert tremendous personnel time and resources. This included the vaccination program that distributed 670 000 doses of vaccine.
Households and businesses
Overall, it was estimated that horse associations lost $281 million, horse businesses $65 million and households $34 million.
Horse deaths
The value of horses that were reported to have died was close to $1 million, despite the fact that equine flu is uncommonly fatal. This number doesn't include intangible costs associated with losing a horse. However, reported deaths may be a minority and it was estimated that true horse death costs may have been $44 million. (However, I suspect the death rate estimate used for this value is high.)
Veterinary treatment
Estimated costs...$35.7 million.
Do the exact numbers matter? No. They simply show that an infectious disease outbreak can cost a lot. In many areas, horses receive little government attention because they are not food animals, despite the fact that the highly mobile horse population is probably at much higher risk of importing a new disease, and despite the fact that the economic impact of the industry is huge (and often overlooked by governments and groups that fund agricultural research).
If nothing else, this should serve as a reminder to government and industry groups that attention needs to be paid to infection control and emergency planning. While groups are often reluctant to put much or any time, effort and funds into these areas, the amount of money that would be spent is inconsequential compared to the potential impact of even a small outbreak.
Image source: www.dailyclipart.net
Proposed US dog importation changes
The USDA's Animal and Plant Health Inspection Service (APHIS) has announced proposed changes to dog importation rules. The changes would tighten rules for dogs being brought into the country for resale, research or veterinary treatment. The reason for the sudden changes isn't clear, but it may be the result of a couple of high-profile importations of rabid dogs. Regardless, it makes sense to pay more attention to companion animal importations, as long as the requirements are practical. The practicality aspect is of particular concern for the large number of people that travel between Canada and the US with their dogs, which is pretty low-risk from an infectious disease standpoint. Balancing policies that help prevent introduction of serious diseases with rules that don't unnecessarily complicate the frequent cross-border movement of people and their pets can be tough. This proposal doesn't cover pet dogs, which is both good and bad.
With the proposed changes, dogs imported for resale, research or veterinary treatment must have:
- an original health certificate
- a valid rabies vaccination certificate
- have an APHIS-issued import permit
The health certificate must clearly describe the dog and certify that:
- it's at least six months of age
- it was vaccinated no more than 12 months prior to the date of importation against distemper, hepatitis, leptospirosis, parvovirus and parainfluenza virus
- it's in good health and "free of any infectious disease or physical abnormality that would endanger the dog or other animals or endanger public health, including parasitic infection, emaciation, lesions of the skin, nervous system disturbances, jaundice or diarrhea."
That's pretty standard, however the last statement can sometimes cause issues. Here, the language is better than in some other protocols because it says "disease," not "infection." It may seem like a minor point, but to me it means a lot. If someone asks me to certify that my dog does not have an infectious disease, I can do that. She doesn't have any clinical evidence of an infection. If someone asks me to declare that she's free of infection, it gets trickier, because infection could be interpreted as disease, but it could also be interpreted as simply carrying an infectious agent. Every dog is carrying multiple microorganisms that could "endanger the dog or other animals or endanger public health" but the risk is rather low from clinically healthy dogs. No veterinarian can ever certify that a dog is not carrying any microorganism that could cause disease.
The restriction of importation for veterinary treatment is a bit of a concern, because in some areas the closest veterinary clinics or referral centres are across the border (one way or the other). It's a difficult issue, because dogs being taken to a veterinarian may be sick, and a veterinarian can't certify that such an animal is free of disease. The report states that "limited exceptions" will be made for the health certificate and rabies vaccination certificate for dogs imported for veterinary care. What "limited exceptions" means and how quickly an exemption can be obtained may determine whether this will impact the availability of veterinary care in some border regions.
Overall, more scrutiny of dog importation makes sense, particularly dogs being imported from developing countries where a variety of imported or exotic diseases may be present. However, these rule changes won't necessarily have an impact on some of the import-associated disease problems that have occurred recently. The current changes only involve dogs imported for resale, research or veterinary treatment. Importation of dogs for research is presumably uncommon and research colonies have pretty strict rules, so I doubt there's a lot of risk there. I also think it would be quite rare for dogs from high risk areas to be imported for research. Importation for veterinary care is also pretty uncommon and I'm not aware of it being implicated in imported disease. I don't know how often dogs are imported for resale, and this may be the area in which these changes have the biggest potential impact. Whether a dog from a Canadian or Mexican puppy mill is any higher risk to other dogs and the public than dogs from (much more common) American puppy mills is debatable. It would be nice to see a proper risk assessment that indicates which situations are the highest risk.
Corynebacterium ulcerans infection from a cat
The latest edition of Emerging Infectious Diseases (Berger et al 2011) describes a case of Corynebacterium ulcerans infection in a women that was likely acquired from her cat.
Corynebacterium ulcerans is a bacterium that's related to C. diphtheriae, the cause of diphtheria. Some strains of C. ulcerans can produce toxins that cause diphtheria-like disease, and with the success of diphtheria vaccination, C. ulcerans is now the leading cause of diphtheria-like disease in people in some regions. Typically, C. ulcerans infections are associated with ingestion of contaminated milk or dairy products, but reports of infections acquired from dogs and cats appear to be on the rise. As is often the case, whether this is because it's becoming more common or that people are simply looking more is unclear.
In this report, a woman from Germany developed diphtheria-like disease, including a sore throat, ear ache, hoarseness and nasal obstruction. A swab was taken from her nose and throat, and toxigenic C. ulcerans was isolated. She didn't report any livestock contact and had not traveled abroad, so other possible sources of infection were considered, particularly other types of animal contact. She had a cat, so nose and throat swabs were collected from her pet, and the same strain of C. ulcerans was isolated.
With this type of investigation, you can't prove that the cat gave the bug to the owner. Since the cat was healthy and tested after the owner was sick, you can't say for sure whether the cat was the original source or if it was infected by the owner. However, with a bug like C. ulcerans that has been associated with pets before and that can be carried by healthy cats, the conclusion that it came from the cat is reasonable. The cat was treated with antibiotics and C. ulcerans was not detected after treatment.
This is an interesting report. It's always good to see people thinking about the relationship between human and animal disease, but at the same time, it's important to put this into context. Yes, C. ulcerans is a potential zoonotic concern, but it's rare. Anytime you see a case report involving a single person in the medical literature, you know it's either something new or very rare. In this case, it's the latter, since we know from previous reports that this bug can cause human infection and be transmitted from animals. Rare doesn't mean never, and you can't dismiss it, but C. ulcerans is just one of many bacteria that can be found in cats and transmitted to people. It's part of the inherent risk of infection that comes with cat ownership. This relatively low risk is hopefully outweighed by the benefits of cat ownership, and the cost-benefit can be maximized by basic infection control and hygiene practices. This report also shows how it's important for physicians to query pet ownership when dealing with infectious diseases in their patients, something that still needs lots of improvement.
