Vesciular stomatitis in Colorado

Vesicular stomatitis (VS) has been reported in a horse in Las Animas County, Colorado. It's the first diagnosed case in the state since 2006, but it's not particularly surprising since this viral disease is periodically identified in horses in various parts of the US, and this case may be associated with northward movement of the virus from the Rio Grande River valley in New Mexico. However, it's noteworthy because VS is a potentially nasty disease and since it's also reportable, diagnosis of a case is accompanied by quarantine and other other control measures.

Vesicular stomatitis typically results in vesicles (small blisters) and ulcers in the mouth, on the tongue and lips, as well as on the udder (udder lesions are more common in cattle compared to other affected species). Lesions around the coronary band of the foot can also develop. Because of these blisters, infected animals may stop eating or drinking, and may be lame. It's a self-limiting disease, meaning it will typically resolve on its own, but animals can develop secondary problems like bacterial infections or severe foot damage, or in some situations the consequences of decreased drinking and eating may be severe, resulting in bigger or longer-term problems. A major concern is that this virus can also infect cattle and produce signs that are similar to the dreaded foot and mouth disease.

The source of infection in this case is not known, but the horse has no history of travel to areas where the disease is active, so insect-borne infection is suspected. That means that the virus must be present in other animals in the region, since blood feeding insects simply spread the virus around, they don't act as reservoirs or amplifiers of the virus. The farm is under quarantine and presumably surveillance is underway to identify other horses that have had contact with the animals on this farm, as well as to monitor for any more cases in the area.

When something like this occurs, travel restrictions for horses (and/or other species) are typically put in place by various governments, ranging from travel bans to requiring animals from areas where the disease is present to be accompanied by a health certificate saying that the horse has no signs of disease and hasn't be on a farm with the disease. Anyone planning travel to, from, or through, involved areas needs to be aware of this and check into transportation rules, including potential import restrictions if they want to enter Canada with a horse.

If you are in an infected region (or nearby), you can do some things to reduce the risk of your horse becoming infected by VS:

  • Restrict travel and avoid areas where the disease is active.
  • Avoid direct contact between horses as much as possible when visiting farms, shows or other places where horses mix.
  • Take basic insect control measures to reduce exposure to biting flies (e.g. black flies).
  • Avoid sharing/trading/selling tack and other items that have close contact with your (or any other) horse.

Vesicular stomatitis is zoonotic but it's of limited concern. Human infections are rare and usually just result in flu-like illness.

More Moroccan rabies

While rare, Morocco continues to be a source of rabies in European animals. The latest case involved a puppy imported into the Netherlands. The (somewhat) brief version of what happened goes like this:

  • On Jan 28, 2012, a Dutch couple bought an 8-week-old puppy in a parking lot in Morocco. The puppy was taken to a local veterinarian, microchipped and given a certificate of good health. It would have been too young to vaccinate against rabies.
  • On Feb 4, the couple travelled from Morocco to Spain by car and ferry. They then obtained a European pet passport from a Spanish vet, despite the fact that the dog was not vaccinated against rabies (an EU requirement for a pet passport).
  • On Feb 11, they returned to the Netherlands. Customs officials "cuddled" with the puppy but apparently didn't ask about rabies vaccination. When they got home, the couple exposed the puppy to many family and friends.
  • On Feb 14, the puppy started to become aggressive. They contacted a veterinary practice, and it was assumed the problem was stress, so a sedative was given. (It's not clear whether the puppy was actually examined. If not, that's a pretty big mistake.)
  • On Feb 15, the puppy was uncontrollable. The report states "When they realized that the puppy originated from Morocco, the veterinarians contacted the Netherlands Food and Consumer Product Safety Authority (NVWA)." The puppy's history should have been a basic question asked when the couple first contacted the veterinary practice about the animal. Regardless, the concern about rabies came to the forefront with that information, and the puppy was euthanized. Rabies was confirmed that evening (a pretty impressive turnaround time for rabies testing).
  • As is typical, an investigation was launched, and a search for people who had contact with the puppy during the period when it was potentially infectious was started. That's not easy when it involves multiple countries, as was the case here, since the potentially infectious period is 10-14 days prior to the onset of clinical abnormalities. The potential contacts included the Moroccan veterinarian, some friends in Spain, the Spanish veterinarian, three customs officials, a couple of unknown people in a Spanish restaurant and at the Malaga airport, and 43 people after arrival in the Netherlands (plus an unknown number of people who petted the puppy on the street).
  • Contact doesn't mean exposure, since rabies isn't transmitted by casual contact, so the type of contact was queried further. The risk is from bites or contact between the dog's saliva and broken skin or mucous membranes (e.g. mouth, eyes). Because of concerns that kids don't accurately recall the type of contact they have (meaning they might fail to mention a little nip or some other high risk contact), all nine children who had contact with the puppy were given post-exposure prophylaxis. The Dutch friends in Spain reported high risk exposure and were also treated, however they had to return to Amsterdam for full treatment since anti-rabies immunoglobulin (antibody) was not available in Spain. Information was provided to Moroccan officials but information about what happened there wasn't available.
  • Overall, it is stated that 45 people needed post-exposure treatment (although who those 45 were isn't really clear). That's a pretty large exposure, resulting is much angst and expense.
  • Two cats and a dog were also exposed to the puppy. The dog had been vaccinated, and received a booster. (It would also be standard protocol to quarantine them for 45 days as well, but that's not stated.) The cats were euthanized because a "suitable quarantine place was not available," a rather strange statement since quarantine isn't a very high tech procedure. 

Obviously, this is of relevance to people that live in Morocco or are going to get a dog from Morocco. Those people need to be aware of rabies, be careful when getting a pet, ensure their pets are properly vaccinated against rabies and be careful around stray animals. This report also highlights a couple of other issues:

  • A parking lot isn't a good place to buy a puppy, for many reasons. A reputable breeder isn't going to sell a puppy there, and there are lots of good, well-evaluated puppies available through good breeders and shelters.
  • Pet importation requirements are pretty weak in a lot of ways, especially if no one actually pays attention to them. That seems to be a recurring theme as well with these imported rabies cases. Here, the puppy was given a European dog passport without the required rabies vaccination, and was not kept in quarantine after arrival. It also went through no less than three customs points in transit, where no one queried rabies vaccination status. The mandatory 3 month quarantine would have prevented exposure of most of the people that required post-exposure treatment.
  • Visitors to areas where rabies is endemic in the dog population need to be aware of it. Encountering stray dogs isn't exactly rare in many countries, and while staying away from strays is a good general rule everywhere, people should be particularly careful in areas where the risk of rabies is high. Travelers also need to be aware of what to do if they are bitten by a stray animal.

Equine Quarantine Recommendations

Quarantine is an important, effective and underused practice on horse farms. Quarantine can reduce the risk of introducing new infectious agents to animals on the farm or limit the spread of something that’s already starting to circulate through the herd.

A recent article from TheHorse.com gives a good overview of why and how to implement quarantine. Importantly, it emphasizes that quarantine is not just for large, high-risk farms, and that any farm can and should have a quarantine plan. Not everyone can implement a quarantine protocol easily. We know and accept that, but the inability to implement a textbook quarantine program can't be used as an excuse to do nothing. Even a cursory quarantine program, with some basic practices to reduce direct and indirect contact of quarantined horses with other horses, can be very useful.

Most of the time, quarantine goes uneventfully and no problems are encountered. That sometimes leads to complacency, but it's the few cases where quarantine contains a problem that makes it all worthwhile. The implications of a single horse getting past quarantine can be huge, both for the individual farm and more broadly (e.g. Australian influenza outbreak). The article has some sound, practical advice that all horse owners should consider.

Image from Chemical Hazard Signs - MySafetySign.com

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.

Hendra virus in a dog

Adding a new twist to the already very concerning situation in Australia, Hendra virus infection has now also been identified in a dog. It's been a bad year for Hendra virus in Australia, with larger numbers of cases of this highly fatal disease in horses in a geographic range that seems to be expanding. Spread by flying foxes (fruit bats), Hendra virus predominantly infects horses, but can be transmitted to people working with infectedhorses.

The Australian Animal Health Laboratory in Geelong has now announced diagnosis of Hendra virus infection in a dog. The dog is from a quarantined farm in Queensland where the virus has been identified in a horse. The dog was healthy and was tested as part of a standard policy to test dogs and cats on infected farms. It's great to see this approach being used, since it helps identify other potential sources proactively - something that is often overlooked in outbreak investigations that focus only on the main species that are already known to be involved.

In this case, the dog had antibodies against the virus in its blood. That means that it was exposed to the virus and mounted an immune response. It doesn't indicate whether it was exposed recently or in the past. Two tests for the virus itself were negative, suggesting that the dog's immune system eliminated the virus (or that the virus isn't really capable of surviving for long in a dog). This is a good news/bad news scenario.

Bad news:

  • Dogs can be infected. It increases the range of known susceptible species.
  • If dogs can be infected and shed live virus, then they could be a source of infection for other individuals, including people.
  • The dog wasn't sick. This might sound like strange "bad news," but healthy carriers of infectious diseases are harder to spot and control than ones that are sick.

Good news:

  • The dog wasn't shedding the virus. That's critical since if dogs can be infected but not infectious (i.e. if they can carry the virus but not transmit it), then they are of limited concern.
  • They have been testing farm dogs and cats as a routine measure, and this was the first positive. Infection of pets therefore must be relatively uncommon even on farms where the virus is active.
  • The dog wasn't sick. While it's only one case and doesn't guarantee dogs won't be affected clinically, this might suggest that dogs just occasionally get exposed with no disease. Since it's highly fatal in other species, that's a good thing.

What should be done based on this?

  • Probably not much more than should have been done before this finding, but it's a good reminder about the potential involvement of other species.
  • Dogs and cats should be kept away from fruit bat roosting sites.
  • Dogs and cats should be kept away from infected horses.
  • If a farm is quarantined because of Hendra virus, dogs and cats should be tested and quarantined. Quarantining the animal while testing is underway helps reduce the risk of an infectious dog or cat (should that occur) transmiting the virus to people on the farm, or wandering away and exposing other people or animals.
  • Animals of any type in areas where Hendra virus is active that get sick with signs that could possibly be consistent with Hendra virus infection should be tested.

This should also be taken as yet another reminder that infectious diseases are unpredictable. Considering the potential involvement of different species in a proactive manner as was done here is critical.

Image: Bay Horse and White Dog by George Stubbs (1724-1806)

This Worms & Germs blog entry was originally posted on equIDblog on 26-Jul-11.

Rabies quarantine in (and of) Santa Cruz County, Arizona

A large number of rabies cases in Santa Cruz County, Arizona has lead to the rare practice of implementing a county-wide rabies quarantine. Fifty-four cases of rabies have been diagnosed so far this year, mainly in skunks. That's about twice as many as normal.

Quarantine is probably not the best description of what they are doing, but they are taking measures to improve vaccination of pets, reduce roaming pets and discourage human-wildlife interaction.

For the next 60 days, the following rules are in place:

  • Dogs and cats must be vaccinated against rabies.
  • Dogs must be confined to the property or on a leash.
  • People are not allowed to feed wild animals.
  • Pet food must not be left outdoors after sundown.

Those are all pretty standard measures that should be used anytime. It sounds like these rules already exist in Santa Cruz County but their "quarantine" means that they will be aggressive in enforcing them. Increasing enforcement is a good idea, but ongoing efforts after this quarantine period are also needed because rabies will continue to be a risk in that area.

Image source: www.acmeanimalremoval.com