Worms and Germs Blog : Animal Health & Diseases : University of Guelph : Ontario Veterinary College : Zoonotic Diseases : Guelph, Hamilton, Ontario

Streptococcus zooepidemicus is an important cause of infections in horses. This bacterium can also be found in healthy horses. When you consider the large number of horses that are infected and the larger number of healthy horses that are carriers, along with the close contact that people have with horses, it's pretty obvious that people are regularly exposed to "Strep zoo". This bacterium is not well-adapted to survive in people and cause infections, so human infections are quite uncommon, but they can occur. There are periodic reports of S. zooepidemicus infections in people, with varying degrees of association with horse-contact.

An upcoming edition of journal Epidemiology and Infection contains a report of S. zooepidemicus meningitis in a 51-year-old woman (Minces et al, 2010). This person had a mild upper respiratory tract infection, then developed signs of meningitis (including fever, unresponsiveness, respiratory distress). A spinal tap was performed and S. zooepidemicus was isolated. The woman fortunately responded to treatment and recovered.

Upon initial questioning of the patient's mother, no animal contact or ingestion of unpasteurized dairy products (another risk factor) was reported. However, it was later revealed that the woman's daughter had started horseback riding at a friend's farm approximately one month earlier. The type of contact that the woman had with horses (if any) at the farm was not reported, nor was there any investigation of S. zooepidemicus shedding by horses on the farm.

Based on the fact that this is typically an equine-associated bacterium and the history of contact (albeit potentially limited or indirect) with horses, horse contact was blamed for the infection. It's a reasonable conclusion but it's far from certain because of the nature of the contact, the lack of any proof of the same strain of S. zooepidemicus in horses on the farm, and previous reports of infections occurring in people with no contact with horses.

Exposure to S. zooepidemicus is an inherent risk of having contact with horses. It's nothing to lose sleep over and is probably relatively low on the list of potential health problems associated with horse contact. The risk is probably greatest in people with compromised immune systems and other general risk factors for disease such as advancing age and pregnancy. Good general hygiene measures, avoiding contact with sick horses and close attention to hand hygiene probably minimize these already low risks.

(click image for source)

This Worms & Germs blog entry was originally posted on equIDblog on 25-May-10.

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A recently reported outbreak affecting horses in Bahrain has been diagnosed as glanders, a very serious bacterial infection caused by the highly contagious bacterium Burkholderia mallei. So far, it has been reported that 8 horses were euthanized over the past 3 weeks because of the infection.

Bahrain's cabinet has allocated BD150 000 to fight the outbreak. Authorities have apparently stated that the outbreak can be "easily" managed, "We have sent samples from nearly 400 horses to a specialist laboratory in the UAE and the 10 results we have got so far give us the all-clear. We now know we can manage this quite easily and are taking appropriate action."

That's a pretty dangerous sentiment to be expressing (and believing) early in an outbreak, but hopefully it's true. "Easily" and "outbreak" aren't often uttered in the same sentence, and it's far from unusual to be fooled by an allegedly contained or controlled outbreak. I'd be very surprised if all of the positive horses have already been identified. Control of glanders involves widespread testing of horses, typically with euthanasia of any infected animals. It sounds like testing is underway and results of this will give a good indication of the extent of the problem. Ten negative samples don't mean that much to me. As more results come in (and if they continue to be negative), more confidence can be had in the assessment that this outbreak is truly contained.

Glanders is not solely a concern for horses. It's a zoonotic disease that can cause rare but serious infection in humans, with a high mortality rate (almost 100% if proper treatment is not administered). People can become infected by direct contact with infected horses, with the bacterium gaining entry through skin abrasions, inhalation or contact with tissues of the mouth and nose. Pneumonia, bloodstream infections and other problems can develop. Burkholderia mallei is a Class B bioterrorism agent. Hopefully, people working around infected horses are using appropriate infection control precautions to reduce the risk of infection.

Hopefully, more information will be available soon about this outbreak and results of ongoing testing.

Image: A horse with glanders (Burkholderia mallei infection), exhibiting the characteristic infectious nasal discharge.  Glanders is a reportable disease which has been eradicated from North America, Australia and most of Europe.

This Worms & Germs blog entry was originally posted on equIDblog on 26-Apr-10.

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The latest edition of the journal Emerging Infectious Diseases contains a paper describing the 2008  Australian Hendra virus outbreak in horses and people.

In this outbreak, there were five horses infected and two humans infected. The horses predominantly had signs of neurological disease, not respiratory disease like some other reports describing this disease. Four horses died. One recovered but was euthanized for public health reasons.

Two people became infected after working with the sick horses, which represents 10% of the total veterinary staff that were exposed to the infected horses.  Both people started off with influenza-like illness, which seemed to improve initially, but then signs of severe neurological disease developed. They were treated with ribavirin, an antiviral drug, as part of an experimental treatment. One of them died after 40 days of illness, the other person survived.

The authors stressed that the effectiveness of ribavirin could not be determined, but they recommend it nonetheless because of the severity of Hendra virus infection and lack of other options. Ribavirin was also used in the 2009 outbreak, but it is clearly not 100% effective since one person died there also.

A number of concerning activities occurred that put people at risk of infection, including a "percutaneous blood exposure while euthanizing an infected horses" (they didn't explain exactly what this was, but it could have been a needlestick), low use of personal protective equipment, and contact with potentially infectious body fluids. This is unfortunately not surprising since the approach to infection control (particularly in terms of zoonotic infections) is often lax in equine medicine. That certainly has to change, particularly in areas where Hendra virus may be present.

Much more information about how to control this potentially devastating virus is needed. Fortunately, infections are uncommon and it is restricted to a fairly small geographic range in Queensland, Australia.

Image source: http://animalphotos.info/

This Worms & Germs blog entry was originally posted on equIDblog on 27-Jan-10.

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I received newsletter today from Intervet (a pharmaceutical company) that is targeted at equine veterinarians. One article discussed rabies in horses. It wasn't bad overall, but I thought the section on what to do when a horse might have been exposed to rabies was worth discussing.

The article asks, "If your client suspects that a horse has been bitten by a rabies-infected animal, what should be done?"

Answer: "Contacting you as the veterinarian is always the first step."

Great first step.  A second step that wasn't mentioned should be, "Try to identify and (safely) capture the animal that bit the horse." This is often impossible but certainly worthwhile if it can be done.  However, if you're trying to catch the offending animal, make sure you don't put yourself at risk of exposure to rabies in the process.  If the animal can be caught, it's rabies status at the time of the bite can be determined (either through testing or quarantine). If it can be shown that the animal wasn't rabid, a lot of stress, hassle and expense can be saved.

"If the horse was previously vaccinated... Then isolate and observe the animal for 45 to 90 days (your clinical evaluation will involve gait analysis, radiography and a spinal tap)."

Boosting the rabies vaccine is also a good idea. The next step, however, needs to be contacting local regulatory officials to find out what you have to do. They determine if, how and how long an animal needs to be quarantined - this is NOT the decision of the local veterinarian nor the animal's owner. Most likely, they will recommend a 45 day quarantine for a vaccinated horse, since this is what is recommended in the NASPHV Compendium on Rabies. The discussion of diagnostic testing makes no sense. There is absolutely no indication to perform diagnostic tests on a horse that has been bitten by a rabies suspect. None. There are no tests that can be used to diagnose rabies in live horses (also exposed horses don't instantly develop signs of rabies). Horses should be monitored closely for signs of rabies during the quarantine period, but that's it.

"...and have the client make a list of all people who had contact with the horse."

This is often done when horses have or are suspected of having rabies, but not horses that are potentially exposed. It is done to help public health personnel contact people that may have been exposed to rabies. A horse that was just bitten by an animal is not a risk for transmission of rabies.  (However, keeping a list of people who have contact with the horse after it's been bitten (i.e. durng the quarantine period) - which should be as short a list as possible - is a reasonable precaution in the unlikely event that the horse does develop rabies.)

"If the animal was not vaccinated, your options are to euthanize and perform a postmortem examination of the brain (the only way to definitely confirm rabies)..."

Euthanasia is one of the options that needs to be considered in an unvaccinated horse that has been exposed, which is one of the reasons that identifying the biting animal and testing it is critical, if it can be done. The last part of the above sentence (from the atricle) is complete nonsense. Why would you test the brain of a normal horse that has been euthanized because it's just been bitten by a potentially rabid animal? The horse isn't being euthanized because it has rabies, it's being euthanized because of the likelihood  of it developing rabies weeks to months later. Testing of the brain will tell you absolutely nothing if the animal was only bitten recently.

"...or isolate and observe the horse for six months and develop the human contact list."

Again, this needs to be decided based on discussions with regulatory personnel who are responsible for dictating what is to be done. A six-month quarantine is a pretty standard recommendation for an unvaccinated animal. Creating a human contact list should not be necessary, since quarantine involves severely restricting contact of people with the horse and only a few (ideally one) person would have any type of contact.

The article wraps up with the very true emphasis on vaccinating horses. It's a cheap measure to prevent a relatively rare but invariably fatal disease.

Click image for source.

This Worms & Germs blog entry was originally posted on equIDblog on 05-Jan-10.

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Streptococcus equi subspecies zooepidemicus (usually just called Strep zooepidemicus) is a common cause of infection in horses. It is an "opportunist" that is often found in healthy horses, but which can cause disease in certain situations. While horses are the natural host of this bacterium, sporadic infections and outbreaks are occasionally reported in dogs at cats, particularly in shelters or other crowded situations. Severe (including fatal) pneumonia can occur, as was reported in a recent outbreak in a humane society in Ottawa. Rarely, S. zooepidemicus can also cause infections in people.

A report in the Journal of Medical Microbiology (Abbott et al) describes a serious S. zooepidemicus infection in a person, that was traced back to a dog. The dog lived on a farm that also had horses. It developed pneumonia and S. zooepidemicus was isolated from its respiratory tract. The dog was treated and recovered. However, the dog owner also became ill with fever, headache, a stiff neck and general malaise. Penicillin was prescribed, but the person's condition did not improve and he/she ended up in the hospital. Streptococcus zooepidemicus was also isolated from this person's nose and throat.  When the dog and human strains were compared using molecular tests, they were related. An investigation of the farm was performed, and while all the horses present at the time were negative for S. zooepidemicus, the bacterium was isolated from a healthy dog.

This is a rare situation and one that shouldn't result in too much concern. It does highlight a couple points that are good to remember:

• Getting cultures is very important for obtaining a diagnosis.
• Animal contact and pet health should be considered whenever someone is sick with a potential infectious disease. Physicians need to know whether their patients have contact with animals. They need to be told if a sick animal is present so they can consider whether the pet and human illness might be related. Knowing to what someone may have been exposed might speed up diagnosis and appropriate treatment.
• Rare things are rare, but they happen. We shouldn't focus on rare events but we have to keep our minds open and recognize that strange things happen with infectious diseases.

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At the ongoing ASM-ESCMID conference on methicillin resistant staphylococci in animals, Dr. Engeline van Duijkeren of Utrecht University (The Netherlands) presented a study on an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in their equine hospital.

From 2006-2008, several horses that underwent surgery at their hospital developed MRSA infections.  MRSA was also isolated from some healthy horses and personnel at the clinic. Early in the process, the hospital was closed for a thorough disinfection and the outbreak stopped, however another outbreak occurred later.  Further study again found people in the clinic that were MRSA carriers. Close to 15% of people in the hospital who handled equine patients were MRSA carriers, which is really astounding when you consider that less than 0.1% of the general population in the Netherlands carries MRSA. When they started testing horses coming into the clinic, they found that 9.3% of horses were carriers when they arrived. Weekly sampling of all hospitalized horses over a five-week period determined that 43% of all horses in the hospital carried MRSA at one point or another during their stay. Additionally, 53% of environmental surface samples were positive for MRSA, which is really not surprising if that many people and horses are carriers.

If horses keep coming into a facility carrying MRSA and people keep getting colonized, MRSA is hard to control. These experiences led the equine hospital at Utrecht to implement more stringent infection control practices to try to contain the problem, but the high MRSA rate in their referral population is going to pose a continual risk.

MRSA outbreaks in horses aren’t new. They’ve been reported by a few hospitals (including ours) and occur in many, many, (many!) more without ever being published. Since MRSA is present in the horse population, equine hospitals are at continual risk of MRSA outbreaks. If a large percentage of horses in the general population are carriers, the risk of outbreaks is higher.

MRSA is clearly a problem in horses in many areas. It’s important to realize that it’s a problem in the general population, not just horses in hospitals. Equine hospitals can amplify the spread of MRSA, but ultimately a lot (if not most) MRSA-positive horses originate from farms, not clinics or hospitals. Equine hospitals need solid infection control programs to reduce  the risk of outbreaks, but the risk will never be completely eliminated. Farms need good infection control programs to reduce the risk of spread of MRSA between horses and between farms, as well as from horses to people (and back). Antibiotics need to be used prudently since antibiotic use is a risk factor for MRSA carriage and infection.

More information about MRSA in horses can be found on the equIDblog Resources page.

This Worms & Germs blog entry was originally posted on equIDblog on 26-Sep-09.

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As a vet, I've been bitten by a wide range of animal species. When people talk about animal bites, they usually think about dogs and cats. Horses can (and do) bite as well. Most horse bites are probably playful nips that hurt a little yet don't cause major problems, but some bites can cause serious injuries and infections can result.

A recent paper in the Journal of Agromedicine (Langley and Morris 2009), with the rather unwieldy title of "That Horse Bit Me: Zoonotic Infections of Equines to Consider after Exposure Through the Bite or the Oral/Nasal Secretions". Bites apparently account for 3-4.5% of the approximately 100 000 annual emergency room visits in the US that are associated with horses. The authors of the paper review infections associated with bites and contact with organisms in the mouth and nose of horses.

A large number of bacteria have been associated with horse bite infections in people, including Actinobacillus, Streptococcus, Psuedomonas and Staphylococcus species. Some viruses can theoretically be transmitted by bites, but there's little evidence that this actually happens.

Although viruses are not of as much of a concern overall, rabies needs to be considered in every bite from a mammal. We pay a lot of attention to rabies with dogs, cats and wildlife, but it often gets ignored with horses. While I'm not aware of any reports of rabies transmission from horses to humans by a bite, it could happen.  Fortunately, rabies is rare in horses so the likelihood of exposure from this species is very low. However signs of rabies aren't always obvious initially, and rabies in horses may mimic other diseases. Sometimes, rabies looks like colic, and human exposure through bites or other contact is possible when handling, evaluating and treating affected horses.

Unlike with dogs and cats, there are no clearly defined protocols for dealing with bites from horses. Any dog or cat that bites a person is supposed to be quarantined for 10 days. The reason for this is if the animal is rabid and the disease is advanced enough for the animal to be capable of spreading rabies virus, it would invariably develop signs of rabies and die within this time period. We don't have similar guidelines for horses. I suspect the 10 day observation period would be adequate but we don't have good data. The paper states that in Kentucky, a 14 day observation period has been used by the state Department of Public Health.

At the conclusion of the paper, the authors make a few important general recommendations for reducing the risk of disease transmission from bites and oral or nasal secretions of horses:

• Use good general hygiene, especially hand hygiene, after any contact with horses.
• Use gloves and gown or lab coat when examining horses in a veterinary clinic or hospital. (This might be overkill for all horses. We don't require gloves for every horse contact, just contact with mucous membranes (e.g. mouth, nose), wounds, incision sites and other high-risk areas. I think bare hands are fine for general contact as long as there is good attention to handwashing after.)
• Consider mask and goggles if the horse is coughing or sneezing.
• Develop standard operating procedures for handling sick horses.
• Use isolation when needed.

I'd add a few more points:

• Avoid bites. Pay attention to what you are doing around horses to reduce the risk of being bitten. Do not encourage playful behaviours (e.g. nipping) that could lead to bites.
• If you are bitten and it breaks the skin, clean the site thoroughly with soap and water. If there is significant trauma, or if the bite is over a joint, hand, foot, or a prosthetic device, you should see a doctor immediately because antibiotics are most likely indicated. If you have a weakened immune system, you should be evaluated by a doctor after any bite.
• Avoid contact with the horse's mouth or nose if you have skin lesions. Cuts and scrapes can allow bacteria to enter your body and cause infections. If you have a cut on your hand, make sure it is covered with a glove or waterproof dressing if you are going to have contact with the horse's mouth or something that came from its mouth (e.g. a bit).

This Worms & Germs blog entry was originally posted on equIDblog on 02-Sep-09.

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I received the following question the other day: "I have a friend who had chemo embolization on tumor on liver in late June. She is in hospital now, and an abscess was discovered on liver.  Pathology results said "equine strep".  Her brother visited immediately after procedure, and he works with horse full time."

Streptococcus is a group of bacteria that includes many different species. There are two main species in horses Streptococcus equi subsp. equi (aka S. equi, the cause of strangles) and Streptococcus equi subsp. zooepidemicus (aka S. zooepidemicus, a cause of various types of infections). As you can guess by the 'equi' name, their natural host is the horse. Strep infections are very common in people, but rarely involve these two species. Nonetheless, infections with either Streptococcus equi or S. zooepidemicus can be found in people, but S. zooepidemicus is most common. Usually, these infections develop in people who are already sick for another reason, have compromised immune systems, or in young children. Interestingly, not everyone that is infected reports direct or even indirect contact with horses.

Back to the question: it's hard to say what's going on here based on the the general term "equine strep", but presumably the person has an infection with S. equi or S. zooepidemicus. Whether horses are actually involved will be tough (or impossible) to determine. It's a tempting hypothesis that the patient's brother carried the bacterium from the farm to the hospital, but I'd be wary about making a definitive statement about the bacterium's origin solely based on that. There are ways to investigate this further, such as trying to isolate Streptococcus species from horses on the farm, typing them and comparing them to the strain that caused disease in the person, but this type of testing is very costly and almost never performed, as human infection with these species is so uncommon.

This should be a good reminder that people who are sick and in hospital are at higher risk for developing infections, and they can get infections from bacteria that rarely cause disease in healthy individuals. While there is no proof of a link to horses (at least in this case), good infection control practices should be used whenever anyone visits someone in the hospital. That would include not wearing barn clothes to the hospital and paying close attention to handwashing.

This Worms & Germs blog entry was originally posted on equIDblog on 26-Aug-09.

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A horse in Harford county Maryland has been euthanized because of rabies. The horse first starting showing signs of disease in mid-July, which manifested as "striking changes in behaviour." The report doesn't say when the horse died, but animals typically die within a few days of the onset of neurological disease. The horse was transferred to the New Bolton Center where rabies was diagnosed. Subsequent testing showed it was a raccoon rabies strain, although that does not mean that a raccoon was the actual source of infection.

Public health officials implemented a 45 day quarantine of the farm. Stray cats (about 25) were caught and euthanized. Fortunately, the family pets were properly vaccinated and have received booster shots (plus presumably a period of observation at home... a much better situation than if they were not vaccinated).

People that had contact with the horse have received rabies post-exposure treatment. This includes one person who had to be tracked down overseas.

Harford County Health Department spokesperson Bill Wiseman said "There was never a risk to public safety. This incident was a great example of public health work in action and cooperation between local, state and in this case, international authorities." I don't buy the statement that there was no risk to public health. While the risk of rabies transmission from infected horses is very low, it's not zero. Rabid horses have killed people because of their abnormal and sometimes aggressive behaviour. Further, the fact that this horse had rabies means that it got it from something. Rabies can have a long incubation period so it's not guaranteed that it acquired it on the farm, but you have to be prudent and assume that there is infected wildlife in the area that could pose a risk for other animals or people. Public health authorities managed the situation well and reduced the public health risks, but there were certainly still risks.

Rabies vaccination is highly effective. There is no statement about whether this horse was adequately vaccinated but it's unlikely. Proper vaccination would likely have prevented this horse's death, as well as the death of the stray animals, cost of vaccination of people, cost of veterinary care for this horse, quarantine of the farm and the associated financial and emotional costs. A dose of vaccine that costs a few dollars could have saved thousands of dollars and emotional stress.

Rabies is a rare disease in horses but its severity means it should not be ingored. Vaccinate your horses.

This Worms & Germs blog entry was originally posted on equIDblog on 14-Aug-09.

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Hendra virus, a virus that can kill horses and people, has resurfaced in Queensland, Australia. This bat-borne disease has caused periodic fatalities in horses and people that work with horses. The latest outbreak is thought to have killed up to three horses and resulted in the potential exposure of at least 30 people. The likelihood of these people getting sick depends on how close their contact was with the sick horses. Close contact with secretions from infected horses seems to be required to transmit disease. One person reported being snorted on by an infected, dying horse and being "covered" in blood, which is certainly concerning. An outbreak last year killed a veterinarian and hospitalized a veterinary nurse.

The farm in question is under quarantine and people that have been exposed are being monitored. There is no treatment for potentially exposed individuals, so they are in the unenviable position of having to wait and see if they get sick.

A virus like this is very hard to control. It's lives in fruit bats and only occasionally crosses into horses. The sporadic nature of disease makes it hard to control and predict when cases will occur. The key is early identification so that there is minimal exposure to other horses and people. People also need to take routine infection control precautions. One veterinarian handled an infected horse without using gloves or a face mask, as recommended, because he had left them in the car. Exposure to a potentially fatal infectious disease is not worth the few minutes of time saved by not following recommended precautions.

This Worms & Germs blog entry was originally posted on equIDblog on 10-Aug-09.

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Rhodococcus equi is a very well recognized pathogen in horses – it is a common cause of pneumonia in foals between the ages of 1-6 months, and infection is also sometimes associated with other problems such as diarrhea, swollen joints and abscesses in other parts of the body. The infection can be very difficult to treat because the bacteria are able to live inside white blood cells, which helps protect them from the body’s immune system, and because they often cause abscesses to form, which are difficult for antibiotics to penetrate. Rhodococcus equi infection in foals has been studied extensively, but there’s still a lot we don’t know how the body defends itself against this organism.  These are a few things we do know:

• Almost all foals are exposed to R. equi as neonates, but most of them never develop signs of infection.
• Giving newborn foals hyperimmune plasma (plasma with extra antibodies against R. equi) may have some beneficial effects on farms where the infection is a recurrent problem, but this practice is still controversial.
• Adult horses are essentially immune to the infection.
• In almost all cases if clinical disease in foals, the R. equi strain involved carries a special gene called vapA.
• Mortality rates in foals vary considerably from 0% to 30%.
• So far, efforts to develop a vaccine to help protect foals have been unsuccessful, but research in this area is ongoing.

People can also be infected with R. equi, and as in foals, pyogranulomatous pneumonia (infection of the lungs which results in the formation of many abscesses) is one of the most common conditions caused by this organism. However, there are a few important differences between infection in people and infection in horses:

• 85% to 90% of people with R. equi infection are immunocompromised, meaning their immune system is weakened or suppressed for some reason, e.g. HIV infection, or immunosuppressive drugs taken by organ transplant or cancer patients.
• Among people infected with R. equi who have normal immune systems (i.e. immunocompetent), about half of the infections are localized, meaning they only affect one small part of the body. Many of these are associated with wound infections.
• Only 20% to 25% of the R. equi isolates in people carry the vapA gene.
• Infection in immunocompetent people can be fatal in approximately 11% of cases, but among HIV-infected patients the mortality rate from R. equi infection can be as high as 50% to 55%.

Rhodococcus equi is actually a soil organism, and this is likely the most common source of the organism for both horses and people. Only approximately 1/3 of humans infected with R. equi report that they have had contact with horses or pigs (pigs can also carry the bacterium). So we don't know how much of a risk an infected foal is to a person.  However, it is prudent for people, particularly those with weakened immune systems, to take precautions to avoid potential transmission of R. equi from horses.

• Try to reduce dust levels on the farm. Because R. equi most often lives in the soil, it can get stirred up into the air in dusty areas, which can then lead to inhalation by animals and people. Doing things like planting grass or other vegetation, installing windbreaks in high-traffic areas, or wetting down dusty stalls or paddocks can help reduce dust levels in the air.
• Keep open wounds and other broken skin covered when working around animals.
• Always wash your hands after handling a foal (or any horse)
• If you have a foal that develops signs of R. equi infection, make sure you have your veterinarian examine it as soon as possible so the diagnosis can be determined and the foal can be treated properly as soon as possible. Some foals with R. equi may develop severe pneumonia very quickly, so it’s important that they are examined right away.

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I was at the annual conference of the Society for Healthcare Epidemiology of America on the weekend. This is a hospital infection control organization, and one of the talks I gave was about animals in healthcare facilities. One question that came up was about unusual service animal species like monkeys. Service animals are specially trained animals that help disabled individuals with specific tasks. The most common examples are seeing-eye dogs. In the US, the American Disabilities Act protects service animals and dictates that they must be allowed to go wherever the person goes. I don't think people have a problem with that in general. However, there are concerns with respect to non-traditional species being used in these roles, and the question at the meeting was about service monkeys. Monkeys can be incredibly strong physically, and they can carry some important infectious zoonotic diseases, so there are concerns about them being allowed in hospitals. Part of the issue is what really makes an animal a service animal.  Should all animals that help someone out (in any capacity) be considered service animals?

That same topic came up in a recent ABC News article that described a seeing-eye horse in Texas, including a video of the owner riding the horse while grocery shopping. 

I have no doubt that this horse helps out its owner and provides great joy, if not increased freedom. However, I'm not convinced that a horse is necessary to fulfill this person's need for a service animal. Why use a horse when a dog could do as good (or a better) job? How was the horse trained? Was it trained under a formal program so that it is truly helpful? What types of health and behaviour screening have been used? What are the additional risks associated with using such a large farm-animal species?

Horses, even based solely on their size, can easily cause injury to members of the public without meaning to, simply by stepping on a person's foot or bumping into them, for example.  Some people might be scared of horses, especially indoors. Horses aren't litter trained, and horse manure can carry potentially infectious agents. I have a big problem with the video of this horse in a grocery store.  At end of the day, is a horse really necessary for what this person needs, and has the horse been adequately evaluated to ensure that it is low risk to the public? I don't think the answer is yes to either question, let alone both.

We certainly must do all that we can to allow full access of appropriate service animals, but we also need ensure that novelty "service" animals don't cloud the picture and potentially have a negative impact on true service animals.  The article states "...the government has begun rethinking whether the regulations should be changed to exclude some animals." That sounds like a great idea to me. Careful review of this issue, including the benefits to people, risks to the public and the need for new species over traditional options all need to be considered. 

Image: captured from video at http://www.abcnews.go.com/GMA/story?id=7157206

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An important step in diagnosing infectious diseases and determining the optimum approach to treatment and management is rapid and accurate diagnostic testing. Many different testing methods are used, particularly bacterial culture (at least for bacterial diseases). Molecular testing has revolutionized the field of microbiology, and is making inroads into the field of diagnostic testing. Polymerase chain reaction (PCR) testing is a very powerful tool that can be used to detect DNA or RNA from specific microorganisms.  This technique can be very useful, but it can also be easily misused or misinterpreted.

The potential PROS of molecular diagnostic testing include:

• Rapid turnaround time: Testing can take as little as a few hours versus a few days for other tests like bacterial culture.
• Sensitivity: Organisms that are difficult or impossible to grow in a lab can be detected, and they can often be detected at lower levels than with other diagnostic methods.

The potential CONS of molecular diagnostic testing include:

• Sample contamination: This is a common concern with highly sensitive molecular tests - even a minute amount of contamination in the sample can cause a false positive result.
• Test inhibition: Samples from complex biological sites (e.g. stool) can contain substances that interfere with the many complex molecular reactions upon which the tests rely. Without good (and proven) methods to prepare the sample, this can result in a false negative result.
• Biologically irrelevant results: Some bacteria that cause disease are also commonly found as part of the normal microflora in healthy animals - simply finding it does not tell you that it is necessarily relevant to the problem. For example, Clostridium difficile can be found in the intestine of approximately 10% of healthy dogs and cats (or more, in some situations), but the diagnosis of C. difficile diarrhea requires detection of the bacterial toxins in stool samples, not just the bacterium itself.  A molecular test that simply identifies the presence of C. difficile, even if it identifies strains that possess the genes to produce toxins, tells you nothing about whether the bacterium was actually producing toxins in the animal.
• Lack of validation: This is a common problem with many (if not most) molecular tests. Some companies, especially those that just run molecular tests, offer a huge array of completely unvalidated and sometimes illogical tests.  It is also important to remember that tests must be validated for each species in which they are used - a test that works well in people will not necessarily work on a sample from a horse or a dog.

Molecular testing can be useful in some situations. If you are unsure, here are some things to ask the lab:

• Do they have a validated test that provides relevant results?  If they don't have good data (ideally published data) that their test is useful, accurate and reproducible, I'd avoid it.
• Do they have a quality control program, which includes running positive and negative control samples with each test batch?

Finally, as with any test that we use in veterinary (or human) medicine, it's important to evaluate all  results in the context of what is happening with the animal - treat the patient, not the test result.

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I spent some time the other night looking at different internet pet pharmacy sites. (Yes, I know that sounds strange, but it was interesting and sometimes appalling.) It's well known that you can buy virtually anything over the internet. Pharmaceuticals are no different. There are numerous online pharmacies that offer drugs for animals. Some are presumably highly reputable companies that do what they are supposed to do: dispense drugs only with a valid prescription from a veterinarian, dispense only drugs that they can sell legally, and ensure that everything they sell is of appropriate quality.

However, it's clear that not all pet pharmacies are equal. Most state that a prescription is required, yet it is unclear how many actually follow this requirement. Some will have their own veterinarian write the prescription (which is illegal because the vet would not have a valid relationship with you and your pet, and would not have examined your pet). Some sites offer products that members of the general public cannot legally obtain or possess in most areas, like rabies vaccine. Virtually all the sites offered a wide range of antibiotics. Few had information about the origin of the products or shipping issues to other countries.  Import regulations are very important because, for example, an individual cannot legally import vaccines into Canada.

Certain things raised some big red flags on some sites:

• No indication of where the pharmacy is geographically. (I'm sure this is because if they don't say they are from a particular country, then it is less likely that the regulatory authorities in that country will look at them.)
• No information about shipping issues.
• No clear statement about how they verify valid veterinary prescriptions.
• Offering a very wide range of drugs, including things like rabies vaccine and narcotics which are not legally obtainable by the public.
• No contact information.

An article from the FDA also has some good points to consider.

Online pharmacies are very much a "buyer beware" situation. The last thing you want is to buy important drugs like antibiotics online and not be certain that you are actually getting the real thing. Counterfeit drugs have been obtained from some of these websites.  If you're treating your pet with an ineffective "fake" antibiotic, your pet's infection will only get worse, and your pet may develop more severe complications.

If you are going to use an internet pharmacy, do some research first, and talk to your veterinarian (you'll need a prescription from him/her anyway).

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We're happy to announce the launch of a sister site to the Worms & Germs blog. This site, equIDblog (available at www.equIDblog.com), is a resource on equine infectious diseases, and has many similarities to this site, with regular blog posts and a collection of information materials pertaining to equine infectious diseases as well as infection control on horse farms and equine hospitals. If you like horses, stop by!

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A recent report in the Journal of the American Veterinary Medical Association by Jesse Blanton and colleagues provided a detailed report of rabies infection in the US in 2007. Here are some of the more interesting points:

• Rabies was diagnosed in 7 258 animals and 1 person. That's a 4.6% increase in animals from 2006, but 2 fewer human cases.
• 93% of cases were wildlife: 37% raccoons, 27% bats, 20% skunks, 7% foxes.
• 0.8% of cases were in cattle and 0.6% were in horses.
• 4% of cases were cats, with the largest numbers of feline cases in Virginia, Florida, Pennsylvania, North Carolina, Maryland, New Jersey, New York, Georgia, Texas and Kansas.  Cat cases peaked in June and July.
• 1.3% of cases were dogs, with the largest number of canine cases in Texas, Georgia and North Dakota. Dog cases did not appear to have a seasonal pattern.
• Small numbers of a variety of other species were diagnosed, including pigs, wolves, opossums, bobcats, coyotes, otters, bears, deer, mongooses (in Puerto Rico), groundhogs and beavers.
• The largest number of rabies cases occurred in Texas (969).
• The infections that occurred were due to several rabies virus variants in circulation in North America, including raccoon rabies virus, skunk rabies virus, arctic fox rabies virus, bat rabies virus and Texas gray fox rabies virus.  In each region of the continent, one or more of these rabies virus variants may be more common.
• No infections with canine rabies virus were identified. Dogs and coyotes were infected by other variants of the rabies virus, but not with the dog variant.  It is believed that dog-to-dog transmission of canine rabies virus no longer occurs in the US.
• The one human rabies case in 2007 occurred in Minnesota, and was probably due to exposure to a rabid bat.

More information on rabies can be found on the  Worms & Germs Resources page, and in the rabies archives.

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For more information on ringworm, see the Worms & Germs post Ringworm: Skin fungus by any other name.  The photos here show ringworm lesions on a person's arm and on a cat's face, respectively.  (Photo credits: A. Yu, Ontario Veterinary College)

Over the past several years, studies have shown that many environmental disinfectants sold and labeled for use against the fungi that cause ringworm (which are called dermatophytes) in animals and people are, in fact, not effective when used in households and veterinary clinics.  The problem is the chemicals are typically tested against a suspension of the organisms in a test tube, but in the “real world” the fungi are usually found on small fragments of infected hairs.  Its possible that the hair shaft protects the fungus from the actions of some disinfectants.

There are a few disinfectants that have been shown to be effective against dermatophytes even when they are found on infected hairs and skin cells in the environment.  The most readily available one is household bleach, used at concentrations of 1:10 to 1:100.  Other effective products include Virkon-S® (a detergent-peroxide based product) and Peroxigard® (an accelerated hydrogen peroxide product) . An environmental spray containing enilconazole (an antifungal agent that is also found in the topical medication Imaverol®) was also found to be very effective. This product is not approved for household use, but it is approved for use in catteries. It is also licensed as a topical treatment for dogs and horses in most of Europe and Canada.

Eliminating ringworm from the household or clinic environment can be difficult, because the fungus can be found anywhere that an infected animal (or person) sheds hair or skin cells.  Here are some guidelines for environmental disinfection of dermatophytes:

• All bedding, brushes, combs, rugs, cages, etc. should be vacuumed, scrubbed, and washed with hot water, detergent, and 1:100 chlorine laundry bleach, or another effective disinfectant (see above). It is best to throw out any items that cannot be thoroughly disinfected.
• Walls, floors, lamps, etc. should be scrubbed and cleaned in a similar manner.
• Carpeted areas may be impossible to effectively decontaminate. If possible, remove the carpet and either wash in hot water and bleach, or discard it. Otherwise, frequent vacuuming with immediate disposal of the collection bag is necessary.
• Vehicle interiors should be decontaminated as much as possible in a similar manner.
• Curtains can be “dry-cleaned” at a professional cleaner.
• Clean heating vents (from the house furnace) as well as possible. If the house is heated by hot air, change the furnace filter once weekly throughout the decontamination process.
• Cleaning and disinfection of the environment should be repeated at least once every 4-6 weeks (the more often, the better) until all affected animals and people have eliminated the fungal infection.

Obviously, environmental clean-up for ringworm is quite an undertaking.  If infection can be identified early, lesions can potentially be kept covered and movement of pets can be restricted to reduce the extent and amount of environmental contamination.

Special thanks to Dr. Anthony Yu (one of the veterinary dermatologists at the Ontario Veterinary College) for providing much of the information in this post, as well at the photos.

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You may notice a recurring theme in many of our posts and on virtually all of the information sheets on the Worms & Germs Resources page: an emphasis on handwashing. There is increasing emphasis on hand hygiene (i.e. hand washing and use of alcohol hand sanitizers) education in hospitals because the hands of healthcare workers are a major (if not the most important) means of disease transmission between patients. Despite hand hygiene being easy, cheap and effective, people rarely wash their hands as often as they should, and they often don't do it properly.

Most of the research about hand hygiene that has been published has focused on its use and impact in human hospitals, but this area is now also being studied more with regard to animals and veterinary medicine. A study published earlier this year in Veterinary Microbiology provided more evidence that hand hygiene is a critical infection control measure when dealing with animals. The study, coordinated by Dr. Maureen Anderson (of Worms&Germs fame) looked at MRSA carriage rate in veterinarians who work with horses. In addition to finding a high rate of MRSA carriage among these veterinarians (which was consistent with other reports indicating that equine vets are at higher than average risk for exposure to MRSA), the study looked at factors associated with MRSA carriage. Vets that reported routinely washing their hands between farms and those that reported washing their hands after contact with potentially infectious cases had a significantly lower rate of MRSA carriage. That should come as absolutely no surprise, but it's one more piece of evidence that we need to pay more attention to this routine infection control measure, in human hospitals, in veterinary environments and in households.

Remember, the 10 most important sources of infection are the fingers on your hands!

Click here for instructions on how to wash your hands properly.

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In Ontario, and many other regions, mid-August is the beginning of the high risk period for West Nile virus infection in people and animals such as horses. The Ontario Veterinary College has published an informational video on YouTube. This video has information about measures you can take to reduce the risk of West Nile virus exposure and disease, for both people and horses. Click on the image to watch the video.  More information about West Nile virus is also available in the blog post entitled West Nile virus in dogs and cats.

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A small outbreak of the potentially deadly Hendra virus was identified in a group of horses near Brisbane, Australia. This virus has caused periodic cases of illness and death in horses, and can be transmitted to people working closely with infected horses. In the latest outbreak, 3 horses have died, making this the worst outbreak since 1994 when 14 horses and 2 people died.  Now, a human case has been identified. This person works at a veterinary clinic that treated infected horses. This individual was admitted to hospital overnight but was discharged, so is presumably not very ill.

While Hendra virus (genus Henipavirus) is only found in Australia, it is a good reminder for everyone about the strange nature of some infectious diseases. The natural reservoir of the virus is the fruit bat. It is believed that horses become exposed when infected fruit bats give birth and contaminate horse pastures with uterine fluids. Horses develop respiratory disease ranging from mild to fatal. Human cases have been reported in people working closely with infected horses. A horse trainer and veterinarian's assistant died in the 1994 outbreak. Close contact is required for transmission to people.

Picture: Locations of previous Henipavirus outbreaks (red stars – Hendra virus; blue stars – Nipah virus) and distribution of Henipavirus flying fox reservoirs (red shading – Hendra virus; blue shading – Nipah virus)

It's very difficult to take specific measures to protect horses, people or other animals from sporadic, rare diseases such as Hendravirus infection. However, common sense infection control measures can reduce the risks associated with any animal contact.

• Wash your hands after contact with any animal.
• Avoid contact with sick animals - consider sick animals to be potentially infectious until proven otherwise.
• Remember that  new animal diseases are regularly being identified, and that they might be able to infect people.
• People that work in veterinary clinics must be diligent and use good infection control practices because they are at higher risk of exposure to various diseases.

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Recently, a story about a man who brought a horse into a hospital to visit his father was widely reported. The horse apparently made it to the man’s room, which included a trip in an elevator. The son, who appeared intoxicated, was eventually asked to leave (and take the horse with him). Said a hospital spokesperson “We do have a pet visitation policy, but it does not include a horse”. Strangely, the horse that was brought to the hospital apparently wasn’t even the father’s horse (which supports suspicions of the son’s lack of sobriety).

There are guidelines about which animals are appropriate for hospital visits, although it shouldn’t take an expert to figure out that a horse is not an appropriate candidate. Kicks, bites, and trauma from being crushed or run over are among the most obvious concerns. Horses can also carry a variety of bacteria that are potentially dangerous, especially to people in hospitals. These include Salmonella and methicillin-resistant Staphylococcus aureus (MRSA). There also aren’t that many house-trained horses out there.

So, while I can easily see how someone in a hospital would like to see his or her horse, there’s no way this should even be considered.

Some closing thoughts
-    Would you like to ride in an elevator with a horse?
-    Would you like to be stuck in an elevator with a horse?
-    Do you think the horse was house trained?
-    Do you think any of the healthcare personnel washed their hands after touching the horse?

This isn't the first time a horse has been in hospital, and some even get invited. The picture is from a story in Veterinary Practice News that described a program where horses were brought into hospitals!

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