Severe Pasteurella infections from palliative pet care
Pasteurella multocida is a bacterium that's commonly found in the mouths of dogs and cats. It's a common cause of cat and dog bite infections in people, but can also be spread through close contact with pets (without bites). It's logical to assume that the closer the contact, the greater the risk of transmission. A recent report in Clinical Infectious Diseases (Myers et al 2012) describes three people with life-threatening Pasteurella infections. A unique aspect was all three people got sick from nursing dying pets.
Case 1
- A 55-year-old woman with sore throat, fever and difficulty swallowing was diagnosed with epiglottitis (inflammation of the epiglottis, a part of the throat region) and hospitalized. Pasteurella multocida was identified on a blood culture. It was subsequently revealed that she had provided palliative care to her dying dog. As part of this, she was dropper-feeding the dog honey, and also eating honey with the dog from the same dropper.
Case 2
- A 63-year-old woman with sore throat, difficulty swallowing and hoarseness was diagnosed with uvulitis (inflammation of a different part of the throat region) and narrowing of her airway. As with Case 1, P. multocida was isolated from her blood. Her cat had died six weeks earlier and she had "continuously held, caressed, hugged and kissed her cat during its last 7 days of life."
Case 3
- A 66-year-old woman was hospitalized with fever, chills, cough and difficulty breathing. She had severe pneumonia and P. multocida was grown from a sample of respiratory secretions. Two weeks before she got sick, she had provided palliative care for her dying cat, by "holding, hugging, and kissing the head of the cat and allowing the cat to lick her hands and arms."
Fortunately all three women recovered from their infections, but the severity of disease is certainly a concern. As is common, there was no attempt to see whether the implicated pets actually carried the same Pasteurella multocida strain as the owners, but here the authors at least had a good excuse, since all of the pets had died before the owners got sick.
There are some interesting points in the Discussion section of the paper.
"Our 3 patients’ histories of having recently provided palliative pet care to their dying animals were obtained only after P. multocida was identified in cultures and only after subsequent detail-oriented, animal contact histories were obtained."
- Pet contact (or animal contact in general) is still not asked enough by physicians investigating unknown illnesses. It's unclear whether it would have made a difference in these cases, but knowing more and knowing it earlier can help speed the path to the right diagnosis. Here, pet contact was only considered after a pet-associated bacterium was identified.
"Simply asking whether or not the patient had a pet would not have uncovered the defined association of these respiratory illnesses with palliative pet care. The patient with P. multocida uvulitis even denied having a pet (it had died 6 weeks previously) and only admitted to having provided palliative pet care when asked specifically if she had any animal contacts in the past 3 months."
- This shows some of the challenges and how care must be taken when asking about pet contact. Simply asking "Do you have a pet?" doesn't cover it.
"Only diligence and very detail-oriented, pet-related histories will likely uncover further patients with invasive P. multocida infection related to the pet owner’s provision of palliative pet care to dying animals."
- This shouldn't be focused on palliative pet care, since that's a minor component of pet contact. Many other people have close contact with their pets, even when the pets are healthy. It's something that should be considered at all times.
Pasteurella bone infection from dogs?
A paper in the journal Orthopedics (Machino et al 2011) describes the case of a 52-year-old man with an infection in the vertebrae of his neck caused by Pasteurella haemolytica. This bacterium (which was renamed Mannheimia haemolytica quite a while ago... I guess their laboratory is a bit behind the times) is most often associated with respiratory disease in cattle. In this case, "because the patient owned 2 dogs and frequently kissed them on the mouth, the cause of infection was thought to be excessive contract with pet dogs."
It's possible, but I have some issues with this.
- Despite the assertion in the paper that this bacterium is a resident in the mouth of dogs and cats, I don't know of much or any evidence supporting this. A different but related bacterium, Pasteurella multocida, is commonly found in the mouths of healthy dogs and cats, but it's not the one that caused disease here. The authors state that Pasteurella haemolytica can be found in 71-90% of cats and 21-60% of dogs, yet the papers they cite didn't actually find P. haemolytica, they found other Pasteurella.
- The authors also state that the recent increase in pet ownership has caused an increase in P. haeamolytica infections from bite wounds, with absolutely no evidence supporting either an increase in infections caused by this bacterium or any role of pets.
- This paper takes the typical medical journal approach of blaming the pet with no effort whatsoever to find out if the pet was really involved. Would it have killed them to get some oral samples from the dogs for culture, to see if they could actually find the same bacterium?
It's disappointing, but not surprising, to see reports like this. It shows a lack of critical thought about the potential role of pets, a lack of care when writing the report, and a weak peer review process for the journal.
Zoonotic diseases are an important issue. However, we need to focus our efforts on real problems, not bad science. This article is so weak and error-filled that it should be retracted, but it's unlikely anything will happen. I'll write a Letter to the Editor, which, based on my limited previous experience in questioning poor zoonotic disease science in human medical journals, will likely be ignored. Well, we'll see.
Feral cats and bat-bite-badness
Sunday's Toronto Sun contained an article entitled "Woman's hand disfigured by cat attack" with the compulsory gross picture. The story is about Brenda Sims, who took in a feral cat, was then bitten by the cat, and then developed severe complications from the bite. The situation is a reminder of the potential problems encountered when dealing with feral animals (cats included) and complications that can occur from any cat bite.
Back in April, Ms. Sims took in a young male cat that she described as "five pounds of pure disease." The cat, named Cheech, had been taken off the streets and was clearly not someone's lost pet. Cheech began following her around the house, growling and hissing. Not surprisingly, the well-meaning woman was eventually bitten.
Ms. Sims has had multiple surgeries since then, including one that removed a large section of tissue from her hand and replaced it with some taken from her thigh. She's been largely unable to work since the injury and faces long term problems with function and appearance of her hand.
Ms. Sims is warning people about the dangers of feral cats. "It's like taking a tiger out of the jungle and into your home, and expecting it to be all good, and be a house cat..."
Dr. John Embil, Director of Infection Prevention and Control for the Winnipeg Regional Health Authority echoes her warning about feral cats, adding that feral cats can transmit rabies or severe bacterial infections such as Pasteurella multocida through bites. That's very true and a good reminder, but it perhaps overstates the importance of "feral." Any cat can carry Pasteurella multocida, along with many other problematic bacteria, in its mouth. A bite from any cat - domestic or feral - can cause serious infections. While an individual feral cat may be more likely to bite than am individual pet cat, most cat bites and cat bite infections are presumably from pet cats because people have more contact with them.
Dr. Embil highlights the problem with cat bites: "The concern we have with cat bites is that the teeth are very long, sharp and pointy. And those teeth can puncture deeply. You can get serious infections." Cat bites can be similar to injecting a bacterial cocktail deep into the tissues, not surprisingly resulting in infection in many cases.
Some take home messages:
- Leave rescuing feral cats to people with experience.
- If you want to rescue a cat, get it from a shelter, humane society or other reputable and experienced organization. They will have assessed the cat's behaviour and health status, which will decrease the chance that you'll get an aggressive and/or sick cat.
- If a cat constantly stalks you around the house looking like it's going to attack (and not like it wants to play), it probably will attack and it shouldn't be in your house.
- Any cat bite can cause severe complications. Every cat bite should be taken seriously and medical advice should be sought. Bites over the hands, feet, joints, tendons, genitals or in people with compromised immune systems typically require antibiotics to help prevent infection.
More information about cat bites can be found on the Worms & Germs Resources page.
Peritoneal dialysis infections and pets
Pasteurella multocida is a bacterium that is commonly found in various pet species. It typically inhabits the upper respiratory tract of healthy pets, although it is an important cause of respiratory disease in rabbits ("snuffles"). It is also a zoonotic pathogen, and human infections are sporadically reported. Most are associated with bites, mainly from cats. Others have involved pets licking wounds or broken skin. Infections seem to be a particular concern in people undergoing dialysis because of kidney failure. Infections have been associated with things like cats chewing on dialysis tubing and pets having contact with catheter sites.
A recent report described another dialysis-associated infection in person with chronic kidney disease and diabetes (Satomura et al 2010, Ther Apher Dial). The person developed peritoneal dialysis-associated peritonitis. Peritonitis is infection of the internal lining of the abdominal cavity (the space between the intestines/other abdominal organs and the body wall). For peritoneal dialysis, a catheter is left in place which passes through the body wall, and infections can occur from bacteria migrating through or along the catheter and into the peritoneal cavity. In this case, Pasteurella multocida was isolated from the infected peritoneal fluid. The source of infection wasn’t clear, and no obvious risk factors like a cat gnawing on the catheter were reported. However, the same bacterium was isolated from a throat swab taken from the person’s cat. Given how common this bacterium is in cats, how uncommon it is in people, and previous reports of cat-associated infection, it’s logical to assume that the cat was the source.
The fact that no clear risk factors were identified in this case highlights the ever-present (but still relatively low) risk to people with dialysis catheters who have contact with cats. Certain things like keeping the cat away from the catheter site and other dialysis items are common sense and presumably very important. However, general hygiene measures are also probably very important. It is logical that a cat owner could frequently get this bacterium on his or her hands from regular interaction with the cat, or potential from contact with objects like food and water bowls. Good attention to hand hygiene, especially before touching the catheter or any dialysis items, must not be overlooked, and should be an important part of counseling of dialysis patients who own pets. Unfortunately, the risks associated with pets are not always discussed by physicians (who may not even ask about pet ownership), so some people don’t get the required information.
Note: Image is from http://www.kidney.org.uk/kids/crf/page09.html. It's presumably meant to be a cute image showing a happy (and otherwise healthy) kid undergoing dialysis. It's interesting that they show a cat in the picture, but no where on the page is there any mention about infection control measures that should be taken around pets. It seems like a missed education opportunity to me.
Meningitis in a baby linked to pet cat
A paper in the Journal of Clinical Microbiology back in 2000 described a case of Pasteurella multocida meningitis in a one-month-old baby that was linked to a pet cat. Pasteurella multocida is a bacterium that can be commonly found in the mouth of healthy dogs and cats - 90% or more of healthy cats may have it in their mouth. The organism can cause infection in humans. These cases are usually associated with close contact with animals, such as bites, scratches and licking wounds. In this case, there was reportedly little contact between the baby and the cat, yet the same P. multocida strain was found in both. The cat was healthy and the bacterium was found in its mouth. There was no clear route of transmission (like a bite or a scratch), however unidentified contact with the cat or (more likely) indirect transmission of the bacterium from the cat to the baby by another person are possible.
This is a good example of the unpredictable nature of zoonotic infections. There was no reported underlying disease that made this baby more susceptible to infection. It's just that being very young (or very old, or immunocompromised) means you're more likely to develop infections from the myriad bacteria that are present all around us. While this infection might not have been preventable, we need to think about good routine precautions involving contact of pets with babies.
- Keep them apart (but not completely). Pets should not be allowed to lick or have other close contact with a young baby. That being said, household pets need to be around the baby to learn to interact with the child safely, and recognize the baby as a member of the family, but supervision is needed and direct contact should be avoided.
- Good hygiene should be used around pets and babies (individually and together). Hands are the main source of disease transmission and regular hand washing is a great infection control tool.
