Tick bite irony
Canadian singer Alanis Morissette wrote a song called "Ironic" that (ironically) doesn't really describe irony: Rain on your wedding day, a free ride when you already paid, a black fly in your Chardonnay... they all suck but they're not ironic. What is ironic is Dr. Ed Breitschswerdt, an internationally renowned veterinary internist and tickborne disease expert, getting bitten and infected by a tick.
Dr. Breitschwerdt has worked on tickborne diseases for decades and is a wealth of knowledge on the subject, in terms of both animal and human infections. He regularly provides advice about how to avoid tickborne illnesses.
Dr. Breitschwerdt wrote an article about his recent tick-encounter, and here are some excerpts:
"...I do "tick checks" after outdoor activity on my farm, but I recently missed one. When I discovered the tick, I followed recommendation I've given to hundreds of individuals in lectures on tick-borne pathogens. I placed the parasite in a vial of alcohol and wrote the date of its removal on the label. This is an important step, as there are at least four tick species that attach to animals and people in North Carolina, and each species can transmit different bacteria that collectively cause a spectrum of diseases. Knowing the species can help the physician or veterinarian understand which infectious agent has been transmitted...The small tick in my armpit remained attached long enough for my body to mount an inflammatory response (itching, swelling and pain) before I noticed and removed it. Not initially feeling an attached tick is the norm, since ticks have evolved the ability to secrete chemicals that block pain and decrease the body's inflammatory response."
- The fact that the tick was present for a while is critical, since it takes time after attachment before a tick starts feeding and can pose a potential risk for disease transmission.
"Nine days after removing my tick I developed severe chills. The next day my symptoms progressed to include fever, muscle pain and headache - classic symptoms of Rocky Mountain spotted fever and human granulocytic or monocytic ehrlichiosis, the three most serious and frequent tick-transmitted diseases of dogs and people in the southeastern United States.
"Typical of the early stages of these diseases, my white blood cell count (the body's first line of defense) was low. My bone marrow responded by sending new white blood cells to fight the infection. After blood was obtained for diagnostic testing, antibiotic treatment was started immediately. This is of critical importance, as a delay in diagnosis and initiation of antibiotics for 24-48 hours greatly increases the severity of illness and the chances of death."
- Testing was performed on the tick and Dr. Breitschwerdt's blood, and Rickettsia rickettsii DNA was found in both. In combination with his clinical signs, including a rash on his arms and legs (see photo), this confirmed the suspected diagnosis of Rocky Mountain spotted fever. This is a serious disease from which approximately 6% of infected people die. Early recognition is critical, but diagnosis is often delayed because of failure to identify or report a tick bite, or failure of physicians to consider the disease.
Dr. Breitschwerdt concludes "This recent experience enhanced my belief that tick-transmitted diseases deserve respect and enhanced, comparative biomedical research. The next time you walk in the beautiful fields and valleys of North Carolina, apply a tick repellent and remember to check carefully for attached ticks when you return home."
Photo: Child's right hand and wrist displaying the characteristic spotted rash of Rocky Mountain spotted fever (source: CDC Public Health Image Library #1962)
Lyme disease from a dog: Don't believe everything you read
InsideToronto.com published an article entitled "Unsuspecting resident contracts Lyme disease from pet dog". However, Lyme disease cannot be transmitted from dogs to people.
Lyme disease is a tickborne disease caused by the bacterium Borrellia burgdorferi. This bacterium is transmitted from wildlife reservoirs to people and pets by ticks that have fed on an infected animal, and then latch onto a person or pet.
The article reports that a woman and her son from Scarborough, Ontario, were diagnosed with Lyme disease after there dog was infected. The owner frequently walked her dog in the Rouge Valley and Morningside Park. After finding a tick on her dog, the owner took the dog to the vet, and it was diagnosed with Lyme disease. She and her son were later diagnosed. The fact that people and pets in the same house got the same disease does not mean that the dog was the source of infection. Lyme disease cannot be transmitted directly between people and animals; ticks must be involved. Additionally, ticks must be attached for approximately 24 hours to efficiently transfer the bacterium. So, if multiple people and a pet in the house got Lyme disease, they were all bitten by ticks, presumably while walking in the woods. (It's also possible that a tick could have been brought into the house by a dog, and then it jumped onto a person). Identification of Lyme disease in a dog does not mean that there is a risk to people from the infected dog, but it does indicate that people may have been exposed in the same manner as the dog, and they should pay attention.
The dog owner in this case is upset that her veterinarian did not warn her about Lyme disease. She wants the College of Veterinarians of Ontario (the provincial licensing body for veterinarians) to "require members to tell people when they may have been exposed to Lyme disease through a pet, as well as what the symptoms are." That's reasonable, to a point. Veterinarians should engage their clients with discussions about zoonotic diseases. If they identify a pet with a zoonotic infection, they should talk about the implications. Similarly, if they identify a pet with an infection to which the owner may have also been exposed (such as Lyme disease), they should mention the risk. However, requiring vets to talk about signs of disease in people starts to cross the line between veterinary and human medicine. Vets should introduce the issue and let physicians take over from there.
People in the Toronto area should not panic based on this report. Lyme disease is quite rare in Ontario, especially in the Toronto area, as the ticks that transmit Lyme disease are not commonly found there.Toronto Public Health reports that an average of nine cases of Lyme disease a year have been diagnosed in people between 1998 and 2007, and that most of these cases were acquired in the US.
Canadian parasite treatment guidelines for pets
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Canadian Guidelines for the Treatment of Parasites in Dogs and Cats have recently been released. These guidelines were developed by an expert panel, consisting of six Canadian veterinary parasitologists and two private practitioners. They provide a good, balanced approach to the treatment of parasites, with an emphasis on the risks present in different regions and in different types of pets. There is very little objective information on which to base some of the recommendations, so many aspects are instead based on expert opinion, not necessarily hard facts, but when data are lacking, that's when opinions from independent experts are most needed. The guidelines provide an overview of recommended treatments along with an explanation of the reasoning. This document is a useful resource for pet owners and veterinarians alike. There is also discussion about why guidelines in Canada differ from those in the US. To download these guidelines click here.
Note: Development of the guidelines was supported by a pharmaceutical company, but the information they contain was developed by the independent experts mentioned above.
Cat Scratch Disease - Bartonella henselae
Bartonella henselae is a small, Gram-negative bacterium that is host-adapted to cats. It may rarely cause mild illness in cats, but most felines, from tiny house cats to the king of the beasts, carry the bacteria with no clinical signs whatsoever. Unfortunately, when B. henselae infects a person it can cause any of several serious conditions (most of which have very long names!). These include bacillary angiomatosis (formation of masses of abnormal blood and lymph vessels), endocarditis (infection of the lining of the heart), chronic lymphadomegally (enlarged lymph nodes), and pyogranulomatous lymphadenitis, better known as cat scratch disease. There are at least four Bartonella species (among many, many other Bartonella species) that can infect cats, but B. henselae is the most common. There are at least nine Bartonella species that can infect humans, seven of which are zoonotic.
Between 5% and 40% of cats in the USA have B. henselae in their bloodstream. It is most common in cats from temperate areas, and is much less common in Canada. Bartonella spp. live in the red blood cells of their host – quite a clever strategy really, because it makes the bacteria readily available to be picked up by vectors like blood-sucking fleas, it protects the bacteria from the hosts immune system so it can live there for a long time, and it may even partially protect the bacteria from antibiotics. Cats can maintain a waxing and waning infection for months or even years. The bacterium is transmitted between animals by the cat flea (Ctenocephalides felis felis). Studies have shown that transmission does not occur between cats kept in a flea-free environment. Some ticks may also be able to transmit the disease. Diagnosis in cats is difficult – blood culture is the most reliable means, but it is not always sensitive. Antibody production only confirms exposure but not active infection. Polymerase chain reaction is often faster but no more sensitive than blood culture. An effective treatment regimen to eliminate B. henselae infection in cats has yet to be determined.
Transmission of B. henselae from cats to humans is thought to occur through contamination of scratches and bites (broken skin) with flea dirt (i.e. partially digested blood from the infected animal that is excreted by fleas = flea poop). Infection in individuals with weakened immune systems can be extremely serious or even fatal. In otherwise healthy people, the infection tends to remain localized, but can still cause massive swelling and abscessation of local lymph nodes. The type of disease that occurs may depend on the strain of Bartonella involved.
There are a few simple steps people can take to decrease the risk of cat scratch disease. These are particularly important for individuals with compromised immune systems, in which infection can be much more severe:
- Keep your pets flea- and tick-free. Effective treatment and prevention products are available from your veterinarian.
- Avoid or prevent situations that may result in bites and scratches from your pet. There is more information about this on the Worms & Germs Resources page and in our archives. If you do accidentally get scratched or bitten, be sure to clean the wound thoroughly. Consider seeking medical attention for bites in particular.
- Be aware of where cats come from. Stray or shelter cats less than one year old are most likely to be infected with B. henselae.
It is also important to note that there is NO evidence that declawing cats decreases the risk of transmission of B. henselae to humans!
As a point of interest, Bartonella quintana (a human-adapted Bartonella species) was the cause of trench fever in World War I, and was transmitted by lice.
Q Fever - From goats to people (and pets!)
Q fever is an infection caused by the proteobacterial organism Coxiella burnetii. Although usually not very common, C. burnetii can be carried by sheep, goats, and cattle, as well as birds and even sometimes cats and dogs. Animals often show no signs of illness, although the infection sometimes causes miscarriage, particularly in sheep and goats. Coxiella burnetii is also transmissible to humans. People are much more susceptible than animals to disease from Q fever. Even so, only about 50% of individuals that become infected show signs of illness, which can range from flu-like symptoms to pneumonia and hepatitis (liver infection). About 1-2% of infections in people are fatal.
Infected animals shed C. burnetii in their stool, urine and milk, but the highest number of organisms are shed in birth fluids and placentae. Coxiella is able to survive very well in hot, dry soil, and when dust and dirt from contaminated areas are stirred up into the air, the organism can be inhaled. This is the most common means of transmission, although direct contact with an infected animal or its stool or urine can also transmit the disease. Transmission from drinking milk from an infected animal is very rare, but is more likely if the milk has not been pasteurized. Cats and dogs can be infected by and transmit C. burnetii in all the same ways (especially through birth fluids), but they very rarely get sick. Ticks can also transmit the disease.
Q fever is one of the most infectious diseases in the world. As little as one C. burnetii organism is enough to infect a susceptible person. There are a few things to keep in mind to help reduce the risk of being exposed to this pathogen:
- Only eat/drink pasteurized dairy products.
- The main risk from cats and dogs (especially cats) is when they give birth. If you have a cat or dog that has kittens/puppies, wear gloves if you have to touch the babies or any placentae. Afterwards, cleaning the area very thoroughly to physically remove any tissue or fluid residue is very important, because most disinfectants cannot kill C. burnetii. Always wash your hands thoroughly after handing newborn kittens or puppies.
- On dry, windy days, avoid farms or areas where sheep or goats are kept.
- Avoid sheep and goat farms during the lambing/kidding season.
Removing ticks
Your veterinarian, physician and/or public health departments should be able to tell you what diseases are of concern in your area. Regardless of where you live, if you and your pet might encounter ticks, you should know how to remove them. Prompt removal is the key. Most tickborne diseases aren't transmitted immediately. Rather, the tick must be attached for a period of time for infection to occur. Therefore, close inspection of your pet (and yourself) for ticks after spending time outside, is important.
The following tick removal tips come from the Centers for Disease Control and Prevention (CDC).
- Remove a tick as soon as you see it.
- Use fine-tipped tweezers to firmly grasp the tick very close to your skin. With a steady motion, pull the tick away from your skin. Then clean your skin with soap and warm water.
- Avoid crushing the tick’s body.
- Do not be alarmed if the tick’s mouthparts remain in the skin. Once the mouthparts are removed from the rest of the tick, it can no longer transmit Lyme disease bacteria.
- If you accidentally crush the tick, clean your skin with soap and warm water or alcohol.
If a large number ticks are present on your pet, you should contact your veterinarian for assistance. Typically, a product that kills ticks will be applied to your pet.
There are various anecdotal recommendations that should be avoided, including burning the tick off with a match and covering the tick with substances such as gasoline, petroleum jelly or nail polish.
Camping with canines - tick tick not!
The warm weather is just about here, and that means the start of camping season. Lots of people love to spend time in the great outdoors during the summer, whether it’s at a summer cottage on the lake, trailer camping in a park with electricity and running water, or roughing it in a tent in the peace and solitude of a more remote wooded location. And many people bring along their faithful companions – their dogs – who enjoy the experience just as much, if not more, than we do.But there are also dangers lurking in the forests – microscopic dangers carried by tiny insects and other bugs. Ticks in particular are problematic. Certain ticks can carry a number of diseases that can make dogs sick, including Lyme disease (caused by Borrelia burgdorferi) and Rocky Mountain Spotted Fever (RMSF)(caused by Rickettsia rickettsii ). Both Lyme disease and RMSF are more common in certain areas where the tick species that carry them are present. You can NOT catch these diseases from your dog, but both you and your dog can be infected by the ticks that carry them. People can also be exposed to these pathogens by accidentally crushing an infected tick while trying to remove it from their dog. Ticks must be removed very carefully to ensure that the entire tick is removed, including the head and mouth pieces, without crushing it. If you're not sure how, contact your veterinarian. Also, the sooner the tick is removed, the less likely it is to transmit certain diseases, so be sure to check your dog thoroughly for ticks when you come back from a walk in the bush.
The Minnesota Department of Health recently reported that the number of cases of (human) Lyme disease increased in that state in 2007. This could be because of spreading tick populations, more people participating in activities in tick-inhabited areas, or increasing awareness and diagnosis of the disease by physicians.
If you and your canine companion will be spending time in some of the wilder and woodier parts of the great outdoors, talk to your veterinarian about what you can do to protect your dog. There are vaccines available for Lyme disease and the bacterial infection leptospirosis (which is also transmissible to people). Flea and tick preventatives are also very important, and many of today’s products are very effective. People should always wear insect repellent when camping or hiking in the woods. Visit the Health Canada website for safety tips on using personal insect repellents. All dogs should be vaccinated for rabies, whether they go camping in the backwoods or they’re house-bound city-slickers.
