Plague in Saskatchewan
Plague has been identified in a dead prairie dog in Grasslands National Park in Saskatchewan, Canada. This disease, caused by the bacterium Yersinia pestis, circulates in small wild mammals in some regions, and is spread by fleas. While plague is endemic in some parts of North America, it's very rare in Canada. (The last reported human case was in 1939).
Prairie dogs are highly susceptible to plague. The most likely problem with plague occurring in prairie dogs in Grasslands National Park will be the impact on the prairie dog population itself. Outbreaks of plague in prairie dogs can be devastating, virtually wiping out entire colonies.
- Plague can be transmitted to people, but the risk here is quite low. For people to become infected, they have to be bitten by a flea that was infected by biting an infected prairie dog (or other animal). The risk of exposure to a flea infected by wildlife is pretty low if people aren't crawling around prairie dog holes and take some basic precautions.
- The risk to pets is similarly low. Cats are more susceptible to plague than dogs, but they have to be exposed via a flea or, more commonly, from hunting and eating infected wildlife. There presumably aren't too many pet cats in Grasslands National Park, so the risk of exposure is probably limited. Dogs are rather resistant to plague, but they are probably at increased risk of exposure in a situation like this because they are more likely to be taken into areas where infected animals and fleas may be present (e.g. with people going hiking).
The greatest public health and domestic pet concern would be if plague spread beyond prairie dogs and into other small mammal populations that live closer to people or that have more contact with pets. The likelihood of this becoming a major problem is pretty low, but it's a serious disease and this situation certainly needs to be monitored.
In response to this case, park personnel are monitoring prairie dog colonies to look for more cases. They are presumably also keeping a close eye out for any other unexpected deaths of small mammals. Park officials have recommended that people stay away from prairie dog colonies, tuck their pants into their socks (to keep out fleas) and use insect repellent on their shoes. They have also closed some areas to domestic pets.
Photo: Black-tailed Prairie Dogs atop their burrows in Grasslands National Park in Saskatchewan, Canada (source: www.canada-photos.com)
Plague in Montana cat
A cat from Ennis, Montana, has been identified as the area's first case of plague in a pet cat this summer. Plague is a disease that conjures up images of medieval pandemics and calls of "bring out your dead" (along with calls of "I'm not dead yet" from Monty Python fans).This bacterial disease, caused by Yersinia pestis, is not just of historical interest, however. It is still an important disease in some regions. In the US, it is present in wildlife in parts of the southwestern US and circulates in wild rodents. Domestic pets mainly become infected through eating infected rodents, but the bacterium can also be spread by fleas.
Cats are quite susceptible to plague, and can develop classical bubonic plague, septicemic plague or pneumonic plague, and only about 33% of infected cats survive. Dogs are relatively resistant to the disease.
Transmission of plague from pets to people is uncommon but most often involves cats. Veterinary personnel and pet owners that care for sick cats are at highest risk. While transmission from cats to people is rare, about 20% of people infected from cats die, so it certainly warrants some precautions.
In areas where plague is present, cat owners should consider the following:
- Keep cats indoors to prevent them from hunting and eating rodents.
- Keep rodents and other wildlife out of the house.
- Have a flea control program in place to prevent or treat flea infestations in pets.
- Never catch and keep wildlife (e.g. prairie dogs) as pets.
Plague in a Colorado cat
A house cat in the Eagle, Colorado area has been diagnosed with pneumonic plague. Plague, caused by the bacterium Yersinia pestis, is a disease that still strikes fear into people. While we are long since removed from the period where the "black death" killed a large percentage of the population in Europe, plague still has a foothold is some regions of the world like the southwestern US. It is present in some wildlife (mainly rodents) and periodically infects people or domestic animals through transmission by infected fleas or direct contact.
Plague is periodically identified in cats - it's almost always outdoor cats that are affected since they have more interaction with wildlife and are at greater risk of flea infestation. Several forms of the disease can occur, including pneumonic, septicemic and bubonic plague. Pneumonic plague is a severe lung infection caused by the plague bacterium which is highly fatal. This form is of particular concern because infected cats can spread the infection to people through aerosols produced by coughing and sneezing, or through contact with respiratory secretions. People caring for sick cats are at risk of developing plague (especially pneumonic plague, which is almost invariably fatal if untreated). Veterinary personnel are at particularly high risk. One study reported that 20% of people who contracted plague from cats worked in vet clinics. Of these, 25% of them died.
If you live in an area where plague is present in wildlife, keep your cat indoors, avoid contact with wild rodents, keep wild rodents out of your house and make sure that you have a flea prevention program for you pets. If these things are done, the risk of disease transmission is very low.
Image source: www.northernsun.com
Plague in a rabbit: New Mexico
Plague has been diagnosed in a dead rabbit found on a private residence in New Mexico. Plague, also known as the black death, is a highly fatal disease of humans and many animals caused by the bacterium Yersina pestis. While often considered a disease of mainly historical interest - having killed a large percentage of people on the planet during a few pandemics over the centuries - plague is actually still alive and well in some regions. In North America, most cases occur in New Mexico, Arizona, Colorado and California.
Yersinia pestis primarily lives in wild rodents and is transmitted by fleas. Many different animal species, including cats, dogs, rabbits and people, can be infected if bitten by a flea from an infected rodent (hence the historical association of the disease with rats). Predatory species (like dogs and cats) can also become infected by eating infected animals. Dogs are relatively resistant to plague and usually only develop mild disease, while cats and rabbits are as susceptible as people, and can develop bubonic, septicemic or pneumonic plague. Transmission of plague from pets to people can occur, and most often involves cats. People can become infected by close contact with sick pets, or being bitten by a flea from such a pet.
Preventing plague in animals involves flea control and reducing exposure to infected wildlife. In areas where plague is active, all pets should be on a flea control program. Cats should be kept indoors to reduce the risk of exposure (e.g. keeps them from hunting infected rodents). Dogs and cats should not be allowed to have contact with dead animals of any kind. Measures to reduce rodent infestations in and around the house are also important.
More information on plague is available in the Worms & Germs archives.
Plague isn't back... It never went away
Plague (aka the "black death") is a fascinating disease. It is one of the most important diseases in human history because it had a devastating impact of the human population during various outbreaks. Many people may not realize it, but plague is not just a historical problem - it is still alive and well in some areas of the world. Plague is caused by the bacterium Yersinia pestis, which tends to circulate in rodent populations and can be spread by fleas. In North America, plague is most common in some regions of the southwestern US, particularly New Mexico, Arizona and Colorado. We're heading into the high-risk season for plague in those areas: March to October.
Plague can infect domestic pets, and pets can be a source of human infection. Cats are quite susceptible to plague, whereas dogs are quite resistant. Cats can transmit plague to people. Pneumonic plague (infection of the lungs with Y. pestis, not to be confused with bubonic plague which is primarily infection of the lymph nodes with Y. pestis (see picture left)) in cats is of particular concern, because in this form the bacterium can be spread through the air over short distances.
Prairie dogs (which some people keep as pets) are also very susceptible to plague.
A paper in Clinical Infectious Diseases a few years ago (Gage et al, 2000) described 23 cat-associated cases of plague in people, five of which were fatal. People were infected by face-to-face contact, bites, scratches or simply caring for an infected cat. Most affected people were cat owners, but some were veterinary clinic personnel. Plague is treatable with antibiotics, but the disease can progress rapidly, so it's important to determine the diagnosis and start treatment as soon as possible.
Here are some things to consider if you live in an area where plague exists:
- Keep pets indoors as much as possible to help prevent exposure to infected wildlife.
- Use routine flea control measures as directed by your veterinarian.
- Consider any cat that develops a fever of unknown origin or enlarged lymph nodes a plague suspect.
- Don't let cats and dogs hunt wild rodents, and don't let them have access to rodent burrows.
- If your pet has been diagnosed with plague, you need to seek medical attention promptly in case you have been exposed. If a person in the household is diagnosed with plague, pets should be investigated as possible sources and should be treated prophylactically in case they have been exposed.
Lower photo: Bubo in the leg of a person infected with bubonic plague (source: Centers for Disease Control and Prevention)
"Black Death" in South Dakota - Plagued Prairie Dogs
While people often consider plague (aka the 'black death') to be something from history books, it is in fact still alive and well is some areas of the world. In North America, it is most common in the southwestern US but can extend into other regions. Plague is caused by the bacterium Yersinia pestis, which is carried primarily by wild rodents. Infection with Yersina pestis can cause bubonic plague (swollen lymph glands), septicemia plague (bloodstream infection) or pneumonic plague (pneumonia/lung infection). An average of 13 human cases are diagnosed in the US every year. In today's modern times, the infection can be effectively treated with antibiotics, but if left untreated the mortality rate is still 50-90%. The Canadian Notifiable Disease Database has never received a report of plague in a human.
Plague has been reported in a variety of animal species, including cats and dogs. However, dogs seem to be relatively resistant to the infection compared to cats. Yersinia pestis gets from rodents to other animals and people mainly by flea bites. Fleas become infected by biting an infected animal, and can then pass on the infection by biting another animal or person. It is also possible for plague to be transmitted by direct contact with infected animals, but this is less common.
A recent report described an outbreak of plague in prairie dogs in western South Dakota. There is concern that the disease could also affect the endangered black-footed ferret in that area. Plague almost always kills prairie dogs, and black-footed ferrets almost exclusively eat prairie dogs.
When plague is present in wild animals in a region, there is always a risk of transmission to people and pets through contact with infected animals or bites from infected fleas. Some basic measures to reduce the risk of plague exposure in areas where the disease exists in wild animals are:
- Keep cats indoors
- Talk to your veterinarian about a flea control program for your pets
- Never touch wild animals, especially sick or dead ones
- Don't keep wild animals as pets
- Try to keep wild animals away from your pets
(Centers for Disease Control and Prevention (CDC) / Janice Carr)
