Posted on Feb 12, 2024, 1 p.m.
One of the most fatal pandemics in human history was known as the Black Death, with between 75-200 million people perishing in a few years. This pandemic called the bubonic plague which was caused by the bacterium Yersinia pestis found in wild rodents and their fleas. Survivors are thought to have given their descendants a genetic advantage, the ability to survive other pandemics. Improved sanitation, personal hygiene, and medical practices ultimately played significant roles in slowing the plague's march of devastation.
The Black Death is unfortunately still with us today, occurring in scattered cases. It is important to diagnose infection early as bubonic plague can progress to septicemic plague (bloodstream infections) and/or pneumonic plague (lung infections) rapidly and these forms are more severe and difficult to treat. Symptoms usually begin within 2-8 days in humans after exposure to an infected animal/flea, this may include but is not limited to sudden onset of fever, nausea, weakness, chills, muscle ache, and visibly swollen lymph nodes called buboes.
While estimates are that up to 60% of the 14th Century European populations were wiped out by the Black Death, today bubonic plague is rare, and as long as the patient is treated accordingly, they can be cured. For treated individuals' mortality rates range from 1-15%, and if left untreated the mortality rate increases to around 50%. However, if bubonic plague progresses to septicemic plague the mortality rates are grimmer, increasing to 40% if treated and 100% if left untreated.
In America, the last urban plague epidemic occurred in Los Angeles from 1924-1925, spreading from urban rats to rural rodent species becoming entrenched in many areas. Since then, the plague has become rare, and it is more plausible in the Western United States, occurring in scattered cases with 496 cases being reported from 1970 to 2020, according to the CDC. During that time the states with the most cases were: California (45), Southern Oregon (19), Utah (15), far Western Nevada (7), Northern New Mexico (253), Northern Arizona (65), and Southern Colorado (66). In recent decades an average of 7 plague cases are reported each year ranging from 1- 17 cases, with 80% being the bubonic form.
Recently Oregon Health Authorities announced its first case since 2015. The most common animals to carry the plague in Central Oregon are squirrels and chipmunks, but rats, mice, and other rodents can also carry the disease. Additionally, pets can become infected while hunting wild rodents. Deschutes County Health Services confirmed the case which was identified and treated in the earlier stages of the disease, posing little risk to the community. All close contacts/neighbors of the resident were contacted, and no additional cases of plagues have emerged during the communicable disease investigation.
In animals, the signs of plague vary, and they are non-specific. According to the American Veterinary Medical Association (AVMA): Bubonic plague means that buboes are present; however, plague can occur without buboes. Signs in animals can include lethargy, depression, anorexia, vomiting, diarrhea, dehydration, fever, enlarged or abscessed lymph nodes draining the site of exposure (e.g., submandibular lymph nodes if the pet ate infective tissues), oral lesions (e.g., necrotic tonsillitis and ulcers), muscle soreness, coughing, hemoptysis, and weight loss. If the disease progresses to septicemic plague, the animal may also develop shock, be dyspneic (likely from pulmonary edema), or develop disseminated intravascular coagulation. Veterinarians consider plague in animals with a systemic infection that has a history of roaming or hunting in a plague-endemic area.
Oregon Health Authorities offer some tips to prevent the spread of plague:
- Avoid all contact with rodents and their fleas. Never touch sick, injured, or dead rodents.
- Keep pets on a leash when outdoors and protect them with flea control products. Do not allow pets to approach sick or dead rodents or explore rodent burrows.
- Pet cats and dogs are highly susceptible to plague, and infected pets can transmit the bacterium to humans. If possible, discourage their hunting of rodents. Consult a veterinarian immediately if your pet becomes sick after being in contact with rodents.
- Residents should keep wild rodents out of homes and remove food, woodpiles, and other attractants for rodents around homes and outbuildings.
- Do not camp, sleep, or rest near animal burrows or areas where dead rodents are observed.
- Refrain from feeding squirrels, chipmunks, or other wild rodents in campgrounds and picnic areas. Store food and refuse in rodent-proof containers.
- Wear long pants tucked into boot tops to reduce exposure to fleas. Apply insect repellent to socks and trouser cuffs to help reduce exposure to fleas.
The CDC offers these tips to help prevent the spread of plague:
- Reduce rodent habitat around your home, workplace, and recreational areas. Remove brush, rock piles, junk, cluttered firewood, and possible rodent food supplies, such as pet and wild animal food. Make your home and outbuildings rodent-proof.
- Wear gloves if you are handling or skinning potentially infected animals to prevent contact between your skin and the plague bacteria. Contact your local health department if you have questions about the disposal of dead animals.
- Use repellent if you think you could be exposed to rodent fleas during activities such as camping, hiking, or working outdoors. Products containing DEET can be applied to the skin as well as clothing and products containing permethrin can be applied to clothing (always follow instructions on the label).
- Keep fleas off of your pets by applying flea control products. Animals that roam freely are more likely to come in contact with plague-infected animals or fleas and could bring them into homes. If your pet becomes sick, seek care from a veterinarian as soon as possible.
- Do not allow dogs or cats that roam free in endemic areas to sleep on your bed.
Plague is a serious illness that can be fatal. If you, a loved one, or a pet is experiencing symptoms seek immediate medical attention. Receiving prompt attention with the correct medications is crucial to prevent complications or death. The earlier treatment is received, the better the chances are for a full recovery.
As with anything you read on the internet, this article should not be construed as medical advice; please talk to your doctor or primary care provider before changing your wellness routine. This article is not intended to provide a medical diagnosis, recommendation, treatment, or endorsement. These statements have not been evaluated by the Food and Drug Administration.
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