Plague outbreak in Colorado - Can we still blame the rats?.

Plague outbreak in 90 years - Caused by a pet dog, dead rodents and other animals in Colorado, United State.
by Jim Chan.

News update: August 6, 2015 - A person has died of the plaque in Colorado, less than two months after a 16-year-old was also killed by the disease. The individual is believed to have contracted the plague from fleas on a dead rodent or other animal. In 2014, A pet dog was responsible for an outbreak of Pneumonic plague in 2014 and according to the Center of Disease Control & Prevention

Image from

http://images.tribe.net/tribe/upload/photo/662/a69/662a69ad-eff5-4538-b7c8-91b0415e2f85

In 2014, A pet dog was responsible for an outbreak of Pneumonic plague and according to the Center of Disease Control & Prevention, this is the first known North American canine-to-human transmission of plague. Investigation revealed that the dog owner had direct contact with his dog while it was showing symptoms of drooling, fever and coughing up blood and the dog was later euthanized at an animal clinic. The dog owner became symptomatic a few days later and diagnosed with Pneumonic plaque. Three more people were also diagnosed later after having direct 

contact with the sick dog or with the dog owner. This finding is a wake up call for public health, veterinarians, medical professionals and clinicians who regularly contact animals and patients as they themselves may be at risk of plague especially in locations where cases of plague have been reported. In such locations, plagues continue to circulate in wild rodents such as rats, and other types of animals that can be carrier of the bacteria such as rock squirrels, ground squirrels, chipmunks, mice, voles, and rabbits can also be affected by plague.

Wild carnivores can become infected by eating other infected preys. The risk of a plague outbreak can also happen in urban environments in North America as a new report by US Centers for Disease Control & Prevention and research by Journal of Medical Entomology indicated rats in New York City harbored the Oriental rat fleas

(Xenopsylla cheopis) that are known to carry the plague bacteria Yersinia pestis. With large population of rats living side-by-side with people in large cities and these rats carry fleas that could transmit the plague to people. 

In July and August, 2015,  The Pueblo City-County Health Department announced that an adult had died from the plague. The health agency indicated in a press release that this individual may have contracted the disease from fleas on a dead rodent or animal. According to the department, the plague can spread through rodent populations in localized areas, which often ends in mass die-offs. This results in hungry infected fleas seeking other sources of blood, which increases the risk to humans and other animals. The health department is currently investigating the situation, along with the Colorado Department of Public Health and Environment. This happened less than two months after a 16-year-old was infected and died in Larimer County, Colorado after suffering from septicemic plague. 

What happen when the pathogen is introduced to start the transmission cycle? 

and  

       Should we worry? 

Now let's look at what plague is and how it is passed on to people.

What is Plague?

Plague is caused by the gram-negative bacterium Yersinia pestis and humans usually get plague after being bitten by a rodent flea that is carrying the plague bacterium or by handling an animal infected with plague. In history, plague killed millions of people in Europe during the Middle Ages known as the the Black Death. Plague is a treatable disease now with the careful use of antibiotics. 

Image from: https://usbio.net/misc/plague-yersinia-pestis-bacteria

What is the Difference Between Bubonic, Septicemic and Pneumonic Plague?

Bubonic plague

This form of plague results from bites of infected fleas . An infection of the 

lymphatic system. The mode of transmission of Bubonic plague which the bacteria (Yersinia pestis) enter the human body through the bite of an infected flea and infecting the lymphatic system. After an incubation period of a few days to weeks, the person will develop symptoms including fever, chills, weakness, and swollen lymph glands. known as buboes (Plague symptoms - Mayo Clinic).

http://www.learnnext.com/nganswers/Bubonic-plague-question-29980.htm

Septicemic plague

Septicemic plague is from bites of infected fleas or from handling an infected animal. This form of plague can occur as the first symptom of plague, or may develop from untreated bubonic plague. 
Symptoms and signs include fever and chills, abdominal pain, diarrhea and vomiting, bleeding from your mouth, nose or rectum, or under your skin, shock, Skin and other tissues may turn black and die, especially on fingers, toes, and the nose (Plague symptoms - Mayo Clinic)

Pneumonic plague

This form of plague is an infection of the respiratory system and is a more serious and rarer form of plague than bubonic plague. This is highly communicable and contagious which can be transmitted from person to person through inhalation. The bacteria infect the lungs directly and cause pneumonia, or can develop when bubonic plague spreads to the lungs.
Symptoms and signs include high fever, overwhelming pneumonia, cough, bloody sputum, chills (Plague's symptoms - Mayo Clinic)

Related links:

Diseases from wildlife & pets

Images of Bubonic & Pneumonic Plague

CDC - Symptoms of Plague

Facts about Pneumonic Plague

Rat in the City