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Forms of the Plague: Transmission, Symptoms and Prevention

  • Synopsis: Published: 2015-06-24 (Revised/Updated 2017-10-27) - Information regarding various types of the plague and how plague can spread and be transmitted to humans. For further information pertaining to this article contact: Thomas C. Weiss at Disabled World.
Plague

Plague is a deadly infectious disease that is caused by the enterobacteria Yersinia pestis. The epidemiological use of the term "plague" is currently applied to bacterial infections that cause buboes, although historically the medical use of the term "plague" has been applied to pandemic infections in general. Plague is often synonymous with "bubonic plague", but this describes just one of its manifestations. Other names have been used to describe this disease, such as "The Black Plague" and "The Black Death"; the latter is now used primarily by scholars to describe the second, and most devastating, pandemic of the disease.

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Quote: "The earlier a person pursues medical attention and receives treatment that is appropriate for plague the better their chances are for a full recovery."

The bacteria that causes plague, 'Yersinia pestis,' continues to exist in a cycle involving rodents and the fleas they carry. In urban areas or places with thick rat infestations, the plague bacteria may cycle between rodents and their fleas. The last urban outbreak of rat-associated plague in America happened in the city of Los Angeles between the year of 1924-1925.

Since that time frame, plague has happened in semi-rural and rural areas of Western America; mainly in semi-arid upland forests and grasslands where a number of types of rodents may be involved. A number of types of animals, such as:

  • Mice
  • Voles
  • Rabbits
  • Wood rats
  • Chipmunks
  • Prairie dogs
  • Rock squirrels
  • Ground squirrels

May be affected by plague. Wild carnivores might become infected by consuming other animals that are infected. Scientists think that plague bacteria circulate at low rates within populations of certain rodents without causing excessive rodent deaths. These infected animals and the fleas they carry serve as long-term reservoirs for the bacteria which is referred to as an, 'enzootic cycle.'

On occasion, other species become infected and cause an outbreak among animals which is referred to as an, 'epizootic.' People are usually at greater risk during or shortly after a plague epizootic. Scientific studies have suggested that epizootics in the southwestern United States are more likely during summers that are cooler after a wet winter. Epizootics are most likely in areas with multiple types of rodents living in diverse habitats and in high densities.

Transmission of the Plague

Plague bacteria may be transmitted to people in some different ways. The ways plague bacteria are transmitted to people include the following:

Contact with Contaminated Tissue or Fluid: People might become infected when they handle body fluids or tissue from a plague-infected animal. For example; a hunter skinning a rabbit or other animal that is infected without using appropriate precautions might become infected with plague bacteria. Exposure of this type most often results in septicemic or bubonic plague.

Flea Bites: Plague bacteria are most often transmitted by the bite of a flea that is infected. During plague epizootics many rodents perish, causing hungry fleas to pursue other sources of blood. People and animals that visit places where rodents have recently died from plague are at risk of being infected from flea bites. Dogs and cats might also bring plague-infected fleas into a person's home. Flea bite exposure might result in septicemic or primary bubonic plague.

Infectious Droplets: When someone has plague pneumonia, they might cough droplets that may then cause pneumonic plague. Usually, this requires direct contact or close contact with someone who has pneumonic plague. Transmission of these droplets is the only way that plague can spread from person-to-person. Spreading of this type has not been documented in America since the year 1924, yet still happens with some frequency in developing countries. Cats are notably susceptible to plague and may be infected by eating rodents that are infected. Ill cats present a risk of transmitting infectious plague droplets to veterinarians or their owners. A number of instances of human plague have happened in America in recent decades due to contact with infected cats.

Symptoms of the Plague

Plague is a very serious illness. If you are experiencing symptoms like the ones listed below, pursue immediate medical attention. What follows are forms of the plague and their associated symptoms.

Bubonic Plague: People develop sudden onset of headaches, fever, chills and weakness in one or more swollen, painful and tender lymph nodes called, 'buboes.' Bubonic plague usually results from the bite of a flea that is infected. The bacteria multiply in the lymph node closest to where the bacteria entered the person's body. If the person is not treated with antibiotics that are appropriate, the bacteria may spread to other parts of the person's body.

Septicemic Plague: People develop chills, fever, abdominal pain, extreme weakness, shock and potentially - bleeding into the skin and other organs. Skin and other tissues might turn black and perish, particularly on toes, fingers and the person's nose. Septicemic plague may happen as the first symptom of plague, or it might develop from untreated bubonic plague. Septicemic plague is the result of bites of infected fleas, or from handling an animal that has become infected.

Pneumonic Plague: People develop headache, fever, weakness and a quickly developing pneumonia with shortness of breath, a cough, chest pain and at times - watery or bloody mucous. Pneumonic plague may develop from inhaling infectious droplets, or might develop from untreated septicemic or bubonic plague after the bacteria spread to the person's lungs. The pneumonia may cause shock and respiratory failure. Pneumonic plague is the most serious form fo the disease and is the only form of plague that may be spread from person-to-person.

Diagnosing Plague

Plague is a potential diagnosis for people who are ill and live in, or have recently visited, the Western United States or any other plague-endemic area. The most common sign of bubonic plague is the swift development of a swollen and painful lymph gland called a, 'bubo.' A known flea bite, or the presence of a bubo, might assist a doctor to consider plague as a cause of the illness.

In many instances - especially in pneumonic and septicemic plague, there are no plain signs that indicate plague. A diagnosis is made by taking samples from the affected person, particularly blood or a portion of a swollen lymph gland and then submitting them for testing in a laboratory. After plague has been identified as a potential cause of the illness, appropriate treatment should start promptly.

Treating the Plague

Plague is a very serious form of illness, although it is treatable with available antibiotics. The earlier a person pursues medical attention and receives treatment that is appropriate for plague the better their chances are for a full recovery. People in close contact with very ill pneumonic plague patients might be evaluated and possibly placed under observation. Preventative antibiotic treatment might also be administered depending upon the timing and type of personal contact. If you live in, or have recently traveled to, the Western United States or any other plague endemic area and experience symptoms of plague, it is vital to pursue medical attention at once.

Preventing the Plague

To help reduce rodent habitat around your work place, home and recreational areas, remove rock piles, brush, cluttered firewood, junk and potential rodent food supplies such as pet and wild animal food. Make your home and outbuildings rodent-proof.

Wear gloves if you are skinning or handling possibly infected animals to prevent contact between your skin and the plague bacteria. Contact your local health department if you have questions concerning the appropriate disposal of animals that are dead. Use repellent if you believe you could be exposed to rodent fleas during activities such as hiking, camping, or otherwise working outdoors. Products containing DEET may be applied to your skin as well as your clothes. Products containing permethrin may also be applied to your clothing.

Keep fleas off of your pets; apply flea control products. Animals that roam freely are more likely to come in contact with plague infected fleas or animals and might bring them into your home. If your pet becomes ill, pursue care from a veterinarian as quickly as you can. Do not permit cats or dogs to roam freely in endemic areas to sleep on your bed.

A vaccine for the plague is not available in America anymore. New plague vaccines are being developed, although they are not expected to become available at any point in the near future.



Related Information:

  1. Climate Change May Affect Plague Distribution and Incidence - The American Society of Tropical Medicine and Hygiene - (2010-09-07)
    https://www.disabled-world.com/health/climate-change-health.php


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