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Plague (human), Biohazard Level 4, (Hazardous).PlagueDoctor

Plague is a disease that affects humans and other mammals. It is caused by the bacterium, Yersinia pestis. 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. Plague is infamous for killing millions of people in Europe during the Middle Ages. Today, modern antibiotics are effective in treating plague. Without prompt treatment, the disease can cause serious illness or death. Presently, human plague infections continue to occur in the western United States, but significantly more cases occur in parts of Africa and Asia. Each year, 1,000–2,500 people get plague across the world.

Plague is a Level 4 Bio-Hazard as defined here: Viruses and bacteria that cause severe to fatal disease in humans, and for which vaccines or other treatments are not available, such as Bolivian and Argentine hemorrhagic fevers, H5N1(bird flu), Dengue hemorrhagic fever, Marburg virus, Ebola virus, hantaviruses, Lassa fever, Crimean-Congo hemorrhagic fever, and other hemorrhagic or unidentified diseases. When dealing with biological hazards at this level the use of a Hazmat suit and a self-contained oxygen supply is mandatory. The entrance and exit of a Level Four bio-lab. will contain multiple showers, a vacuum room, an ultraviolet light room, autonomous detection system, and other safety precautions designed to destroy all traces of the biohazard. Multiple airlocks are employed and are electronically secured to prevent both doors opening at the same time. All air and water service going to and coming from a Biosafety Level 4 (P4) lab will undergo similar decontamination procedures to eliminate the possibility of an accidental release.

 

 

Plague (human), Biohazard Level 4, (Hazardous).PlagueDoctor

Plague is a disease that affects humans and other mammals. It is caused by the bacterium, Yersinia pestis. 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. Plague is infamous for killing millions of people in Europe during the Middle Ages. Today, modern antibiotics are effective in treating plague. Without prompt treatment, the disease can cause serious illness or death. Presently, human plague infections continue to occur in the western United States, but significantly more cases occur in parts of Africa and Asia. Each year, 1,000–2,500 people get plague across the world.

Plague is a Level 4 Bio-Hazard as defined here: Viruses and bacteria that cause severe to fatal disease in humans, and for which vaccines or other treatments are not available, such as Bolivian and Argentine hemorrhagic fevers, H5N1(bird flu), Dengue hemorrhagic fever, Marburg virus, Ebola virus, hantaviruses, Lassa fever, Crimean-Congo hemorrhagic fever, and other hemorrhagic or unidentified diseases. When dealing with biological hazards at this level the use of a Hazmat suit and a self-contained oxygen supply is mandatory. The entrance and exit of a Level Four bio-lab. will contain multiple showers, a vacuum room, an ultraviolet light room, autonomous detection system, and other safety precautions designed to destroy all traces of the biohazard. Multiple airlocks are employed and are electronically secured to prevent both doors opening at the same time. All air and water service going to and coming from a Biosafety Level 4 (P4) lab will undergo similar decontamination procedures to eliminate the possibility of an accidental release.

 

 

Types of Plagues

 

Types of Plagues

There are 3 types of plague; all can be potentially deadly, if not treated.

  • Bubonic, which causes lymph nodes to swell.
  • Septicemic, which comes about when the plague gets into the bloodstream.
  • Pneumonic, which is a type of pneumonia. It can be spread from person to person.

 

Transmission

 

Transmission

Plague is usually found in rodents -- mainly prairie dogs. It's transmitted through the fleas they carry.

Plague often is identified when there is an unusual die-off of prairie dogs in an area. When an infected animal dies, the fleas leave the carcass to find another host, thus spreading the disease. Most human plague cases occur when humans are bitten by infected fleas. Less commonly, people are infected by direct contact with blood or tissues from an infected animal or from pets that become infected and transmit the disease.  

 

Symptoms

 

Symptoms

PlagueLabThe plague bacteria can be transmitted to humans in the following ways:

Flea bites. Plague bacteria are most often transmitted by the bite of an infected flea. During plague epizootics, many rodents die, causing hungry fleas to seek 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 may also bring plague-infected fleas into the home. Flea bite exposure may result in primary bubonic plague or septicemic plague.

Contact with contaminated fluid or tissue. Humans can become infected when handling tissue or body fluids of a plague-infected animal. For example, a hunter skinning a rabbit or other infected animal without using proper precautions could become infected with plague bacteria. This form of exposure most commonly results in bubonic plague or septicemic plague.

Infectious droplets. When a person has plague pneumonia, they may cough droplets containing the plague bacteria into air. If these bacteria-containing droplets are breathed in by another person they can cause pneumonic plague. Typically this requires direct and close contact with the person with pneumonic plague. Transmission of these droplets is the only way that plague can spread between people. This type of spread has not been documented in the United States since 1924, but still occurs with some frequency in developing countries. Cats are particularly susceptible to plague, and can be infected by eating infected rodents. Sick cats pose a risk of transmitting infectious plague droplets to their owners or to veterinarians. Several cases of human plague have occurred in the United States in recent decades as a result of contact with infected cats.

Plague symptoms depend on how the patient was exposed to the plague bacteria. Plague can take different clinical forms, but the most common are bubonic, pneumonic and septicemic.

 

Symptoms of plague appear within two to six days after exposure.

They include fever, chills, headache, weakness, muscle pain, swollen lymph glands in the groin, armpits or limbs. Symptoms of plague include a sudden onset of high fever, muscle pain, malaise, nausea and vomiting, or a general feeling of being ill.

Individuals with bubonic plague will develop a large, swollen, painful lymph node in the area of a flea bite, usually in the groin or armpit. If untreated, the disease can enter the bloodstream or lungs, which are severe, life-threatening complications.

Individuals with pneumonic plagues (the lung form) develop fever, headache, weakness, shortness of breath, chest pain, cough which can lead to respiratory failure.

 

Symptoms by type

 

plaguetypesForms of plague.

Bubonic plague: Patients develop sudden onset of fever, headache, chills, and weakness and one or more swollen, tender and painful lymph nodes (called buboes). This form usually results from the bite of an infected flea. The bacteria multiply in the lymph node closest to where the bacteria entered the human body. If the patient is not treated with the appropriate antibiotics, the bacteria can spread to other parts of the body.

Septicemic plague: Patients develop fever, chills, extreme weakness, abdominal pain, shock, and possibly bleeding into the skin and other organs. Skin and other tissues may turn black and die, especially on fingers, toes, and the nose. Septicemic plague can occur as the first symptom of plague, or may develop from untreated bubonic plague. This form results from bites of infected fleas or from handling an infected animal.

Pneumonic plague: Patients develop fever, headache, weakness, and a rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery mucous. Pneumonic plague may develop from inhaling infectious droplets or may develop from untreated bubonic or septicemic plague after the bacteria spread to the lungs. The pneumonia may cause respiratory failure and shock. Pneumonic plague is the most serious form of the disease and is the only form of plague that can be spread from person to person (by infectious droplets).Pneumonic plague is the most serious form of the disease and is the only form of plague that can be spread from person to person (by infectious droplets from coughing). Although human cases occur infrequently, plague is severe and potentially life-threatening if not detected and quickly treated with common antibiotics.

Plague is a serious illness. If you are experiencing symptoms like those listed here, seek immediate medical attention. Prompt treatment with the correct medications is critical to prevent complications or death.

 

Diagnosis

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Diagnosis

Plague is a plausible diagnosis for people who are sick and live in, or have recently traveled to, the western United States or any other plague-endemic area. The most common sign of bubonic plague is the rapid development of a swollen and painful lymph gland called a bubo. A known flea bite or the presence of a bubo may help a doctor to consider plague as a cause of the illness.

In many cases, particularly in septicemic and pneumonic plague, there are no obvious signs that indicate plague. Diagnosis is made by taking samples from the patient, especially blood or part of a swollen lymph gland, and submitting them for laboratory testing. Once plague has been identified as a possible cause of the illness, appropriate treatment should begin immediately.

 

Clinician Information

 

Treatment.

 

Treatment.

There is no widely available vaccine for the disease but it is curable with proper antibiotics if diagnosed and treated early. Plague is a very serious illness, but is treatable with commonly available antibiotics. The earlier a patient seeks medical care and receives treatment that is appropriate for plague, the better their chances are of a full recovery.

People in close contact with very sick pneumonic plague patients may be evaluated and possibly placed under observation. Preventive antibiotic therapy may also be given, depending on the type and timing of personal contact.

If you live or have recently traveled to the western U.S. or any other plague endemic area and have symptoms suggestive of plague, seek health care immediately.

 

Protection

Protection:.

Individuals can greatly reduce their risk of becoming infected with plague by taking simple precautions, to prevent plague exposure: .

  • Do not directly handle any sick or dead rodents.
  • Avoiding contact with wild rodents and their fleas.
  • Keep pets away from wildlife, especially dead rodents.
  • Don't let dogs or cats hunt prairie dogs or other rodents.
  • Don't allow pets to roam freely. Do not let pets sleep in your bed.
  • 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. Treat all pets for fleas according to a veterinarian's advice. 
  • Do not feed prairie dogs or other rodents - this attracts them to your property, brings them in close contact with other rodents and increases the risk of disease transmission.
  • Do not feed rodents in picnic or campground areas.
  • Leave your pets at home when visiting areas with elevated plague risk.
  • Be aware of rodent populations in your area and report sudden die-offs or multiple dead animals to your local health department.
  • Reduce rodent habitat around your home, work place, 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.
  • De-flea pets routinely.
  • Avoid rodent burrows and fleas.
  • bugsprayUse insect repellents when visiting or working in areas where plague might be active or rodents might be present. 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).
    • Higher percentages of active ingredient provide longer protection. Use products with the following active ingredients:
    • DEET (Products containing DEET include Off!, Cutter, Sawyer, and Ultrathon)
    • Picaridin (also known as KBR 3023, Bayrepel, and icaridin products containing picaridin include Cutter Advanced, Skin So Soft Bug Guard Plus, and Autan [outside the US])
    • Oil of lemon eucalyptus (OLE) or PMD (Products containing OLE include Repel and Off! Botanicals)
    • IR3535 (Products containing IR3535 include Skin So Soft Bug Guard Plus Expedition and SkinSmart)
    • Always follow product directions and reapply as directed:
    • If you are also using sunscreen, apply sunscreen first and insect repellent second.
    • Follow package directions when applying repellent on children. Avoid applying repellent to their hands, eyes, and mouth.
    • Use permethrin-treated clothing and gear (such as boots, pants, socks, and tents). You can buy pre-treated clothing and gear or treat them yourself:
      • Treated clothing remains protective after multiple washings. See the product information to find out how long the protection will last.
      • If treating items yourself, follow the product instructions carefully.
      • Do not use permethrin directly on skin.
  • Wear rubber gloves and other protection when 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 disposal of dead animals.
  • Do not camp next to rodent burrows and avoid sleeping directly on the ground.
  • Be aware that cats are highly susceptible to this disease.
  • In case of illness, see a physician immediately.
  • Do not touch dead animals. Fleas can be transferred from a dead animal to you.

If living in the area with plague, you may need to take these additional steps:

  • Keep food tightly sealed and away from rodents.
  • Stay in housing that is free of rodents and has proper sanitation.
  • Protect yourself and pets:
  • Do not allow pets to sleep in your bed.
  • Do not allow pets to roam free in areas where plague is known to occur.
  • Talk to a veterinarian about protecting pets from fleas.
  • Avoid handling sick or dead animals. If you must handle a sick or dead animal, wear gloves, cover your skin, and use additional personal protective equipment if possible.

Contact your physician if you develop a high fever and other plague symptoms following a fleabite or direct contact with dead rodents.

 

Note: A plague vaccine is no longer available in the United States. New plague vaccines are in development but are not expected to be commercially available in the immediate future.

 

Plague in the US

 

Plague in the United States

Plague was first introduced into the United States in 1900, by rat–infested steamships that had sailed from affected areas, mostly from Asia. Epidemics occurred in these port cities. The last urban plague epidemic in the United States occurred in Los Angeles from 1924 through 1925. Plague then spread from urban rats to rural rodent species, and became entrenched in many areas of the western United States. Since that time, plague has occurred as scattered cases in rural areas. Most human cases in the United States occur in two regions:

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  • Northern New Mexico, northern Arizona, and southern Colorado
  • California, southern Oregon, and far western Nevada

 

 

Between 1900 and 2012, 1006 confirmed or probable human plague cases occurred in the United States. Over 80% of United States plague cases have been the bubonic form. In recent decades, an average of seven human plague cases have been reported each year (range: 1–17 cases per year). Plague has occurred in people of all ages (infants up to age 96), though 50% of cases occur in people ages 12–45. It occurs in both men and women, though historically is slightly more common among men, probably because of increased outdoor activities that put them at higher risk.

Plague Worldwide

Plague epidemics have occurred in Africa, Asia, and South America but most human cases since the 1990s have occurred in Africa. Almost all of the cases reported in the last 20 years have occurred among people living in small towns and villages or agricultural areas rather than in larger towns and cities. Between 1,000 and 2,000 cases each year are reported to the World Health Organization (WHO), though the true number is likely much higher.  It is hard to assess the mortality rate of plague in developing countries, as relatively few cases are reliably diagnosed and reported to health authorities. WHO cites mortality rates of 8–10%, however some studies (WHO, 2004) suggest that mortality may be much higher in some plague endemic areas.

 

Ecology

 

Ecology

The bacteria that cause plague,Yersinia pestis, maintain their existence in a cycle involving rodents and their fleas. In urban areas or places with dense rat infestations, the plague bacteria can cycle between rats and their fleas. The last urban outbreak of rat-associated plague in the United States occurred in Los Angeles in 1924-1925.

Since that time, plague has occurred in rural and semi-rural areas of the western United States, primarily in semi-arid upland forests and grasslands where many types of rodent species can be involved. Many types of animals, such as rock squirrels, wood rats, ground squirrels, prairie dogs, chipmunks, mice, voles, and rabbits can be affected by plague. Wild carnivores can become infected by eating other infected animals.

Scientists think that plague bacteria circulate at low rates within populations of certain rodents without causing excessive rodent die-off. These infected animals and their fleas serve as long-term reservoirs for the bacteria. This is called the enzootic cycle.

Occasionally, other species become infected, causing an outbreak among animals, called an epizootic. Humans are usually more at risk during, or shortly after, a plague epizootic. Scientific studies have suggested that epizootics in the southwestern United States are more likely during cooler summers that follow wet winters. Epizootics are most likely in areas with multiple types of rodents living in high densities and in diverse habitats.

 

 

 

 

History

 

 

Plague has a remarkable place in history and has had enormous effects on the development of modern civilization. Some scholars have even suggested that the collapse of the Roman Empire may be linked to the spread of plague by Roman soldiers returning home from battle in the Persian Gulf in 165 AD. For centuries, plague represented disaster for people living in Asia, Africa and Europe and because the cause of plague was unknown, plague outbreaks contributed to massive panic in cities and countries where it appeared.

Numerous references in art, literature and monuments attest to the horrors and devastation of past plague epidemics. We now know that plague is caused by a bacterium called Yersinia pestis that often infects small rodents (like rats, mice, and squirrels) and is usually transmitted to humans through the bite of an infected flea.  In the past, black rats were the most commonly infected animals and hungry rat fleas would jump from their recently-dead rat hosts to humans, looking for a blood meal. Pneumonic plague, a particular form of plague infection, is instead transmitted through infected droplets in a sick person's cough.

 

Plague has a remarkable place in history and has had enormous effects on the development of modern civilization. Some scholars have even suggested that the collapse of the Roman Empire may be linked to the spread of plague by Roman soldiers returning home from battle in the Persian Gulf in 165 AD. For centuries, plague represented disaster for people living in Asia, Africa and Europe and because the cause of plague was unknown, plague outbreaks contributed to massive panic in cities and countries where it appeared.

Numerous references in art, literature and monuments attest to the horrors and devastation of past plague epidemics. We now know that plague is caused by a bacterium called Yersinia pestis that often infects small rodents (like rats, mice, and squirrels) and is usually transmitted to humans through the bite of an infected flea.  In the past, black rats were the most commonly infected animals and hungry rat fleas would jump from their recently-dead rat hosts to humans, looking for a blood meal. Pneumonic plague, a particular form of plague infection, is instead transmitted through infected droplets in a sick person's cough.

Three Major Plague Pandemics

The Justinian Plague

The first recorded pandemic, the Justinian Plague, was named after the 6th century Byzantine emperor Justinian I. The Justinian Plague began in 541 AD and was followed by frequent outbreaks over the next two hundred years that eventually killed over 25 million people (Rosen, 2007) and affected much of the Mediterranean basin--virtually all of the known world at that time.

"Black Death" or the Great Plague

The second pandemic, widely known as the "Black Death" or the Great Plague, originated in China in 1334 and spread along the great trade routes to Constantinople and then to Europe, where it claimed an estimated 60% of the European population (Benedictow, 2008). Entire towns were wiped out. Some contemporary historians report that on occasion,there were not enough surviviors remaining to bury the dead (Gross, 1995). Despite the vast devastation caused by this pandemic, however, massive labor shortages due to high mortality rates sped up the development of many economic, social, and technical modernizations (Benedictow, 2008). It has even been considered a factor in the emergence of the Renaissance in the late 14th century.

 

Modern Plague

The third pandemic, the Modern Plague, began in China in the 1860s and appeared in Hong Kong by 1894. Over the next 20 years, it spread to port cities around the world by rats on steamships. The pandemic caused approximately 10 million deaths (Khan, 2004). During this last pandemic, scientists identified the causative agent as a bacterium and determined that plague is spread by infectious flea bites. Rat-associated plague was soon brought under control in most urban areas, but the infection easily spread to local populations of ground squirrels and other small mammals in the Americas, Africa, and Asia. These new species of carriers have allowed plague to become endemic in many rural areas, including the western U.S.

However, as a bacterial disease, plague can be treated with antibiotics, and can be prevented from spreading by prompt identification, treatment and management of human cases. Applications of effective insecticides to control the flea vectors also provide assistance in controlling plague.

Recent Outbreaks

The most recent plague epidemics have been reported in India during the first half of the 20th century, and in Vietnam during wartime in the 1960s and 1970s. Plague is now commonly found in sub-Saharan Africa and Madagascar, areas which now account for over 95% of reported cases (Stenseth, 2008).

Plague as a Weapon of War

As a highly contagious disease with an extremely high mortality rate if left untreated, Yersinia pestis has been used as a weapon of biological warfare for centuries. Some warfare strategies have included catapulting corpses over city walls, dropping infected fleas from airplanes, and aerosolizing the bacteria during the Cold War (Stenseth, 2008). More recently, plague raised concern as an important national security threat because of its potential for use by terrorists.

 

PlagueDoctorPerson wearing a hat, a mask suggestive of a bird beak, goggles or glasses, and a long gown. The clothing identifies the person as a "plague doctor" and is intended as protection. Descriptions indicate that the gown was made from heavy fabric or leather and was usually waxed. The beak contained pungent substances like herbs or perfumes, thought at the time to purify the air and helpful in relieving the stench. The person also carries a pointer or rod to keep patients at a distance. (Library of Medicine)

 

 

 

 

 

 

 

 

Resources

 

Resources

Some links below require a subscription. Scientific journals can be accessed at some municipal and many university libraries. Please visit Pub Med for additional information

Plague and Yersinia pestis

Benedictow, Ole J. 2004. The Black Death 1346-1353: The Complete History. Woodbridge: Boydell Press.

Chase, M. 2003. The Barbary Plague: The Black Death in Victorian San Francisco. New York: Random House.

Dennis, DT, Gage KL, Gratz N, Poland JD, and Tikhomirov E. (Principal authors). Plague Manual

. World Health Organization. Geneva, Switzerland. 172 pp., 1999.

Gross, L. How the plague bacillus and its transmission through fleas were discovered: reminiscences from my years at the Pasteur Institute in Paris. Proc Natl Acad Sci U S A. 1995 August 15; 92(17): 7609–7611.

Human plague--four states, 2006. MMWR Morb Mortal Wkly Rep. 2006 Sep 1;55(34):940-3. 

Khan, IA. Plague: the dreadful visitation occupying the human mind for centuries.

Trans R Soc Trop Med Hyg. 2004 May;98(5):270-7.

Kugeler KJ, Staples JE, Hinckley AF, Gage KL, Mead PS. Epidemiology of human plague in the United States, 1900–2012

. Emerg Infect Dis. 2015 Jan.

Stenseth NC, Atshabar BB, Begon M, Belmain SR, Bertherat E, et al. Plague: Past, Present, and Future.PLoS Med. 2008 5(1): e3.

Rosen, William (2007), Justinian's Flea: Plague, Empire, and the Birth of Europe. Viking Adult; pg 3; ISBN 978-0-670-03855-8.

Plague Ecology

Gage KL and Kosoy MY. The natural history of Plague: Perspectives from more than a century of research. Ann Rev Entomology. 50:505-528, 2005.(Pub Med / Abstract)

Eisen RJ, Enscore RE, Biggerstaff BJ, Reynolds PJ, Ettestad P, Brown T, Pape J, Tanda D, Levy CE, Engelthaler DM, Cheek J, Bueno Jr. R, Targhetta, Montenieri JA, Gage KL. Human plague in the southwestern United States, 1957-2004: Spatial models of elevated risk of human exposure to Yersinia pestis.

 J Med Entomol, 44:530-537, 2007.

Enscore, RE, Biggerstaff BJ, Brown TL, Fulgham RF, Reynolds PJ, Engelthaler DM, Levy CE, Parmenter RR, Montenieri JA, Cheek JE, Grinnell RK, Ettestad PJ, and Gage KL. Modeling relationships between climate and the frequency of human plague cases in the southwestern United States, 1960-1997.

 Am J Trop Med Hyg 66:186-196, 2002.

Plague Surveillance and Control

Gage KL. Plague Surveillance (Chapter 6). Plague Manual

. Dennis, DT, Gage KL, Gratz N, Poland JD, and Tikhomirov E. (Principal authors). World Health Organization. Geneva, Switzerland. pp. 135-165, 1999a.

Gratz NG. Control of Plague Transmission (Chapter 5). Plague Manual

. Dennis, OT, Gage KL, Gratz N, Poland JD, and Tikhomirov E. (Principal authors). World Health Organization. Geneva, Switzerland. pp. 97-134,1999a.

Transmission and Risk Management

Hinckley AF, Biggerstaff BJ, Griffith KS, Mead PS. Transmission dynamics of primary pneumonic plague in the USA

 Epidemiol Infect. 2011 Jul 7:1-7.

Inglesby TV, Henderson DA, O’Toole T, Dennis DT. Safety precautions to limit exposure from plague-infected patients.

 JAMA 284:1648-1649, 2000.

Koirala J. Plague: disease, management, and recognition of act of terrorism.

 Infect Dis Clin North Am. 2006 Jun;20(2):273-87, viii.

Kool J. Risk of Person-to-Person Transmission of Pneumonic Plague.

 Clin Inf Dis 2005; 40:1166–72.

Bioterrorism

Inglesby TV, Dennis DT, Henderson DA, Bartlett JG, Ascher MS, Eitzen E, Fine AD, Friedlander AM, Hauer J, Koerner JF, Layton M, McDade J, Osterholm MT, O’Toole T, Parker G, Perl TM, Russell PK, Schoch-Spana M, Tonat K. Plague as a biological weapon: medical and public health management. Working Group on Civilian Biodefense.

 JAMA 284:2281-2290, 2000.

http://www.cdc.gov/plague/