Dr.Charles Patrick Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.
Q. What is the incubation period for plague?
A. A person usually becomes ill with bubonic plague 2 to 6 days after being infected. When bubonic plague is left untreated, plague bacteria invade the bloodstream. When plague bacteria multiply in the bloodstream, they spread rapidly throughout the body and cause a severe and often fatal condition. Infection of the lungs with the plague bacterium causes the pneumonic form of plague, a severe respiratory illness. The infected person may experience high fever, chills, cough, and breathing difficulty, and expel bloody sputum. If plague patients are not given specific antibiotic therapy, the disease can progress rapidly to death.
Q. What is the mortality rate of plague?
A. About 14% (1 in 7) of all plague cases in the United States are fatal.
Q. How many cases of plague occur in the U.S.?
A. Human plague in the United States has occurred as mostly scattered cases in rural areas (an average of 10 to 20 persons each year). Globally, the World Health Organization reports 1,000 to 3,000 cases of plague every year.
A bacterium, Yersinia pestis, causes the disease in animals and humans.
Plague is a disease that is transmitted from infected animals, usually by fleas, to humans.
Plague then may be transmitted from humans to others by direct contact or by touching or breathing droplets that contain the bacterium,
Yersinia pestis. Untreated plague causes much suffering and deaths in humans.
Symptoms of plague vary and are grouped into three types:
Septicemic: In general, septicemic plague patients do not develop buboes.
Instead symptoms may include fever, chills, weakness, bleeding under the skin, abdominal pain, and septic shock with low blood pressure.
Plague is preliminarily diagnosed by physical examination and by cultures of blood or other sites; definitive diagnosis is done by immunological tests that identify Y. pestis specifically.
Plague is treated by several types of antibiotics.
The history of plague infections of humans is extensive, and plague bacteria are considered to be
biological weapons by some governments.
Although plague is endemic in some animal populations, fleas can transfer Y. pestis from animals to man; once a person is infected, the disease can easily be transmitted to other humans by direct and indirect contact with droplets or material touched by the infected person.
Prevention of plague is done by eliminating areas where animals, especially rodents, congregate and by avoiding the fleas the rodents carry. Some infections can be prevented by taking antibiotics soon after exposure to the disease.
There are no commercially available vaccines against plague; however, there is a small amount available from the U.S. government for researchers that work with
Y. pestis.
Ongoing research includes trying to develop a plague vaccine with few side effects; others are exploring the
Y. pestis genome for insights into its pathogenic mechanisms.
What is plague?
Plague, a disease that is endemic in some animal
populations (mainly rodents), is caused by the
Yersinia pestis bacterium. This bacterium can
be transmitted to humans, usually by a vector such as fleas. Plague usually
starts with a flea bite where Y. pestis is transmitted from the flea bite site
to lymph nodes that swell (buboes). This type of plague is termed bubonic
plague. The bacteria can spread into the bloodstream and eventually infect other
organs. In some patients, the bacteria can enter the bloodstream without lymph
node swelling (termed septicemic plague); in others, the patients can inhale or
swallow droplets that contain Y. pestis that infect the lungs (termed pneumonic
plague). Death occurs in about 50%-90% of all people who develop infection
with Y. pestis and are not treated; even with treatment, about 15% of infected
people will still die. Epidemics of this devastating disease have occurred many
times in the past. Skin areas and buboes in untreated people may become dark or
a black color as the disease progresses, so plague was originally termed "Black
Death."
What is the history of the plague?
Plague or Black Death has been mentioned in most regions of the world for
centuries. Once it became established in a population before effective
treatments were established, it would rapidly travel through a population in a
settlement, town, or city and kill so many people that historians said there were
not enough people left alive to bury all of the dead. In the 1300s, the Black
Death killed about one-third of Europe's population. In 1894, two
investigators, Dr. Alexandre Yersin and Dr. Shibasaburo Kitasato, almost simultaneously described bipolar
staining organisms in buboes and organs of people who died from plague. Yersin
also deduced the connection between rats and plague; the organism was named
Yersinia after Yersin. Dr. Paul-Louis Simond, in 1898, discovered the vector of the disease was
a flea. Plague or its cause, Y. pestis, has been used by humans as a weapon
(bioterrorist weapon) against other humans for centuries, including this current
time. In medieval times, bodies of plague victims were hurled over city walls in
an attempt to infect many inhabitants and thus weaken the defense capability of
the city. Currently, the CDC considers Y. pestis a category A microbial agent
for potential or actual use as a weapon for use against other humans. Although
people may be vaccinated (not readily available to most individuals) or treated
with antibiotics, the organism is still attractive to some biological weapon
designers because Y. pestis may be aerosolized (for example, Y. pestis may be
placed in droplets or small inhalable particles that may be sprayed by several
methods into the air) and thus easily inhaled by unprotected individuals to
produce a rapidly debilitating or lethal infection in many individuals exposed
to the aerosol. Although most world countries say this type of weapon should
never be used, the potential for development and use is likely to be explored or
even exploited by some individuals.
Low blood pressure, also referred to as hypotension, is blood pressure that is so low that it causes symptoms or signs due to the low flow of blood through the arteries and veins. Some of the symptoms of low blood pressure include light-headedness, dizziness, or even fainting if not enough blood is getting to the brain. Diseases and medications can also cause low blood pressure. When the flow of blood is too low to deliver enough oxygen and nutrients to vital organs such as the brain, heart, and kidneys; the organs do not function normally and may be permanently damaged.
Abdominal pain is pain in the belly and can be acute or chronic. Causes include inflammation, distention of an organ, and loss of the blood supply to an organ. Abdominal pain can reflect a major problem with one of the organs in the abdomen such as the appendix, gallbladder, large and small intestine, pancreas, liver, colon, duodenum, and spleen.
Pneumonia is inflammation of one or both lungs with consolidation. Pneumonia is frequently but not always due to infection. The infection may be bacterial, viral, fungal or parasitic. Symptoms may include fever, chills, cough with sputum production, chest pain, and shortness of breath.
Headaches can be divided into two categories: primary headaches and secondary headaches. Migraine headaches, tension headaches, and cluster headaches are considered primary headaches. Secondary headaches are caused by disease. Headache symptoms vary with the headache type. Over-the-counter pain relievers provide short-term relief for most headaches.
Lymph nodes help the body's immune system fight infections. Causes of swollen lymph nodes (glands) may include infection (viral, bacterial, fungal, parasites). Symptoms of swollen lymph nodes vary greatly. They can sometimes be tender, painful or disfiguring. The treatment of swollen lymph nodes depends upon the cause.
Chronic cough is a cough that does not go away and is generally a symptom of another disorder such as asthma, allergic rhinitis, sinus infection, cigarette smoking, GERD, postnasal drip, bronchitis, pneumonia, medications, and less frequently tumors or other lung disease. Treatment of chronic cough is dependant upon the cause.
Although a fever technically is any body temperature above the normal of 98.6 degrees F. (37 degrees C.), in practice a person is usually not considered to have a significant fever until the temperature is above 100.4 degrees F (38 degrees C.). Fever is part of the body's own disease-fighting arsenal: rising body temperatures apparently are capable of killing off many disease- producing organisms.
Chest pain is a common complaint by a patient in the ER. Causes of chest pain include broken or bruised ribs, pleurisy, pneumothorax, shingles, pneumonia, pulmonary embolism, angina, heart attack, costochondritis, pericarditis, aorta or aortic dissection, and reflux esophagitis. Diagnosis and treatment of chest pain depends upon the cause and clinical presentation of the patient's chest pain.
Influenza (flu) is a respiratory illness caused by a virus. Flu symptoms include fever, cough, sore throat, runny nose, headache, fatigue, and muscle aches. The flu may be prevented with an annual influenza vaccination.
Medical shock is a life-threatening medical condition. There are several types of medical shock, septic shock, anaphylactic shock, cardiogenic shock, hypovolemic shock, and neurogenic shock. Causes of shock include heart attack, heart failure, heavy bleeding (internal and external), infection, anaphylaxis, spinal cord injury, severe burns, chronic vomiting or diarrhea. Low blood pressure is the key sign of sock. Treatment is dependant upon the type of shock.
Bioterrorism is a form of terrorism where there is the intentional release of biological agents such as viruses, germs, or bacteria. Diseases caused by bioterrorism agents include anthrax, botulism, plague, smallpox, tularemia, brucellosis, food poisoning, Q fever, ricin toxin poisoning, cholera, epidemic typhus, viral encephalitis, XDR TB, and MDR TB.
Drug resistance (antimicrobial resistance) is the ability of bacteria, fungi, parasites, and viruses to grow, even in the presence of a drug that would normally kill it (or limit it's growth). Drug resistance is a growing problem, particularly for infections such as MRSA, VRE (vancomycin-resistant enterococci), tuberculosis, HIV, STDs, gonorrhea, flu, pneumonia, malaria, E. coli, salmonella, Campylobacter, which causes diarrhea and gastroenteritis. Learn how to protect yourself from resistance to drugs.
Increasing use of antimicrobials in humans, animals,
and agriculture has resulted in many microbes developing resistance to these
powerful drugs.
Many infectious diseases are increasingly difficult
to treat because of antimicrobial-resistant organisms, including HIV infection, staphylococcal
infection, tuberculosis, influenza, gonorrhea, candida infection, and malaria.
Between 5 and 10 percent of all hospital patients
develop an infection, leading to an increase of about $5 billion in annual
U.S. healthcare costs.
About 90,000 of these patients die each year as a
result of their infection, up from 13,300 patient deaths in 1992.
People infected with antimicrobial-resistant organisms are more likely
to have longer hospital stays and may require more complicated treatment.