The Worlds Fight Against Microbes
Many infectious diseases that were nearly eradicated from the industrialized world, and newly emerging diseases are now breaking out all over the world due to the misuse of medicines, such as antibiotics and antivirals, the destruction of our environment, and shortsighted political action and/or inaction.
Viral hemorrhagic fevers are a group of diseases caused by viruses from four distinct families of viruses: filoviruses, arenaviruses, flaviviruses, and bunyaviruses. The usual hosts for most of these viruses are rodents or arthropods, and in some viruses, such as the Ebola virus, the natural host is not known. All forms of viral hemorrhagic fever begin with fever and muscle aches, and depending on the particular virus, the disease can progress until the patient becomes deathly ill with respiratory problems, severe bleeding, kidney problems, and shock. The severity of these diseases can range from a mild illness to death (CDC I).
The Ebola virus is a member of a family of RNA (ribonucleic acid) viruses known as filoviruses. When these viruses are magnified several thousand times by an electron microscope they have the appearance of long filaments or threads. Filoviruses can cause hemorrhagic fever in humans and animals, and because of this they are extremely hazardous. Laboratory studies of these viruses must be carried out in special maximum containment facilities, such as the Centers for Disease Control (CDC) in Atlanta, Georgia and the United States Army Medical Research Institute of Infectious Diseases (USAMRIID), at Fort Detrick in Frederick, Maryland (CDC I, II).
The Ebola hemorrhagic fever in humans is a severe, systemic illness caused by infection with Ebola virus. There are four subtypes of Ebola virus (Ebola-Zaire, Ebola-Sudan, Ebola-Ivory Coast, and Ebola-Reston), which are not just variations of a single virus, but four distinct viruses. Three of these subtypes are known to cause disease in humans, and they are the Zaire, Sudan, and Ivory Coast subtypes. Out of all the different viral hemorrhagic fevers known to occur in humans, those caused by filoviruses have been associated with the highest case-fatality rates. These rates can be as high as 90 percent for epidemics of hemorrhagic fever caused by Ebola-Zaire virus. No vaccine exists to protect from filovirus infection, and no specific treatment is available (CDC II).
The symptoms of Ebola hemorrhagic fever begin within 4 to 16 days after infection. The patient develops chills, fever, headaches, muscle aches, and a loss of appetite. As the disease progresses vomiting, diarrhea, abdominal pain, sore throat, and chest pain can occur. The blood fails to clot and patients may bleed from injection sites as well as into the gastrointestinal tract, skin, and internal organs (CDC I).
The Ebola virus is spread through close personal contact with a person who is very ill with the disease, such as hospital care workers and family members. Transmisson of the virus can also occur from the reuse of hypodermic needles in the treatment of patients. This practice is common in developing countries where the health care system is underfinanced (CDC I).
Until recently, only three outbreaks of Ebola among people had been reported. The first two outbreaks occurred in 1976. One was in western Sudan, and the other in Zaire. These outbreaks were very large and resulted in more than 550 total cases and 340 deaths. The third outbreak occurred in Sudan in 1979. It was smaller with only 34 cases and 22 deaths. Three additional outbreaks were identified and reported between 1994 and 1996: a large outbreak in Kikwit, Zaire with 316 cases and 244 deaths; and two smaller outbreaks in the Ivory Coast and Gabon. Each one of these outbreaks occurred under the challenging conditions of the developing world. These conditions including a lack of adequate medical supplies and the frequent reuse of needles, played a major part in the spread of the disease. The outbreaks were controlled quickly when appropriate medical supplies were made available and quarantine procedures were used (CDC I).
Ebola-Reston, the fourth subtype, was discovered in 1989. The virus was found in monkeys imported from the Philippines to a quarantine facility in Reston, Virginia which is only about ten miles west of Washington, D. C. (Preston 109). The virus was also later detected in monkeys imported from the Philippines into the United States in 1990 and 1996, and in Italy in 1992. Infection caused by this subtype can be fatal in monkeys; however, the only four Ebola-Reston virus infections confirmed in humans did not result in the disease. These four documented human infections resulted in no clinical illness. Therefore, the Ebola-Reston subtype appears less capable of causing disease in humans than the other three subtypes. Due to a lack of research of the Ebola-Reston subtype there can be no definitive conclusions about its pathogenicity (CDC II).
Staphylococcus is a genus of nonmotile, spherical bacteria. Some species are normally found on the skin and in the throat, and certain species can cause severe life-threatening infections, such as staphylococcal pneumonia (Mosby 1477). Despite the age of antibiotics, staph infections remain potentially lethal. By 1982 fewer than 10 percent of all clinical staph cases could be cured with penicillin, which is a dramatic shift from the almost 100 percent penicillin susceptibility of Staphylococcus in 1952. Most strains of staph became resistant to penicillin's by changing their DNA structure (Garrett 411).
The fight against staph switched from using the mostly ineffective penicillin to using methicillin in the late 1960's. By the early 1980's, clinically significant strains of Staphylococcus emerged that were not only resistant to methicillin, but also to its antibiotic cousins, such as naficillin. In May 1982 a newborn baby died at the University of California at San Francisco's Moffit Hospital. This particular strain was resistant to penicillin's, cephalosporin's, and naficillin. The mutant strain infected a nurse at the hospital and three more babies over the next three years. The only way further cases could be prevented was to aggressively treat the staff and babies with antibiotics to which the bacteria was not resistant, close the infected ward off to new patients, and scrub the entire facility with disinfectants. This was not an isolated case, unfortunately. Outbreaks of resistant bacteria inside hospitals were commonplace by the early 1980's. The outbreaks were particularly common on wards that housed
The most susceptible patients, such as burn victims, premature babies, and intensive care patients. Outbreaks of methicillin resistant Staphylococcus aureus (MRSA) increased in size and frequency worldwide throughout the 1980's (Garrett 412).
By 1990, super-strains of staph that were resistant to a huge number of drugs existed naturally. For example, an Australian patient was infected with a strain that was resistant to cadmium, penicillin, karamycin, neomycin, streptomycin, tetracycline, and trimethoprim. Since each of these drugs operated biomechanically the same as a host of related drugs the Australian staph was resistant, to varying degrees, some thirty-one different drugs (Garrett 413).
A team of researchers from the New York City Health Department, using genetic fingerprinting techniques, traced back in time over 470 MRSA strains. They discovered that all of the MRSA bacteria descended from a strain that first emerged in Cairo, Egypt in 1961, and by the end of that decade the strain's descendants could be found in New York, New Jersey, Dublin, Geneva, Copenhagen, London, Kampala, Ontario, Halifax, Winnipeg, and Saskatoon. Another decade later they could be found world wide (Garrett 414).
New strains of bacteria were emerging everywhere in the world by the late 1980's, and their rates of emergence accelerated every year. In the U. S. alone, an estimated $200 million a year was spent on medical bills because of the need to use more exotic and expensive antibiotics, and longer hospitalization for everything from strep throat to life-threatening bacterial pneumonia. These trend, by the 90's, had reached the level of universal, across-the-board threats to humans of all ages, social classes, and geographic locations (Garrett 414).
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Antibiotic Resistance in Bacteria For over 50 years, antibiotics have been the answer to many bacterial infections. Antibiotics are chemical substances that are secreted by living things. Doctors prescribed these medicines to cure many diseases. During World War II, it treated one of the biggest killers during wartime - infected wounds. It was the beginning of the antibiotic era. Book Report: The Hot Zone The monkeys, imported from the Philippines, were to be sold as Laboratory animals. Twenty-nine of a shipment of one hundred died within a month. Dan Dalgard, the veterinarian who cared for the monkeys, feared they were dying From Simian Hemorrhagic Fever, a disease lethal to monkeys but harmless to Humans. Dr. Dalgard decided to enlist Book Report: The Hot Zone The monkeys, imported from the Philippines, were to be sold as Laboratory animals. Twenty-nine of a shipment of one hundred died within a month. Dan Dalgard, the veterinarian who cared for the monkeys, feared they were dying From Simian Hemorrhagic Fever, a disease lethal to monkeys but harmless to Humans. Dr. Dalgard decided to enlist Biological and Historical Information on the Ebola Virus The Ebola virus belongs to the family Filoviridae. The Ebola virus is characterized by massive bleeding and destruction of internal tissues. The virus is named after the Ebola river in the Democratic Republic of Congo, Africa where the virus was first found. Three types of the Ebola virus have been found. They are named after The Ebola Virus A virus is an ultramicroscopic infectious organism that, having no independent metabolic activity, can replicate only within a cell of another host organism. A virus consists of a core of nucleic acid, either RNA or DNA, surrounded by a coating of antigenic protein and sometimes a lipid layer surrounds it as well. The virus provides