Although autoimmune disorders arise from a response to a self antigen, they range over a wide spectrum-from those that affect a single organ or tissue (organ-specific) to those that are systemic, affecting many Autoimmune Disorders 555 Table 18. Although most people recover from glomerulonephritis and heal completely within 3 to 12 months, some have permanent residual kidney damage, and a few die. Bloodsucking flies, such as the tsetse fly and the deer fly, are related to horse flies. While this reduced the bacterial population, it still left up to 1 million microbes per gram of food-many thousands of times the number needed to sicken someone with a weakened immune system. Much unnecessary anguish could be avoided if people, especially children, were taught to appreciate unfamiliar animals without touching them. However, most viruses are limited to only one host and to only specific cells and/or tissues of that host. The Disk Diffusion Method In the disk diffusion method, or Kirby-Bauer method, a standard quantity of the causative organism is uniformly spread over an agar plate. Yeasts are included among the ascomycetes, even though most yeasts have no known sexual stage. Only a half dozen or so cases have been reported in the United States; curiously, these cases tended to involve problems somewhat higher up in the digestive tract. Drainage fields cannot be used where the water table is too high or the soil is insufficiently permeable, such as in rocky areas. When more favorable conditions are restored, germination occurs-endospores begin to develop into vegetative cells. Finally, increasing concentration may increase the effects of most antimicrobial chemical agents. When a cysticercus dies, it releases toxins and usually causes a severe, or even fatal, allergic response. Match the white blood cell type with one of its key functions: (a) Initiate adaptive host - Basophil - defense responses - Mast cell - Eosinophl (b) Secrete histamine - - (c) Defend against parasitic worms - Neutrophil - - Dendritic cell (d) Produce myeloperoxidase and - other microbicidal substances. Severe skin inflammation results from body defenses that prevent further migration of the parasites. The organisms themselves are sometimes useful, as when they can serve as a source of protein. Other Diseases of the Nervous System 787 Wound botulism is the least common form of botulism; no more than one case per year has been seen in the United States since 1942. Application of these techniques could greatly improve prenatal diagnosis of many genetic defects. In fact, most of the outbreaks, including the one in 1995, were the result of poor medical conditions in hospitals. Osmotic Pressure High concentrations of sugar or salt create osmotic pressure that results in the plasmolysis of cells (causes them to lose water) and prevents growth of microorganisms in highly sweetened or salted foods. Before vaccine was available, almost everyone had chickenpox by the Chickenpox does age of 30. Some employers hire only individuals with positive histoplasmosis skin tests, and therefore immunity to histoplasmosis, to work in high-risk environments. More people live long enough to develop degenerative diseases, and as they age their likelihood of developing a malignant disease increases. A few hours later the area around the cut became warm, red, swollen, and perhaps even painful. Symptoms such as abdominal pain, nausea, vomiting, and diarrhea (excessive frequency and looseness of bowel movements), but usually not fever, appear 1 to 6 hours after ingestion of contaminated food. Species of Clostridium, Bacillus, Staphylococcus, Streptococcus, and several other bacteria produce exotoxins. The cost of capture, shipping, and holding in quarantine to detect diseases is high, so a parrot may cost $3,000. Agricultural activities that contribute the most to the emission of greenhouse gases are enteric fermentation in domestic livestock and management of the manure they produce. In contrast, enzymes that are synthesized by genes that are sometimes active and sometimes inactive, depending on the presence or absence of substrate, are called inducible enzymes. No disinfectant is likely to satisfy all these criteria, so the agent that meets the greatest number of criteria for the task at hand is chosen. But when a mixture of live R-type and heat-killed S-type pneumococci-neither of which is lethal by itself-is injected, the mice die, and live S-type organisms as well as R-types are recovered from the dead animals.
Fleas in homes and on pets are controlled by insecticides with residual effects for days to weeks after application. These drugs easily enter the cytoplasm of host cells, making them especially useful at killing intracellularly infecting bacteria. In addition, the time for processing your home preserves will depend on the altitude where you live. Some also have breaks in mucous membranes that line the digestive, respiratory, urinary, or reproductive system. Even when allergens pass through membranes, phagocytic cells usually engulf them in normal individuals but sometimes fail to do so completely in allergic individuals. Microorganisms continue to be important to researchers who are attempting to further our knowledge of these processes. This disease is caused by various Borrelia species, such as (a) Borrelia recurrentis (among blood cells; 1,275X), carried by ticks (Eric Grave/Phototake) and by (b) lice such as the body louse (32X). Thus, acute phase proteins form a nonspecific host defense mechanism distinct from both the inflamma tory response and hostspecific immune defenses. Sometimes treatment was based on the notion that imbalances in body fluids caused disease. If the eyes instead of the mouth are the site of initial infection, vesicles appear on the cornea and eyelids, causing keratoconjunctivitis (kera-to-kon-junk-ti-vitis). If they survive and proliferate, they can attack self antigens and trigger B cell activity with antibody production. In fact, a few pathogens even multiply Adherence and Ingestion Following chemotaxis and the arrival of phagocytes at the infection site, the infectious agents become at tached to the plasma membranes of phagocytic cells. For example, penicillin molecules can act as haptens, bind to protein molecules, and elicit an allergic reaction, which is really a hypersensitivity reaction of the immune system. The disease itself does not occur either because whole organisms are not used or because they have been sufficiently weakened to have lost their virulence. Certain individuals, especially West African blacks and persons of Mediterranean origin, are protected from malaria by carrying the gene for sickle-cell anemia. The affected age group and the large inoculum required to transmit the disease may be responsible for its being called the 'kissing disease. IgG and IgM act in the blood to neutralize viruses directly or to promote their destruction by complement. Discard these items, and wash hands immediately and thoroughly after seeing each patient. A vaccine exists, but it is not always protective and must be readministered every 3 to 5 years. Yogurt is made by adding Streptococcus thermophilus and Lactobacillus bulgaricus to milk. Botulism is also an important disease in wetland birds, especially during ecological disturbances. Antigenic shift results from gene reassortment, possibly after two different viruses infect the same cell; for example, bird and human influenza viruses infect a pig cell and exchange large segments of their genomes. Trichlosan, made of two joined phenol rings, has become very popular in consumer products such as antibacterial soaps, kitchen cutting boards, highchair trays, toys, hand lotions, etc. Methylotrophic bacteria can fix nitrogen when provided with methane, methanol, or hydrogen from various substrates. Some 30,000 Britons, or 1 in 2,000, are throught to have "slient" infections, double that previously thought. In an outbreak of mad cow disease in Britain early in the 1990s, the infectious prion originally came from a protein supplement in the feed. Phenol is used to disinfect surfaces and destroy discarded cultures; amylphenol destroys vegetative organisms and inactivates viruses on skin and inanimate objects; chlorhexidine gluconate is especially effective as a surgical scrub. But there is still the matter of the dead worms which may have to be removed surgically. Hence, the flow of lymph depends on skeletal muscle contractions, which squeeze the vessels, forcing the lymph toward the lymphatic ducts.
Diseases
Although enamel is the hardest substance in the body, it can be attacked by microbial-produced acids and enzymes. Many diseases such as tuberculosis, Pseudomonas aeruginosa pneumonia in patients having cystic fibrosis, and unhealing wounds such as diabetic foot ulcers are all biofilms. Incessantly busy in swamp and field, these minute benefactors release the frozen elements and return them to the common stock, so that they may pass through other cycles as parts of other living bodies. Fungi serve two functions in soil: They decompose plant tissues such as cellulose and lignin, and their mycelia form networks around soil particles, giving the soil a crumbly texture (Chapter 11, p. Certain streptococcal strains have an antigen that is very similar to heart cell antigens. Scientists from the Woods Hole Oceanographic Institution in Massachusetts took their search to a depth of more than 1,800 meters in the Gulf of Califor- Mount St. Other needed concentration of semisynthetic penicillins, includantibiotics by 50 times. Listeriosis is responsible for many cases of fetal damage, sometimes not appearing until several weeks after birth, with onset of meningitis. That is why a substance such as copper sulfate is used to control algal growth in water to be purified with chlorine. This is the reason your doctor admonishes you to be sure to take all of an antibiotic prescription and not to stop taking it once you begin to feel better. But people living near the equator needed a different mix of less efficient microbes to keep from becoming obese and developing type 2 diabetes, heart trouble, or other diseases associated with obesity. Gajdusek and Brown suspect that infected material may retain its deadliness for more than a decade under such circumstances. Dry Heat, Moist Heat, and Pasteurization Dry heat probably does most of its damage by oxidizing molecules. However, the means of inactivation varies according to the nature of the antigen and the kind of antibody with which it reacts. You might be surprised to learn that the parrot could have been smuggled to the United States and could be infected with ornithosis. Both kinds of killer cells contain granules of a lethal protein, perforin, which is released when they bind to a target cell. Your parents or grandparents, however, probably became immune to both kinds of measles and to mumps by acquiring and then recovering from these diseases. Unlike endospores, they lack dipicolinic acid and have only limited resistance to high temperatures. But people with infectious diseases are members of a population; they acquire infectious diseases and transmit them within a population. Acne occurs in both males and females because the hormones are produced by the adrenal glands as well as by the testes. However, urine specimens should be delivered to the lab promptly and refrigerated during any delays, as microbes will multiply rapidly in urine left sitting out at room temperature. Then the enzymes and toxins inside of the phagolysosome cannot reach and kill the bacteria. In respiratory anaphylaxis the airways become severely constricted and filled with mucus secretions, and the allergic individual may die of suffocation. All are derived from pluripotent stem cells, cells that form a continuous supply of blood cells, in the bone marrow. Some laboratories also use a gel diffusion test to detect toxin-producing strains. Pathogenic mycobacteria have an exceedingly long generation time (12 to 18 hours, compared with 20 to 30 minutes for most bacteria), which accounts for the long time (up to 8 weeks) it takes to produce a visible colony on laboratory media. Photosynthetic is unavailable in organisms are limited to locations with oceans, seas, and adequate sunlight. The disease is treated with 60 days of ciprofloxacin (Cipro) as the drug of choice.
Both the toxicity and flammability of ethylene oxide can be reduced by using it in gas that contains 90% carbon dioxide. If microbes enter the nasal sinuses, which are hollow cavities lined with mucous membrane within the skull, sinus infections can occur. In rare instances the disease progresses to meningitis, arthritis, and pericarditis. When treated with mild heat or with some dilute acids, alkalis, or other agents for a short time, proteins are temporarily denatured. Much research effort is now being devoted to determining which substances are carcinogens (cancer-producing compounds). As we consider the many applications of microbiology-from food production to mining-we must also discuss food spoilage and methods of preservation. A century ago, 30 to 50% of patients died; most deaths occurred by suffocation in children under age 4. Microorganisms adjust to limited nutrient supplies by increasing the quantities of enzymes they produce, by making enzymes to metabolize another available nutrient, or by adjusting their metabolic activities to grow at a rate consistent with availability of nutrients. Chronic meningitis occurs with extension of underlying diseases such as syphilis or tuberculosis. Because gouda is a hard cheese, it must ripen for a relatively long period-3 months to a year-depending on the size of the wheel. Deneb Karentz, a researcher at the Laboratory of Radiobiology and Environmental Health (University of San Francisco), has devised a simple method for measuring ultraviolet penetration and intensity. Unfortunately, many tumors and cancers show little regard for control by the immune system. Indeed, plague is thought to have persisted for years among similar wild rodent populations of the Central Asian steppe before breaking out to decimate Europe as the 'Black Death' in 1346. If parents would not give honey to children under 1 year, most cases could be prevented. When water contains large quantities of organic matter, decomposers rapidly deplete the oxygen supply as they oxidize the organic matter. As with Enterotubes, the tray is incubated, test results are determined, and the values 1, 2, and 4 are summed for sets of three tests. It would be safer to remove the chlorine before releasing the effluent, but this is rarely done today, although the cost is not great. Resistance (R) plasmids carry genes that provide resistance to various antibiotics such as chloram-phenicol and tetracycline and to heavy metals such as arsenic and mercury. Acne Acne (acne vulgaris) affects more than 80% of teenagers and many adults, too. For example, large amounts of sugar or irritants in the medium can cause some organisms to form a larger-than-normal capsule. Because immunity is not always lifelong, 'booster shots' are often needed to maintain it. Bacterial Skin Diseases Many bacteria are found among the normal microflora of the skin. The distortion allows one or more bases to be added or deleted, and a frameshift mutation results. These areas have a normal microflora similar to that of skin, with Staphylococcus epidermidis and corynebacteria being most numerous. Oroya fever probably develops in people with no immunity, and verruga peruana occurs in those with partial immunity. In August 1993, an unvaccinated herd of beef cattle in southeastern South Dakota began to sicken. Treatment with isoniazid is effective except for resistant organisms, which must be treated with "second- or third-line" drugs. Because deaths from infectious diseases have decreased, average life spans have increased. To begin the study of host-microbe interactions, we will look at a variety of relationships between host and microbe and see how some of these relationships result in disease. In debilitated individuals it can cause candidiasis (kandi-diuh-sis), or moniliasis, in one or several tissues. Those with late mutations would have few mutated progeny, and those without a mutation would have none. Another species kills honey bees, and a third lives harmlessly in the Colorado potato beetle, an insect that damages potato, eggplant, and tomato plants.
Some localities in Pennsylvania are being forced to drink bottled water until they can afford to add sand filters to their treatment plants to trap Giardia cysts. How is it that the fastidious organism Legionella pneumophilia can survive inside a phagolysosome Failure of a hospital to launder sheets properly led to an outbreak of vulvovaginitis in female pediatric patients who acquired it from sitting on the sheets. When the raccoons eat the bait, they also ingest enough vaccine to prevent them from acquiring rabies. If the antibody is present, it reacts with the antigen and forms immune complexes. As standards of living improved and people covered more of their bodies, the surest means of transmitting the treponeme was via sexual activity and warm, moist reproductive tracts. In addition to bone cancer, interferon is now used to treat renal cell carcinoma, kidney cancer, melanoma, multiple myeloma, carcinoid tumors, and some lymphomas. The disease is ordinarily transmitted by sexual means, but it can be passed in body fluids such as saliva. Likewise, packing many articles close together in an autoclave lengthens the processing time to as much as 60 minutes to ensure sterility. Members of genera belonging to the Enterobacteriaceae family cause such diseases as meningitis, bacillary dysentery, typhoid, and food poisoning. In the middle-aged and elderly, meningoencephalitis can appear without any preceding symptoms. Exposure to the virus in infancy produces mild symptoms or no symptoms and confers immunity to later infection. The sulfate-reducing bacteria are among the oldest life forms, probably more than 3 billion years old. Retherefore, plant breeders searchers now hope to control have developed varieties some crop-destroying insects whose streaks are genetically by infecting them with speproduced. Complete details of this event were found in Anthrax, the Investigation of a Deadly Outbreak, by Jeanne Guillemin, 1999, University of California Press. Guinea worm, Dracunculis medinensis, affects only humans, and it actually uses its human host to further its life cycle. Some breweries dispose of these wastes by drying them and marketing them as supplements to animal feed, or as the T famous Australian product, Vegemite, beloved throughout the British empire. Ford Doolittle, "Uprooting the Tree of Life," Scientific American (February 2000), p. Today at least 130 different species of birds, including ducks, chickens, and turkeys, are found to carry a form of this disease. Several vaccines and toxoids have been licensed for general use in the United Sates; their properties are summarized in Table 17. Trichomoniasis is diagnosed by microscopic examination of smears of vaginal or urethral secretions and treated with metronidazole (Flagyl) and restoration of normal vaginal pH in women. And the arboviruses are a collection of arthropodborne viruses (including togaviruses, flaviviruses, bunyaviruses, and arenaviruses). Viable specimens can be obtained by swabbing a bowel lesion during internal examination of the bowel. Why must patients who recover from tetanus be immunized against tetanus afterward In humans there are three groups of interferons, called alpha, beta, and gamma Table 16. TranSducTion the discovery of Transduction In transduction, genetic material is carried by a bacteriophage (phage). It originally referred to the four basic body fluids, or "humors"- blood, phlegm, yellow bile, and black bile-which ancient physicians believed must be present in proper proportions for an individual to enjoy good health. The symbiotic association between fungi and the roots of plants is called: (d) Karyogamy (a) Hyphae (b) Plasmogamy (e) Dimorphism (c) Mycorrhizae 11. In the electron micrograph, coronaviruses are being taken into the cytoplasm of a host cell (magnification unknown). They often suffer severe digestive tract problems, especially involving inflammation, which can contribute to behavior problems. Tapes or other sterilization indicators should be placed inside and near the center of large packages to determine whether heat penetrated them.
Such methods, combined with improved fermentation procedures, have been quite successful. The repressor is a protein that binds to the operator and prevents transcription of the adjacent Z, Y, and A genes. Unfortunately, it causes insomnia and ataxia (inability to coordinate voluntary movements), especially in elderly patients, who also are often severely affected by influenza infections. Match each of the following innate defense mechanisms with its associated structure or body fluid: - Lysozyme - - Very acidic pH - - Sebum and fatty acids - - Low pH, flushing action - of urine - Mucociliary escalator - - Phagocytes - (a) Urogenital tract (b) Skin (c) Tears and saliva (d) Stomach (e) Lower respiratory tract (f) Bronchial tubes lymphocytes, which in turn produce antibodies capable of fighting against the specific antigen. Between patients, all items that could be contaminated with oral secretions or blood must be disinfected. Although in about half of human cases the vector is never identified, tularemia is most often associated with cottontail rabbits; the number of cases reported always rises significantly during rabbit-hunting season. If three bases, or a multiple of three bases, were inserted or lost, what would happen A new use for genetic probes will be to look for resistance genes in organisms, in order to avoid delays in effective treatment. Many fungi reproduce both sexually and asexually, but a few have only asexual reproduction. Drugs used to treat other trypanosome infections are of no use because they fail to reach the parasites inside cells. If 20% of the organisms die in the first minute, 20% of those remaining alive will die in the second minute, and so on. Cold viruses are more often spread by fomites than by close contact with infected persons. Let us look at some examples to understand the differences among contamination, infection, and disease. The defensive capability of humoral immunity depends on recognizing antigens associated with pathogens. The cell walls of the bacterium responsible for rheumatic fever (Streptococcus pyogenes) contain molecules of M protein, which inter feres with adherence. However, jet travel could bring virulent strains from North Africa or other parts of the world at any time. Carried by at least 43 species of mosquitoes, it has infected over 60 species of birds and countless other animals, plus humans. Hantavirus Pulmonary Syndrome In May and June 1993, 24 cases of severe respiratory illness among residents of the Four Corners area of the southwestern United States were reported. Subsequent analysis of such cells has shown that half the intracellular proteins are enzymes for tryptophan synthesis. But a "harmless" microbe could act as a parasite if it gains access to a part of the body where it would not normally exist. Drugs are available to kill microfilariae rapidly, but toxins from very many dying microfilariae can cause anaphylactic shock. Allergic reactions can be limited to mild skin rashes and itching, or they can be lifethreatening. Salmonellas have also been traced to contaminated water and to food contaminated by carriers. There, experts would isolate strains of phages that could cure infections caused by these organisms. With return of cold weather it has had a new outbreak of over 160 cases in January through March 2014, after only 2 cases in the summer of 2013. Antimicrobial drugs generally act on an important microbial structure or function that usually differs from its counterpart in animals. Physicians worldwide criticized President Fujimori for his foolhardy defense of the Peruvian fisheries industry. If the impairment occurs during speech development, as it often does, speech can be adversely affected. Establishment of mandatory testing of dairy herds for tuberculosis every 3 years (the time it takes an infection to progress to a transmissible stage) has greatly decreased incidence of the disease in the United States. Zygotes pass through the stomach wall and produce sporozoites, which eventually make their way to the salivary glands. A third view is that there was a fourth branch, possibly viruses, that contributed genes to the Eukarya. When Chlamydia or Ureaplasma are responsible for infection, they usually are sexually transmitted and cause non-gonococcal urethritis, which is discussed later.
Condurango. Colchicindon.
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Respiratory symptoms such as sore throat, cough, and other cold symptoms, fever, headache, and malaise are frequently seen. Most patients experience respiratory and kidney problems, abdominal pain, sore throat, and severe bleeding as well. The organism is: (a) Haemophilus influenzae type A (b) Neisseria meningitidis (c) Haemophilus influenzae type B (d) Streptococcus pneumoniae (e) Listeria monocytogenes 5. Bacterial infections of heart valves often cause permanent valve damage, and poliovirus infections leave permanent paralysis. Changes certain characteristics of an organism, depending on which genes are transferred. Before widespread immunization, most children had measles before they were 10 years old. In these hosts the bacteria either cause obvious disease or are carried without producing harmful effects. Bread In bread, yeast is used as a leavening agent-that is, to produce gas that makes the dough rise. Surveys of pregnant women reveal that 11% have Chlamydia in the cervix; postpartum fever is common among infected women. Health care workers in the United States should be alert to the possibility that patients may have acquired such parasites while traveling in tropical areas. One-third of all septicemia cases are nosocomial and appear within 24 hours after an invasive medical procedure has been performed. These discoveries stimulated the development of a group of substances called sulfonamides, or sulfa drugs. Or you may have a severe cold with a sore throat, cough, fever, and headache, but the disease runs its course in a week or so without any permanent effects. The Marburg virus was first recognized in Germany when technicians preparing monkey kidney cell cultures died of a hemorrhagic disease. Although this dream has been realized for smallpox and probably will be true for polio shortly after the turn of the century, many infectious diseases remain a serious health threat. Classification of bacteria has posed taxonomic problems over the centuries and still does. Large processing plants provide opportunities for contamination of great quantities of food unless sanitation is strictly practiced. In the majority of cases, the infection is chronic, asymptomatic, and self-limiting. They hypothesized that a group of urkaryotes, the earliest or original cells, gave rise to the eukaryotes directly rather than by way of prokaryotes. Relatively rare in the United States, with less than 106 cases reported per year, chancroid is seen most frequently in developing countries of Africa, the Caribbean, and Southeast Asia. An antigen is a substance the body identifies as foreign and toward which it mounts an immune response-often it is also referred to as an immunogen. Radiation causes damage by causing the formation of dimers of: (a) Guanidine and cytosine (b) Cytosine and thymidine (c) Adenine and cytosine (d) Guanidine and adenine (e) Thymidine and adenine 14. Between 1 year and puberty, gonorrhea usually occurs as vulvovaginitis in girls who have been sexually molested. The ability of a pathogen to invade and grow in host tissues, called invasiveness, is related to particular virulence factors. Because both these mechanisms represent molecular defenses, we will discuss them later in this chapter. Bunyaviruses can be transmitted by arthropods, but rodents typically are the principal host. Artificially acquired active immunity is produced when a person is exposed to a vaccine containing live, weakened, or dead organisms or their toxins.
Pseudomonas infection can cause severe scarring of the cornea and distorted vision, or even blindness. The disease is most frequently seen during wars and other conditions of overcrowding and poor sanitation. They have the distilled knowledge of countless years of treating illness, and in recent years more Western scientists are becoming apprenticed to these healers to help save this information. The interactions among organisms and between the organisms and their environment can be quite different in different microenvironments, no matter how close together they are. Nocardiosis, marked by lesions and abscesses, infects primarily the lungs but can infect the skin or other organs. The stabbing pains shot through her hands, like knives constantly slashing through her fingers, alternating with electrical shocks. Courtesy of OvaMed Courtesy of OvaMed Microbiology Roadmap Visit the companion website for the Microbiology Roadmap with practice questions, current examples, and other tools to help you study, review, and master the key concepts of the chapter. It is now known that the Russians grew great quantities of smallpox virus for possible use in biological warfare, and that stocks from this supply have probably reached other Soviet-allied countries. Asiatic cholera, common in Asia and other regions with poor sanitation, is treated with fluid and electrolyte replacement and tetracycline. Some mosquitoes, which are temporary parasites, harbor the malaria parasite or other parasites. That concentration should be maintained at the sites of infection because it is the minimum concentration that will cure the disease. Chloroquine and Primaquine Currently the most widely used antimalarial agents are the synthetic agents chloroquine (Aralen) and primaquine. As of yet, about one-half of the cases have spread human to human; Birds themselves do not suffer any ill effects from it. Those who are infected release the virus, and it makes its way into the tissues of susceptible individuals. Leukocytes, such as neutrophils and macrophages, sometimes force their way between cells of the capillary walls (diapedesis) during infections. We have now completed the discussion of cellmediated immunity-how it is initiated and how its effects are produced. The fungus enters the body through the lungs or wounds, where it causes disfiguring granulomatous, pus-producing lesions and multiple abscesses in skin and subcutaneous tissue. Erysipelas (eri-sipe-las; from the Greek erythros, for red, and pella, for skin), also called St. In 1796, Jenner inoculated an 8-year-old boy with cowpox and 6 weeks later inoculated him with smallpox. It is treated with chloroquine and can be prevented by avoiding contact with ticks. Regular hospital disinfectants and alcohol-based hand gels do not kill the spores. This reduces the possibility that people who are themselves immune can serve as reservoirs of infection by carrying the virus in their intestines and passing it on to others. Often, before a remediation project is started in the field, organisms will be tested in the laboratory for the ability to metabolize the contaminant. The postal workers who developed pulmonary anthrax in the 2001 attacks, and who were saved by heroic efforts, have not regained their former health. Bacteriophage viruses are now licensed for use in killing bacteria that may cause food poisoning or spoilage. Bacterial Vaginitis Vaginitis, or vaginal infection, usually is caused by op- portunistic organisms that multiply when the normal vaginal microflora are disturbed by antibiotics or other factors. Health scientists use these properties to identify infectious prokaryotes in the laboratory, but such identification does not necessarily reflect evolutionary relationships among the organisms. The viruses replicate and have low pathogenicity but are excreted intermittently over many months, during which time they can infect others.
Another problem with this product is possible contamination with pig molecules or pig pathogens if purification processes fail. The gene responsible for such immunity does not protect the lysogen against infection by a different type of temperate phage or by a virulent phage. When this was first tried, workers in the detergent factories developed respiratory problems and skin irritations. Recent studies in the United States show that 24% of people being treated for one tickborne disease are actually also infected with a second or third such disease. Thus, viruses have been classified as bacterial viruses (bacteriophages), plant viruses, or animal viruses. Kingdom Fungi the fungi include some unicellular and many multicellular organisms that obtain nutrients solely by absorption. Cytomegaloviruses are a widespread and diverse group of: (a) Cytoviruses (b) Retroviruses (c) Poxviruses (d) Herpesviruses (e) Mycoplasmas 21. How would you respond to parents who wish to avoid (a) all vaccines for their infant or (b) pertussis vaccine for their infant Wandering worms cause abscesses in the liver and other organs and sometimes traumatize victims or doctors examining them for other disorders by crawling from body openings such as the nose or umbilicus. If you had a phage suspension in a test tube, how could you determine the number of viruses in the tube The season of the year in which epidemics occur may help identify the causative agent. In denaturation, hydrogen and disulfide bonds are disrupted, and the functional shape of the protein molecule is destroyed. Parasitic worm diseases, such as hookworm disease and ascariasis, also are studied by epidemiologists. Vector control is an effective means of controlling infectious diseases if the vector, such as an insect or rodent, can be identified and its habitat, breeding habits, and feeding behavior determined. Even after the initial disease has subsided, patients are subject to relapses as dormant protozoa become activated, emerge from the liver, and initiate a new cycle of disease. Toxins from pathogens have stimulated neural centers; you interpret the stimuli as nausea. However, often their keen observations of nature give the clues needed to find the source of a disease. The first of these helminths was identified by the German parasitologist Theodor Bilharz in the 1850s, so the disease is also called bilharzia (bil-harze-a). Older people had cross-reactive antibodies from earlier exposure or vaccination from the 1977 "swine flu" scare, indicating how very long flu antibodies can remain protective. At the same time, phage tails are assembled from newly formed base plates, sheaths, and collars. A mutation occurs wherever the analog causes the insertion of guanine instead of adenine in the subsequent replication. All these enzymes, factors, and cells increase the inflammatory response, leading to swollen, painful joints. Consequently, this compound is now used only in special situations and generally in combination with other drugs. It may be possible to acidify certain foods by the addition of lemon juice, citric acid, or vinegar. Bromine is sometimes used in the form of gaseous methyl bromide to fumigate soil that will be used in the propagation of bedding plants. The presence of a few, nonmultiplying, bacteria in the blood is termed: (a) Viremia (d) Toxemia (b) Septicemia (e) Secondary infection (c) Bacteremia 12. Then, as soon as the rains begin, the number of new cases drops to zero-only to climb again at the start of the dry season. Primaquine is the drug of choice for eliminating parasites from the liver and other tissues if they have been infected. We do know that conditions were right for an explosion in the rodent population, guaranteeing more contact between rodent feces and humans. It is thought that the virus can travel within nerve fibers, accounting for multiple sections of intestine and all layers of the bowel being involved. They appear to play a role in some B-cell and T-cell interactions and may account for some symptoms of infectious mononucleosis.
Since 1980, a total of 143 out of 145 cases of paralytic polio have been associated with oral polio vaccine. The bread becomes light and porous because of spaces created by carbon dioxide bubbles. Suppose that the health department of city A mounts a successful campaign to get children immunized against measles. Yellow Fever Yellow fever was first studied by Carlos Finlay and Walter Reed in the early 1900s when infection of workers threatened to disrupt the construction of the Panama Canal. For example, an adhesin on attachment pili of certain the syphilis strains of Escherichia coli attaches to recepspirochete uses tors on certain host epithelial cells. Epidemics caused by influenza B viruses are limited geographically and tend to center around schools and other institutions. Principles of Parasitology 313 A few parasites are facultative parasites: They normally are free-living, such as some soil fungi, but they can obtain nutrients from a host, as many fungi do when they cause skin infections. Such classification is complicated by two problems: (1) No sexual cycle has been observed for some fungi, and (2) it is often difficult to match the sexual and asexual stages of some fungi. Plants, for example, produce chemical defenses that can wall off areas dam aged or infected by bacteria or fungi. In many small villages where the people depend on water from blackflyinfested rivers, nearly all inhabitants who live past middle age are blind. A similar protein, lactoferrin, present in sa liva, mucus, and milk, also binds iron inhibiting bacterial growth. The rotaviruses 10 rotavirus parare the most common cause of severe ticles is sufficient diarrhea in infants and in young children to cause infection and diarrhea. The large numbers of nonimmune people who had emigrated from nonendemic areas were exposed to immune people who carried the poliovirus. Insects act as biological vectors when they transmit pathogens actively; that is, the infectious agent must complete part of its life cycle in the vector before the insect can transmit the infective form of the microbe. Chancroid begins with the appearance of soft, painful lesions called chancres, which bleed easily, on the genitals 3 to 5 days after sexual exposure. In this method a constant quantity of microbial inoculum (specimen) is introduced into a series of broth cultures containing decreasing concentrations of a chemotherapeutic agent. Those who have recently been infected will shed the virus continuously for about 18 months. In fact, they display only a few characteristics associated with living organisms. For example, a strain of Penicillium chrysogenum that once produced 60 mg of penicillin per liter of culture now produces 20 g/l. Because our bodies function at lower temperatures than the newly set temperature, we feel cold and have chills at this stage. Recently many products have appeared on the market, claiming to do a good job of cleaning your hands with a little gel instead of oldfashioned soap and water. So, a bite on the ankle received while kicking off a rabid animal may be less hazardous than one on the trunk or neck. It can be prevented by immunizing pets and people at risk and by avoidance of contact with wild animals by those who are not immunized. Bacterial Sexually Transmitted Diseases Gonorrhea the term gonorrhea means "flow of seed" and was coined in a. A frameshift mutation occurs following the: (a) Insertion of one base (b) Insertion of more than one base (c) Deletion of one base (d) Deletion of more than one base (e) All of these 13. When ex- Viruses anD CanCer Cancer is known as a set of diseases that perturbs the normal behavior and functioning of cells. This mechanism bypasses a reaction inhibited by an antimicrobial agent that occurs in other sulfonamide-resistant bacteria. Condoms can reduce but not eliminate transmission because they have a significant failure rate. Most reactions are localized, but generalized anaphylactic reactions sometimes occur, especially when drugs are given by injection.
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