Precautions Stress, alcohol consumption, and prescription medicines can interfere with the conversion of linoleic acid to its derivatives. In addition, to improve prostaglandin production, the use of unprocessed, unheated omega-6 oils in the cis form is recommended. General use Most people receive sufficient amounts of omega-6 fatty acids in their diet. Deficiencies are considered to be rare and limited to people with severe malabsorption, short bowel syndrome, or for people on an extremely low fat diet. Long term exclusive or excessive use of flaxseed oil, which contains large amounts of omega-3 fatty acids, can result in omega-6 fatty acid deficiency and require the addition of oils containing omega-6 fatty acids to the diet. Interactions Nutrients essential for the use of omega-6 fatty acids in the body include magnesium, selenium, zinc, and vitamins A, carotene, B3, B6, C, and E. The disease, which causes progressive paralysis, is marked by periods of exacerbation and remission. Subspecies of ophiopogon include several with a great variety of ornamental leaves, ranging from all-green to green with white, cream-colored or golden edges. The flowers appear in mid-summer, and are followed by shining blackberry-like seeds that remain throughout the winter. There are species of this plant that grow and thrive in either full sun or full shade. Ophiopogon is able to tolerate a very wide variety of adverse conditions, including extreme heat, soil that is dry even to the point of drought, or high humidity. Liriope spicata, also known as Ophiopogon japonicus, is a creeping variety with fast-spreading, slender tuberous roots that can prove to be quite invasive. It forms a rhizome with smaller fibrous roots growing outward; the tuber itself has a bittersweet taste. Frey, PhD General use Ophiopogon japonicus has long been used in Oriental herbal medicine. The earliest reference to its use is in the Shennong Bencao Jing, or Herbal Classic of the Divine Plowman. Ophiopogon is thought to be effective in clearing away what Chinese medical practitioners call "heat in the heart" and irritability. Ophiopogon is an antiseptic that is particularly useful in the healing of mouth sores. Its sedative qualities provide relief for insomnia, heart palpitations, anxiety, and restlessness. It is similar to the many chemical sedatives used in Western medicine in that it reduces muscle spasm. Ophiopogon also moistens the mucous membranes of the body by stimulating the production of mucosal fluids. Because of these qualities, ophiopogon is used in formulas to treat constipation, dry throat, and chronic dry bronchitis. Because ophiopogon has been shown to lower blood sugar and regenerates necessary cells in the pancreatic isles of Langerhans, it is also considered useful in treating the fluid imbalance caused by diabetes, as evidenced by excessive thirst and urination. According to the United States Department of Agriculture phytochemical database developed at the 1489 Onion see Allium cepa Ophiopogon Description Ophiopogon is a perennial herbaceous plant that is native to the Orient. Under the name mai men dong, its tuberous root is a highly prized and indispensable part of Chinese herbal medicine. It is commonly known in the Western world as lily-turf or Liriope spicata, and is a member of the lily, or Liliaceae, family. The tufted mounds that ophiopogon forms are usually about 1 ft (30cm) in height and diameter. It has been found to stimulate the production of milk in nursing mothers and to reduce inflammation. It has cough suppressing properties, and is used in treating nearly all lung-related illnesses, including bronchitis, whooping cough, tuberculosis, hemoptysis (coughing up blood), sore throat, laryngitis, and cough. A chemical present in the plant has shown effectiveness in the treatment of lung tumors.
Genome-sequencing projects provide detailed information about gene content and organization in different species and even in different members of the same species, allowing inferences about how genes function and genomes evolve. They also provide important information about evolutionary relationships among organisms and about factors that influence the speed and direction of evolution. Comparative genomics is the field of genomics that compares similarities and differences in gene content, function, and organization among genomes of different organisms. However, there are exceptions, such as that of Vibrio cholerae, the bacterium that causes cholera, which has two circular chromosomes, and that of Borrelia burgdorferi, which has one large linear chromosome and 21 smaller chromosomes. Results m 2/+ m 2/m 2 +/+ 7 Some fish homozygous for recessive mutations are produced. Although this range in genome size might seem extensive, it is much less than the enormous range of genome sizes seen in eukaryotes, which can vary from a few million base pairs to hundreds of billions of base pairs. Escherichia coli, the most widely used bacterium for genetic studies, has a fairly typically genome size at 4. Archaea and bacteria are similar Conclusion: the mutagenesis screen produces fish with a mutation affecting the trait. In this illustration, M1 represents a dominant mutation and m2 represents a recessive mutation. Surprisingly, genome size also varies extensively within some species; for example, different strains of E. Among prokaryotes, the number of genes typically varies from 1000 to 2000, but some species have as many as 6700 and others as few as 480. Interestingly, the density of genes is rather constant across all species, with an average of about one gene per 1000 bp. Thus, prokaryotes with larger genomes will have more genes, in contrast with eukaryotes, for which there is little association between genome size and number of genes (see the section on eukaryotic genomes). The evolutionary factors that determine the size of prokaryotic genomes (as well as eukaryotic genomes) are still largely unknown. Thus, selection may favor smaller genomes in organisms that occupy environments where rapid reproduction is advantageous. Prokaryotes with the smallest genomes tend to be in species that occupy restricted habitats, such as bacteria that live inside other organisms. The constant environment and metabolic functions supplied by the host organism may allow these bacteria to survive with fewer genes. Bacteria with the larger genomes tend to occupy highly complex and variable environments, such as the soil or the root nodules of plants. In complex environments where resources are abundant, there may be little need for rapid division (which favors smaller genomes). An example of a large-genome bacterium occupying a complex environment is Streptomyces coeliocolor, a filamentous bacterium with a genome size of 8,677,507 bp. This bacterium has been called the "Boy Scout" bacterium because it has a diverse set of genes and therefore follows the Scout motto: be prepared. In addition to the usual housekeeping genes for genetic functions such as replication, transcription, and translation, its genome contains a number of genes for the breakdown of complex carbohydrates, allowing it to consume decaying matter from plants, animals, insects, fungi, and other bacteria. It has genes for a large number of proteins that produce secondary metabolites (breakdown products) that can function as antibiotics and protect against desiccation and low temperatures. In this species, a large genome with lots of genes appears to be beneficial in the complex environment that it inhabits. Metabolism Unknown Ionic homeostasis Protein synthesis Energy Transport facilitation Cellular biogenesis Intracellular transport Protein destination Cellular communication and signal transduction 11. Proportion of the circle occupied by each color represents the proportion of genes affecting various known and unknown functions in E. Another mechanism for gaining new genetic information is horizontal gene transfer, a process by which both closely and distantly related bacterial species periodically exchange genetic information over evolutionary time. Horizontal gene transfer has been recognized for some time, but analyses of many microbial genomes now indicate that it is more extensive than was formerly recognized. The widespread occurrence of horizontal transfer has caused some biologists to question whether distinct species even exist in bacteria (see Chapter 8 for more discussion of this matter).
The bacteria often form clusters of parallel arrays (palisades) in culture, referred to as Chinese characters. Fewer than five cases due to routine immunization are diagnosed per year in the United States. Disease in the United States occurs in elderly and alcoholic individuals-often those of low socioeconomic status-as well as in Native Americans. Clinical Features Respiratory Diphtheria Upper respiratory tract illness due to C. Clinical diagnosis is based on the constellation of sore throat; low-grade fever; and a tonsillar, pharyngeal, or nasal pseudomembrane. Occasionally, weakness, dysphagia, headache, and voice change are the initial manifestations. Massive swelling of the tonsils and "bull-neck" diphtheria resulting from submandibular and paratracheal edema can develop. This illness is further characterized by foul breath, thick speech, and stridorous breathing. They begin with dysphagia and nasal dysarthria and progress to cranial nerve involvement, including weakness of the tongue and facial numbness. Several weeks later, a generalized sensorimotor polyneuropathy with prominent autonomic dysfunction (including hypotension) may occur. Diagnosis A definitive diagnosis is based on compatible clinical findings and isolation of C. Diphtheria Diphtheria antitoxin is the most important component of treatment and should be given as soon as possible. Because antitoxin is produced in horses, current protocol includes a test dose to rule out immediate-type hypersensitivity. Pts who exhibit hypersensitivity should be desensitized before receiving a full dose. Cultures should document eradication of the organism 1 and 14 days after completion of antibiotic therapy. The interval between onset of local disease and antitoxin administration also predicts outcome. Td (tetanus and diphtheria toxoids) is recommended for routine booster use in adults at 10-year intervals or for tetanus-prone wounds. Close contacts of pts with respiratory diphtheria should have throat specimens cultured for C. Treatment consists of removal of the source of infection and administration of vancomycin. In the United States, serogroup B causes most sporadic disease, serogroup C causes most outbreaks, and serogroup Y is becoming more prevalent, particularly among older pts and pts with underlying chronic disease. Rates of meningococcal disease are highest among infants and children; a second peak in teenagers is due to residence in barracks, dormitories, or other crowded situations. Household contact with a meningococcal disease pt or a meningococcal carrier, household or institutional crowding, exposure to tobacco smoke, and a recent viral upper respiratory infection are risk factors for colonization and invasive disease. Pathogenesis Meningococci colonize the upper respiratory tract, are internalized by nonciliated mucosal cells, enter the submucosa, and reach the bloodstream. Morbidity and mortality from meningococcemia have been directly correlated with the amount of circulating endotoxin, which can be 10- to 1000-fold higher than levels seen in other gram-negative bacteremias. Deficiencies in antithrombin and proteins C and S can occur during meningococcal disease, and there is a strong negative correlation between protein C activity and mortality risk.
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Although no long-haired progeny are observed, it is possible that just by chance no long-haired rabbits would be produced among the 8 progeny of the cross. Let p equal the probability of a kitten being black and q equal the probability of a kitten being gray. The binomial is (p q)6, the expansion of which is: (p q)6 p6 6p5q 15p4q2 20p3q3 15p2q4 6p1q5 q6 (See the section on the Binomial Expansion and Probability for an explanation of how to expand the binomial. The probabilities of p and q are both 1/2; so the overall probability is 20(1/2)3 (1/2)3 20/64 5/16. The following genotypes are crossed: Aa Bb Cc Dd Aa Bb Cc Dd Give the proportion of the progeny of this cross having each of the following genotypes: (a) Aa Bb Cc Dd, (b) aa bb cc dd, (c) Aa Bb cc Dd. It is theoretically possible, although unlikely, that the parent is heterozygous and just by chance no long-haired progeny were produced. If this female has a litter of six kittens, what is the probability that three will be black and three will be gray To find the probability of any combination of genotypes, simply multiply the probabilities of the different genotypes: a. In corn, purple kernels are dominant over yellow kernels, and full kernels are dominant over shrunken kernels. A corn plant having purple and full kernels is crossed with a plant having yellow and shrunken kernels, and the following progeny are obtained: purple, full purple, shrunken yellow, full yellow, shrunken 112 103 91 94 66 Chapter 3 What are the most likely genotypes of the parents and progeny If the probability that the difference between observed and expected is due to chance is low, the progeny are not really in the predicted ratio and some other, significant factor must be responsible for the deviation. The observed and expected numbers are: Phenotype purple, full purple, shrunken yellow, full yellow, shrunken Observed 112 103 91 94 Expected 400 100 400 100 400 100 400 100 Purple yellow produces approximately 1/2 purple and 1/2 yellow. A 1: 1 ratio is usually caused by a cross between a heterozygote and a homozygote. Because purple is dominant, the purple parent must be heterozygous (Pp) and the yellow parent must be homozygous (pp). The purple progeny produced by this cross will be heterozygous (Pp) and the yellow progeny must be homozygous (pp). Full shrunken produces 1/2 full and 1/2 shrunken, or a 1: 1 ratio, and so these progeny phenotypes also are produced by a cross between a heterozygote (Ff) and a homozygote (ff); the full-kernel progeny will be heterozygous (Ff) and the shrunken-kernel progeny will be homozygous (ff). Now combine the two crosses and use the multiplication rule to obtain the overall genotypes and the proportions of each genotype: P Purple, full Pp Ff Yellow, shrunken pp ff /4 /4 1 /4 1 /4 1 1 to determine the probability that the difference between observed and expected is due to chance, we calculate a chisquare value with the formula 2 [(observed expected)2/ expected]: 2 = = = (112 - 100)2 (103 - 100)2 (91 - 100)2 (94 - 100)2 + + + 100 100 100 100 32 92 62 122 + + + 100 100 100 100 144 9 81 36 + + + 100 100 100 100 = 1. To obtain this probability, we first calculate the degrees of freedom, which F1 Pp Ff = 1 2 purple * 1 2 full = 1 4 purple, full for a goodness-of-fit chi-square test are n 1, where n equals 1 1 1 the number of expected phenotypic classes. In this case, there are Pp ff = 2 purple * 2 shrunken = 4 purple, shrunken four expected phenotypic classes; so the degrees of freedom 1 1 1 pp Ff = 2 yellow * 2 full = 4 yellow, full equal 4 1 3. We must now look up the chi-square value in a pp ff = 1 2 yellow * 1 2 shrunken = 1 4 yellow, shrunken chi-square table (see Table 3. We select the row corresponding to 3 degrees of freedom and look along this row to find our Our genetic explanation predicts that, from this cross, we should calculated chi-square value. The calculated chi-square value of see 1/4 purple, full-kernel progeny; 1/4 purple, shrunken-kernel 2. A total of 400 progeny were produced; so calculated chi-square value is therefore 0. These observed probability that the difference between what we observed and numbers do not fit the expected numbers exactly. Could the what we expected is due to chance, which in this case is high, difference between what we observe and what we expect be due and so chance is likely responsible for the deviation. If the probability is high that chance alone is conclude that the progeny do appear in the 1: 1: 1:1 ratio responsible for the difference between observed and expected, predicted by our genetic explanation. In which phases of mitosis and meiosis are the principles of segregation and independent assortment at work What are the addition and multiplication rules of probability and when should they be used Give the genotypic ratios that may appear among the progeny of simple crosses and the genotypes of the parents that may give rise to each ratio. What does the probability associated with a chi-square value indicate about the results of a cross At times in the past, red hair in humans was thought to be a recessive trait and, at other times, it was thought to be a dominant trait. Assign symbols for the alleles in this cross and give genotypes for all the individual plants.
Crossing over between ss and e produces ss+ e and st st+ ss e+ chromosomes: st st ss ss e: e st ss e st ss e: st ss e st ss e st+ ss st st st ss ss+ ss e e e+ st+ ss e 50 Scarlet 52 e st ss+ e+ Ebony 43 We now know the locations of all the crossovers; their locations are marked with a slash in Figure 7. Calculating the recombination frequencies Next, we can determine the map distances, which are based on the frequencies of recombination. We calculate recombination frequency by adding up all of the recombinant progeny, dividing this number by the total number of progeny from the cross, and multiplying the number obtained by 100%. To determine the map distances accurately, we must include all crossovers (both single and double) that take place between two genes. Recombinant progeny that possess a chromosome that underwent crossing over between the eye-color locus (st) and the bristle locus (ss) include the single cross+ / ss e st / ss+ e+) and overs (st + + / ss / e and the two double crossovers (st and st / ss+ / e); see Figure 7. Chromosome 1 (X) Yellow body Scute bristles White eyes Facet eyes Echinus eyes Ruby eyes Crossveinless wings Cut wings Singed bristles Lozenge eyes Vermilion eyes Miniature wings Sable body Garnet eyes Forked bristles Bar eyes Fused veins Carnation eyes Bobbed hairs Chromosome 2 Net veins Aristaless antenna Star eyes Held-out wings Dumpy wings Clot eyes 19. The map distance between the bristle locus (ss) and the body locus (e) is determined in the same manner. The recombinant progeny that possess a crossover between ss and e are the sin+ ss+ / e and st ss / e+ gle crossovers st st / ss / e+ and the double crossovers and + /. This map distance can be obtained by summing the map distances between st and ss and between ss and e (14. Interference and the coefficient of coincidence Map distances give us information not only about the distances 181 182 Chapter 7 that separate genes, but also about the proportions of recombinant and nonrecombinant gametes that will be produced in a cross. Theoretically, we should be able to calculate the proportion of double-recombinant gametes by using the multiplication rule of probability (see Chapter 3), which states that the probability of two independent events occurring together is calculated by multiplying the probabilities of the independent events. Applying this principle, we should find that the proportion (probability) of gametes with double crossovers between st and e is equal to the probability of recombination between st and ss multiplied by the probability of recombination between ss and e, or 0. Multiplying this probability by the total number of progeny gives us the expected number of double-crossover progeny from the cross: 0. Only 8 double crossovers-considerably fewer than the 13 expected-were observed in the progeny of the cross (see Figure 7. The calculation assumes that each crossover event is independent and that the occurrence of one crossover does not influence the occurrence of another. But crossovers are frequently not independent events: the occurrence of one crossover tends to inhibit additional crossovers in the same region of the chromosome, and so double crossovers are less frequent than expected. The degree to which one crossover interferes with additional crossovers in the same region is termed the interference. To calculate the interference, we first determine the coefficient of coincidence, which is the ratio of observed double crossovers to expected double crossovers: coefficient of coincidence = number of observed double crossovers x number of expected double crossovers For the loci that we mapped on the third chromosome of D. The interference is calculated as interference = 1 - coefficient of coincidence So the interference for our three-point cross is: interference = 1 - 0. When interference is complete and no double-crossover progeny are observed, the coefficient of coincidence is 0 and the interference is 1. Sometimes a crossover increases the probability of another crossover taking place nearby and we see more double-crossover progeny than expected. In this case, the coefficient of coincidence is greater than 1 and the interference is negative. The interference equals 1 - the coefficient of coincidence; it indicates the degree to which one crossover interferes with additional crossovers. Fewer double crossovers took place than expected on the basis of single-crossover frequencies. More double crossovers took place than expected on the basis of single-crossover frequencies. A crossover in one region interferes with additional crossovers in the same region.
It can also reduce edema and high blood pressure as well as contribute to sympathetic nervous system sedation. Deep tissue, trigger point, and both active and passive movements alleviate stress on weight-bearing joints, muscles, and fascial tissues to reduce neck and back pain caused by poor posture and strain on the uterine ligaments. During labor, women whose partners use basic massage strokes on their backs and legs have shorter, less complicated labors. For post-Caesarean mothers, specific therapeutic techniques can also reduce scar tissue formation and facilitate the healing of the incision and related soft tissue areas. In certain Irish hospitals laboring women are held and touched by a doula (labor assistant) or midwife through most of their notably short, uncomplicated labors. As massage therapy resumes its place within Western healthcare methods, pregnancy massage is becoming one of its fastest growing specialized applications. A pregnant woman can expect to enjoy many of the same techniques, draping, and professional demeanor offered all massage therapy clients. The lower back, hips, and neck benefit from sensitively applied deep tissue, neuromuscular, and movement therapy. Edema in the legs and arms may be relieved with the gliding and kneading strokes of Swedish or lymphatic drainage massage. Pregnant women should expect a thorough health and prenatal intake interview with their therapists. Cost, procedures, and insurance coverage are similar to those for other massage client populations. Preparations In addition to the preparations listed in the massage therapy entry, some expectant women will be asked to secure a release from their maternity healthcare provider, especially those with complications or high risk factors. Benefits Profound physiologic, functional, emotional, relational, and lifestyle changes occur during gestation and labor, often creating high stress levels. Too much stress can negatively affect maternal and infant health, resulting in reduced uterine blood supply and higher incidence of miscarriage, prematurity, and other complications. Massage therapy can help a woman approach her due date with less anxiety as well as less physical discomfort. It is better to avoid massage if the woman has vaginal bleeding, abdominal pain, or diarrhea. Side effects There are no known side effects to receiving appropriate prenatal massage therapy. Research & general acceptance Current research on the benefits of touch is providing a contemporary basis for its reintroduction into maternity care. Scientists have found that rats restricted from cutaneous self-stimulation had poorly developed placentas and 50% less mammary gland development. Their litters were often ill, stillborn, or died shortly after birth due to poor mothering skills. Women who are nauseated and/or vomiting prenatally experienced a decrease in these discomforts when they applied finger pressure to a specific acupuncture point (acupressure) on their forearm several times each day. Pregnant women massaged twice weekly for five weeks experienced less anxiety, leg, and back pain. When compared with control groups who practiced relaxation exercises only, the women who had had massage reported better sleep and improved moods, and their labors had fewer complications, including fewer premature births. Studies show that when women receive nurturing touch during later pregnancy, they touch their babies more frequently and lovingly. During labor the presence of a doula, a woman providing physical and emotional support, including extensive touching and massage, reduces the length of labor and number of complications, interventions, medications, and Caesarean sections. Pregnancy massage increases blood flow, relaxes muscles, reduces water retention, and makes the skin more supple.
Relaxation therapy should not be performed while operating a motor vehicle or in other situations where full and alert attention is necessary. Research & general acceptance Relaxation therapies have been successfully used in relieving stress and anxiety for many years, and are generally well-accepted by the medical community for this purpose. Recent research published in 1999 has also indicated that relaxation therapy may be useful in reducing the incidence of preterm labor in women at risk for delivering prematurely. The study also found that women who discontinued relaxation exercises for whatever reasons delivered earlier and had lower birthweight babies than those who continued the treatment. Training & certification Relaxation therapy techniques are used by many licensed therapists, counselors, psychologists, psychiatrists, and other healthcare professionals. There are many self-help books, audiotapes, and videos available that offer instruction in relaxation techniques. It can also be applied after sports or exercise for discomfort caused by bruises or sore muscles. Many people who use Rescue Remedy recommend it for pets and plants, as well as for humans. In the sun method, flower heads are floated in a clear glass bowl filled with natural spring water and allowed to soak in bright sunlight for three hours. In the boiling method, flowering twigs are boiled for half an hour in a large pan of spring water. After the water has cooled, the plant parts are removed and the remaining water is mixed with an equal part of brandy. Preparations the liquid form of Rescue Remedy is available in the United States for about $12 for a 20-mL bottle. Unlike the individual flower essences, which are taken two drops at a time, Rescue Remedy is taken in four-drop doses. It can be dropped directly on the tongue-care being taken not to touch the dropper-or added to a glass of water and sipped slowly. People who are concerned about the alcohol content of the tincture may add the Rescue Remedy to a cup of hot tea or other warm beverage, which will cause the alcohol to evaporate. Rescue Remedy is safe to use several times a day to treat emotional stress, as the flower essences in it are too dilute to cause any overdose effects. Rescue Remedy cream contains crab apple in addition to the five flower essences in the liquid preparation. Bach intended Rescue Remedy "as an emotional first-aid kit and not as a quick replacement for the 38 individual remedies. For example, someone who is afraid of something specific and identifiable would be advised to take Mimulus, whereas someone who suffers from nameless anxiety would take Aspen. Bach is said to have chosen the five essences included in Rescue Remedy because he thought that they would act rapidly and cover most types of emotional crisis. For terror, panic attacks, and hysteria; also recommended for recurrent nightmares. For those who tend to think and act impulsively, or become tense and irritable when upset. None of the Bach flower remedies are intended for use in treating infectious diseases or internal injuries. The Bach Centre in England, however, does recommend that persons taking disulfiram (Antabuse) as part of treatment for alcohol abuse should consult their physicians before using any of the Bach flower essences. Although the amount of alcohol in four drops of Rescue Remedy is very small, it could conceivably trigger a reaction to disulfiram. Unlike other homeopathic remedies, Bach flower essences are not affected by such substances as coffee, 1727 Restless leg syndrome. Coffee, camphor, menthol, peppermint-flavored mouthwash or toothpaste, and eucalyptus are considered antidotes.
A macrolide-containing regimen should be given for 12 months after sputum cultures become negative. Treatment with rifampin (600 mg/d), isoniazid (300 mg/d), and ethambutol (15 mg/kg daily) should be administered for at least 12 months after the last positive culture. These organisms may infect surgical or traumatic wounds, contaminated injection sites, or sites of body piercing. Experts recommend up to 6 months of treatment for bacteremic or disseminated cutaneous disease and 12 months of treatment after sputum cultures are negative for pulmonary disease. Antimycobacterial treatment has not yet been shown to be helpful; surgical treatment is important. The classic presentation is a red macule that expands slowly to form an annular lesion with a bright red outer border and central clearing; central erythema, induration, necrosis, or vesicular changes or many red rings within an outer ring are also possible. Recurrent attacks decrease yearly, but a few pts have chronic arthritis with bony and cartilage erosion. Serologic testing should be undertaken when the pt has at least an intermediate pretest likelihood of having Lyme disease. IgM and IgG testing should be done in the first month of illness, after which IgG testing alone is adequate. Lyme Borreliosis Except for neurologic and cardiac disease, most treatment can be oral. Doxycycline (100 mg bid) is the agent of choice for men and nonpregnant women and is also effective against anaplasmosis. Amoxicillin (500 mg tid), cefuroxime (500 mg bid), erythromycin (250 mg qid), and newer macrolides are alternative agents, preferred in that order. More than 90% of pts have good outcomes with a 14-day course of treatment for localized infection or a 21-day course for disseminated infection. Chronic Lyme disease: Persistent musculoskeletal and neurocognitive symptoms with fatigue occur in a small percentage of pts after antibiotic treatment. Further antibiotic courses are not helpful; treatment consists of symptom-based supportive care. Although convalescence is longer the later antibiotics are given, the overall prognosis remains excellent, with minimal or no residual deficits. Clinical Features Disease is manifest by primary skin lesions that become disseminated with time. Diagnosis Diagnosis is based on clinical presentation and dark-field microscopy of scrapings from lesions. Rodents, particularly rats, are the most important disease reservoir, but many mammalian species can harbor the organisms. Risk factors in the United States include recreational water activities, occupational activities that result in exposure to animals or animal waste. Pathogenesis Entry of the organisms via skin abrasions or intact mucous membranes is followed by leptospiremia and widespread dissemination.
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