By Z. Tyler. Waldorf College.
The increase in chemokines and cytokines activates a smooth muscle phenotype change such that normally contractile cells become migratory and proliferate and move to form a cap over the developing lesion effective 20 mg prednisolone. Macrophages present in the lesion especially Nitric oxide is generated by the oxidation of generate substantial amounts of the reactive L-arginine into L-citrulline by the action of an oxygen species order prednisolone on line amex. So buy prednisolone 5 mg with visa, endothelium because it directly regulates vas- within the vicinity of the lesion there are high cular tone by increasing vasodilatation (wid- levels of mediators of both inflammatory and ening of arteries) generic 5 mg prednisolone overnight delivery, inhibits platelet aggregation oxidative stress responses. This damaging (reducing blood clot formation), reduces leuco- milieu actually switches off protective antioxi- cyte migration into the intima, and decreases dant defences, such as the expression and activ- the contractile to synthetic phenotypic change ity of the enzymes, superoxide dismutase and of smooth muscle cells. Inflammation and Biomarkers more than just a biomarker, with proposed of Atherosclerosis roles in the development and progression of atherosclerosis. McGrath Exercise, Inflammation cardiovascular morbidity and mortality and Atherosclerosis (Hambrecht et al. Atherosclerotic coronary arteries exhibit a reduced ability to Lifestyle modifications including diet, exer- dilate in response to increased blood flow, cise and weight control are recommended for which can cause a critical ischaemia even with the treatment of atherosclerosis. To test for endothelial and low blood cholesterol as the primary goal function, the usual test is to measure vasocon- (Williams et al. The recommendation striction in response to acetylcholine, with more was walking briskly for 30 mins for 5 days, or constriction indicating worse endothelial func- a combination of jogging/vigorous physical tion. It was also disease patients, intensive exercise training recommended that every adult should per- for 4 weeks decreased coronary artery vaso- form activities that maintain or increase mus- constriction, in response to acetylcholine, by cular strength and endurance for a minimum 54% (Hambrecht et al. Mechanistically, 4 weeks of regu- proportional improvement in cholesterol levels lar exercise training in coronary artery disease and reduction in risk for atherosclerosis. The beneficial effects of exercise on cardiovascular risk may be due to weight loss, improved body Exercise and biomarkers fat distribution, increased insulin sensitivity, of inflammation improved lipid profile and lowering of blood pressure (Mora et al. Firstly, 6 months of exercise to aerobic exercise may also be related to training decreased systemic cytokine levels improved nitric oxide generation. Many epidemiologi- In another study, rats that were exercised by cal studies have reported strong associations swimming 1 h/day, 5 days/week for 5 weeks between saturated fat and trans fatty acid showed after acute ischaemia was induced by intake, plasma cholesterol levels and death ligation of the left coronary artery that the size rates from atherosclerosis-related disease. It of the myocardial infarction was decreased by therefore follows that nutrition is one of the 30% (McElroy et al. This was associated modifiable risk factors for atherosclerosis with an exercise-induced increase in capil- (Chiuve et al. Approximately 5000 years style inclusive of regular physical activity ago, however, it was discovered that salt could and a diet rich in vegetables and fruits, whole be used to preserve food and now our diet grain high-fibre foods, fish at least twice a contains a large amount of highly salted proc- week, low saturated fat (<7% of energy), low essed foods. This high salt intake represents a trans fat (<1% of energy), fat-free or low-fat major challenge to our kidneys that must fil- dairy products, minimal hydrogenated fats ter and excrete these large salt concentrations. Although the general popula- sure with age (Intersalt Cooperative Research tion is becoming increasingly aware of these Group, 1988; He et al. There are many different diets and panzees showed that increasing salt consump- supplements available and treating physicians tion from 0. Advice given not have a high salt intake have a lower adult about nutrition therefore remains quite varied blood pressure. For example, in an isolated with regards to timing, frequency, amount of tribe, the Yanomamo Indians, their blood certain food components and calorie intake. Intervention studies to reduce salt intake Salt consistently show an improvement in blood pressure. It is currently recommended that There is substantial evidence for a causal rela- salt intake is 5–6 g/day but a further reduc- tionship between salt intake and blood pres- tion to 3–4 g/day has a much greater effect sure. On high salt intake is directly related to left ven- the basis of the fall in blood pressure from a tricular hypertrophy, an effect independent of meta-analysis study of randomized salt reduc- blood pressure. Both raised blood pressure and tion trials, it was suggested that reducing salt left ventricular hypertrophy are risk factors for intake by 6 g/day (in a population where cur- heart failure (He et al. There have now rent salt intake is 9–12 g/day) would lead to been several studies that have shown that a reduction in the incidence of stroke by 24% a reduction in salt intake is one of the most and heart attack by 18%, which would pre- cost-effective interventions to reduce cardio- vent ~2. One of the major bioactive com- under consideration as important in the pre- ponents is hydroxytyrosol, which is a major vention of cardiovascular disease. This component has been shown to inhibit lipid peroxidation, enhance cholesterol efflux and inhibit platelet aggrega- Saturated fatty acids tion (Covas et al. In a Similar to olive oil, the major mechanism of major study, the Seven Countries Study, where protection is through improving the lipo- 11,579 men, aged 40–49 years, were followed protein profile (Mukuddem-Petersen et al. Because it was documented that men in Japan had of their increasingly recognized cardiovas- very low saturated fat intake compared with cular benefits, nutritional guidelines often Japanese immigrants in California. Associated now include nut consumption (Johnson and with this, coronary heart disease, body weight Kennedy, 2000; Krauss et al. Clinical data also support that omega-3 been shown to improve the major risk factors fatty acids protect against coronary heart dis- for coronary heart disease, including lipo- ease. Olive oil has also been shown to exert to two servings of fish per week, or equivalent anti-inflammatory and antioxidant properties in omega-3 supplement if fish intolerant, or no (Perez-Jimenez et al. Finally, it has been shown that Lipid Prevention Study showed that in 18,645 omega-3 fatty acids can inhibit the secretion of patients with hypercholesteremia, treated with metalloproteinases from macrophages, thus statins alone or statins and a high-dose highly increasing plaque stability (Thies et al. Overall, the evidence is very strong that omega-3 are cardioprotective, with Fruits and vegetables greater than 25 published trials showing that intake of fish oil is associated with decreased ‘They should build houses, and inhabit them; risk of cardiovascular events. It is without known coronary heart disease eat fish now estimated that an inadequate consump- at least twice a week. For those patients with tion of fruit and vegetables accounts for up to coronary heart disease, it is recommended 2. Following on, projections suggest that Supplementation itself poses issues because increasing consumption of fruit and vegeta- the source of supplements is very important, bles by 600 g per day could decrease the global on the basis of concerns about the method of burden of coronary heart disease and stroke by processing and potential contamination by 31% and 19%, respectively (Lock et al. Pharmaceutical Meta-analysis showed that risk decreased grade products that have undergone rigor- by 4% for every portion of fruit or vegetable ous quality control testing are recommended intake (Dauchet et al. At the cellular studies have confirmed the benefits of fruit level, omega-3 fatty acids decrease smooth and vegetable intake (Dauchet et al. Omega-3 fatty acids there are very few randomized control trials have been shown to reduce the expression of to show the protective role in coronary heart endothelial cell adhesion molecules (Collie disease, and to determine the mechanisms by et al. Cardiovascular Disease and Inflammation 253 Vegetables and fruits, as well as cocoa, tea (ii) weekly consumption of potatoes (4–5 and wine, all contain polyphenols that are sug- servings), fish (4–5 servings), olives, pulses gested to be cardioprotective (Kuhnau, 1976; and nuts (more than 4 servings) and eggs and Hertog et al. A Finland study showed sweets (1–3 servings); (iii) monthly consump- that very low intake of these polyphenols tion of red meat and meat products (4–5 serv- was associated with increased mortality from ings) (Dontas et al. Dietary patterns and atherosclerosis Summary and Conclusions A meal consists of a variety of foods with complex combinations of nutrients that could There is no question that endothelial dys- well have synergistic or interactive effects. Exercise individual components is the Mediterranean training represents a non-pharmacological diet. This diet includes: (i) daily consump- treatment that reduces inflammation, tion of unrefined cereals and cereal products, improves endothelial function and impor- vegetables (2–3 servings), fruit (4–6 serv- tantly decreases atherosclerosis and protects ings), olive oil, dairy products (1–2 servings) against myocardial ischemia. Atherosclerosis is an inflammatory disease and a number of biomarkers have been identified that can predict atherosclerosis. Exercise studies completed in cycling, running and swimming show a decrease in inflammatory markers and exercise has been shown to reduce the extent of atherosclerosis. McGrath generation, which represents a major cardio- regime, good nutrition practices are cru- protective mechanism because it decreases cial. There is now strong evidence that some cytokine production and increases antioxi- foods or food components can decrease dant defences. It is highly likely that other cardiovascular risk, and/or improve coro- mechanisms await discovery. A healthful lifestyle inclusive cardiac patients such that exercise affords of exercise and nutrition plans should there- protection if there is a cardiovascular event. Intersalt Cooperative Research Group (1988) Intersalt: an international study of electrolyte excretion and blood pressure. American Journal of Physiology Regulatory Integrative and Comparative Physiology 291, R1756–R1763. Day School of Biomedical Sciences & Pharmacy, Priority Research Centre for Brain & Mental Health Research, University of Newcastle and Hunter Institute of Medical Research, Newcastle, Australia Introduction 260 Stress: A Biological Mechanism to Meet Uncontrollable Unpredictable Threats 261 Why is stress clinically relevant? Indeed, these alterations aim of the current chapter is to introduce are so similar to those observed in patients the reader to recent findings demonstrat- with depression that it has been proposed ing the ability of stress to promote inflam- that inflammation might in fact represent mation within the central nervous system a significant causal factor in this type of and to critically evaluate the evidence link- psychopathology. Given that nutraceuticals ing these changes to alterations in mental and dietary supplements, such as long- health. Wood) Stress and Inflammation: An Emerging Story 261 Stress: A Biological Mechanism Why is stress clinically relevant? Problems can arise, while others are life threatening (predatory however, when the stress response is repeat- attack).
Therefore discount prednisolone 40mg visa, people need to learn the facts in order to better understand how Lyme disease can be prevented and cured order prednisolone overnight delivery. As with any vector-borne disease buy cheap prednisolone, a public education program is an extremely important means of minimizing the fear buy generic prednisolone, risk and spread of Lyme disease. Disease Name 12 Despite the name, this disease occurs most often in the eastern two-thirds of North America. This wide-ranging disease has several names, including tick fever, tick-borne typhus fever, black fever, black measles, New World spotted fever and Mexican spotted fever. Ticks are the natural hosts, serving as both reservoirs and vectors of the rickettsial organism. Causative Agent Rickettsia rickettsii usually infects members of the tick family Ixodidae (hard ticks). Rickettsiae are transmitted to a vertebrate host through saliva while a tick is feeding. It usually takes about six hours of attachment and feeding before the rickettsiae are transmitted to the host. In general, about 1-3 percent of the tick population carries Rickettsia rickettsii, even in areas where the majority of human cases are reported. Ticks can also become infected with Rickettsia rickettsii while feeding on blood from the host in either the larval, nymphal or adult stage. After an immature tick develops into the next stage, Rickettsia rickettsii may be transmitted to a second host during the feeding process. Furthermore, male ticks may transfer Rickettsia rickettsii to female ticks through body fluids or spermatozoa during the mating process. A female tick can also transmit Rickettsia rickettsii to her eggs in a process called transovarial transmission. Biting Arthropod Vector Ticks transmit the organism to vertebrates primarily by their bite. Less commonly, infections may occur following exposure to crushed tick tissues, fluids or tick feces. Vector Control Ticks on private property, especially backyards, can be controlled with acaricides-insecticides, such as permethrin. Tick-borne relapsing fever is caused by many species of Borrelia and is transmitted to humans by the soft Ornithodoros ticks. It is referred to as ―endemic tick-borne relapsing fever‖ to distinguish it from ―epidemic louse-borne relapsing fever‖, which is caused by Borrelia recurrentis and is transmitted to humans by the body louse Pediculus corporis. Causative Agent Tick-borne relapsing fever is caused by a spirochete, Borrelia hermsii. Over the years, there have been approximately 40 documented cases; however, because of the possibility of misdiagnoses, this figure may under-represent the true number of cases. Biting Arthropod Vector The tick Ornithodoros hermsi is the known vector of Borrelia hermsii in eastern Washington and northern Idaho. Most human cases of tick-borne relapsing fever have been associated with log cabins or houses containing rodent nests (particularly of chipmunks and pine squirrels) and Ornithodoros hermsi ticks. Because it feeds rapidly and its bite is relatively painless, it may go unnoticed. Promptly remove nests and treat the cabins with insecticides to kill any remaining ticks. The International Committee on Taxonomy of Viruses has reclassified the agent of Colorado tick fever as a Coltivirus (still in the family of Reoviridae). The 1999 New York epidemic demonstrated that, without sustained vector mosquito control in urban areas, even the world’s most affluent cities are at risk for epidemic arboviral disease. The goal of these disease management programs should be to implement mosquito control early enough to prevent or decrease the risk of human infection with a mosquito-borne virus. Ideally, mosquito vector management programs, sometimes called public health mosquito control programs, should be based on already existing nuisance mosquito management programs. With experienced and knowledgeable staff and readily available equipment and materials, a nuisance control program can easily be enlarged to include disease vector mosquito species. The objective of nuisance mosquito control programs is to reduce mosquito annoyance to an acceptable level. The objective of public health mosquito control, on the other hand, is to prevent transmission of mosquito-borne diseases to humans. Populations of nuisance mosquitoes may also be reduced but that is not the primary objective. Unfortunately, in many areas, there is insufficient local demand for ongoing nuisance mosquito management programs because there is no serious nuisance mosquito problem, the local population is too small, or the per capita costs are too high. Vector mosquitoes must then be controlled using licensed mosquito control contractors. Mosquitoes have four distinct stages during their life cycle: egg, larva, pupa and adult. The length of time that a mosquito takes to complete its life cycle varies according to food availability, weather conditions and the species of mosquito involved. Under favourable conditions, some mosquitoes can complete their entire life cycle in only 8-10 days. A variety of methods, materials and equipment is used in monitoring and management. Information on mosquito control programs can also be obtained from the American Mosquito Control Association website at http://www. Trained personnel conduct mosquito surveys to identify the species that are present, track the population levels during the spring and summer, and determine appropriate management alternatives. The first step in surveillance is to do sampling to identify and map where these mosquitoes are found. Sample forms for recording information about individual breeding sites are provided in an xviii Ontario Ministry of the Environment document and in the Municipal Mosquito Control 19 Guidelines. Notes describing natural features, human influences and adjacent fisheries should be recorded. Areas that do not have significant populations of vector mosquito species need not be targeted for control (in a nuisance mosquito control program, all sites with significant numbers of larvae would be targeted). Whereas most species of mosquito are a nuisance to people, very few are actually considered a health risk: Culex tarsalis and Culex pipiens for West Nile Virus and St. Louis encephalitis, Culex tarsalis and O dorsalis for Western equine encephalitis, and A freeborni, A earlei and A puntipennis for malaria. Once the mapping of mosquitoes within a jurisdiction is complete, the mosquito management officials should undertake a risk assessment of the different sites and develop prescriptions for action should a public health risk be identified. Protocols that should be followed and forms 19 that can be used are provided in the Municipal Mosquito Control Guidelines. Vector species surveillance may involve the collection of live female mosquitoes for virus isolation. Virus surveillance involves three main components: Health care providers should be advised to watch for symptoms of infection and order 77 diagnostic tests on probable human cases. In half of those cases, dead bird hot spots were identified a full month before the first human infections (R. Carney, Coordinator, California West Nile Virus Dead Bird Surveillance Program, personal communication, February 2006). They can be used to determine the onset of, and increase in, virus in the bird population. Using epidemiological techniques to monitor equine and avian cases is very important to determine early trends and to allow reasonable response times for vector management activities. Reporting networks for bird and mammal cases involve veterinarians, laboratories, wildlife agencies, agriculture agencies and organizations, and the general public. These reporting systems require proactive and ongoing effort to implement and maintain. Provincial health agencies must collaborate with these partners to establish, maintain and analyze these databases. Any alterations of natural water bodies requires prior consultations with environment and fisheries officials.
The intensity of S1 is diminished by the onset of the heart murmur; S2 is normal in small ventricular septal defects prednisolone 5 mg free shipping, but it increases in intensity in mod- erate ventricular septal defect; S2 is loud and single in patients with pulmonary hypertension purchase prednisolone 20 mg online. Frequently cheap 20mg prednisolone overnight delivery, secondary to the holosystolic murmur buy prednisolone without a prescription, S1 and S2 are masked by the murmur spanning the entire duration of systole. Ventricular septal defect murmurs may be 2–5/6 in intensity and harsh in quality, it is best heard over the left lower sternal border. A mid-diastolic rumble at the apical region is often heard in large ventricular septal defects due to the increased flow across the mitral valve. The degree of cardiomegaly and increased vascular markings is proportional to the amount of left to right shunting. In pulmo- nary vascular obstructive disease, the cardiac size is normal with no evidence of increase in pulmonary vascular markings, but the pulmonary artery segment at the mid left border of the cardiac silhouette may be more prominent. Left atrial dilatation and left ventricular hypertrophy may be seen in moderate ventricular septal defect. Most chest leads, particularly the right chest leads in this tracing show increase in anterior (tall R waves) and posterior (deep S waves) forces indicating right and left ventricular hypertrophy. Echocardiography can measure the right ventricular and pulmonary pressures by assessing the pressure gradient across the defect as well as assess the degree of shunting. Echocardiography can also identify associated lesions such as aortic valve prolapse and regurgitation, coarctation of the aorta, or double-chambered right ventricle. Cardiac Catheterization Cardiac catheterization is typically not required for diagnosis since echocardiography can provide all details required to plan management. Cardiac catheterization is indicated in older children with pulmonary hypertension to assess the pulmonary vascular resistance prior to surgical repair. Therapeutic interventional cardiac catheterization has been increasing in recent years. Device closure of muscular ventricular septal defect is now performed in many centers due to the difficulty accessing these defects surgically and the ability to close such defects effectively without the need for surgery. Device closure of the membranous ventricular septal defect is still under investigation, but soon will become more widely used. Small ventricular septal defects can be managed conservatively in patients with no history of congestive heart failure or pulmonary hypertension. Surgical closure is indicated in symptomatic infants including congestive heart failure, failure to thrive or recurrent respiratory infections and those who fail medical management. Surgery is also indicated in children with significant left to right shunting and ven- tricular dilatation prior to 2 years of age. Infants with large ventricular septal defect and pulmonary hypertension should have surgical repair between 3 and 12 months of age. Mortality is higher in the presence of multiple ventricular septal defects, other associated defects, and in young infants less than 2 months of age. Surgical complications may include: residual ventricular septal defect, right bundle branch block or complete heart block, or injuries to the tricuspid or aortic valve. If the repair was performed through the ventricle (ven- triculotomy), this will cause a ventricular scar that might affect its function and may also cause ventricular arrhythmias. Indications for closure of ventricular septal defects of the muscular type using interventional cardiac catheterization approach are similar to that of surgical approach. Maintaining a good dental hygiene is important, but endocarditis prophylaxis is not indicated based on the most recent recommendations of the American Heart Association. Case Scenarios Case 1 A 3-month-old male infant presented with a 2-week history of decreased feeding, shortness of breath, cough, and wheezing. The diagnosis of bronchiolitis was made by the primary care physician and he was admitted to the general pediatric floor for further management. On physical examination, the infant was in respiratory dis- tress, his heart rate was 142 bpm, respiratory rate was 66 breaths per minute, blood pressure was 90/50 mmHg, and oxygen saturation was 98% while breathing room air. The precordium was hyperactive, there was 3/6 holosystolic murmur at the left sternal border and no diastolic murmur. The abdomen was soft, the liver was palpable (3 cm below costal margin), the peripheral perfusion was normal, and there was no peripheral edema noted. Khalid and Ra-id Abdulla The respiratory distress in this child is most likely secondary to a congestive heart failure rather than simple bronchiolitis. The presence of an active precordium, heart murmur, and a palpable liver are signs of left to right shunt, pulmonary over- circulation, and volume overload. The murmur and the respiratory distress did not develop earlier in life due the high pulmonary vascular resistance at birth that prevents significant left to right shunting. This usually drops in the first few weeks of life causing an increase in pulmonary circulation and volume overload. This emphasizes the importance of followup in young infants as a normal newborn exam may not exclude the presence of a congenital heart disease. Echocardiography provides an accurate assessment regarding the type and size of the ventricular septal defect. Treatment with anti-congestive heart fail- ure medications is warranted in this patient. This may include diuretics, such as furosemide (Lasix); inotropic agent, such as digoxin; and after load reducing agent, such as captopril. Indication of surgical closure depends on the size of the defect and response to medical therapy. If the infants continue to be symp- tomatic in spite of medical management then surgery is recommended. Interventional cardiac catheter closure of defect is recommended if they are of the muscular type. Chest examination shows minimal retractions, there is normal vesicular breath sounds bilaterally with no wheezing or crackles, cardiac examination revealed an active precordium, and there is normal upper and lower extremity pulses. Cardiac auscultation showed a grade 2/6 holosystolic murmur at the lower left sternal border, the abdomen was soft with no hepatomegaly. Echocardiography revealed a moderate apical muscular ventricular septal defect with left to right shunting; there is mild right ventricular dilatation. Cardiac catheterization was performed and hemodynamic data showed a signifi- cant left to right shunt with a Qp: Qs ratio of 2. The angiogram confirmed the diagnosis of a moderate size apical ventricular septal defect. Ventricular septal defect device closure was performed during the catheterization procedure with no adverse effect and effective elimina- tion of left to right shunting. Defects in the apical region of the ventricular septum are difficult to close surgically due to their loca- tion. Device closure of muscular ventricular defects is now possible using specially made devices. The proximity of the aortic and atrioventricular valves and the con- duction pathways to the membranous, inlet, or outlet ventricular defects, makes it more difficult to close these defects with a device, although experimental attempts are underway to develop such devices and methodologies, particularly those for perimembrenous ventricular septal defects. On the other hand, muscular defects are remotely situated from any vital structures and thus more amenable to device closure. They present with increased work of breathing or an increasing need for mechanical ventilatory support. The murmur in these premature infants tends to be systolic rather than continuous. Pharmacological agents such as indomethacin and ibuprofen are the first line of management in this age group. In the rare instances where this is not pos- sible, surgical ligation is performed. Definition The ductus arteriosus is a vascular structure connecting the left main pulmonary artery to the upper part of the descending aorta just distal to the left subclavian artery. The ductus arteriosus is an important structure in fetal circulation, allowing the right ventricle to pump blood directly to the descending aorta thus bypassing the pulmonary circulation. In normal newborns, the ductus is mostly closed by the second or third day of life and is fully sealed by 2–3 weeks of life. Khalid (*) Children’s Heart Institute, Mary Washington Hospital, 1101 Sam Perry Blvd. The frequency is much higher in premature infants and infants with congenital rubella syndrome and Trisomy 21. Pathology The ductus arteriosus remains patent in utero due to low oxygen tension in the blood and a high level of circulating prostaglandins.
This requires eliminating mosquito breeding and rest- ing sites in an endemic area or protecting animals from mos- quito contact by maintaining them in an insect-proof enclo- sure order 40mg prednisolone otc. A killed-virus vaccine was used in cap- tive whooping cranes to protect the rest of the breeding flock following the 1984 outbreak buy genuine prednisolone line. Field data suggest that immunity in those cranes is being boosted by natural infec- tions after their release discount prednisolone 5mg with visa. Human pre-exposure vaccination is recom- mended for people who may handle infected tissues order prednisolone 40mg amex. These strains are classified as mesogenic or moderately concern throughout much of the world’s agricultural com- virulent. Lentogenic strains do not usually cause disease in infection with pathogenic or disease causing strains. Prior to adult chickens, but these forms can cause serious respiratory 1990, this disease had rarely been reported as a cause of disease in young birds. In addition to poultry, more than 230 species from more virus within the avian paramyxovirus-1 group. Captive- tion of chickens of all ages with mortality in affected flocks reared gamebirds, such as pheasants and Hungarian partridge, often reaching 100 percent. Mostly sub- piratory and neurologic tissues and is referred to as neuro- adult cormorants died in these cormorant colonies. In 1997, nesting failure of a cormorant colony at the pet birds and by other means. During the most countries by 1973, and it was associated with the im- 1992 epizootic, a domestic turkey flock in the Midwestern portation and movement of caged psittacine species. This panzootic differs in that pigeons and doves kept by bird fanciers and raised for Distribution food are the primary species involved. The first of these highly in double-crested cormorants are the beginning of a fourth pathogenic strains appears to have arisen in Southeast Asia; panzootic. Most cormorant mortality has occurred in the Upper sible for the second panzootic involving poultry appears to Midwest and the Canadian prairie provinces, although smaller have arisen in the Middle East in the late 1960s; it reached outbreaks have occurred at Great Salt Lake, in southern Cali- Table 21. Mortality generally only in young birds, but for very young chicks the death rate is low. Disease seldom seen in adults, but serious illness (generally nonlethal) can occur in young chickens. Asymptomatic lentogenic Infects the intestine but causes no forms of visible disease in chickens of any age. As the disease progressed, they were unable to have occurred in breeding colonies. Mortality has occurred rise when approached and they laid on their sides and exhib- during the months of March through September. By day Clinical signs, observed only in sick juvenile double- 4, torticollis and wing droop began to appear, followed by crested cormorants, include torticollis or twisting of the head paralysis of one or both legs. Muscular tremors and neck, ataxia or lack of muscular coordination, tremors, also became increasingly noticeable at this time. Gross Lesions Dead cormorants examined at necropsy have had only nonspecific lesions. Mildly enlarged livers and spleens and mottled spleens have been noted, but these may be the result of other concurrent diseases, such as salmonellosis. Whole carcasses should be submitted, and the samples should be representa- tive of all species and age-classes affected. Clinically ill birds should be collected, euthanized by acceptable methods (see Chapter 5, Euthanasia), and, if possible, a blood sample should be collected from euthanized birds and the sera sub- mitted with the specimens. Contact with the diagnostic labo- ratory is recommended to obtain specific instructions on specimen collection, handling, and shipment. A good field history describing field observations is of great value (see Chapter 1) and should be included with the submission. Humans and their equipment have had the greatest role because contami- nated surfaces provide mechanical transportation for the vi- A rus to new locations and to susceptible bird populations. Most reported cases in hu- mans have occurred among poultry slaughterhouse workers, laboratory personnel, and vaccinators applying live virus vaccines. Aerosols, rather than direct contact, are most often involved as the route for transmission to humans. Newcastle Disease 179 180 Field Manual of Wildlife Diseases: Birds Chapter 22 Avian Influenza Synonyms Fowl pest, fowl plague, avian influenza A. Frequent Common Wild birds, especially waterfowl and shorebirds, have long Occasional been a focus for concern by the poultry industry as a source Rare or unknown for influenza infections in poultry. For these reasons, this chapter has Waterfowl been included to provide natural resource managers with basic information about avian influenza viruses. Cause Shorebirds Avian influenza is usually an inapparent or nonclinical viral infection of wild birds that is caused by a group of viruses known as type A influenzas. These viruses are main- tained in wild birds by fecal-oral routes of transmission. This virus changes rapidly in nature by mixing of its genetic com- Gulls and terns ponents to form slightly different virus subtypes. Avian in- fluenza is caused by this collection of slightly different viruses rather than by a single virus type. The virus subtypes are identified and classified on the basis of two broad types of antigens, hemagglutinan (H) and neuraminidase (N); 15 H Marine birds and 9 N antigens have been identified among all of the known type A influenzas. Different combinations of the two antigens appear more frequently in some groups of birds than others. In waterfowl, Upland gamebirds for example, all 9 of the neuraminidase subtypes and 14 of the 15 hemagglutinin subtypes have been found, and H6 and H3 are the predominant subtypes. In shorebirds and gulls, 10 different hemagglutinin subtypes and 8 neuraminidase subtypes have been found. Many of the antigenic combina- Ratites tions of subtypes are unique to shorebirds. Hemagglutinin sub- types H5 and H7 are associated with virulence or the ability Cranes to cause severe illness and mortality in chickens and turkeys. However, two viruses with the same subtype antigens can vary in virulence for domestic birds. Species Affected Songbirds Avian influenza viruses have been found in many bird species, but are most often found in migratory waterfowl, especially the mallard duck. However, the only mortality event known in wild birds killed common terns in Raptors South Africa in 1961. This was the first influenza virus from marine birds and it was classified as subtype H5N3. Other wild birds yielding influenza viruses include various species of shorebirds, gulls, quail, pheasants, and ratites (ostrich and Figure 22. Experimental infections of domestic birds with viruses enza virus in various bird groups. Species shown are typical of these flyways (Modified from Hawkins and others, 1984). Likewise, virulent are usually highly virulent and may cause up to 100 percent viruses or viruses that cause disease in domestic fowl do not mortality in infected flocks. Too little is known about the impact of influenza viruses on Distribution the reproductive performance of wild birds to assess whether Although influenza tends to be most commonly detected or not they are affected in the same manner as poultry. Gross Lesions The majority of North American waterfowl migration takes Avian influenza virus infection in wild birds is not indi- place within four broad geographic areas (Fig 22. Common terns that died in South species other than waterfowl follow these same migratory Africa did not have gross lesions, but a few birds had micro- pathways from their breeding grounds to the wintering scopic evidence of meningoencephalitis or inflammation of grounds and return to the breeding grounds. These lesions were not type that are found in birds in adjacent flyways will differ, reproducible during experiments. Mallards experimentally especially if the birds from each flyway do not mix during infected with a virulent influenza virus developed discrete migration. In any given year the percentage of waterfowl and purple areas of lung firmness and cloudy lung coverings. However, virulent viruses are rarely found in wild birds, and Likewise, the percentage of birds carrying virus in an fly- these lesions may not appear in natural infections. The virus subtype found in birds that use a flyway are rarely the same in consecutive years. Frequent Seasonality Common Influenza virus has been found in wild birds throughout Occasional the year, but waterfowl are the only group in which these Rare or unknown viruses are found year round. The number of infected waterfowl decreases in the Spring fall as birds migrate toward their southern wintering grounds Summer and is lowest in the spring, when only one bird in 400 is Fall infected during the return migration to the north.