By K. Ramon. University of Sioux Falls.
Vaccine protection Not all vaccines protect animals from infection 80 mg propranolol amex, although the prevention of disease progression may be sufficient to reduce transmission and hence aid in controlling disease spread 40 mg propranolol overnight delivery. The pathogen will continue to circulate amongst unvaccinated individuals, but the purpose of a vaccination programme is to deliver the vaccine to a sufficient proportion of the population to enable an overall reduction in levels of transmission. Consequently an effective vaccination campaign will confer benefits even to the unvaccinated proportion of the population (often referred to as ‘herd immunity’). The effectiveness of a vaccine in a given population is a function of the efficacy of the vaccine (i. The level of vaccination coverage required to achieve disease control benefits will vary between host and pathogen populations. Sustained effort will be required in order to maintain the benefits of vaccination in the face of sources of re-infection (e. Ongoing surveillance is, therefore, an important tool for monitoring the progress of vaccination programmes. Not all vaccines deliver life-long immunity and in some cases periodic re- administration may be required to deliver disease control benefits. Vaccination and disease surveillance Vaccination programmes may interfere with disease surveillance. For example, clinical surveillance may be more difficult in populations with a mixture of vaccinated and unvaccinated animals, as the disease may be unevenly distributed. Many serological tests cannot distinguish between antibodies that have been derived from vaccination or from natural infection, although some differential diagnostic tests do exist or may be developed. Interpretation of serology results can be greatly assisted by marking vaccinated animals, so that it is at least known whether samples have been taken from vaccinated or non-vaccinated animals. This may also be important to avoid the adverse welfare and financial implications of over-dosing individuals. Vaccination storage and application Vaccines should be stored at the correct refrigeration temperatures at all times and must be used before expiry dates. Selecting a vaccination programme When selecting a vaccination programme, the following should be considered: The programme should have a clear purpose and objective Once the target animal population and area have been defined, vaccination should be carried out as comprehensively as possible Separate vaccination personnel should be used for herds and flocks thought to have infection to minimise the spread of the disease between them Individual herds and flocks should be gathered separately to minimise the spread of disease Vaccinated animals should be permanently marked for future identification Vaccination programmes should be accompanied by other measures such as disease surveillance, livestock movement controls and quarantine (where possible and appropriate) Vaccination programmes should be accompanied by public awareness campaigns Examples of vaccination programmes: 1. Blanket vaccination is the comprehensive vaccination of ‘all’ susceptible animals over a large area. This may be favoured when the disease has become well established, when there are many sources of infection, or when other disease control measures are impractical and/or ineffective. Areas with known and suspected infection and areas thought to be at high risk of disease should be covered. Ring vaccination is the rapid creation of a belt of vaccinated animals around an infected area. This can be implemented to contain a fast spreading disease outbreak, in situations where the effectiveness of other methods is unlikely to succeed, or in areas which are too inaccessible for blanket vaccination or other disease control measures. Epidemiological factors and resource availability should be assessed to determine the width of the vaccination zone. Specific considerations for vaccination of wildlife Vaccination of domestic livestock has been widely used and may often present a practical disease control option where an effective vaccine exists. Vaccination of wildlife is more challenging owing to many technological and logistical barriers including difficulties in delivering it to a sufficiently large proportion of the target population. Also, only few vaccines have been tested sufficiently to demonstrate their safety and efficacy and achieve a licence for their use in wild hosts. Even domestic animal vaccines against the same pathogen, may need to undergo significant testing to determine their safety and efficacy in wild hosts. The aim of any wildlife vaccination programme needs to be clear from the outset, for example, does the vaccination programme aim to reduce mortality, reduce suffering, reduce the risk of spread to livestock or humans, or to ensure the viability of the population? There may be risks associated with the vaccine itself, either in target or non-target populations. Live vaccines have the greatest potential for problems following release into the environment. Also, the ecological consequences of vaccination should be considered, including the possibility of altering demographic processes (e. Delivery of the vaccine to the target population may be logistically difficult or prohibitively expensive.
The adage of ‘prevention is better than cure’ is fundamental to disease management generic 80mg propranolol otc. Costs of disease management must be weighed against the benefits of preventing problems proven propranolol 80 mg, in particular long term issues negatively impacting livelihoods, public health, domestic animal production and biodiversity. The spectrum of disease management practices is broad and may entail nothing more than routine wetland management practices through to major interventions for large scale disease control operations, depending on the issue, its scale and potential impact. Disease management practices may be focused on the environment, the hosts present in the wetland and its catchment, or, in the case of infectious disease, the parasite or pathogen, or any combination thereof. The outcome of disease is dependent on the relationship between a host and its environment, and in the case of infectious disease, the pathogen also. The figure shows some of the factors (outside the circles) which influence this relationship and thus some of the factors that can be targeted for disease control. Rinderpest – eradication of a disease affecting all sectors Rinderpest, once described as “the most dreaded bovine plague known”, became the first disease of animals to be eradicated by human intervention. This acute viral disease has been responsible for the death of domestic cattle for millennia, adversely affecting livestock, wildlife and agricultural livelihoods, bringing starvation and famine. In its classical, virulent form, rinderpest infection can result in 80-95% mortality in domestic cattle, yaks, buffalo and many other wild ungulate species. The disease has had far reaching conservation impacts affecting the abundance, distribution and community structure of many species as well as becoming a source of conflict between agricultural and wildlife interests. Clinical signs include: fever, depression, loss of appetite, discharges from the eyes and nose, erosions throughout the digestive tract, diarrhoea and death. Weight loss and dehydration, caused by enteric lesions, can cause death within 10-12 days. Key Actions Taken to eradicate rinderpest included the development of vaccines, disease surveillance, diagnostic tools and community-based health delivery. Initially, mass livestock vaccination programmes were implemented followed by improved disease surveillance and focussed vaccination campaigns (containing any remaining reservoirs of disease). Disease surveillance and accreditation continued until 2011, when on June 28th the world was declared free from rinderpest. Outcomes: The benefits derived from the eradication of rinderpest are numerous and include: protected rural livelihoods, increased confidence in livestock-based agriculture, an opening of trade in livestock and their products and increased food security. Veterinary services worldwide have become more proficient as a consequence of the fight against rinderpest and the conservation of numerous African ungulates has also benefited. The socio-economic benefits of rinderpest eradication are said to surpass those of virtually every other agricultural development programme and will continue to do so. Rinderpest was successfully eradicated due to ongoing, concerted, international efforts that built on existing disease control programmes in affected countries. Only through international coordination can other such transboundary diseases be controlled and eliminated, as isolated national efforts often prove unsustainable. It is important to note that different stakeholders will likely have different ideas about when interventions are required and ideally these can be addressed within management and contingency plans in ‘peacetime’ i. It is important to understand that disease management may be thwarted by poor understanding of disease ecology and dynamics, and thus the appropriate management practices to mitigate. Inappropriate disease management practices can even result in counter-productive consequences and novel disease problems. Hence, a good evidence base is important, appreciating that this may be difficult to attain due to complexities or limitations of diagnosis, surveillance, and other knowledge gaps. As human development and livestock have encroached into wild habitats, not surprisingly infectious diseases have spread between these populations, negatively affecting all three sectors. Movements of people and extensive trade in wild and domestic animals have resulted in the global spread of a number of pathogens, causing particular problems where infectious agents are novel and new hosts are immunologically naïve. The complexities of disease dynamics in wildlife have resulted in unpredicted disease emergence. Diseases of wildlife that affect humans or their livestock have sometimes led to eradication programmes targeted at wildlife which have not necessarily resulted in reduced disease prevalence but, instead, serious long term consequences for biodiversity, public health and well- being, and food security, whilst failing to address causal problems. It has become common understanding that the world can no longer deal with diseases of people, domestic livestock and wildlife in isolation and, instead, an integrated ‘One World One Health’ approach to health has developed. Delivering integrated approaches and responses across the medical, veterinary, agricultural and wildlife sectors can be problematic given existing organisational roles and structures but demonstrating the benefits this can bring should help promote this progressive way of working. The recent global eradication of rinderpest provides an example of how one disease with impacts across all sectors requires global coordinated efforts to bring about success and benefits for all.
Investigations The normal squamous epithelium of the oesophagus These are rarely necessary to make the diagnosis buy 80 mg propranolol visa, al- issensitivetotheeffectsofacidandthusacuteinﬂamma- though imaging such as ultrasound is sometimes used quality 80mg propranolol. Contin- uing inﬂammation may manifest as ulceration, scaring, Management ﬁbrosis and stricture formation. Surgical treatment is usually advised electively to reduce Continuing inﬂammation may result in glandular ep- the risk of complications. However, longstanding, large ithelial metaplasia (a change from the normal squamous herniaswhicharerelativelyasymptomaticmaybetreated epitheliumtoglandularepithelium)termedBarrett’soe- conservatively, as they have a low risk of incarceration sophagus, which predisposes to neoplasia. Direct hernias are reduced and the defect Clinical features closed by suture or synthetic mesh. Indirect hernias are Patients complain of symptoms of dyspepsia (see ear- repaired by surgical removal of the herniation sac from lier in this chapter) particularly heartburn, a retroster- the spermatic cord. If the internal ring is enlarged it is nal burning pain aggravated by bending or lying down. For other hernias, the principle is to Effortless regurgitation of food and acid (waterbrash) excise the sac and obliterate the opening either by sutur- into the mouth may occur. Gastrooesophageal reﬂux disease Management Deﬁnition Patients are managed as for dyspepsia, i. Chapter 4: Disorders of the oesophagus 157 Older patients and those with suspicious features should diameter of 10–15 mm. It may be axial/sliding, r Patients should be advised to lose weight if obese, and paraesophageal/rolling or mixed. Prevalence r The most effective relief is provided by proton pump Increases with age, very common in elderly patients (up inhibitors; however, many patients have adequate to 70%). This can eventually shorten the oesoph- terprevious upper gastrointestinal tract surgery. Symptoms may result from pressure on the heart latation to stretch the stricture to achieve a luminal orlungs. Oesophagus Gastro-oesophageal Herniated Diaphragm junction stomach Stomach Sliding (axial) hernia 90% Para-Oesophageal (rolling) hernia 10% Disrupts normal anti-reflux mechanisms Anti-reflux mechanisms intact Figure 4. Patients with a slid- Patients may present with a lump in the throat and dys- ing hernia may present with symptoms of dyspepsia due phagiawithregurgitationofundigestedfoodsomehours to gastro-oesophageal reﬂux. Endoscopic techniques may be used in elderly Investigations patients, with a large dependent pouch, who are unﬁt Chest X-ray may reveal a gas bubble above the di- for surgery. Endoscopycanestablishtheextent Plummer–Vinson syndrome and severity of inﬂammation and exclude oesophageal Deﬁnition carcinoma. Plummer–Vinson syndrome or Paterson–Brown–Kelly syndrome is an unusual combination of iron deﬁciency Management anaemia and dysphagia. In fundoplication (open or laparo- the upper oesophagus with the formation of a post- scopic) the gastric fundus is mobilised and wrapped cricoid web. Thereisahighriskofupper patients) to reduce the risk of strangulation and other oesophageal or pharyngeal malignancy. Surgery consists of ex- cisionoftheperitonealsac,reductionoftheherniaand closure of the defect. Webs are dilated endoscopically to relieve obstruction, iron deﬁciency anaemia is treated. Pharyngeal pouch Deﬁnition Achalasia A false diverticulum arising at the junction of the oe- sophagus and the pharynx. Deﬁnition Achalasia is a disordered contraction of the oesophagus Aetiology/pathophysiology of neuromuscular origin. In co-ordinationbetweenthecontractionofthepharynx andrelaxationoftheupperoesophagealsphinctercauses Aetiology the pharyngeal mucosa to herniate posteriorly between Degeneration is seen in the vagus nerve associated with the upper and lower ﬁbres of the inferior constrictor adecrease in ganglionic cells in the Auerbach’s nerve muscle (Killian’s dehiscence). Chagas’ disease in Chapter 4: Disorders of the oesophagus 159 South America is very similar where infection by Try- oesophageal sphincter. Surgical intervention is indicated panosoma cruzi causes destruction of the myenteric in those who fail to respond; a 10–12 cm incision is made plexus. Gastro-oesophageal reﬂux is a The neuromuscular damage causes disordered motility complication with both procedures. On manom- etry there is aperistalsis and incomplete relaxation of Diffuse oesophageal spasm the lower oesophageal sphincter in response to swallow- ing. The gastrooesophageal sphincter classically remains Deﬁnition tightly closed and there is dilation of the oesophagus.
It contains lactate which is converted to bicarbonate for correction of metabolic acidosis when it exists (if haemodynamic and liver function are normal) discount 40 mg propranolol with amex. Remarks – For correction of hypovolaemia due to haemorrhage proven 40 mg propranolol; administer 3 times the lost volume only if: • blood loss does not exceed 1500 ml in adults; • cardiac and renal function are not impaired. However, at least 12 hours before reconstitution of the vaccine, the diluent must be refrigerated between 2°C and 8°C so that the diluent and lyophilised powder are at the same temperature: a temperature difference during reconstitution may reduce vaccine efficacy. It is recommended to administer the 1st dose at 6 weeks of age, the 2nd dose at 10 weeks of age and the 3rd dose at 14 weeks of age. If a child has not been vaccinated at 6 weeks of age, start vaccination as soon as possible. Remarks – If the vaccination is interrupted before the complete series has been administered, it is not necessary to start again from the beginning. Continue the vaccination schedule from where it was interrupted and complete the series as normal. Vaccination should be postponed in the event of severe acute febrile illness (minor infections are not contra-indications). Continue the vaccination schedule from where it was interrupted and complete the series as normal. For information, for travellers: 3 injections on Day 0, Day 7 and Day 28; a booster dose every 3 years if risk persists. An accelerated schedule is possible (3 doses on Day 0, Day 7 and Day 14) but this is likely to result in lower antibody levels than the standard schedule. The 3rd dose should be given at least 10 days before departure to ensure an adequate immune response and access to medical care in the event of adverse reactions. Contra-indications, adverse effects, precautions – Do not administer to patients with history of an allergic reaction to a previous injection of Japanese encephalitis vaccine. However, at least 12 hours before reconstitution of the vaccine, the diluent must be refrigerated between 2°C and 8°C so that the diluent and lyophilised powder are at the same temperature: a temperature difference during reconstitution may reduce vaccine efficacy. Contra-indications, adverse effects, precautions – Do not administer to patients with severe immune depression or history of an allergic reaction to a previous injection of measles vaccine. Remarks 4 – Immunity develops 10 to 14 days after injection, and lasts for at least 10 years (when administered at 9 months). However, at least 12 hours before reconstitution of the vaccine, the diluent must be refrigerated between 2°C and 8°C so that the diluent and lyophilised powder are at the same temperature: a temperature difference during reconstitution may reduce vaccine efficacy. However, at least 12 hours before reconstitution of the vaccine, the diluent must be refrigerated between 2°C and 8°C so that the diluent and lyophilised powder are at the same temperature: a temperature difference during reconstitution may reduce vaccine efficacy. Any vaccine removed from the cold chain and not used within 4 days or exposed to temperatures > 40°C must be discarded. However, at least 12 hours before reconstitution of the vaccine, the diluent must be refrigerated between 2°C and 8°C so that the diluent and lyophilised powder are at the same temperature: a temperature difference during reconstitution may reduce vaccine efficacy. However, at least 12 hours before reconstitution of the vaccine, the diluent must be refrigerated between 2°C and 8°C so that the diluent and lyophilised powder are at the same temperature: a temperature difference during reconstitution may reduce 4 vaccine efficacy. Dosage and vaccination schedule – Child over 1 year and adult: 2 doses administered at least 2 weeks apart – Shake the vial, squirt the suspension into the mouth (1. For young children, the contents of the vial can be drawn up in a syringe and squirted into the mouth. Contra-indications, adverse effects, precautions – Do not administer to children less than one year. If the patient vomits the dose of vaccine, wait for 10 minutes, re-administer the same dose and follow with a larger volume of water. Dosage and vaccination schedule – The 1st dose of vaccine should be administered as soon as possible after exposure, even if the patient seeks medical attention long after exposure (rabies incubation period may last several months). The schedule will depend on the patient’s vaccination status prior to exposure and the route of administration used (follow manufacturer’s instructions). Booster doses are recommended for persons exposed to permanent or frequent contact with the virus. However, at least 12 hours before reconstitution of the vaccine, the diluent must be refrigerated between 2°C and 8°C so that the diluent and lyophilised powder are at the same temperature: a temperature difference during reconstitution may reduce vaccine efficacy. Contra-indications, adverse effects, precautions – No contra-indication (including during pregnancy and breast-feeding).
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