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Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
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Prophylactic vaccination is available against poliomyelitis, measles, Japanese encephalitis, and rabies. Hyper immune immunoglobulin has been used for prophylaxis of measles, herpes zoster virus, HSV-2, vaccine, rabies, and some other infections in high-risk groups.
Development of new therapies has been hindered by the lack of appropriate animal model systems for some important viruses and also because of the difficulty in conducting human clinical trials for diseases that are rare. Nonetheless, numerous innovative approaches to antiviral therapy are available including candidate thiazolide and purazinecarboxamide derivatives with potential broad-spectrum antiviral efficacy. New herpes virus drugs include viral helicase-primase and terminase inhibitors. A promising new area of research involves therapies based on enhanced understanding of host antiviral immune responses.
Modern vaccination programmes aim not only to provide a high level of protection from clinical disease for the dam, but, crucially, to protect against viraemia and prevent the production of PIs. While the immune mechanisms involved are the same, the level of immune protection required for foetal protection is much higher than for prevention of clinical disease.
While challenge studies indicate that killed, as well as live, vaccines prevent foetal infection under experimental conditions, the efficacy of vaccines under field conditions has been questioned. The birth of PI calves into vaccinated herds suggests that killed vaccines do not stand up to the challenge presented by the viral load excreted by a PI in the field.
The mainstay of eradication is the identification and removal of persistently infected animals. Re-infection is then prevented by vaccination and high levels of biosecurity, supported by continuing surveillance. PIs act as viral reservoirs and are the principal source of viral infection but transiently infected animals and contaminated fomites also play a significant role in transmission.
Leading the way in BVD eradication, almost 20 years ago, were the Scandinavian countries. Despite different conditions at the start of the projects in terms of legal support, and regardless of initial prevalence of herds with PI animals, it took all countries approximately 10 years to reach their final stages.
Once proven that BVD eradication could be achieved in a cost efficient way, a number of regional programmes followed in Europe, some of which have developed into national schemes.
Vaccination is an essential part of both control and eradication. While BVD virus is still circulating within the national herd, breeding cattle are at risk of producing PI neonates and the economic consequences of BVD are still relevant. Once eradication has been achieved, unvaccinated animals will represent a naïve and susceptible herd. Infection from imported animals or contaminated fomites brought into the farm, or via transiently infected in-contacts will have devastating consequences.
The best prevention against viral pneumonia is vaccination against influenza, adenovirus, chickenpox, herpes zoster, measles, and rubella.
Viral entry is the earliest stage of infection in the viral life cycle, as the virus comes into contact with the host cell and introduces viral material into the cell. The major steps involved in viral entry are shown below. Despite the variation among viruses, there are several shared generalities concerning viral entry.
Rotavirus is highly contagious and cannot be treated with antibiotics or other drugs. Because improved sanitation does not decrease the prevalence of rotaviral disease, and the rate of hospitalisations remains high despite the use of oral rehydrating medicines, the primary public health intervention is vaccination. In 1998, a rotavirus vaccine was licensed for use in the United States. Clinical trials in the United States, Finland, and Venezuela had found it to be 80 to 100% effective at preventing severe diarrhoea caused by rotavirus A, and researchers had detected no statistically significant serious adverse effects. The manufacturer, however, withdrew it from the market in 1999, after it was discovered that the vaccine may have contributed to an increased risk for intussusception, a type of bowel obstruction, in one of every 12,000 vaccinated infants. The experience provoked intense debate about the relative risks and benefits of a rotavirus vaccine.
In 2006, two new vaccines against infection were shown to be safe and effective in children, and in 2009, the WHO recommended that rotavirus vaccine be included in all national immunisation programmes.
The incidence and severity of rotavirus infections has declined significantly in countries that have acted on this recommendation. A 2014 review of available clinical trial data from countries routinely using rotavirus vaccines in their national immunisation programs found that rotavirus vaccines have reduced rotavirus hospitalisations by 49–92 percent and all cause diarrhoea hospitalisations by 17–55 percent. In Mexico, which in 2006 was among the first countries in the world to introduce rotavirus vaccine, diarrhoeal disease death rates dropped during the 2009 rotavirus season by more than 65 percent among children age two and under. In Nicaragua, which in 2006 became the first developing country to introduce a rotavirus vaccine, severe rotavirus infections were reduced by 40 percent and emergency room visits by a half. In the United States, rotavirus vaccination since 2006 has led to drops in rotavirus-related hospitalisations by as much as 86 percent. The vaccines may also have prevented illness in non-vaccinated children by limiting the number of circulating infections. In developing countries in Africa and Asia, where the majority of rotavirus deaths occur, a large number of safety and efficacy trials as well as recent post-introduction impact and effectiveness studies of Rotarix and RotaTeq have found that vaccines dramatically reduced severe disease among infants. In September 2013, the vaccine was offered to all children in the UK, aged between two and three months, and it is expected to halve the cases of severe infection and reduce the number of children admitted to hospital because of the infection by 70 percent. In Europe, hospitalisation rates following infection by rotavirus have decreased by 65% to 84% following the introduction of the vaccine. Globally, vaccination has reduced hospital admissions and emergency department visits by a median of 67%.
Rotavirus vaccines are licensed in over 100 countries, and more than 80 countries have introduced routine rotavirus vaccination, almost half with the support of Gavi, the Vaccine Alliance. To make rotavirus vaccines available, accessible, and affordable in all countries—particularly low- and middle-income countries in Africa and Asia where the majority of rotavirus deaths occur, PATH (formerly Program for Appropriate Technology in Health), the WHO, the U.S. Centers for Disease Control and Prevention, and Gavi have partnered with research institutions and governments to generate and disseminate evidence, lower prices, and accelerate introduction.
Rotaviruses infect the young of many species of animals and they are a major cause of diarrhoea in wild and reared animals worldwide. As a pathogen of livestock, notably in young calves and piglets, rotaviruses cause economic loss to farmers because of costs of treatment associated with high morbidity and mortality rates. These rotaviruses are a potential reservoir for genetic exchange with human rotaviruses. There is evidence that animal rotaviruses can infect humans, either by direct transmission of the virus or by contributing one or several RNA segments to reassortants with human strains.
Until recently, it was generally assumed that the prognosis for individuals with diastolic dysfunction and associated intermittent pulmonary edema was better than those with systolic dysfunction. In fact, in two studies appearing in the New England Journal of Medicine in 2006, evidence was presented to suggest that the prognosis in diastolic dysfunction is the same as that in systolic dysfunction.
Despite increasing incidence of HFpEF effective inroads to therapeutics have been largely unsuccessful. Currently, recommendations for treatment are directed at symptom relief and co-morbid conditions. Frequently this involves administration of diuretics to relieve complications associated with volume overload, such as leg swelling and high blood pressure.
Commonly encountered conditions that must be treated for and have independent recommendations for standard of care include atrial fibrillation, coronary artery disease, hypertension, and hyperlipidemia. There are particular factors unique to HFpEF that must be accounted for with therapy. Unfortunately, currently available randomized clinical trials addressing the therapeutic adventure for these conditions in HFpEF present conflicting or limited evidence.
Specific aspects of therapeutics should be avoided in HFpEF to prevent the deterioration of the condition. Considerations that are generalizable to heart failure include avoidance of a fast heart rate, elevations in blood pressure, development of ischemia, and atrial fibrillation. More specific to HFpEF include avoidance of preload reduction. As patients display normal ejection fraction but reduced cardiac output they are especially sensitive to changes in preloading and may rapidly display signs of output failure. This means administration of diuretics and vasodilators must be monitored carefully.
HFrEF and HFpEF represent distinct entities in terms of development and effective therapeutic management. Specifically cardiac resynchronization, administration of beta blockers and angiotensin converting enzyme inhibitors are applied to good effect in HFrEF but are largely ineffective at reducing morbidity and mortality in HFpEF. Many of these therapies are effective in reducing the extent of cardiac dilation and increasing ejection fraction in HFrEF patients. It is unsurprising they fail to effect improvement in HFpEF patients, given their un-dilated phenotype and relative normal ejection fraction. Understanding and targeting mechanisms unique to HFpEF are thus essential to the development of therapeutics.
Randomized studies on HFpEF patients have shown that exercise improves left ventricular diastolic function, the heart's ability to relax, and is associated with improved aerobic exercise capacity. The benefit patients seem to derive from exercise does not seem to be a direct cardiac effect but rather is due to changes in peripheral vasculature and skeletal muscle, which show abnormalities in HFpEF patients.
Patients should be regularly assessed to determine progression of the condition, response to interventions, and need for alteration of therapy. Ability to perform daily tasks, hemodynamic status, kidney function, electrolyte balance, and serum natriuretic peptide levels are important parameters. Behavioral management is important in these patients and it is recommended that individuals with HFpEF avoid alcohol, smoking, and high sodium intake.
In cases of viral pneumonia where influenza A or B are thought to be causative agents, patients who are seen within 48 hours of symptom onset may benefit from treatment with oseltamivir or zanamivir. Respiratory syncytial virus (RSV) has no direct acting treatments, but ribavirin in indicated for severe cases. Herpes simplex virus and varicella-zoster virus infections are usually treated with aciclovir, whilst ganciclovir is used to treat cytomegalovirus. There is no known efficacious treatment for pneumonia caused by SARS coronavirus, MERS coronavirus, adenovirus, hantavirus, or parainfluenza. Care is largely supportive.
Many factors influence the time course and extent of remodeling, including the severity of the injury, secondary events (recurrent ischemia or infarction), neurohormonal activation, genetic factors and gene expression, and treatment. Medications may attenuate remodeling. Angiotensin-converting enzyme (ACE) inhibitors have been consistently shown to decrease remodeling in animal models or transmural infarction and chronic pressure overload. Clinical trials have shown that ACE inhibitor therapy after myocardial infarction leads to improved myocardial performance, improved ejection fraction, and decreased mortality compared to patients treated with placebo. Likewise, inhibition of aldosterone, either directly or indirectly, leads to improvement in remodeling. Carvedilol, a 3rd generation beta blocker, may actually reverse the remodeling process by reducing left ventricular volumes and improving systolic function. Early correction of congenital heart defects, if appropriate, may prevent remodeling, as will treatment of chronic hypertension or valvular heart disease. Often, reverse remodeling, or improvement in left ventricular function, will also be seen.
The goal of management of ARVD is to decrease the incidence of sudden cardiac death. This raises a clinical dilemma: How to prophylactically treat the asymptomatic patient who was diagnosed during family screening.
A certain subgroup of individuals with ARVD are considered at high risk for sudden cardiac death. Associated characteristics include:
- Young age
- Competitive sports activity
- Malignant familial history
- Extensive RV disease with decreased right ventricular ejection fraction.
- Left ventricular involvement
- Syncope
- Episode of ventricular arrhythmia
Management options include pharmacological, surgical, catheter ablation, and placement of an implantable cardioverter-defibrillator.
Prior to the decision of the treatment option, programmed electrical stimulation in the electrophysiology laboratory may be performed for additional prognostic information. Goals of programmed stimulation include:
- Assessment of the disease's arrhythmogenic potential
- Evaluate the hemodynamic consequences of sustained VT
- Determine whether the VT can be interrupted via antitachycardia pacing.
Regardless of the management option chosen, the individual is typically advised to undergo lifestyle modification, including avoidance of strenuous exercise, cardiac stimulants (i.e.: caffeine, nicotine, pseudoephedrine) and alcohol. If the individual wishes to begin an exercise regimen, an exercise stress test may have added benefit.
If an affected individual begins to experience severe TDBBB, then medical intervention is often advised. Suggested therapy for the treatment of TDBBB can include the prescription of certain medications or the implantation of a pacemaker device. Advised medications would possess anti-coagulant mechanisms to reduce the risk of blood clot formation ensuring that no further restriction of arteries would deprive the heart of oxygen and further damage the bundle branches. The use of a pacemaker would ensure that the heart receives a constant rhythmic electrical input that never changes in frequency. While this would effectively eliminate the occurrence of TDBBB, the pacemaker would restrict the patient's heart to a permanent rhythm, eliminating the ability of patients to perform physical activity. Future pacemakers that adaptively respond to physiological requirements are being developed in order to negate the limitations observed with their current use.
As previously stated, management of HFpEF is primarily dependent on the treatment of symptoms and exacerbating conditions. Currently treatment with ACE inhibitors, calcium channel blockers, beta blockers, and angiotensin receptor blockers are employed but do not have a proven benefit in HFpEF patients. Additionally, use of Diuretics or other therapies that can alter loading conditions or blood pressure should be used with caution. It is not recommended that patients be treated with phosphodiesterase-5-inhibitors or digoxin.
Antimineralocorticoid is currently recommended for patients with HFpEF who show elevated brain natriuretic peptide levels. Spironolactone is the first member of this drug class and the most frequently employed. Care should be taken to monitor serum potassium levels as well as kidney function, specifically glomerular filtration rate during treatment.
Beta blockers play a rather obscure role in HFpEF treatment but appear to play a beneficial role in patient management. There is currently a deficit of clinical evidence to support a particular benefit for HFpEF patients, with most evidence resulting from HFpEF patients' inclusion in broader heart failure trials. However, some evidence suggests that vasodilating beta blockers, such as nebivolol, can provide a benefit for patients with heart failure regardless of ejection fraction. Additionally, because of the chronotropic perturbation and diminished LV filling seen in HFpEF the bradycardic effect of beta blockers may enable improved filling, reduced myocardial oxygen demand and lowered blood pressure. However, this effect also can contribute to diminished response to exercise demands and can result in an excessive reduction in heart rate.
ACE inhibitors do not appear to improve morbidity or mortality associated with HFpEF alone. However, they are important in the management of hypertension, a significant player in the pathophysiology of HFpEF.
Angiotensin II receptor blocker treatment shows an improvement in diastolic dysfunction and hypertension that is comparable to other anti-hypertensive medication.
Pharmacologic management of ARVD involves arrhythmia suppression and prevention of thrombus formation.
Sotalol, a beta blocker and a class III antiarrhythmic agent, is the most effective antiarrhythmic agent in ARVD. Other antiarrhythmic agents used include amiodarone and conventional beta blockers (i.e.: metoprolol). If antiarrhythmic agents are used, their efficacy should be guided by series ambulatory holter monitoring, to show a reduction in arrhythmic events.
While angiotensin converting enzyme inhibitors (ACE Inhibitors) are well known for slowing progression in other cardiomyopathies, they have not been proven to be helpful in ARVD.
Individuals with decreased RV ejection fraction with dyskinetic portions of the right ventricle may benefit from long term anticoagulation with warfarin to prevent thrombus formation and subsequent pulmonary embolism.
The coronavirus which causes ECE has a counterpart strain that has more systemic effects with a higher mortality rate. This systemic syndrome has been compared to Feline infectious peritonitis in cats.
Generally, diastolic dysfunction is a chronic process. When this chronic condition is well tolerated by an individual, no specific treatment may be indicated. Rather, therapy should be directed at the root cause of the stiff left ventricle, with potential causes and aggravating factors like high blood pressure and diabetes treated appropriately. Conversely (as noted above), diastolic dysfunction tends to be better tolerated if the atrium is able to pump blood into the ventricles in a coordinated fashion. This does not occur in atrial fibrillation (AF), where there is no coordinated atrial activity and the left ventricle loses around 20% of its output. However, in chronic AF and in geriatric patients, AF is better tolerated and the cardiologist must choose between a stable AF at a lower rate and the risk of having an intermittent AF if he pretends to treat AF aggressively with all the thrombo-embolic risk it implies. In the same light, and also as noted above, if the atrial fibrillation persists and is resulting in a rapid heart rate, treatment must be given to slow down that rate. Usually digoxin maintains a stable rhythm. The use of a self-expanding device that attaches to the external surface of the left ventricle has been suggested, yet still awaits FDA approval. When the heart muscle squeezes, energy is loaded into the device, which absorbs the energy and releases it to the left ventricle in the diastolic phase. This helps retain muscle elasticity.
The role of specific treatments for diastolic dysfunction "per se" is as yet unclear. Diuretics can be useful, if these patients develop significant congestion, but patients must be monitored because they frequently develop hypotension.
Beta-blockers are the first-line therapy as they induce bradycardia and give time for ventricles to fill. There is some evidence that calcium channel blocker drugs may be of benefit in reducing ventricular stiffness in some cases (verapamil has the benefit lowering the heart rate). Likewise, treatment with angiotensin converting enzyme inhibitors, such as enalapril, ramipril, and many others, may be of benefit due to their effect on preventing ventricular remodeling but under control to avoid hypotension.
Therapies that support reverse remodeling have been investigated, and this may suggests a new approach to the prognosis of cardiomyopathies (see ventricular remodeling).
Early detection and treatment are associated with higher rates of recovery and decreased morbidity and mortality.
Treatment for PPCM is similar to treatment for congestive heart failure. Conventional heart failure treatment includes the use of diuretics, beta blockers (B-B), and angiotensin-converting enzyme inhibitors (ACE-I) after delivery. Diuretics, preferably furosemide, help the body to get rid of excess water weight and also lower blood pressure. ACE-I and B-B improve blood circulation and contribute to the reversal of the immune system dysfunction associated with PPCM. If ACE-I is not well tolerated by the patient, it can be replaced by angiotensin receptor blockers (ARB). Hydralazine with nitrates may replace ACE-I in breastfeeding mothers or before delivery; however, evidence suggests that this course of treatment may not be as effective as ACE-I but beneficial when necessary.
If EF is less than 35%, anticoagulation is indicated, as there is a greater risk of developing left ventricular thrombi (blood clots). Sometimes implantation of a left ventricular assist device (LVAD) or even heart transplant also becomes necessary.
It is important that the patient receives regular follow-up care including frequent echocardiograms to monitor improvement or the lack thereof, particularly after changes of medical treatment regimes.
Patients who do not respond to initial treatment, defined as left ventricular EF remaining below 20% at two months or below 40% at three months with conventional treatment may merit further investigation, including cardiac magnetic resonance imaging (MRI), cardiac catheterization, and endomyocardial biopsy for special staining and for viral polymerase chain reaction (PCR) analysis. Antiviral therapy, immunoabsorption, intravenous gamma globulin, or other immunomodulation therapy may then be considered accordingly, but following a controlled research-type protocol.
Since no one knows for sure exactly when to discontinue treatment, even when recovery occurs quickly, it is still recommended that both ACE-I and B-B be continued for at least one year after diagnosis.
Some people with bundle branch blocks are born with this condition. Many other acquire it as a consequence of heart disease. People with bundle branch blocks may still be quite active, and may have nothing more remarkable than an abnormal appearance to their ECG. However, when bundle blocks are complex and diffuse in the bundle systems, or associated with additional and significant ventricular muscle damage, they may be a sign of serious underlying heart disease. In more severe cases, a pacemaker may be required to restore an optimal electrical supply to the heart muscle.
Treatment of TIC involves treating both the tachyarrhythmia and the heart failure with the goal of adequate rate control or restoration of the normal heart rhythm (aka. normal sinus rhythm) to reverse the cardiomyopathy. The treatment of the tachyarrhythmia depends on the specific arrhythmia, but possible treatment modalities include rate control, rhythm control with antiarrhythmic agents and cardioversion, radiofrequency (RF) catheter ablation, or AV node ablation with permanent pacemaker implantation.
For TIC due to atrial fibrillation, rate control, rhythm control, and RF catheter ablation can be effective to control the tachyarrhythmia and improve left ventricular systolic function. For TIC due to atrial flutter, rate control is often difficult to achieve, and RF catheter ablation has a relatively high success rate with a low risk of complications. In patients with TIC due to other types of SVT, RF catheter ablation is recommended as a first-line treatment. In patients with TIC due to VT or PVCs, both antiarrhythmics and RF catheter ablation can be used. However, the options for antiarrhythmic agents are limited because certain agents can be proarrhythmic in the setting of myocardial dysfunction in TIC. Therefore, RF catheter ablation is often a safe and effective choice for treatment VT and PVCs causing TIC. In cases where other treatment strategies fail, AV node ablation with permanent pacemaker implantation can also be used to treat the tachyarrhythmia.
The treatment of heart failure commonly involves neurohormonal blockade with beta-blockers and angiotensin convertase inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) along with symptomatic management with diuretics. Beta-blockers and ACE inhibitors can inhibit and potentially reverse the negative cardiac remodeling, which refers to structural changes in the heart, that occurs in TIC. However, the need to continue these agents after treatment of the tacharrhythmia and resolution of left ventricular systolic dysfunction remains controversial.
It has been proposed that viral meningitis might lead to inflammatory injury of the vertebral artery wall.
The Meningitis Research Foundation is conducting a study to see if new genomic techniques can the speed, accuracy and cost of diagnosing meningitis in children in the UK. The research team will develop a new method to be used for the diagnosis of meningitis, analysing the genetic material of microorganisms found in CSF (cerebrospinal fluid). The new method will first be developed using CSF samples where the microorganism is known, but then will be applied to CSF samples where the microorganism is unknown (estimated at around 40%) to try and identify a cause.
Treatment is generally supportive. Rest, hydration, antipyretics, and pain or anti-inflammatory medications may be given as needed.
Herpes simplex virus, varicella zoster virus and cytomegalovirus have a specific antiviral therapy. For herpes the treatment of choice is aciclovir.
Surgical management is indicated where there is extremely increased intracranial pressure, infection of an adjacent bony structure (e.g. mastoiditis), skull fracture, or abscess formation.
The majority of people that have viral meningitis get better within 7-10 days.
Medical management of patients with CRS is often challenging as focus on treatment of one organ may have worsening outcome on the other. It is known that many of the medications used to treat HF may worsen kidney function. In addition, many trials on HF excluded patients with advanced kidney dysfunction. Therefore, our understanding of CRS management is still limited to this date.
Diuretics
ACEI, ARB, renin inhibitors, aldosterone inhibitors
Natriuretic peptides
Vasopressin antagonists
Adenosine antagonists
Ultrafiltration
Inotropes