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Ribavirin is one medication which has shown good potential for the treatment of HPIV-3 given recent in-vitro tests (in-vivo tests show mixed results). Ribavirin is a broadscale anti-viral and is currently being administered to those who are severely immuno-compromised, despite the lack of conclusive evidence for its use. Protein inhibitors and novel forms of medication have also been proposed to relieve the symptoms of infection.
Furthermore, antibiotics may be used if a secondary bacterial infection develops. Corticosteroid treatment and nebulizers are also a first line choice against croup if breathing difficulties ensue.
There is currently no effective marburgvirus-specific therapy for MVD. Treatment is primarily supportive in nature and includes minimizing invasive procedures, balancing fluids and electrolytes to counter dehydration, administration of anticoagulants early in infection to prevent or control disseminated intravascular coagulation, administration of procoagulants late in infection to control hemorrhaging, maintaining oxygen levels, pain management, and administration of antibiotics or antimycotics to treat secondary infections. Experimentally, recombinant vesicular stomatitis Indiana virus (VSIV) expressing the glycoprotein of MARV has been used successfully in nonhuman primate models as post-exposure prophylaxis. Novel, very promising, experimental therapeutic regimens rely on antisense technology: phosphorodiamidate morpholino oligomers (PMOs) targeting the MARV genome could prevent disease in nonhuman primates. Leading medications from Sarepta and Tekmira both have been successfully used in European humans as well as primates.
There is no cure for polioencephalitis so prevention is essential. Many people that become infected will not develop symptoms and their prognosis is excellent. However, the prognosis is dependent on the amount of cellular damage done by the virus and the area of the brain affected. Many people that develop more severe symptoms can have lifelong disabilities or it can lead to death. Supportive treatments include bed rest, pain relievers, and a nutritious diet. Many drugs have been used to treat psychiatric symptoms such as Clonazepam for insomnia and Desvenlafaxine or Citalopram for depressed mood.
Herpes outbreaks should be treated with antiviral medications like Acyclovir, Valacyclovir, or Famcyclovir, each of which is available in tablet form.
Oral antiviral medication is often used as a prophylactic to suppress or prevent outbreaks from occurring. The recommended dosage for suppression therapy for recurrent outbreaks is 1,000 mg of valacyclovir once a day or 400 mg Acyclovir taken twice a day. In addition to preventing outbreaks, these medications greatly reduce the chance of infecting someone while the patient is not having an outbreak.
Often, people have regular outbreaks of anywhere from 1 to 10 times per year, but stress (because the virus lies next to the nerve cells), or a weakened immune system due to a temporary or permanent illness can also spark outbreaks. Some people become infected but fail to ever have a single outbreak, although they remain carriers of the virus and can pass the disease on to an uninfected person through asymptomatic shedding (when the virus is active on the skin but rashes or blisters do not appear).
The use of antiviral medications has been shown to be effective in preventing acquisition of the herpes virus. Specific usage of these agents focus on wrestling camps where intense contact between individuals occur on a daily basis over several weeks. They have also been used for large outbreaks during seasonal competition, but further research needs to be performed to verify efficacy.
Despite decades of research, no vaccines currently exist.
Recombinant technology has however been used to target the formation of vaccines for HPIV-1, -2 and -3 and has taken the form of several live-attenuated intranasal vaccines. Two vaccines in particular were found to be immunogenic and well tolerated against HPIV-3 in phase I trials. HPIV-1 and -2 vaccine candidates remain less advanced.
Vaccine techniques which have been used against HPIVs are not limited to intranasal forms, but also viruses attenuated by cold passage, host range attenuation, chimeric construct vaccines and also introducing mutations with the help of reverse genetics to achieve attenuation.
Maternal antibodies may offer some degree of protection against HPIVs during the early stages of life via the colostrum in breast milk.
There is no specific treatment for Japanese encephalitis and treatment is supportive, with assistance given for feeding, breathing or seizure control as required. Raised intracranial pressure may be managed with mannitol. There is no transmission from person to person and therefore patients do not need to be isolated.
A breakthrough in the field of Japanese encephalitis therapeutics is the identification of macrophage receptor involvement in the disease severity. A recent report of an Indian group demonstrates the involvement of monocyte and macrophage receptor CLEC5A in severe inflammatory response in Japanese Encephalitis infection of the brain. This transcriptomic study provides a hypothesis of neuroinflammation and a new lead in development of appropriate therapeutic against Japanese encephalitis.
Infection with Japanese encephalitis confers lifelong immunity. There are currently three vaccines available: SA14-14-2, IC51 (marketed in Australia and New Zealand as JESPECT and elsewhere as IXIARO) and ChimeriVax-JE (marketed as IMOJEV). All current vaccines are based on the genotype III virus.
A formalin-inactivated mouse-brain derived vaccine was first produced in Japan in the 1930s and was validated for use in Taiwan in the 1960s and in Thailand in the 1980s. The widespread use of vaccine and urbanization has led to control of the disease in Japan, Korea, Taiwan, and Singapore. The high cost of this vaccine, which is grown in live mice, means that poorer countries have not been able to afford to give it as part of a routine immunization program.
The most common adverse effects are redness and pain at the injection site. Uncommonly, an urticarial reaction can develop about four days after injection. Vaccines produced from mouse brain have a risk of autoimmune neurological complications of around 1 per million vaccinations. However where the vaccine is not produced in mouse brains but in vitro using cell culture there is little adverse effects compared to placebo, the main side effects are headache and myalgia.
The neutralizing antibody persists in the circulation for at least two to three years, and perhaps longer. The total duration of protection is unknown, but because there is no firm evidence for protection beyond three years, boosters are recommended every three years for people who remain at risk. Furthermore, there is also no data available regarding the interchangeability of other JE vaccines and IXIARO.
In September 2012 the Indian firm Biological E. Limited has launched an inactivated cell culture derived vaccine based on SA 14-14-2 strain which was developed in a technology transfer agreement with Intercell and is a thiomersal-free vaccine.
Key measures to prevent outbreaks of the disease are maintaining hygiene standards and using screening to exclude persons with suspicious infections from engaging in contact sports. A skin check performed before practice or competition takes place can identify individuals who should be evaluated, and if necessary treated by a healthcare professional. In certain situations, i.e. participating in wrestling camps, consider placing participants on valacyclovir 1GM daily for the duration of camp. 10-year study has shown 89.5% reduction in outbreaks and probable prevention of contracting the virus. Medication must be started 5 days before participation to ensure proper concentrations exist.
There are currently no Food and Drug Administration-approved vaccines for the prevention of MVD. Many candidate vaccines have been developed and tested in various animal models. Of those, the most promising ones are DNA vaccines or based on Venezuelan equine encephalitis virus replicons, vesicular stomatitis Indiana virus (VSIV) or filovirus-like particles (VLPs) as all of these candidates could protect nonhuman primates from marburgvirus-induced disease. DNA vaccines have entered clinical trials. Marburgviruses are highly infectious, but not very contagious. Importantly, and contrary to popular belief, marburgviruses do not get transmitted by aerosol during natural MVD outbreaks. Due to the absence of an approved vaccine, prevention of MVD therefore relies predominantly on behavior modification, proper personal protective equipment, and sterilization/disinfection.
Treatment of acute rotavirus infection is nonspecific and involves management of symptoms and, most importantly, management of dehydration. If untreated, children can die from the resulting severe dehydration. Depending on the severity of diarrhoea, treatment consists of oral rehydration therapy, during which the child is given extra water to drink that contains specific amounts of salt and sugar. In 2004, the World Health Organisation (WHO) and UNICEF recommended the use of low-osmolarity oral rehydration solution and zinc supplementation as a two-pronged treatment of acute diarrhoea. Some infections are serious enough to warrant hospitalisation where fluids are given by intravenous therapy or nasogastric intubation, and the child's electrolytes and blood sugar are monitored. Probiotics have been shown to reduce the duration of rotavirus diarrhoea, and according to the European Society for Pediatric Gastroenterology "effective interventions include administration of specific probiotics such as "Lactobacillus rhamnosus" or "Saccharomyces boulardii", diosmectite or racecadotril." Rotavirus infections rarely cause other complications and for a well managed child the prognosis is excellent.
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.
There are no specific antiviral drugs for dengue; however, maintaining proper fluid balance is important. Treatment depends on the symptoms. Those who are able to drink, are passing urine, have no "warning signs" and are otherwise healthy can be managed at home with daily follow-up and oral rehydration therapy. Those who have other health problems, have "warning signs", or cannot manage regular follow-up should be cared for in hospital. In those with severe dengue care should be provided in an area where there is access to an intensive care unit.
Intravenous hydration, if required, is typically only needed for one or two days. In children with shock due to dengue a rapid dose of 20 mL/kg is reasonable. The rate of fluid administration is then titrated to a urinary output of 0.5–1 mL/kg/h, stable vital signs and normalization of hematocrit. The smallest amount of fluid required to achieve this is recommended.
Invasive medical procedures such as nasogastric intubation, intramuscular injections and arterial punctures are avoided, in view of the bleeding risk. Paracetamol (acetaminophen) is used for fever and discomfort while NSAIDs such as ibuprofen and aspirin are avoided as they might aggravate the risk of bleeding. Blood transfusion is initiated early in people presenting with unstable vital signs in the face of a "decreasing hematocrit", rather than waiting for the hemoglobin concentration to decrease to some predetermined "transfusion trigger" level. Packed red blood cells or whole blood are recommended, while platelets and fresh frozen plasma are usually not. There is not enough evidence to determine if corticosteroids have a positive or negative effect in dengue fever.
During the recovery phase intravenous fluids are discontinued to prevent a state of fluid overload. If fluid overload occurs and vital signs are stable, stopping further fluid may be all that is needed. If a person is outside of the critical phase, a loop diuretic such as furosemide may be used to eliminate excess fluid from the circulation.
The virus is most often spread by person to person contact with the stool or saliva of the infected person. Two types of vaccines have been developed to prevent the occurrence and spread of the poliomyelitis virus. The first is an inactivated, or killed, form of the virus and the second is an attenuated, or weakened, form of the virus. The development of vaccines has successfully eliminated the disease from the United States. There are continued vaccination efforts in the U.S. to maintain this success rate as this disease still occurs in some areas of the world.
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.
Vaccines are available (ATCvet codes: for the inactivated vaccine, for the live vaccine, plus various combinations).
Given that avian reovirus infections are widespread, the viruses are relatively resistant outside the host, and that vertical and horizontal transmission occurs, eradicating avian reovirus infection in commercial chicken flocks is very unlikely. In addition, absence of detectable seroconversion and failure to detect virus in cloacal swabs are unreliable indicators of resisting infection, or transmission via the egg. Thus, the most proactive and successful approach to controlling this disease is through vaccination. Since chicks are more prone to being detrimentally affected by the disease right after hatching, vaccine protocols that use live and killed vaccines are designed to provide protection during the very early stages of life. This approach has been accomplished through active immunity after early vaccination and a live vaccine or passive immunity from maternal antibodies followed with vaccination of the breeder hens. Currently, efforts toward administering inactivated or live vaccines to breeding stock to allow passive immunity to the offspring via the yolk are being taken.
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.
A vaccine has been conditionally approved for use in animals in the US. It has been shown that knockout of the NSs and NSm nonstructural proteins of this virus produces an effective vaccine in sheep as well.
In terms of treatment, ribavirin is not registered for hepatitis E treatment, though off-label experience for treating chronic hepatitis E with this compound exists. The use of low doses of ribavirin over a three-month period has been associated with viral clearance in about two-thirds of chronic cases. Other possible treatments include pegylated interferon or a combination of ribavirin and pegylated interferon. In general, chronic HEV infection is associated with immunosuppressive therapies, but remarkably little is known about how different immunosuppressants affect HEV infection. In individuals with solid-organ transplantation, viral clearance can be achieved by temporal reduction of the level of immunosuppression.
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.
In unvaccinated humans, rabies is almost always fatal after neurological symptoms have developed.
Vaccination after exposure, PEP, is highly successful in preventing the disease if administered promptly, in general within 6 days of infection. Begun with little or no delay, PEP is 100% effective against rabies. In the case of significant delay in administering PEP, the treatment still has a chance of success.
Five of the first 43 patients (12%) treated with the Milwaukee protocol survived, and those receiving treatment survived longer than those not receiving the treatment.
Treatment after exposure can prevent the disease if administered promptly, generally within 10 days of infection. Thoroughly washing the wound as soon as possible with soap and water for approximately five minutes is effective in reducing the number of viral particles. Povidone-iodine or alcohol is then recommended to reduce the virus further.
In the US, the Centers for Disease Control and Prevention recommends people receive one dose of human rabies immunoglobulin (HRIG) and four doses of rabies vaccine over a 14-day period. The immunoglobulin dose should not exceed 20 units per kilogram body weight. HRIG is expensive and constitutes most of the cost of post exposure treatment, ranging as high as several thousand dollars. As much as possible of this dose should be injected around the bites, with the remainder being given by deep intramuscular injection at a site distant from the vaccination site.
The first dose of rabies vaccine is given as soon as possible after exposure, with additional doses on days 3, 7 and 14 after the first. Patients who have previously received pre-exposure vaccination do not receive the immunoglobulin, only the postexposure vaccinations on days 0 and 3.
The pain and side effects of modern cell-based vaccines are similar to flu shots. The old nerve-tissue-based vaccinations that require multiple painful injections into the abdomen with a large needle are inexpensive, but are being phased out and replaced by affordable World Health Organization intradermal-vaccination regimens.
Intramuscular vaccination should be given into the deltoid, not the gluteal area, which has been associated with vaccination failure due to injection into fat rather than muscle. In infants, the lateral thigh is recommended.
Awakening to find a bat in the room, or finding a bat in the room of a previously unattended child or mentally disabled or intoxicated person, is an indication for post-exposure prophylaxis (PEP). The recommendation for the precautionary use of PEP in bat encounters where no contact is recognized has been questioned in the medical literature, based on a cost–benefit analysis. However, a 2002 study has supported the protocol of precautionary administering of PEP where a child or mentally compromised individual has been alone with a bat, especially in sleep areas, where a bite or exposure may occur without the victim being aware. Begun with little or no delay, PEP is 100% effective against rabies. In the case in which there has been a significant delay in administering PEP, the treatment should be administered regardless, as it may still be effective. Every year, more than 15 million people get vaccination after potential exposure. While this works well, the cost is significant.
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.
Avian reoviruses belong to the genus "Orthoreovirus", and "Reoviridae" family. They are non-enveloped viruses that undergo replication in the cytoplasm of infected cells. It has icosahedral symmetry and contains a double-shelled arrangement of surface protein. Virus particles can range between 70–80 nm. Morphologically, the virus is a double stranded RNA virus that is composed of ten segments. The genome and proteins that are encoded by the genome can be separated into three different sizes ranging from small, medium, or large. Of the eleven proteins that are encoded for by the genome, two are nonstructural, while the remaining nine are structural.
Avian reoviruses can withstand a pH range of 3.0–9.0. Ambient temperatures are suitable for the survival of these viruses, which become inactive at 56 °C in less than an hour. Common areas where this virus can survive include galvanized metal, glass, rubber, feathers, and wood shavings. Avian reovirus can survive for up to ten days on these common areas in addition to up to ten weeks in water.
Cultivation and observation of the effects of avian reovirus is most often performed in chicken embryos. If infected into the yolk sac, the embryo will succumb to death accompanied by hemorrhaging of the embryos and cause the foci on the liver to appear yellowish-green. There are several primary chicken cell cultures/areas that are susceptible to avian reoviruses, which include the lungs, liver, kidney, and fibroblasts of the chick embryo. Of the following susceptible areas, liver cells from the chick embryo have been found to be the most sensitive for primary isolation from clinical material.
Typically, the CPE effect of avian reoviruses is the production of syncytia. CPE, or cytopathic effects are the visible changes in a host cell that takes place because of viral infection. Syncytia is a single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei.
Acute infection does not usually require treatment and most adults clear the infection spontaneously. Early antiviral treatment may be required in fewer than 1% of people, whose infection takes a very aggressive course (fulminant hepatitis) or who are immunocompromised. On the other hand, treatment of chronic infection may be necessary to reduce the risk of cirrhosis and liver cancer. Chronically infected individuals with persistently elevated serum alanine aminotransferase, a marker of liver damage, and HBV DNA levels are candidates for therapy. Treatment lasts from six months to a year, depending on medication and genotype. Treatment duration when medication is taken by mouth, however, is more variable and usually longer than one year.
Although none of the available drugs can clear the infection, they can stop the virus from replicating, thus minimizing liver damage. As of 2008, there are seven medications licensed for the treatment of infection in the United States. These include antiviral drugs lamivudine (Epivir), adefovir (Hepsera), tenofovir (Viread), telbivudine (Tyzeka) and entecavir (Baraclude), and the two immune system modulators interferon alpha-2a and PEGylated interferon alpha-2a (Pegasys). In 2015 the World Health Organization recommended tenofovir or entecavir as first-line agents. Those with current cirrhosis are in most need of treatment.
The use of interferon, which requires injections daily or thrice weekly, has been supplanted by long-acting PEGylated interferon, which is injected only once weekly. However, some individuals are much more likely to respond than others, and this might be because of the genotype of the infecting virus or the person's heredity. The treatment reduces viral replication in the liver, thereby reducing the viral load (the amount of virus particles as measured in the blood). Response to treatment differs between the genotypes. Interferon treatment may produce an e antigen seroconversion rate of 37% in genotype A but only a 6% seroconversion in type D. Genotype B has similar seroconversion rates to type A while type C seroconverts only in 15% of cases. Sustained e antigen loss after treatment is ~45% in types A and B but only 25–30% in types C and D.
Treatment is symptomatic and aims to prevent dehydration in young pigs, using products such as electrolyte and energy supplements. Good biosecurity protocols such as adequate quarantine, isolation of cases, and disinfection help prevent entry or spread of the disease in the herd. In Canada, the Canadian Swine Health Board developed detailed protocols on how to adequately disinfect transportation vehicles for live hogs and ensure the quality of the disinfecttion protocol.