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Investigational vaccines exist for Argentine hemorrhagic fever and RVF; however, neither is approved by FDA or commonly available in the United States.
The structure of the attachment glycoprotein has been determined by X-ray crystallography and this glycoprotein is likely to be an essential component of any successful vaccine.
Preventing Omsk Hemorrhagic Fever consists primarily in avoiding being exposed to tick. Persons engaged in camping, farming, forestry, hunting (especially the Siberian muskrat) are at greater risk and should wear protective clothing or use insect repellent for protection. The same is generally recommended for persons at sheltered locations.
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.
Measures to reduce contact between the vesper mouse and humans may have contributed to limiting the number of outbreaks, with no cases identified between 1973 and 1994. Although there are no cures or vaccine for the disease, a vaccine developed for the genetically related Junín virus which causes Argentine hemorrhagic fever has shown evidence of cross-reactivity to Machupo virus, and may therefore be an effective prophylactic measure for people at high risk of infection. Post infection (and providing that the person survives the infection), those that have contracted BHF are usually immune to further infection of the disease.
The VHF viruses are spread in a variety of ways. Some may be transmitted to humans through a respiratory route. According to Soviet defector Ken Alibek, Soviet scientists concluded China may have tried to weaponise a VHF virus during the late 1980's but discontinued to do so after an outbreak . The virus is considered by military medical planners to have a potential for aerosol dissemination, weaponizaton, or likelihood for confusion with similar agents that might be weaponized.
Omsk Hemorrhagic Fever could be diagnosed by isolating virus from blood, or by serologic testing using immunosorbent serological assay. OHF rating of fatality is 0.5–3%. There is no specific treatment for OHF so far but one way to help get rid of OHF is by supportive therapy. Supportive therapy helps maintain hydration and helps to provide precautions for patients with bleeding disorders.
With the exception of yellow fever vaccine neither vaccines nor experimental vaccines are readily available. Prophylactic (preventive) ribavirin may be effective for some bunyavirus and arenavirus infections (again, available only as IND).
VHF isolation guidelines dictate that all VHF patients (with the exception of dengue patients) should be cared for using strict contact precautions, including hand hygiene, double gloves, gowns, shoe and leg coverings, and faceshield or goggles. Lassa, CCHF, Ebola, and Marburg viruses may be particularly prone to nosocomial (hospital-based) spread. Airborne precautions should be utilized including, at a minimum, a fit-tested, HEPA filter-equipped respirator (such as an N-95 mask), a battery-powered, air-purifying respirator, or a positive pressure supplied air respirator to be worn by personnel coming within 1,8 meter (six feet) of a VHF patient. Multiple patients should be cohorted (sequestered) to a separate building or a ward with an isolated air-handling system. Environmental decontamination is typically accomplished with hypochlorite (e.g. bleach) or phenolic disinfectants.
All persons suspected of Lassa fever infection should be admitted to isolation facilities and their body fluids and excreta properly disposed of.
Early and aggressive treatment using ribavirin was pioneered by Joe McCormick in 1979. After extensive testing, early administration was determined to be critical to success. Additionally, ribavirin is almost twice as effective when given intravenously as when taken by mouth. Ribavirin is a prodrug which appears to interfere with viral replication by inhibiting RNA-dependent nucleic acid synthesis, although the precise mechanism of action is disputed. The drug is relatively inexpensive, but the cost of the drug is still very high for many of those in West African states. Fluid replacement, blood transfusion, and fighting hypotension are usually required. Intravenous interferon therapy has also been used.
When Lassa fever infects pregnant women late in their third trimester, induction of delivery is necessary for the mother to have a good chance of survival. This is because the virus has an affinity for the placenta and other highly vascular tissues. The fetus has only a one in ten chance of survival no matter what course of action is taken; hence, the focus is always on saving the life of the mother. Following delivery, women should receive the same treatment as other Lassa fever patients.
Work on a vaccine is continuing, with multiple approaches showing positive results in animal trials.
Treatment is similar to hepatitis B, but due to its high lethality, more aggressive therapeutic approaches are recommended in the acute phase. In absence of a specific vaccine against delta virus, the vaccine against HBV must be given soon after birth in risk groups.
Control of the "Mastomys" rodent population is impractical, so measures focus on keeping rodents out of homes and food supplies, encouraging effective personal hygiene, storing grain and other foodstuffs in rodent-proof containers, and disposing of garbage far from the home to help sustain clean households . Gloves, masks, laboratory coats, and goggles are advised while in contact with an infected person, to avoid contact with blood and body fluids. These issues in many countries are monitored by a department of public health. In less developed countries, these types of organizations may not have the necessary means to effectively control outbreaks.
Researchers at the USAMRIID facility, where military biologists study infectious diseases, have a promising vaccine candidate. They have developed a replication-competent vaccine against Lassa virus based on recombinant vesicular stomatitis virus vectors expressing the Lassa virus glycoprotein. After a single intramuscular injection, test primates have survived lethal challenge, while showing no clinical symptoms.
Prophylaxis by vaccination, as well as preventive measures like protective clothing, tick control, and mosquito control are advised. The vaccine for KFDV consists of formalin-inactivated KFDV. The vaccine has a 62.4% effectiveness rate for individuals who receive two doses. For individuals who receive an additional dose, the effectiveness increases to 82.9%. Specific treatments are not available.
The "Candid #1" vaccine for AHF was created in 1985 by Argentine virologist Dr. Julio Barrera Oro. The vaccine was manufactured by the Salk Institute in the United States, and became available in Argentina in 1990.
"Candid #1" has been applied to adult high-risk population and is 95.5% effective. On 29 August 2006 the Maiztegui Institute obtained certification for the production of the vaccine in Argentina. A vaccination plan is yet to be outlined, but the budget for 2007 allows for 390,000 doses, at AR$8 each (about US$2.6 or €2 at the time). The Institute has the capacity to manufacture, in one year, the 5 million doses required to vaccinate the entire population of the endemic area.
Between 1991 and 2005 more than 240,000 people were vaccinated, achieving a great decrease in the numbers of reported cases (94 suspect and 19 confirmed in 2005).
The Junín vaccine has also shown cross-reactivity with Machupo virus and, as such, has been considered as a potential treatment for Bolivian hemorrhagic fever.
Attempts are ongoing to infect the mosquito population with bacteria of the "Wolbachia" genus, which makes the mosquitoes partially resistant to dengue virus. While artificially induced infections with "Wolbachia" is effective, it is unclear if naturally acquired infections are protective. Working is still ongoing as of 2015 to determine the best type of "Wolbachia" to use.
Prevention strategies include reducing the breeding of midges through source reduction (removal and modification of breeding sites) and reducing contact between midges and people. This can be accomplished by reducing the number of natural and artificial water-filled habitats and encourage the midge larvae to grow.
Oropouche fever is present in epidemics so the chances of one contracting it after being exposed to areas of midgets or mosquitoes is rare.
Prevention depends on control of and protection from the bites of the mosquito that transmits it. The World Health Organization recommends an Integrated Vector Control program consisting of five elements:
1. Advocacy, social mobilization and legislation to ensure that public health bodies and communities are strengthened;
2. Collaboration between the health and other sectors (public and private);
3. An integrated approach to disease control to maximize use of resources;
4. Evidence-based decision making to ensure any interventions are targeted appropriately; and
5. Capacity-building to ensure an adequate response to the local situation.
The primary method of controlling "A. aegypti" is by eliminating its habitats. This is done by getting rid of open sources of water, or if this is not possible, by adding insecticides or biological control agents to these areas. Generalized spraying with organophosphate or pyrethroid insecticides, while sometimes done, is not thought to be effective. Reducing open collections of water through environmental modification is the preferred method of control, given the concerns of negative health effects from insecticides and greater logistical difficulties with control agents. People can prevent mosquito bites by wearing clothing that fully covers the skin, using mosquito netting while resting, and/or the application of insect repellent (DEET being the most effective). However, these methods appear not to be sufficiently effective, as the frequency of outbreaks appears to be increasing in some areas, probably due to urbanization increasing the habitat of "A. aegypti". The range of the disease appears to be expanding possibly due to climate change.
Treatment is mostly supportive. Ribavirin is effective "in vitro" and has been used by mouth during outbreaks, but there is no trial evidence to support its use.
The United States armed forces maintain special stocks of ribavirin to protect personnel deployed to Afghanistan and Iraq from CCHF.
Oropouche Fever has no cure or specific therapy so treatment is done by relieving the pain of the symptoms through symptomatic treatment. Certain oral analgesic and anti-inflammatory agents can help treat headaches and body pains. In extreme cases of oropouche fever the drug, Ribavirin is recommended to help against the virus. This is called antiviral therapy. Treatments also consist of drinking lots of fluids to prevent dehydration.
Asprin is not a recommended choice of drug because it can reduce blood clotting and may aggravate the hemorrhagic effects and prolong recovery time.
The infection is usually self-limiting and complications are rare. This illness usually lasts for about a week but in extreme cases can be prolonged. Patients usually recover fully with no long term ill effects. There have been no recorded fatalities resulting from oropouche fever.
Brazilian hemorrhagic fever (BzHF) is an infectious disease caused by the Sabiá virus, an Arenavirus. The Sabiá virus is one of the arenoviruses from South America to cause hemorrhagic fever. It shares a common progenitor with the Junin virus, Machupo virus, Tacaribe virus, and Guanarito virus. It is an enveloped RNA virus and is highly infectious and lethal. Very little is known about this disease, but it is thought to be transmitted by the excreta of rodents.
There have only been three documented infections of the Sabiá virus, only one of which occurred naturally and the other two cases occurred in the clinical setting. The only naturally occurring case was in 1990, when a female agricultural engineer who was staying in the neighborhood of Jardim Sabiá near São Paulo, Brazil contracted the disease. She presented with hemorrhagic fever and died. Her autopsy showed liver necrosis. A virologist who was studying the woman's disease contracted the virus but survived. Ribavirin was not given in these first two cases. Four years later, in 1994, a researcher was exposed to the virus in a level 3 biohazard facility at Yale University when a centrifuge bottle cracked, leaked, and released aerosolized virus particle. He was successfully treated with ribavirin.
Ribavirin is thought to be effective in treating the illness, similar to other arenaviruses. Compared to the patients who did not receive ribavirin, the patient who was treated with it had a shorter and less severe clinical course. Symptomatic control such as fluids to address dehydration and bleeding may also be required.
The Sabiá virus is a Biosafety Level 4 pathogen.
This virus has also been implicated as a means for bioterrorism, as it can be spread through aerosols.
From September 1989 through December 2006, the State of Portuguesa recorded 618 cases of VHF. Nearly all of the cases were individuals who worked or lived in Guanarito during the time they became infected. The case fatality rate was 23.1%.
Because the virus is contracted by aerosol dissemination, concern arose shortly after the first cases emerged in 1989 due to fear of biological warfare. Potential biological terrorism agents were identified and categorized in 1999 by the Centers for Disease Control and Prevention (CDC) as part of the Congressional initiative to further response capabilities to biological weapons. Arenaviruses causing hemorrhagic fevers, along with a genus of virus called filoviruses, were categorized in Category A; these are pathogens with the highest potential impact on public health safety.
A notable event in the timeline of this virus' scientific knowledge was the unexplained disappearance of a vial of the virus at the University of Texas Medical Branch Galveston National Laboratory, announced 2013 March 24.
Where mammalian tick infection is common, agricultural regulations require de-ticking farm animals before transportation or delivery for slaughter. Personal tick avoidance measures are recommended, such as use of insect repellents, adequate clothing, and body inspection for adherent ticks.
When feverish patients with evidence of bleeding require resuscitation or intensive care, body substance isolation precautions should be taken.
The disease develops from March to September, with the highest infections occurring in June. The disease is found almost exclusively in the western United States and Canada, mostly in high mountain areas such as Colorado and Idaho. The CTFV was first isolated from human blood in 1944.
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.
Venezuelan hemorrhagic fever (VHF) is a zoonotic human illness first identified in 1989. The disease is most prevalent in several rural areas of central Venezuela and is caused by the Guanarito virus (GTOV) which belongs to the Arenaviridae family. The short-tailed cane mouse ("Zygodontomys brevicauda") is the main host for GTOV which is spread mostly by inhalation of aerosolized droplets of saliva, respiratory secretions, urine, or blood from infected rodents. Person-to-person spread is possible, but uncommon.
Argentine hemorrhagic fever was one of three hemorrhagic fevers and one of more than a dozen agents that the United States researched as potential biological weapons before the nation suspended its biological weapons program. The Soviet Union also conducted research and developing programs on the potential of the hemorragic fever as a biological weapon.
Marburgviruses are World Health Organization Risk Group 4 Pathogens, requiring Biosafety Level 4-equivalent containment, laboratory researchers have to be properly trained in BSL-4 practices and wear proper personal protective equipment.