Monday, October 18, 2010
Monday, October 4, 2010
HISTORY OF EBOLA
Ebola is the virus Ebolavirus (EBOV), a viral genus, and the disease Ebola hemorrhagic fever (EHF), a viral hemorrhagic fever (VHF). The virus is named after the Ebola River Valley in the Democratic Republic of the Congo (formerly Zaire), which is near the site of the first recognized outbreak in 1976 at a mission hospital run by Flemish nuns.[1] It remained largely obscure until 1989 when several widely publicized outbreaks occurred among monkeys in the United States.
The virus interferes with the endothelial cells lining the interior surface of blood vessels and with coagulation. As the blood vessel walls become damaged and destroyed, the platelets are unable to coagulate, patients succumb to hypovolemic shock. Ebola is transmitted through bodily fluids, while conjunctiva exposure may also lead to transmission.
There are five recognized species within the ebolavirus genus, which have a number of specific strains.[2] The Zaire virus is the type species, which is also the first discovered and the most lethal. Electron micrographs show long filaments, characteristic of the Filoviridae viral family.
The virus interferes with the endothelial cells lining the interior surface of blood vessels and with coagulation. As the blood vessel walls become damaged and destroyed, the platelets are unable to coagulate, patients succumb to hypovolemic shock. Ebola is transmitted through bodily fluids, while conjunctiva exposure may also lead to transmission.
There are five recognized species within the ebolavirus genus, which have a number of specific strains.[2] The Zaire virus is the type species, which is also the first discovered and the most lethal. Electron micrographs show long filaments, characteristic of the Filoviridae viral family.
Treatment
There is no standard treatment for Ebola hemorrhagic fever. Treatment is primarily supportive and includes minimizing invasive procedures, balancing electrolytes (since patients are frequently dehydrated), replacing lost coagulation factors to help stop bleeding, maintaining oxygen and blood levels, and treating any complicating infections. Convalescent plasma (factors from those that have survived Ebola infection) shows promise as a treatment for the disease. Ribavirin is ineffective. Interferon is also thought to be ineffective. In monkeys, administration of an inhibitor of coagulation (rNAPc2) has shown some benefit, protecting 33% of infected animals from a usually 100% (for monkeys) lethal infection (however, this inoculation does not work on humans). In early 2006, scientists at USAMRIID announced a 75% recovery rate after infecting four rhesus monkeys with Ebolavirus and administering Morpholino antisense drugs.[33] Development of improved Morpholino antisense conjugated with cell penetrating peptides is ongoing.[34]
A hospital isolation ward in Gulu, Uganda, during the October 2000 outbreak
In May 2010, a group of scientists from the National Emerging Infectious Diseases Laboratories at Boston University announced they had developed a drug containing small interfering RNAs packaged into Stable nucleic acid lipid particles (SNALPs) that prevented reproduction of the virus in monkeys.[35][36] The group's leader Thomas Geisbert claimed the results of the group's study showed their experimental treatment resulted in "complete protection" of monkeys from the virus. Virologist Heinz Feldmann hailed the findings of the study as a "milestone" that could be used to combat similar viruses.[37] Geisbert claimed a lack of market interest could impair the development of the treatment for humans, given the comparatively low number of Ebola cases worldwide.[38] The trial on monkeys had been funded by the United States Department of Defense.[36]
There is no standard treatment for Ebola hemorrhagic fever. Treatment is primarily supportive and includes minimizing invasive procedures, balancing electrolytes (since patients are frequently dehydrated), replacing lost coagulation factors to help stop bleeding, maintaining oxygen and blood levels, and treating any complicating infections. Convalescent plasma (factors from those that have survived Ebola infection) shows promise as a treatment for the disease. Ribavirin is ineffective. Interferon is also thought to be ineffective. In monkeys, administration of an inhibitor of coagulation (rNAPc2) has shown some benefit, protecting 33% of infected animals from a usually 100% (for monkeys) lethal infection (however, this inoculation does not work on humans). In early 2006, scientists at USAMRIID announced a 75% recovery rate after infecting four rhesus monkeys with Ebolavirus and administering Morpholino antisense drugs.[33] Development of improved Morpholino antisense conjugated with cell penetrating peptides is ongoing.[34]
A hospital isolation ward in Gulu, Uganda, during the October 2000 outbreak
In May 2010, a group of scientists from the National Emerging Infectious Diseases Laboratories at Boston University announced they had developed a drug containing small interfering RNAs packaged into Stable nucleic acid lipid particles (SNALPs) that prevented reproduction of the virus in monkeys.[35][36] The group's leader Thomas Geisbert claimed the results of the group's study showed their experimental treatment resulted in "complete protection" of monkeys from the virus. Virologist Heinz Feldmann hailed the findings of the study as a "milestone" that could be used to combat similar viruses.[37] Geisbert claimed a lack of market interest could impair the development of the treatment for humans, given the comparatively low number of Ebola cases worldwide.[38] The trial on monkeys had been funded by the United States Department of Defense.[36]
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