Reston ebolavirus

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Reston ebolavirus
Virus classification
Group:	Group V ((-)ssRNA)
Order:	Mononegavirales
Family:	Filovirus
Genus:	Ebolavirus
Species:	Reston ebolavirus

The Reston ebolavirus (REBOV), previously classified as Reston Ebola virus—also referred to as Ebola Reston, Reston virus, or Asian filovirus—is classified as a species of the Ebola. It was discovered in crab-eating macaques from Hazleton Laboratories (now Covance)^[A] in 1989. This attracted significant media attention. Despite its status as a level-4 organism, the Reston ebolavirus is non-pathogenic to humans however hazardous to monkeys;^[1][2] the perception of its lethality was confounded due to the monkey's coinfection with Simian hemorrhagic fever virus (SHFV).^[3]

[edit] History

[edit] Discovery

While investigating on an outbreak of Simian hemorrhagic fever (SHFV) in the November of 1989, an electron microscopist from USAMRIID discovered filoviruses similar in appearance to Ebola in tissue samples taken from Crab-eating Macaque imported from the Philippines to Hazleton Laboratories in Reston, Virginia. The filovirus was further isolated by Dr. Peter B. Jahrling, and over the period of three months over a third of the monkeys died—at a rate two or three a day.^[4]

Blood samples were taken from 178 animal handlers during the incident.^[5] Of them, six eventually became seroconverted^[B] and tested positive for a filovirus antigen using the ELISA test. They remained asymptomatic. In January 1990, an animal handler at Hazelton cut himself while performing a necropsy on the liver of an infected Cynomolgus. Under the direction of the Center for Disease Control and Prevention (CDC) the animal handler was placed under surveillance for the duration of the incubation period. When the animal handler failed to become ill, it was concluded that the virus had a low pathogenicity to humans.^[6]

[edit] Investigation

Cynomolgus, or Crab-eating Macaques, imported from the Philippines were found to be carrying the filovirus.

Following the discovery of the filovirus in Crab-eating Macaques, an investigation tracing the infection was conducted by the CDC. The monkeys were imported from the Philippines, which had no previous record of SHFV or Ebola infections. It was suspected that the monkeys contracted both diseases while in transit aboard KLM airlines before reaching Reston. Shipments were tracked to New York City, Texas, and Mexico City, none of which produced cases of infection.^[7][C]

By January 1990, Hazelton Laboratories recovered from its previous losses and began importing monkeys again from the same establishment in Manila that had provided the original animals. The imported monkeys became infected and were euthanized.^[5] In early February the CDC received reports of the disease in Alice, Texas. In March the Division of Quarantine at the CDC secured a temporary ban on the importation of monkeys into the United States from anywhere in the world.^[8]

Following the announcement of the Ebola outbreak in Reston, Virginia, a serosurvey was conducted to assess the prevalence of the infection. Of the several hundred serums received by the CDC, approximately ten percent showed some reaction to the Ebola virus antigen—though usually at low levels.^[D][E] Counterintuitively, the majority of the monkeys found positive were from Indonesia.^[9]

In May 1990 an investigation led by Susan Fisher-Hoch, Steve Ostroff, and Jerry Jennings was sent to Indonesia. During the investigation, it was hypothesized that there could be a cross infection since monkeys suspected of illness were typically placed in gang cages containing up to twenty to thirty other monkeys suspected of illness. Upon arrival they were told that most of the monkeys were imported from the island of Sumatra. The investigation team found no trace of the virus in either case.^[10]

Following the investigation in Indonesia, an experiment was conducted in the level-4 lab at the CDC campus in DeKalb County, Georgia with thirty-two monkeys: sixteen Green monkeys (Cercopithecus aethiops) and sixteen Crab-eating Macaques. Half of the sixteen Green monkeys and Crab-eating Macaques were infected with the Asian filovirus (Ebolavirus Reston ebolavirus) and the other half with an African filovirus (Ebolavirus Zaire virus). The African filovirus was lethal to nearly all monkeys. However, most of the monkeys infected with the Asian strain recovered in a month. The surviving monkeys were kept for two years to detect any trace of the virus - none was found. However, the monkeys continued to possess a high level of antigen.^[3]

[edit] Post-Reston

Following the test at the CDC campus in DeKalb County, Georgia, two of the monkeys who have survived the Asian filovirus were infected with a very large dose of the Zaire ebolavirus in an effort to produce an Ebola vaccine. One of the two monkeys remained resistant, the second died.^[3]

The physical building in which the outbreak occurred was demolished on 30 May 1995 and a new building constructed in its place. This facility, which is part of the Isaac Newton Square office park, became a Kindercare and is a Mulberry Child Care and preschool center as of 2007.^{[citation needed]}

The virus reemerged in Italy in 1992, and again in a monkey export facility in the Philippines in 1996.

On 11 December 2008, pigs from farms slightly north of Manila, Philippines tested positive for the virus. The CDC and the World Health Organization are investigating.^[11] On 23 January 2009, Philippine health officials announced that a hog farm worker had been infected with the virus. Although the man was asymptomatic and the source of the infection is uncertain, this could represent the first case of pig-to-human transmission of the Reston ebolavirus—a fact that could cause concern, as pigs may be able to transmit more deadly diseases to humans. The situation is undergoing further investigation.^[12]

[edit] Notes

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