1. Ebola Outbreak – summary of an Honors Thesis from Stanford University Copyright 1999 by Tara Waterman
Reston, VA
Hazelton Research Products
(currently Covance Laboratories)

2. On October 2, 1989, 100 cynomolgus macaques from Ferlite Farms in Mindanao Island, Philippines were flown from Manila, through Amsterdam to New York, and then transported by truck to Hazleton Research Products' (HRP) Reston Primate Quarantine Unit in Reston, Virginia.
These monkeys were placed in Room F of the Reston Unit on October 4. HRP's Reston Unit already had approximately 500 cynomolgus monkeys when this shipment arrived.
Because of the 1976 Marburg incident, all primates imported into the United States must be quarantined for 30 days to insure that they are disease free before they are released. This particular shipment of nonhuman primates had a far larger number of deaths in Room F than would normally have been expected.
The HRP veterinarian conducted a few necropsies of the dead monkeys from this shipment in Room F and, based on the clinical symptomatology and on gross anatomy, made an initial diagnosis of simian hemorrhagic fever (SHF). SHF is a terrible disease in monkeys (fortunately it does not infect humans) and is easily transmitted amongst them.
The HRP vet sent samples of the dead monkey tissue to United States Medical Research Institute of Infectious Diseases (USAMRIID) for conclusive diagnosis. SHF was isolated in the tissue cultures that HRP sent to USAMRIID. Before USAMRIID finished their diagnosis,

3. HRP made the decision to euthanize all of the remaining monkeys in Room F to prevent possible further spread.
During the 10 days following the euthanization of the monkeys in Room F, there were sporadic deaths in the remaining monkey population at Reston. The pattern of the deaths nor the pathology in the dead monkeys was indicative of SHF. The HRP vet became alarmed by this.
Meanwhile, USAMRIID was conducting additional tests on the monkey tissue cultures and discovered that Ebola was also responsible for the Reston monkey deaths from an electron micrograph of damaged tissue from one of the dead Reston monkeys.
Unfortunately, the pathogen was not contained by the euthanization of the monkeys in Room F. 29 additional monkeys in Room H had also died. The monkeys in Room H were from a separate shipment (but from the same supplier, Ferlite Farms) that had arrived at the Reston Unit on November 8. 

4. Were the Room H monkeys contracting the pathogen from the Reston Quarantine Unit or were they infected with the pathogen back in the Philippines?
The Room F monkeys were euthanized on November 16. The Room H shipment of monkeys arrived on November 8. Both the Room F and Room H cynomolgus monkey shipments came from Ferlite Farms in the Philippines. Ferlite Farms was experiencing a hemorrhagic disease outbreak concurrently.
It is likely that the Room H monkeys were sub-clinically harboring EBO on arrival. EBO has an incubation period ranging from five to seven days in nonhuman primates

5. On November 29, the Center for Disease Control (CDC) and the Virginia Department of Health met with USAMRIID, and a coherent plan of action was formulated to insure the safety of the community and the humane treatment of the Reston primates.
Because of the threat that Ebola might spread to the remaining animals in the quarantine unit and that it might infect the staff, the remaining animals (~500) in Room H were euthanized on November 30, 1989.
On November 28, 1989, Ferlite Farms, unknowingly, sent a shipment of EBO-infected cynomolgus monkeys to Philadelphia. 

6. The mode of transmission for the other three handlers is not known.
Six of the 178 people who had contact with the infected monkeys at the Reston Quarantine Unit seroconverted. All six of the individuals worked with the primates. None of the six who seroconverted developed a filovirus-related illness.
Of them, four (all of whom were animal handlers at one quarantine facility) had serologic evidence of recent infection with Ebola-Reston. It is likely that one of the four infected himself when he cut his finger while performing a necropsy on an infected monkey.
The mode of transmission for the other three handlers is not known.
Electron micrograph of Ebola Reston virus taken at the US Army Medical Research Institute ofInfectious Diseases (USAMRIID) by Dr. Tom Geisbert. It was graciously supplied by Dr. Art Anderson.

7. On January 31, 1990, Ferlite Farms sent a shipment of 100 macaques to Hazleton's Texas Primate Center (TPC) in Alice, TX. A day later, 100 monkeys from Ferlite were also sent to HRP's Reston Unit. Within the first week of arrival, the monkeys at both facilities had clinical signs that were identical to the signs during the first Reston outbreak.
The two separate shipments of monkeys from Ferlite to Reston and Alice had no contact after they left Ferlite Farms. From February 1 through March 15, 46 of 52 animals in one of the quarantine rooms died. The surviving six tested positive for filovirus. Necropsy samples from the TPC monkeys were sent to the Center for Disease Control (CDC) for conclusive diagnosis. The CDC determined that the monkeys were co-infected with SHF and Ebola. 

8. Texas outbreak, number 2. In March of 1996, 100 colony raised macaques from Ferlite Farms were shipped from Manila to Houston by way of Hong Kong and Rome. These monkeys arrived to TPC on March 21. On March 27, one of the monkeys from this shipment showed signs of illness and died on March 30. Necropsy of this dead monkey indicated a pneumonic process, and the liver tested positive for Ebola.
On April 10, a second monkey that was housed at the opposite end of the block of cages from the index case became ill. On April 13, this monkey's serum tested positive for Ebola and was sacrificed. (20 days after the monkey arrived and 13 days after the incubation period was over if it contracted EBO from the Philippines).
If the monkeys were quarantined for 30 days prior to being shipped to the US, how come they developed EBO-R once they reached the US? The incubation period of EBO in nonhuman primates is 5-7 days.