Scientists at Fort Detrick continue probe of Ebola virus found in Texas Army, CDC investigating whether it has spread to 2nd monkey house


FREDERICK -- Government scientists wearing plastic "space suits" planned to work all though last night to determine if the Ebola virus that infected at least two monkeys at a Texas breeding facility had spread to a second monkey house there.

The scientists, at Fort Detrick's U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), continued their probe as Texas health officials began killing 48 monkeys in a building run by a company that supplies animals to research laboratories around the country.

Evidence of Ebola in a second monkey house would force the slaughter of an additional 50 monkeys at the breeding facility, about 40 miles west of Corpus Christi. Army couriers were planning to retrieve a shipment of monkey plasma from an American Airlines flight landing at Dulles Airport in the late afternoon.

The Army and the federal Centers for Disease Control and Prevention are working together to see how widely Ebola has spread through the animal farm. Late last week, they determined that two monkeys kept in the same building were infected with Ebola Reston -- a strain that is infectious to monkeys but not to humans.

Later, USAMRIID tentatively found evidence of filovirus -- the family of threadlike viruses that includes Ebola -- in plasma taken from a monkey living in a nearby building. But the CDC reached the opposite conclusion, prompting the agencies to request additional specimens to see if the virus had indeed spread.

Ebola Reston is named for the strain that swept through a primate facility in Reston, Va., in 1989. That epidemic, resulting in the destruction of a large monkey colony, was the subject of the best seller "The Hot Zone."

Dr. Peter Jahrling, senior scientist at USAMRIID, emphasized yesterday that Ebola Reston is not dangerous to humans -- unlike the Ebola Zaire strain that killed more than 200 people in the Central African country last year.

"It's a bad news problem for the primate colony, but it is not a public health problem," Dr. Jahrling said. The Reston strain was judged not to be infectious after four scientists who were exposed to the virus in 1989 developed antibodies but never got sick.

Nonetheless, scientists handling the monkey specimens continued to take the most extreme precautions known to medical science. They work behind sea-green cinder-block walls, wear blue space suits and breathe filtered air that is piped into their suits through yellow hoses.

"I, for one, am not ready to take off my space suit just because four people in Reston didn't get sick," Dr. Jahrling said. Most of the laboratory work at Fort Detrick is being done by Joan Geisbert, a technician.

The room is under negative air pressure -- meaning that any opening to the outside world would cause air to rush into, not out of the laboratory. Room air is exhausted through filters capable of trapping the smallest viral particles.

The Army's infectious disease institute was designed to study ways to protect U.S. troops from biological weapons that could be unleashed in warfare. But it has increasingly become involved in the study of lethal infections posing risks to civilians.

The institute is one of only five facilities in the world equipped with Biosafety Level Four laboratories, the kind being used to study Ebola. Level Four agents are those for which there are no treatments or vaccines.

Army scientists are relying heavily on the electron microscope, which can detect the threadlike particles that are characteristic of Ebola and other filovirus strains. The CDC is busy deciphering the genetic blueprint of the viruses -- a technique that can distinguish one strain from another.

HRP, a private company, operated the Reston facility as well as the Texas center now under study. In both cases, the firm obtained its monkeys from the same supply house in the Philippines.

Dr. Jahrling said it was unclear if the Reston strain came from the Philippine forests where the monkeys were captured, or if the monkeys caught the virus in captivity from other animals imported from Africa to the Philippines.

Yesterday, the Philippines banned the export of live monkeys. A government official said the ban would remain in effect while a task force investigated breeding farms in that country.

Pub Date: 4/18/96

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