April 24, 2004
Contacts (Media Only):
Peper Long, National Zoo 
202-673-0206 or 202-673-0209
Carolyn Martin 202-236-2367
National Zoo Closes Great Ape House and Outdoor Gorilla Yard
The Great Ape House and outdoor gorilla yard were closed to the public late Saturday afternoon, and may remain closed for several weeks as a precautionary measure, due to an inconclusive tuberculosis (TB) test result in a four-year-old male Zoo gorilla.
In making the decision to close the exhibit, National Zoo experts consulted with their colleagues at other zoos and the Smithsonian's occupational health physician, Dr. Thomas Lawford. Zoo officials decided to take extra precaution even though all of the gorillas are clinically healthy at this time, including the young gorilla with the questionable test result.
According to Dr. Lawford, people who have visited the Great Ape House in recent weeks were at little to no risk of contracting TB, even if further tests on the gorilla confirm the bacteria's presence. The likelihood of contracting the disease is remote, because TB is most often transmitted through close contact, such as when an animal or person coughs.
The young gorilla shows no signs of illness and is not coughing. Also, an x-ray taken on the animal showed no signs of infection. This morning, Zoo veterinarians began precautionary medical treatment on the gorilla using isoniazid, an anti-tubercular medicine for animals and humans.
According to the Zoo's policy, staff and volunteers at the Great Ape House are tested annually for TB; they will be re-tested, as a precautionary measure.
On April 14, Zoo veterinarians gave the gorilla a skin test for TB as part of its routine exam. The gorilla's skin was checked after 72 hours for signs of infection, and on April 17, results were inconclusive. On April 23, Zoo veterinarians performed a lung wash to obtain cells and organisms from the gorilla's lungs. This material was sent to a California lab to determine the presence of the TB bacterium. Zoo vets also examined some of the material under the microscope and found a few bacteria suggestive of TB.
Based on that data and consultation with other experts, Zoo officials took added precaution and closed the Great Ape House and outdoor gorilla yard late Saturday afternoon, April 24.
On Monday, April 26, Zoo vets will conduct another test on the gorilla, looking for signs of an immune system response to TB or another bacteria. Results of that immune response test will be known after a week. That test and the previous skin tests will provide data to Zoo veterinarians, but will not provide a conclusive determination. The only definitive test for TB is from the lung wash, because it shows the presence or absence of the actual TB bacterium. Because it can take many weeks for the TB bacteria to grow, the test results from the lung wash will not be known for up to 12 weeks.
At the National Zoo, all gorillas and orangutans are given routine physical exams that include a skin test for TB. All recent TB tests have been negative.
Zoo officials decided it was important for the gorillas to have regular access to their outdoor yards to maintain their well-being. Thus, visitors will not be allowed in those viewing areas. Orangutans that are usually on exhibit in the Great Ape House separate from gorillas will have access to outdoor yards and to the O-Line.
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