Three workers from Jakarta´s Ragunan Zoo have been hospitalized with suspected H5N1 avian influenza, increasing the number of suspected human cases in Indonesia to as many as seven, according to news services.

The zoo was closed yesterday after 19 captive birds tested positive for the H5N1 virus. The ailing zoo workers include a 28-year-old guide and a 39-year-old vendor, the Associated Press (AP) reported in a statement attributed to I Nyoman Kandun, Indonesia´s director general of communicable disease control. A Reuters report today said a third person from the zoo, also a food worker, was hospitalized late last night.

The latest cases apparently bring the number of suspected case-patients in Indonesia to seven. But Reuters quoted Indonesian Health Minister Siti Fadilah Supari as saying only six people have been hospitalized.

On Sep 16, officials confirmed that the death of a 37-year-old woman from Jakarta a few days earlier was due to H5N1 avian flu. As of yesterday, news services were reporting that four children had been hospitalized with suspected cases. They included two girls, aged 3 and 6; a 7-year-old; and a 9-year-old boy who is related to the 37-year-old victim.

Initial tests on two children were positive for H5N1, Reuters reported. Blood samples from the patients were being tested in Hong Kong, the story said.

Yesterday the government declared that the avian flu situation was an "extraordinary" health incident. That declaration, which expires in 21 days but can be renewed, allows for forced hospitalization of people who have possible avian flu symptoms, the AP said. Forty-four hospitals have been designated to treat avian flu patients. Those patients will receive free medication, Supari told the AP.

Government officials sought to maintain calm today, balancing expressions of confidence that they could handle the situation with statements aimed at educating people about the problem and its seriousness.

The state of high alert "is to calm people, not to bring more panic," Reuters quoted Supari as saying.

Haryadi Wibisono, a director of disease control at the country´s health ministry, told Agence France-Presse (AFP), "This is a serious problem for Indonesia and the whole world and therefore it should be dealt with seriously."

Ragunan Zoo, the chief zoo in bustling Jakarta, was to be closed for 3 weeks to allow for testing of animals and workers. Of the 500 zoo employees, 143 have been identified as being at high risk for exposure to the virus, the Jakarta Post said today. The city has a population of 12 million, with another 9 million in outlying towns, according to Nature magazine.

Besides the 37-year-old woman, other reported cases of avian flu in Indonesia have included a 38-year-old man and his two daughters who died in July, plus a farm worker who tested positive for antibodies to the virus last March, though he had not been sick. However, the World Health Organization (WHO) recognizes only the 37-year-old woman and 38-year-old man as laboratory-confirmed cases.

Indonesia´s spate of possible cases comes as the WHO is warning that the world would have little time to respond to signs of an emerging flu pandemic, AFP and Reuters reported today.

"There´s a very short time period—2 to 4 weeks between the onset of the first case—in which containment is possible," Hitoshi Oshitani, a WHO communicable disease expert, said today in an address to the WHO´s Regional Committee for the Western Pacific in Noumea, New Caledonia.

In comparing pandemic flu to SARS, Oshitani said, "The pandemic virus is much more difficult, maybe impossible, to contain once it starts."