emerging diseases. (This program and its subordinate elements are discussed in more detail in the research and training section later in this chapter.)
The CDC's participation in the WHO global influenza surveillance network. Information obtained through the network allows the CDC to predict the potential impact of influenza on the United States in any given year. This information is crucial for influenza vaccine manufacturers, who need a minimum of six months' lead time to prepare and distribute adequate quantities of new vaccine.
As part of its international efforts, the CDC produces and sends (free of charge) WHO influenza virus detection and identification kits to 117 foreign national WHO collaborating laboratories and to 68 U.S. collaborating laboratories. These laboratories collect and identify influenza virus isolates and forward information about their findings, as well as actual virus samples, to the CDC on a weekly basis. The CDC also receives influenza virus isolates and information from about 50 foreign laboratories, provides the WHO with information collected from U.S. collaborating laboratories, and receives weekly reports from the WHO on the level of influenza activity in the other reporting countries.
Laboratories and research groups in several key areas of the world, such as the People's Republic of China, Hong Kong, Singapore, and the Pacific Basin, the areas in which most new strains originate, are also in regular contact with the CDC. Recently, the global influenza surveillance system improved its coverage of the Far East. In cooperation with the Chinese National Influenza Center in Beijing, the CDC has supported a national surveillance network in the People's Republic of China. This network has greatly increased the number and timeliness of influenza isolates that are available for analysis at the CDC from that country.
The CDC's foreign field stations. Similar to the previously mentioned NIAID ICTDR program, the CDC overseas affiliates (see Table 3-2 above) provide passive surveillance information and expertise that is available to the host country for assistance in investigating outbreaks.
Rockefeller Foundation's International Clinical Epidemiology Network. The network trains physicians from other nations in medical epidemiology, including infectious disease epidemiology. Through these efforts, a continuing interaction with U.S. universities is fostered, and collaborative activities aimed at infectious disease surveillance and response to emerging diseases are possible. (This program is discussed in greater detail in the research and training section later in this chapter.)
USAID-supported International Center for Diarrheal Disease Research, Bangladesh (ICDDR, B). Of almost equal importance to its contributions in cholera epidemiology and treatment have been the pioneering efforts of this laboratory in the surveillance of diarrheal diseases throughout the Asian