Efforts to monitor avian influenza in Asia continue to be hampered by a lack of viral sequence data from China, a World Health Organization (WHO) expert told
Julie Hall, WHO coordinator for communicable disease surveillance and response in China, was among 17 experts from WHO, the Food and Agriculture Organization (FAO), and the Chinese government who visited remote Qinghai province last week to investigate the deaths of more than 1,000 wild birds at a nature reserve.
"We would like the data in as timely a manner as possible. The government has shared data with us before so we are confident they will do so again," she said. "It's very important to get the sequence data for the development of diagnostic reagents and to compare it with the Vietnamese strain and [to fulfill] China's request for us to check the sensitivity of the China-made primers. Even more importantly, we need to see if the PCR primers developed by WHO, China, and other countries are sensitive enough to detect it in humans," she said.
The joint mission of experts who visited the northwestern province last week said that Chinese authorities have acted fast to contain the outbreak among wild birds in Qinghai, but that more needs to be done in terms of surveillance and testing.
"We felt there was some lack in the sampling of wild birds, surveillance of domestic birds and understanding of migratory routes, and we understand that the ministries will request international assistance [in these areas]," Noureddin Mona, the FAO's Beijing-based representative to China, Mongolia and North Korea, told
The area affected by the outbreak has been sealed off, domestic poultry within a 20-mile radius has been culled, and all other poultry in the province has been vaccinated. Fever clinics have been set up and people in close contact with poultry are being screened for signs of fever or flu. Samples from the five species of bird affected have all been tested for H5N1, but the other 184 species on the lake have not.
"We don't know if there are other migratory species that have been infected and are asymptomatic," said Hall. "Also, there have been no reported cases in domestic animals but only limited sampling of poultry. No vaccine is 100% effective and it's important that vaccinated birds are under surveillance."
Attendance at fever clinics is low and laboratory testing is suboptimal, said Hall. "Experience in Vietnam has shown that this is quite a difficult disease to test for. We recommend triple testing including virus culture, serology and real-time PCR using a variety of primers with the results cross-checked with the virus circulating in animals."
The ability to check samples in Centers for Disease Control and Prevention facilities in the United States and at another of the WHO's Collaborating Center Network laboratories in Japan is significant because it will help to ensure that any results generated within Vietnam are accurate and have not been contaminated in the process of testing.
"It is essential that recent avian influenza information in Vietnam be shared with the global community," said Hans Troedsson, WHO's representative in Vietnam, in a statement.