Work

Multiple Introductions of Avian Influenza Viruses (H5N1), Laos, 2009–2010

Year: 2012

Type: article

Abstract: Avian infl uenza viruses (H5N1) of clades 2.3.4.1, 2.3.4.2, and 2.3.2.1 were introduced into Laos in 2009-2010.To investigate these viruses, we conducted active surveillance of poultry during March 2010.We detected viruses throughout Laos, including several interclade reassortants and 2 subgroups of clade 2.3.4,one of which caused an outbreak in May 2010.S ince 2003, highly pathogenic avian infl uenza virus (H5N1) has spread from southern China throughout Southeast Asia and to Europe and Africa (1,2).Since 2003, Laos has experienced outbreaks of clade 1 (2003), clade 2.3.4 (2006, 2007, 2008, 2009, 2010), and clade 2.3.2 viruses (twice in 2008) (3,4).Active surveillance of domestic ducks and chickens in Laos has been limited, but serum antibodies against subtypes H5 and H9 have been detected in ducks.In addition, subtype H5N1 virus was isolated from healthy ducks in 2006, and subtype H3N8 virus was detected in 2007 (4,5).To explore the diversity, extent, and endemicity of avian infl uenza viruses in Laos, we conducted a survey of healthy domestic poultry throughout the country in March 2010. The StudySerum samples were collected in 9 of 17 provinces in Laos from healthy ducks and chickens in live-bird markets, village backyard fl ocks, and layer duck farms.Cloacal, tracheal, and environmental (fecal and water) swab specimens were also collected and placed immediately in transport medium (Figure).Swab specimens were screened in pools of 4 by using a real-time reverse transcription PCR for the matrix (M) gene segment (6).Positive pools were reextracted individually, retested, tested for hemagglutinin 5 (H5) by real-time reverse transcription PCR (7), and injected into 10-11-day-old embryonated chicken eggs.Sequencing was conducted by using an Illumina (San Diego, CA, USA) platform (swabs and isolates) (8,9) and conventional Sanger sequencing (isolates).Illumina reads were fi rst mapped to a database of publicly available human, avian, and swine infl uenza virus reference sequences from the Western Hemisphere Americas and Eurasia, and then remapped against references with the highest number of reads and best average coverage.Final average coverage varied between samples and segments with ranges of 123-24,163 (9 samples), 21-18,671 (12 samples) and 9-436 for sample A/duck/Lao/670/10.Isolate genotypes were verifi ed by using Sanger

Source: Emerging infectious diseases

DOI: 10.3201/eid1807.111642