Swine influenza surveillance in East and Southeast Asia: a systematic review

East and Southeast Asia are important pig- and poultry-producing areas, where the majority of production takes place on small-scale farms with low biosecurity levels. This systematic review synthesizes data on swine influenza virology, serology and epidemiology in East and Southeast Asia. A total of 77 research articles, literature reviews and conference papers were selected and analyzed from 510 references retrieved from PubMed and ISI Web of KnowledgeSM. The number of published articles increased in the last 3 years, which may be attributed to improvement in monitoring and/or a better promotion of surveillance data. Nevertheless, large inequalities in surveillance and research among countries are underlined. Virological results represent the largest part of published data, while the serological and epidemiological features of swine influenza in East and Southeast Asia remain poorly described. The literature shows that there have been several emergences of swine influenza in the region, and also considerable evidence of multiple introductions of North American and avian-like European strains. Furthermore, several avian-origin strains are isolated from pigs, including H5 and H9 subtypes. However, their low seroprevalence in swine also shows that pigs remain poorly infected by these subtypes. We conclude that sero-epidemioligical investigations have been neglected, and that they may help to improve virological surveillance. Inter- and intra-continental surveillance of gene flows will benefit the region. Greater investment is needed in swine influenza surveillance, to improve our knowledge of circulating strains as well as the epidemiology and disease burden in the region.published_or_final_versio

A case-control study to identify risk factors associated with avian influenza subtype H9N2 on commercial poultry farms in Pakistan

A 1:1 matched case-control study was conducted to identify risk factors for avian influenza subtype H9N2 infection on commercial poultry farms in 16 districts of Punjab, and 1 administrative unit of Pakistan. One hundred and thirty-three laboratory confirmed positive case farms were matched on the date of sample submission with 133 negative control farms. The association between a series of farm-level characteristics and the presence or absence of H9N2 was assessed by univariable analysis. Characteristics associated with H9N2 risk that passed the initial screening were included in a multivariable conditional logistic regression model. Manual and automated approaches were used, which produced similar models. Key risk factors from all approaches included selling of eggs/birds directly to live bird retail stalls, being near case/infected farms, a previous history of infectious bursal disease (IBD) on the farm and having cover on the water storage tanks. The findings of current study are in line with results of many other studies conducted in various countries to identify similar risk factors for AI subtype H9N2 infection. Enhancing protective measures and controlling risks identified in this study could reduce spread of AI subtype H9N2 and other AI viruses between poultry farms in Pakistan

Preliminary laboratory results of an epidemiological study on avian and swine influenza in Vietnam

Poster PresentationThe Program can be viewed at: http://pasteur-network-meeting.org/KH2011/Downloads/PROGRAMME_FINAL.pdfBackground: To study the pig-poultry interspecies transmission, the French Agricultural Research Center for International Development (CIRAD) carried out a cross-sectional survey in pig and poultry farms and a longitudinal study in a local pig slaughterhouse in North Vietnam from April 2009 to February 2010. The preliminary laboratory results of this study are presented here. A screening of sera by a commercial competitive enzyme-linked immunosorbent assay (cELISA) for influenza A was done in Vietnam, and further serological analyses on cELISA positive sera and virological analyses were performed in the Pasteur Research Centre in Hong Kong. Results: A total of 2340 pigs were sampled in farms and 678 in slaughterhouse, with 22.3% positive by cELISA in farms, and 37.2% in slaughterhouse; 1554 poultry (ducks and chickens) were sampled in farms, with 30.4% positive by cELISA. In Hong Kong, 710 pigs and 37 poultry swabs were analyzed by isolation in cell culture and quantitative reverse transcription polymerase chain reaction (qRT-PCR), and 677 pigs and 472 poultry cELISA positive sera by hemagglutination inhibition (HI) tests and H5 pseudoparticle-based seroneutralization assay (H5pp). No virus was isolated nor detected by qRT-PCR in swabs from pigs and poultry. Among pigs, 13.3% of sera in farms and 17.6% in slaughterhouse were positive for at least one strain tested, 19.1% for poultry sera. According to the considered subsets, 5.5% to 11.3% of sera were positive by cELISA but remained negative by HI test and H5pp assay for the tested strains. Pig sera were tested positive against strains of H1N1 (12.1% in farms, 17.1% in slaughterhouse), H9N2 (1.7% in farms, 1.2% in slaughterhouse), and H5N1 (0.7% in farms, 0.1% in slaughterhouse), HI tests did not reveal evidence of infection by a H3 subtype. For poultry, some sera were positive against H5N1 (11.8%) and H9N2 (9.7%) strains, but no positive serum against H6 strains was detected. Sera in pigs and poultry were found to cross-react between several subtypes and strains within a subtype. Conclusion: Several strains were found in both pigs and poultry sera, suggesting the occurrence of inter-species transmission. The interpretation of analyses can be challenging due to the lack of information on the viral strains circulating in field and to the potential cross-reaction between different strains. Further analyses are carried out in order to identify the possible circulation of other strains and to evaluate the performance of the cELISA

Evidence for freedom from swine influenza in a remote area of Northern Vietnam

Swine influenza is responsible for one of the most prevalent disease affecting the swine industry worldwide. Epidemiological surveys rarely focus on remote areas, because traditional farming systems characterized by locally consumed production and low pig densities are considered as having little influence on the emergence, re-emergence, persistence or spread of swine influenza viruses. In addition, routine disease investigations in remote areas are often neglected due to logistic and economical constraints. A bank of swine sera collected in 2005 in the ethnic minorities households of Ha Giang province (Northern Vietnam) located adjacent to the Chinese border was analyzed to estimate the seroprevalence of swine influenza (SI) and to identify potential risk factors for infection. The results suggest that this specific agro-ecological system is free from SI and is not favourable to SI spread either through pig-to-pig transmission, or through poultry-to-pig transmission. © 2011 Elsevier B.V

Evidence for freedom from swine influenza in a remote area of Northern Vietnam

Swine influenza is responsible for one of the most prevalent disease affecting the swine industry worldwide. Epidemiological surveys rarely focus on remote areas, because traditional farming systems characterized by locally consumed production and low pig densities are considered as having little influence on the emergence, re-emergence, persistence or spread of swine influenza viruses. In addition, routine disease investigations in remote areas are often neglected due to logistic and economical constraints. A bank of swine sera collected in 2005 in the ethnic minorities households of Ha Giang province (Northern Vietnam) located adjacent to the Chinese border was analyzed to estimate the seroprevalence of swine influenza (SI) and to identify potential risk factors for infection. The results suggest that this specific agro-ecological system is free from SI and is not favourable to SI spread either through pig-to-pig transmission, or through poultry-to-pig transmission

Looking for avian influenza in remote areas. A case study in Northern Vietnam

Epidemiological surveys of avian influenza infections rarely focus on backyard poultry systems in remote locations because areas with low levels of poultry production are considered to have little influence on the emergence, re-emergence, persistence or spread of avian influenza viruses. In addition, routine disease investigations in remote areas often are neglected due to the lower availability and relatively high cost of veterinary services there. A bank of avian sera collected in 2005 from ethnic minority households in Ha Giang province (Northern Vietnam), located on the Chinese border, was analysed to estimate the seroprevalence of avian influenza virus (AIV) during a H5N1 epidemic and to identify potential risk factors for infection. The results suggest that the chicken population had been exposed to AIV with a seroprevalence rate of 7.2% [1.45; 10.5]. The H5 and H9 subtypes were identified with a seroprevalence of 3.25% [2.39; 4.11] and 1.12% [0.61; 1.63], respectively. The number of inhabitants in a village and the distance to the main national road were the most influential risk factors of AIV infection, and high-risk clusters were located along the road leading to China. These two results suggest a virus spread through commercial poultry exchanges and a possible introduction of AIV from southern China. Remote areas and small-scale farms may play an under-estimated role in the spread and persistence of AIV. © 2011 Elsevier B.V. All rights reserved.Article in Pres

Transmission of pandemic influenza H1N1 (2009) in Vietnamese swine in 2009-2010

The pandemic of 2009 was caused by an H1N1 (H1N1pdm) virus of swine origin. This pandemic virus has repeatedly infected swine through reverse zoonosis, although the extent of such infection in swine remains unclear. Objective This study targets small and commercial pig producers in North Vietnam, in order to estimate the extent of H1N1pdm infection in swine and to identify the risk factors of infection. Methods Virologic and serologic surveillance of swine was carried out in 2009-2010 in pig farms (38 swabs and 1732 sera) and at a pig slaughterhouse (710 swabs and 459 sera) in North Vietnam. The sera were screened using a influenza type A-reactive ELISA assay, and positive sera were tested using hemagglutination inhibition tests for antibody to a panel of H1-subtype viruses representing pandemic (H1N1) 2009 (H1N1pdm), triple reassortant (TRIG), classical swine (CS), and Eurasian avian-like (EA) swine lineages. Farm-level risk factors were identified using a zero-inflated negative binomial model. Results We found a maximal seroprevalence of H1N1pdm of 55·6% [95% CI: 38·1-72·1] in the slaughterhouse at the end of December 2009, 2weeks after the peak of reported human fatalities with H1N1pdm. Farm-level seroprevalence was 29% [95% CI: 23·2-35·7]. In seropositive farms, within-herd seroprevalence ranged from 10 to 100%. We identified an increased risk of infection for farms that specialized in fattening and a decreased risk of infection in farms hiring external swine workers. Conclusions Our findings suggest extensive reverse-zoonotic transmission from humans to pigs with subsequent onward transmission within pig herds. © 2011 Blackwell Publishing Ltd.link_to_subscribed_fulltex

Vectopole Sud, a french network of platforms for research in medical, veterinary and agricultural entomology

Six institutional partners, CIRAD, CNRS, EID Méditerranée, INRA, IRD and the Univer-sity of Montpellier have been working together since 2010 on the issue of arthropod vectors of pathogens that cause infectious diseases in humans and animals, and insect pests responsible for damages to crops. This collaboration for over 8 years has resulted in the creation of “Vectopole Sud”, a Montpellier network of platforms dedicated to re-searches on arthropods of medical, veterinary and agricultural importance. The network draws from the infrastructure and expertise of each partner to improve early warning systems, monitoring, control of pests and vectors in order to protect hu-man health, agriculture and livestock production. The network has received continuous funding by the French Government and the Occitanie Region enabling it to modernize its different laboratories and rearing facilities and support the research activities. Vectopole Sud includes four experimental platforms, confined insectariums and associ-ated laboratories, which are open to national and international partners. Overall, the Vec-topole Sud has a network of partners in Europe and tropical regions worldwide, notably through IRD and CIRAD, two French institutions supporting research for development. Vectopole Sud brings together over 400 researchers and technicians from five research units belonging to the Montpellier University of Excellence and Agropolis International scientific communities. It conducts multidisciplinary research and expertise on biolo-gy, public & animal health, ecology, environmental science, genetics, and evolutionary medicine. It contributes to a better environment, animal health and human wellbeing through an integrated One Health approach, by fighting human and animal diseases to ensure more productive and sustainable farming systems (food security). We will present the different platforms of the Vectopole Sud network, its various activi-ties (infrastructures, research, services and training) as well as its different perspectives. www.vectopole-sud.f