Detecting influenza and emerging avian influenza virus by influenza and pneumonia surveillance systems in a large city in China, 2005 to 2016.

BACKGROUND: Detecting avian influenza virus has become an important public health strategy for controlling the emerging infectious disease. METHODS: The HIS (hospital information system) modified influenza surveillance system (ISS) and a newly built pneumonia surveillance system (PSS) were used to monitor the influenza viruses in Changsha City, China. The ISS was used to monitor outpatients in two sentinel hospitals and to detect mild influenza and avian influenza cases, and PSS was used to monitor inpatients in 49 hospitals and to detect severe and death influenza cases. RESULTS: From 2005 to 2016, there were 3,551,917 outpatients monitored by the ISS system, among whom 126,076 were influenza-like illness (ILI) cases, with the ILI proportion (ILI%) of 3.55%. After the HIS was used, the reported incident cases of ILI and ILI% were increased significantly. From March, 2009 to September, 2016, there were 5,491,560 inpatient cases monitored by the PSS system, among which 362,743 were pneumonia cases, with a proportion of 6.61%. Among pneumonia cases, about 10.55% (38,260/362,743) of cases were severe or death cases. The pneumonia incidence increased each year in the city. Among 15 avian influenza cases reported from January, 2005 to September, 2016, there were 26.7% (4/15) mild cases detected by the HIS-modified ISS system, while 60.0% (9/15) were severe or death cases detected by the PSS system. Two H5N1 severe cases were missed by the ISS system in January, 2009 when the PSS system was not available. CONCLUSIONS: The HIS was able to improve the efficiency of the ISS for monitoring ILI and emerging avian influenza virus. However, the efficiency of the system needs to be verified in a wider area for a longer time span in China.

Estimating the transmissibility of hand, foot, and mouth disease by a dynamic model.

OBJECTIVE: Hand, foot, and mouth disease (HFMD) is a serious public health issue in many countries; however, its transmissibility in county-level outbreaks remains unclear. The aim of this study is to estimate the transmissibility of HFMD epidemics on both city level and county level, for a better understanding of the transmission dynamics of HFMD epidemics. STUDY DESIGN: Simulation based on data obtained from the China Information System for Disease Control and Prevention. METHODS: The weekly number of reported HFMD cases from April 2009 to December 2017 in nine regions of Changsha City was collected. A susceptible-infectious-recovered model was used to estimate the transmissibility of HFMD. The reproduction number of reported cases during the ascending (denoted as Rasc) and descending (denoted as Rdes) period was used to describe the transmissibility of HFMD. RESULTS: The Rasc and Rdes for HFMD in Changsha was 1.44 (95% confidence interval [CI]: 1.41-1.48) and 0.71 (95% CI: 0.69-0.73), respectively. There was no statistical significance of Rasc values among nine regions (F = 1.056, P = 0.396), nor of Rdes values among nine regions (F = 1.676, P = 0.106). The average Rasc (1.53, 95% CI: 1.46-1.61) from 2009 to 2012 was higher than the one (1.37, 95% CI: 1.34-1.40) from 2013 to 2017 (t = 3.974, P < 0.001), but the average Rdes (0.67, 95% CI: 0.63-0.70) from 2009 to 2012 was lower than the one (0.74, 95% CI: 0.73-0.76) from 2013 to 2017 (t = -3.751, P < 0.001). CONCLUSIONS: The epidemic of HFMD in Changsha City is still grim, and integrated strategies should be taken for controlling and preventing HFMD.

Rabies Virus Transmission in Solid Organ Transplantation, China, 2015-2016.

We report rabies virus transmission among solid organ transplantation recipients in Changsha, China, in 2016. Two recipients were confirmed to have rabies and died. Our findings suggest that more attention should be paid to the possibility of rabies virus transmission through organ transplantation for clinical and public health reasons.

Evidence-Based interventions of Norovirus outbreaks in China.

BACKGROUND: In resource-limited settings where laboratory capacity is limited and response strategy is non-specific, delayed or inappropriate intervention against outbreaks of Norovirus (NoV) are common. Here we report interventions of two norovirus outbreaks, which highlight the importance of evidence-based modeling and assessment to identify infection sources and formulate effective response strategies. METHODS: Spatiotemporal scanning, mathematical and random walk modeling predicted the modes of transmission in the two incidents, which were supported by laboratory results and intervention outcomes. RESULTS: Simulation results indicated that contaminated water was 14 to 500 fold more infectious than infected individuals. Asymptomatic individuals were not effective transmitters. School closure for up to a week still could not contain the outbreak unless the duration was extended to 10 or more days. The total attack rates (TARs) for waterborne NoV outbreaks reported in China (n = 3, median = 4.37) were significantly (p < 0.05) lower than worldwide (n = 14, median = 41.34). The low TARs are likely due to the high number of the affected population. CONCLUSIONS: We found that school closure alone could not contain Norovirus outbreaks. Overlooked personal hygiene may serve as a hotbed for infectious disease transmission. Our results reveal that evidence-based investigations can facilitate timely interventions of Norovirus transmission.

Influenza A (H1N1) transmission by road traffic between cities and towns.

Influenza A (H1N1) was spread widely between cities and towns by road traffic and had a major impact on public health in China in 2009. Understanding regulation of its transmission is of great significance with urbanization ongoing and for mitigation of damage by the epidemic. We analyzed influenza A (H1N1) spatiotemporal transmission and risk factors along roads in Changsha, and combined diffusion velocity and floating population size to construct an epidemic diffusion model to simulate its transmission between cities and towns. The results showed that areas along the highways and road intersections had a higher incidence rate than other areas. Expressways and county roads played an important role in the rapid development stage and the epidemic peak, respectively, and intercity bus stations showed a high risk of disease transmission. The model simulates the intensity and center of disease outbreaks in cities and towns, and provides a more complete simulation of the disease spatiotemporal process than other models.

[The warning model and influence of climatic changes on hemorrhagic fever with renal syndrome in Changsha city].

OBJECTIVE: To realize the influence of climatic changes on the transmission of hemorrhagic fever with renal syndrome (HFRS), and to explore the adoption of climatic factors in warning HFRS. METHODS: A total of 2171 cases of HFRS and the synchronous climatic data in Changsha from 2000 to 2009 were collected to a climate-based forecasting model for HFRS transmission. The Cochran-Armitage trend test was employed to explore the variation trend of the annual incidence of HFRS. Cross-correlations analysis was then adopted to assess the time-lag period between the climatic factors, including monthly average temperature, relative humidity, rainfall and Multivariate Elño-Southern Oscillation Index (MEI) and the monthly HFRS cases. Finally the time-series Poisson regression model was constructed to analyze the influence of different climatic factors on the HFRS transmission. RESULTS: The annual incidence of HFRS in Changsha between 2000 - 2009 was 13.09/100 000 (755 cases), 9.92/100 000 (578 cases), 5.02/100 000 (294 cases), 2.55/100 000 (150 cases), 1.13/100 000 (67 cases), 1.16/100 000 (70 cases), 0.95/100 000 (58 cases), 1.40/100 000 (87 cases), 0.75/100 000 (47 cases) and 1.02/100 000 (65 cases), respectively. The incidence showed a decline during these years (Z = -5.78, P < 0.01). The results of Poisson regression model indicated that the monthly average temperature (18.00°C, r = 0.26, P < 0.01, 1-month lag period; IRR = 1.02, 95%CI: 1.00 - 1.03, P < 0.01), relative humidity (75.50%, r = 0.62, P < 0.01, 3-month lag period; IRR = 1.03, 95%CI: 1.02 - 1.04, P < 0.01), rainfall (112.40 mm, r = 0.25, P < 0.01, 6-month lag period; IRR = 1.01, 95CI: 1.01 - 1.02, P = 0.02), and MEI (r = 0.31, P < 0.01, 3-month lag period; IRR = 0.77, 95CI: 0.67 - 0.88, P < 0.01) were closely associated with monthly HFRS cases (18.10 cases). CONCLUSION: Climate factors significantly influence the incidence of HFRS. If the influence of variable-autocorrelation, seasonality, and long-term trend were controlled, the accuracy of forecasting by the time-series Poisson regression model in Changsha would be comparatively high, and we could forecast the incidence of HFRS in advance.

Hand, foot, and mouth disease in Changsha City, China, 2009-2017: a new method to analyse the epidemiological characteristics of the disease.

Objectives: By adopting a new method, this study aimed to analyse the epidemiological characteristics of hand, foot, and mouth disease (HFMD) in nine districts and counties (cities) of Changsha City, China, from 2009 to 2017.Methods: The reported HFMD cases were collected in Changsha from 2009 to 2017. The traditional descriptive method and a new method (index system) including six indices (richness index N, Simpson diversity index D, Shannon diversity index H, Berger-Parker dominance index d, Shannon evenness index E, and Morisita-Horn similarity index C) were used to describe the epidemiological characteristics of HFMD in Changsha.Results: There were 214155 HFMD reported in Changsha during the study period. The incidence of the disease was higher in even-numbered years (2010, 2012, 2014, and 2016) than in uneven-numbered years (2009, 2011, 2013, 2015, and 2017), with two peaks in May to June and October to November every year. The age of onset was mainly from 0 to 5 years old, and the death was mainly from 0 to 2 years old. According to occupational classification, districts and counties (cities) had a high degree of similarity of the composition of HFMD, and there was no regional difference.Conclusions: Changsha had a yearly increasing trend of HFMD from 2009 to 2017, and the key population for prevention and control was children aged in 0-5 years old. Seasonal distribution of high incidence and peak incidence were occurred in even-numbered years. The sub-regions of the city shared moderate diversity and high similarity of occupational distribution of HFMD.

Clinical and epidemiological characteristics of a young child infected with avian influenza A (H9N2) virus in China.

Three cases of the avian influenza A (H9N2) virus have been documented in Changsha, which is a large city that has nine districts and a population of 7.04 million in central South China. Among these patients, one was a girl and two were boys. The ages of the patients were 9 months, 2 years, and 15 years. Two cases of H9N2 were detected in September, 2015 and one was detected in 2017. Two patients were children who had not reached the age for kindergarten and one was a student. These three cases were all mild and were detected in a sentinel hospital of the Chinese Influenza Surveillance System. We describe the clinical and epidemiological features of the youngest patient with H9N2 in 2017 and the surveillance results of the H9N2 virus in live poultry markets in Changsha. From January 2014 to December 2017, 4212 samples were collected in live poultry markets in Changsha, among which 25.81% (1087/4212) were H9N2-positive. Public health concerns should be addressed for emerging H9N2 virus infection, and more strategies should be performed before this virus mutates to be more transmissible and highly pathogenic.

Evaluating the effects of common control measures for influenza A (H1N1) outbreak at school in China: A modeling study.

BACKGROUND: Influenza A (H1N1) outbreaks have become common at schools in China since 2009. However, the effects of common countermeasures for school influenza outbreak have not been quantified so far, including isolation, vaccination, antivirus and school closure. We conducted a mathematically modeling study to address this unsolved issue. METHODS: We collected data of all small-scale school outbreaks caused by influenza A that occurred in Changsha city between January 2009 and December 2013. Two outbreaks (one was in 2009 and the other one was in 2013) were used for simulating the effects of single and combined use of common measures, including isolation (Iso), therapeutics (T), prophylactics (P), vaccinating 70% of susceptible individuals prior to the outbreak (VP70), vaccinating 70% of susceptible individuals every day during the outbreak (VD70) and school closure of one week (S1w). A susceptible-exposed-infectious/asymptomatic-recovered (SEIR) model was developed to implement the simulations based on the natural history of influenza A. RESULTS: When no control measures are taken, the influenza is expected to spread quickly at school for the selected outbreak in 2013; the outbreak would last 56 days, and the total attack rate (TAR) would reach up to 46.32% (95% CI: 46.12-46.52). Of all single control measures, VP70 is most effective to control the epidemic (TAR = 8.68%), followed by VP50, VD70, VD50 and Iso. The use of VP70 with any other measure can reduce TAR to 3.37-14.04% and showed better effects than any other combination of two kinds of measures. The best two-measure combination is 'S1w+VP70' (TAR = 3.37%, DO = 41 days). All combinations of three kinds of measures were not satisfactory when Vp70 and VD70 were excluded. The most effective three-intervention combination was 'Iso+S1w+VP70' (with TAR = 3.23%). When VP70 or VD70 is included, the combinations of four or five kinds of interventions are very effective, reducing TAR to lower than 5%. But the TAR of combination of 'T+P+Iso+S1w' is 23.20%. Similar simulation results were observed for the selected outbreak in 2009. CONCLUSION: Vaccinating no less than 70% of individuals prior to the outbreak and isolation are recommended as single measures to control H1N1outbreak at school. The combination of VP70+S1w can achieve very good control for school outbreak.

Clinical, epidemiological and virological characteristics of the first detected human case of avian influenza A(H5N6) virus.

A human infection with novel avian influenza A H5N6 virus emerged in Changsha city, China in February, 2014. This is the first detected human case among all human cases identified from 2014 to early 2016. We obtained and summarized clinical, epidemiological, and virological data from this patient. Complete genome of the virus was determined and compared to other avian influenza viruses via the construction of phylogenetic trees using the neighbor-joining approach. A girl aged five and half years developed fever and mild respiratory symptoms on Feb. 16, 2014 and visited hospital on Feb. 17. Throat swab specimens were obtained from the patient and a novel reassortant avian influenza A H5N6 virus was detected. All eight viral gene segments were of avian origin. The hemagglutinin (HA) and neuraminidase (NA) gene segments were closely related to A/duck/Sichuan/NCXN11/2014(H5N1) and A/chicken/Jiangxi/12782/2014(H10N6) viruses, respectively. The six internal genes were homologous to avian influenza A (H5N2) viruses isolated in duck from Jiangxi in China. This H5N6 virus has not gained genetic mutations necessary for human infection and was suggested to be sensitive to neuraminidase inhibitors, but resistant to adamantanes. Epidemiological investigation of the exposure history of the patient found that a live poultry market could be the source place of infection and the incubation period was 2-5days. This novel reassortant Avian influenza A(H5N6) virus could be low pathogenic in humans. The prevalence and genetic evolution of this virus should be closely monitored.

Transmissibility of the Influenza Virus during Influenza Outbreaks and Related Asymptomatic Infection in Mainland China, 2005-2013.

We collected 2768 Influenza-like illness emergency public health incidents from April 1, 2005 to November 30, 2013reported in the Emergency Public Reporting System. After screening by strict inclusion and exclusion criteria, there were 613 outbreaks analyzed with susceptible-exposed-infectious/asymptomatic-removed model in order to estimate the proportion of asymptomatic individuals (p) and the effective reproduction number (Rt). The relation between Rt and viral subtypes, regions, outbreak sites, populations, and seasons were analyzed. The mean values of p of different subtypes ranged from 0.09 to 0.15, but could be as high as up to 0.94. Different subtypes, provinces, regions, and sites of outbreak had statistically significantly different Rt. In particular, the southern region also manifested different Rt by affected population size and seasonality. Our results provide China and also the rest of the world a reference to understand characteristics of transmission and develop prevention and control strategies.

[A model for evaluation of key measures for control of chikungunya fever outbreak in China].

OBJECTIVE: To analyze the transmission pattern of Chikungunya (CHIK) fever in community and evaluate the effectiveness of mosquito control, case isolation and other key control measures by using ordinary differential equation (ODE) model. METHODS: According to natural history of CHIK, an ODE model for the epidemiological analysis of CHIK outbreak was established. The key parameters of the model were obtained by fitting the model with reported outbreak data of the first CHIK outbreak in China. Then the outbreak characteristics without intervention, the effectiveness of mosquito control and case isolation were simulated. RESULTS: Without intervention, an imported case would cause an outbreak in a community with population of 11 000, and cumulative case number would exceed 941 when the total attack rate was 8.55%. The results of our simulation revealed that the effectiveness of case isolation was not perfect enough when it was implemented alone. Although the number of cases could be decreased by case isolation, the duration of outbreak would not be shortened. Differently, the effectiveness of mosquito control was remarkable. In addition, the earlier the measure was implemented, the better the effectiveness would be. The effectiveness of mosquito control plus case isolation was same with mosquito control. CONCLUSION: To control a CHIK outbreak, mosquito control is the most recommended measures. However, case isolation is also necessary as the supplementation of mosquito control.

The Effectiveness of Age-Specific Isolation Policies on Epidemics of Influenza A (H1N1) in a Large City in Central South China.

During the early stage of a pandemic, isolation is the most effective means of controlling transmission. However, the effectiveness of age-specific isolation policies is not clear; especially little information is available concerning their effectiveness in China. Epidemiological and serological survey data in the city of Changsha were employed to estimate key model parameters. The average infectious period (date of recovery-date of symptom onset) of influenza A (H1N1) was 5.2 days. Of all infected persons, 45.93% were asymptomatic. The basic reproduction number of the influenza A (H1N1) pandemic was 1.82. Based on the natural history of influenza A (H1N1), we built an extended susceptible-exposed-infectious/asymptomatic-removed model, taking age groups: 0-5, 6-14, 15-24, 25-59, and ≥60 years into consideration for isolation. Without interventions, the total attack rates (TARs) in each age group were 42.73%, 41.95%, 20.51%, 45.03%, and 37.49%, respectively. Although the isolation of 25-59 years-old persons was the most effective, the TAR of individuals of aged 0-5 and 6-14 could not be reduced. Paradoxically, isolating individuals ≥60 year olds was not predicted to be an effective way of reducing the TAR in this group but isolating the age-group 25-59 did, which implies inter-age-group transmission from the latter to the former is significant. Isolating multiple age groups increased effectiveness. The most effective combined isolation target groups were of 6-14 + 25-59 year olds, 6-14 + 15-24 + 25-59 year olds, and 0-5 + 6-14 + 25-59 + ≥60 year olds. The last of these isolation schemas reduced the TAR of the total population from 39.64% to 0.006%, which was exceptionally close to the effectiveness of isolating all five age groups (TAR = 0.004%).

Analysis of the full-length genome of a novel strain of the H7N9 avian influenza virus.

The aim of the present study was to analyze the evolution and variation of a novel strain of the avian influenza virus. The virus-positive specimens [A/Changsha/2/2013 (H7N9)] from a patient infected with the novel avian influenza A (H7N9) virus was amplified by reverse transcription-PCR and the full genome was sequenced. The sequencing results were submitted to GenBank and then analyzed by phylogenetic tree analysis using BioEdit and Mega5 software. The phylogenetic tree of the hemagglutinin (HA) and neuraminidase genes revealed that A/Changsha/2/2013 (H7N9) and all the new H7N9 viruses in 2013 were in a large cluster, and their nucleotide evolutionary distances were closely associated. Phylogenetic tree analyses of the nucleoprotein and nonstructural genes demonstrated two main branches. One branch contained novel H7N9 viruses isolated from avian, human and environmental sources in different regions. The other branch contained three novel H7N9 virus strains isolated from environmental sources in Shanghai. All the phylogenetic trees of the matrix protein, polymerase acidic, polymerase basic protein 1 and polymerase basic protein 2 genes also showed two branches, with each branch including the novel H7N9 virus strains isolated from avian, human and environmental sources in different regions. Molecular characterization demonstrated that 52 novel H7N9 viruses sequenced to date contain the G228S and G186V mutations in the receptor binding site of the HA protein. The full-genome sequences of A/Changsha/2/2013 and analyses of its molecular characteristics suggest that the A/Changsha/2/2013 H7N9 virus strain has molecular characteristics that may facilitate adaptation of the virus to mammalian hosts and may even bind to human receptors.

Risk of imported Ebola virus disease in China.

BACKGROUND: More than 600,000 annual arrivals from Africa, 1.4 billion population and developing health care systems render China at non-negligible risk of imported Ebola virus disease (EVD). METHOD: According to the natural history of EVD, we constructed a deterministic SEIR model. Three published EVD outbreaks in Africa were enrolled to calculate the basic reproduction number (R0) of EVD. Scenarios representing unreported and reported (with n weeks delay) imported EVD in China were simulated to evaluate the effectiveness of interventions assumed to be implemented in different periods of the outbreaks. RESULTS: Based on previous Africa outbreak incidence datasets, our mathematical model predicted the basic reproduction number of EVD in the range of 1.53-3.54. Adopting EVD prevalence at 0.04-0.16% from the same datasets and estimated missing information and monitoring rates at 1-10%, a total of 6-194 imported cases were predicted. Be a single case left unidentified/unreported, total attack rate was predicted to reach 60.19%-96.74%. Curve fitting results showed that earlier intervention benefits in exponential and linear decrease in prevalence and duration of outbreak respectively. CONCLUSION: Based on past outbreak experience in China, there is a need to implement an internet-based surveillance and monitoring system in order to reinforce health policy, track suspected cases and protect the general public by timely interventions.

Investigation of key interventions for shigellosis outbreak control in China.

Shigellosis is a major public health concern in China, where waterborne disease outbreaks are common. Shigellosis-containing strategies, mostly single or multiple interventions, are implemented by primary-level health departments. Systematic assessment of the effectiveness of these measures is scarce. To estimate the efficacy of commonly used intervention strategies, we developed a Susceptible-Exposed-Infectious/Asymptomatic-Recovered-Water model. No intervention was predicted to result in a total attack rate (TAR) of 90% of the affected population (95% confidence interval [CI]: 86.65-92.80) and duration of outbreak (DO) of 89 days, and the use of single-intervention strategies can be futile or even counter-productive. Prophylactics and water disinfection did not improve TAR or DO. School closure for up to 3 weeks did not help but only increased DO. Isolation alone significantly increased DO. Only antibiotics treatment could shorten the DO to 35 days with TAR unaffected. We observed that these intervention effects were additive when in combined usage under most circumstances. Combined intervention "Isolation+antibiotics+prophylactics+water disinfection" was predicted to result in the lowest TAR (41.9%, 95%CI: 36.97-47.04%) and shortest DO (28 days). Our actual Shigellosis control implementation that also included school closure for 1 week, attained comparable results and the modeling produced an epidemic curve of Shigellosis highly similar to our actual outbreak data. This lends a strong support to the reality of our model that provides a possible reference for public health professionals to evaluate their strategies towards Shigellosis control.

[Study on the efficacy of quarantine during outbreaks of acute hemorrhagic conjunctivitis outbreaks at schools through the susceptive-infective-quarantine-removal model].

To assess the efficacy of quarantine for acute hemorrhagic conjunctivitis (AHC) outbreaks control in schools, by using the Compartment Model. Through combining the characters of both AHC and compartment model, we built a susceptive-infective-removal (SIR) model suited for AHC outbreaks control in schools, and then quarantine was added into the model to develop a susceptive-infective-quarantine-removal (SIQR) model. An outbreak of AHC in Changsha in 2011 was employed as a sample to assess the effect of quarantine for the prevention and control of AHC. Basic reproduction number (λ0) of the AHC outbreak without intervention was 6.80, thus the transmission speed of the disease became quite fast. If no intervention had been adopted, almost all the students, faculties and staff members would have been infected within 23 days, and the accumulative cases would become 738, with the total attack rate (TAR) as 99.73%. The peak of the outbreak was at Sep. 11th and the number of new cases was 126 on that day. The efficacy would have been different if quarantine forces had been taken at different time and differently. The bigger and earlier the quarantine force had been adopted, the lower morbidity peak and the smaller TAR would have been appeared, with better efficacy of outbreak control. If the quarantine rate had been taken at the level of 90% on the sixth day, the accumulative case would have been reduced to 132 and the TAR had become 17.84% consequently. Quarantine program could be used as a main intervention approach to be employed for ACH outbreak at schools.

[Genetic analysis of the NS genes of H5N1 avian influenza viruses isolated from sewage in poultry markets].

In order to investigate the transmission risk of H5N1 avian influenza viruses (AIV) from sewage in Changsha poultry markets, the evolution relationship and molecular characteristics of non-structural (NS) genes of H5N1 AIV from sewage were analyzed. Nine H5N1 AIV environmental sewage specimens were collected from Changsha poultry markets. The NS genes were amplifyed by PCR and then sequenced with TA cloning. Amino acid(aa) sequence alignment and phylogenetic tree analysis were conducted by Lasergene and Mega5 software. Eight NS genes TA cloning were constructed successfully. Phylogenetic tree indicated that they were belonged to the allele A subgroup. Aa homology analysis showed 90.1% 92.5% identity in NS1 proteins and 91.0% - 92.6% identity in NS2 proteins compared with reference viruses of the allele A (A/chicken/ Hubei/ w h/ 1999). The homologies of the amino sequences of NS1 and NS2 in this study were 93.8%-100.0% and 98.4%-100.0%, respectively. The C terminal of all eight H5N1 NS1 proteins from sewage in poultry markets carried a ESEV of PL motif and the 92 amino acids were E, furthermore, the 80 to 84aa were missed which were the characteristics of highly pathogenic AIV. The NS genes of H5N1 AIV from sewage in poultry markets have molecular characteristics of highly pathogenic and have the potential risk of H5N1 virus spreading.