Following the emergence of H7N9 influenza in March 2013, local animal and public health authorities in China have been closing live bird markets as a measure to try to control the H7N9 influenza epidemic. The role of live bird market (LBM) closure on the spread of N7N9 influenza following the closure of LBMs during March to May 2013 (the first wave) and October 2013 to March 2014 (the second wave) is described in this paper. Different provinces implemented closure actions at different times, and intensive media reports on H7N9 in different provinces started at different times. Local broiler prices dropped dramatically in places with outbreaks and more live chickens were transported to other LBMs in neighboring areas without human cases from infected areas when live bird markets were being closed. There were six clusters of human infection from March to May 2013 and October 2013 to March 2014 and there may have been intensive poultry transportation among cluster areas. These findings provide evidence that the closure of LBMs in early waves of H7N9 influenza had resulted in expansion of H7N9 infection to uninfected areas. This suggests that provincial authorities in inland provinces should be alert to the risks of sudden changes in movement patterns for live birds after LBM closure or increased publicity about LBM closure.
Dairy cattle brucellosis is a chronic bacterial disease, which is caused by Brucella abortus and mainly characterized by abortion in dairy cattle. With the rapid development of breeding industry of milk cows in China, the infectious cases of dairy cattle brucellosis show an increasing trend. Particularly in Jilin province, the annual number of the positive cases of dairy cattle was only 3 cows in 1987, and went up to 168 cows in 2005. Based on the situation of the brucellosis infection in Jilin province, we propose an Susceptible-Exposed-Infected-Virus (SEIV) dynamical model with outside transferred amount to describe the transmission of brucellosis amongst dairy cattle in this paper. We calculate the basic reproduction number R0 and prove that the equilibria are globally stable. Moreover, using the real data of nearly 20 years in Jilin province, we estimate the parameter values in the system. As a result, we can predict the number of infections as time increases. According to the prediction for the next 30 years, we can conclude that the disease will persist if we just take existing measures. If culling, sterilizing and decreasing the number of outer importing are used together, dairy cattle brucellosis will be well controlled.
Pseudorabies (PR), also known as Aujeszky's disease, is a highly contagious disease affecting pigs and a wide range of animals. Pseudorabies is enzootic in many countries. In China, it is a priority animal disease for control and eradication, however the data on disease frequency in intensive pig farms and the information on associated risk factors is inadequate. A cross-sectional study of intensive pig farms (≥350 sows) in Shanghai was conducted to determine herd-level prevalence of PRV and associated risk factors. Following a two-stage random sampling design, a total of 1,349 sow serum samples were tested by gpI-ELISA from a total of 91 intensive pig farms in Shanghai. A herd was classified as positive if at least one PRV test-positive sow was present. Information on putative risk/protective factors was collected using questionnaires to pig farm owners or veterinarians. A logistic regression model was built to identify risk/protective factors for herd positivity. The results indicated that the herd-level true prevalence was 67.6% (95% CI:57.0 -77.0). In the multivariable logistic regression model using backward stepwise procedure, two risk factors were found to be significantly associated with herd positivity: 'Breeding with introduced sows in the last 12 months' (OR=3.5, 95%CI:1.2, 10.3) and 'Presence of stray dogs or cats' (OR=4.0, 95%CI: 1.2, 12.6). The multivariable logistic model fitted the data well. Hosmer-Lemeshow goodness of fit test showed 2 = 10.86 (df = 8, p = 0.21 > 0.05) and the predictability (area under the ROC curve) was 0.86. This study suggested that PR was highly endemic in intensive pig farms in Shanghai. The risk and protective factors identified in this study could be useful to improve the prevention policy of PR in Shanghai and other areas of China.
A cross‐sectional survey was conducted from 2015 to 2018 to assess the risk of zoonotic influenza to humans at the human–pig interface in Guangdong Province, south China. One hundred and fifty‐three pig farmers, 21 pig traders and 16 pig trade workers were recruited using convenience sampling and surveyed at local pig farms, live pig markets and slaughterhouses, respectively. Questionnaires were administered to collect information on the biosecurity and trading practices adopted and their knowledge and beliefs about swine influenza (SI). Most (12 of 16) trade workers said they would enter piggeries to collect pigs and only six of 11 said they were always asked to go through an on‐farm disinfection procedure before entry. Only 33.7% of the interviewees believed that SI could infect humans, although pig farmers were more likely to believe this than traders and trade workers (p < .01). Several unsafe practices were reported by interviewees. ‘Having vaccination against seasonal flu’ (OR = 3.05, 95% CI: 1.19–8.93), ‘Believe that SI can cause death in pigs’ (no/yes: OR = 8.69, 95% CI: 2.71–36.57; not sure/yes: OR = 4.46, 95% CI: 1.63–14.63) and ‘Keep on working when getting mild flu symptoms’ (OR = 3.80, 95% CI: 1.38–11.46) were significantly and positively correlated to ‘lacking awareness of the zoonotic risk of SI’. ‘Lacking awareness of the zoonotic risk of SI’ (OR = 3.19, 95% CI: 1.67–6.21), ‘Keep on working when getting mild flu symptoms’ (OR = 3.59, 95% CI: 1.57–8.63) and ‘Don't know SI as a pig disease’ (OR = 3.48, 95% CI: 1.02–16.45) were significantly and positively correlated to ‘not using personal protective equipment when contacting pigs’. The findings of this study would benefit risk mitigation against potential pandemic SI threats in the human–pig interface in China.
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