@article{Lau_Zhang_Leung_Cowling_Wu_Peiris_2017, title={Identifying Key Transmission Route of Avian Influenza A(H9N2) in Live Poultry Markets}, volume={9}, url={https://ojphi.org/ojs/index.php/ojphi/article/view/7689}, DOI={10.5210/ojphi.v9i1.7689}, abstractNote={<div style="left: 72px; top: 272.606px; font-size: 11.3333px; font-family: sans-serif; transform: scaleX(1.08137);" data-canvas-width="51.022666666666666">Objective</div><div style="left: 84px; top: 284.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.997338);" data-canvas-width="304.6037333333333">This study assessed the transmission of low pathogenic avian</div><div style="left: 72px; top: 297.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.01655);" data-canvas-width="317.1633333333333">influenza in live poultry market setting, using paired fecal and</div><div style="left: 72px; top: 311.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.97936);" data-canvas-width="315.9415999999999">drinking water samples from a longitudinal surveillance program.</div><div style="left: 72px; top: 324.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03533);" data-canvas-width="315.6899999999997">The relative contribution of transmission via direct fecal-oral route</div><div style="left: 72px; top: 337.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00199);" data-canvas-width="188.85866666666675">versus drinking water will be determined.</div><div style="left: 72px; top: 363.273px; font-size: 11.3333px; font-family: sans-serif; transform: scaleX(1.11794);" data-canvas-width="66.10733333333333">Introduction</div><div style="left: 84px; top: 375.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03262);" data-canvas-width="303.7106666666666">Live poultry markets (LPMs) continue to operate in many Asian</div><div style="left: 72px; top: 388.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.04683);" data-canvas-width="317.6778666666666">countries. Low pathogenic avian influenza (LPAI) viruses are</div><div style="left: 72px; top: 401.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.02932);" data-canvas-width="315.554">often endemic in the poultry, and LPM presents the opportunity for</div><div style="left: 72px; top: 415.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.986749);" data-canvas-width="314.29599999999994">human-poultry interactions and potential human infections with avian</div><div style="left: 72px; top: 428.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00984);" data-canvas-width="79.94533333333334">influenza viruses.</div><div style="left: 84px; top: 441.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.995207);" data-canvas-width="302.57620000000003">As a series of interventions to control avian influenza transmission</div><div style="left: 72px; top: 455.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.983943);" data-canvas-width="316.2884000000002">in Hong Kong LPMs, local health authority implemented market</div><div style="left: 72px; top: 468.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.04481);" data-canvas-width="315.81239999999985">rest days once every month since mid-2001, and an additional rest</div><div style="left: 72px; top: 481.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03914);" data-canvas-width="315.55286666666683">day every month since 2003, during which all unsold poultry were</div><div style="left: 72px; top: 495.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.96219);" data-canvas-width="315.90306666666686">slaughtered and the stalls cleaned and disinfected. Rest days were</div><div style="left: 72px; top: 508.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.0378);" data-canvas-width="315.6650666666668">found to effectively reduce avian influenza A(H9N2) isolation rate</div><div style="left: 72px; top: 521.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.947266);" data-canvas-width="315.6605333333333">to baseline level for a few days following the rest days. However,</div><div style="left: 72px; top: 535.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.02605);" data-canvas-width="315.50980000000004">H9N2 isolation rate was still observed to be increasing between the</div><div style="left: 72px; top: 548.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.997983);" data-canvas-width="314.64733333333334">rest days, indicating the existence of efficient transmission in spite of</div><div style="left: 72px; top: 561.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00805);" data-canvas-width="115.20333333333333">rapid turnover of poultry.</div><div style="left: 84px; top: 575.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00546);" data-canvas-width="304.9573333333333">In LPMs, poultry are usually stored in cages where drinking</div><div style="left: 72px; top: 588.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03956);" data-canvas-width="315.7330666666668">water is shared among poultry. This is analogous to environmental</div><div style="left: 72px; top: 601.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.0413);" data-canvas-width="315.65259999999955">contamination in the wild, but transmissibility may even be higher</div><div style="left: 72px; top: 615.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.04452);" data-canvas-width="315.4270666666667">due to the dense environment. The use of drinking water for avian</div><div style="left: 72px; top: 628.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.989361);" data-canvas-width="316.4470666666665">influenza surveillance in LPM setting was suggested to be more</div><div style="left: 72px; top: 641.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03223);" data-canvas-width="315.60499999999996">sensitive than fecal samples (1). However, the relative contribution</div><div style="left: 72px; top: 655.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.989336);" data-canvas-width="316.40626666666674">of direct fecal-oral versus water transmission routes in the LPM</div><div style="left: 72px; top: 668.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.02707);" data-canvas-width="315.56873333333334">setting was not yet understood. This study aimed to determine their</div><div style="left: 72px; top: 681.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03765);" data-canvas-width="315.4961999999998">role, which will have implications in the control of avian influenza</div><div style="left: 72px; top: 695.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00252);" data-canvas-width="60.134666666666675">transmission.</div><div style="left: 72px; top: 720.606px; font-size: 11.3333px; font-family: sans-serif; transform: scaleX(1.07312);" data-canvas-width="46.59133333333333">Methods</div><div style="left: 84px; top: 732.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.02437);" data-canvas-width="305.1772000000001">We analyzed 7,321 paired fecal and drinking water samples</div><div style="left: 72px; top: 745.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03029);" data-canvas-width="315.5426666666665">from a longitudinal surveillance programme during the period with</div><div style="left: 72px; top: 759.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.99368);" data-canvas-width="316.93439999999987">2 monthly rest days in the LPMs. Samples were collected from</div><div style="left: 72px; top: 772.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.01207);" data-canvas-width="317.0137333333332">chicken cages and subsequently cultured. Positive isolates were</div><div style="left: 72px; top: 785.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00312);" data-canvas-width="316.435733333333">subtyped by hemagglutination-inhibition tests and neuraminidase</div><div style="left: 72px; top: 799.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00553);" data-canvas-width="314.9476666666667">inhibition test. Data were aggregated by sampling occasion and days</div><div style="left: 72px; top: 812.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00243);" data-canvas-width="83.08466666666668">after the rest days.</div><div style="left: 84px; top: 825.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.99369);" data-canvas-width="302.4957333333333">A compartmental transmission model which incorporated turnover</div><div style="left: 72px; top: 839.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.996682);" data-canvas-width="316.5626666666667">and overnight stay of poultry, virus contamination and decay in</div><div style="left: 72px; top: 852.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.04657);" data-canvas-width="315.4021333333333">drinking water was fitted to the data (Figure 1). A 12-hour trading</div><div style="left: 72px; top: 865.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.02038);" data-canvas-width="315.43386666666663">day was assumed. Based on the parameterized model, we simulated</div><div style="left: 72px; top: 879.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00378);" data-canvas-width="314.8853333333333">the scenario that water transmission was prohibited to assess the role</div><div style="left: 72px; top: 892.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00607);" data-canvas-width="158.33800000000002">of transmission via drinking water.</div><div style="left: 72px; top: 917.94px; font-size: 11.3333px; font-family: sans-serif; transform: scaleX(1.08488);" data-canvas-width="40.93600000000001">Results</div><div style="left: 84px; top: 929.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.963971);" data-canvas-width="304.16513333333324">H9N2 isolation rates ranged from 0-25% for fecal samples and</div><div style="left: 72px; top: 943.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03986);" data-canvas-width="315.56420000000014">0-56% for drinking water samples. A clear increasing trend can be</div><div style="left: 72px; top: 956.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.988278);" data-canvas-width="314.4535333333334">seen over days after the rest days (Figure 2). The estimated parameter</div><div style="left: 72px; top: 969.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.970275);" data-canvas-width="314.15886666666665">for water transmission is higher than the parameter for direct fecal-oral</div><div style="left: 408px; top: 271.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.01045);" data-canvas-width="315.1607333333334">transmission. Simulation results show that transmission via drinking</div><div style="left: 408px; top: 284.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.947852);" data-canvas-width="315.9189333333332">water plays a major role in the amplification of LPAI in the LPM</div><div style="left: 408px; top: 297.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00183);" data-canvas-width="81.532">setting (Figure 2).</div><div style="left: 408px; top: 323.273px; font-size: 11.3333px; font-family: sans-serif; transform: scaleX(1.10259);" data-canvas-width="68.01133333333334">Conclusions</div><div style="left: 420px; top: 335.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.976701);" data-canvas-width="304.5028666666666">Our study showed that drinking water has a major role in the</div><div style="left: 408px; top: 348.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.02572);" data-canvas-width="315.45993333333337">transmission and amplification of LPAI H9N2 in LPMs, comparing</div><div style="left: 408px; top: 361.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.01211);" data-canvas-width="316.8924666666667">to direct fecal-oral transmission route. Given the relatively low</div><div style="left: 408px; top: 375.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.0347);" data-canvas-width="315.6526">prevalence of H9N2 in chicken, direct transmission is governed by</div><div style="left: 408px; top: 388.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.01476);" data-canvas-width="315.25253333333325">chance events, while chickens are consistently exposed to viruses in</div><div style="left: 408px; top: 401.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00402);" data-canvas-width="314.8774000000001">drinking water if contaminated. Drinking water could be targeted for</div><div style="left: 408px; top: 415.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.972756);" data-canvas-width="314.39459999999985">intervention to control LPAI transmission in LPM. The use of drinking</div><div style="left: 408px; top: 428.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.978617);" data-canvas-width="314.5113333333333">fountain or frequent disinfection of drinking water may be considered.</div><div style="left: 408px; top: 441.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.960649);" data-canvas-width="315.97333333333324">Avian influenza viruses (e.g. H5N1) may differ in their pattern of</div><div style="left: 408px; top: 455.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.02125);" data-canvas-width="315.37833333333344">virus shedding via oral versus fecal routes and thus extrapolation of</div><div style="left: 408px; top: 468.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.988242);" data-canvas-width="314.4093333333333">these results to other viruses needs to be done with caution. However,</div><div style="left: 408px; top: 481.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.03887);" data-canvas-width="315.7126666666666">H7N9 viruses are similar to H9N2 viruses by being shed primarily</div><div style="left: 408px; top: 495.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.01349);" data-canvas-width="315.0949999999999">via the respiratory / oral route (2) and it is reasonable to assume that</div><div style="left: 408px; top: 508.567px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.974924);" data-canvas-width="314.3968666666666">these conclusions would apply to H7N9 virus which is of major public</div><div style="left: 408px; top: 521.901px; font-size: 11.3333px; font-family: serif; transform: scaleX(0.995999);" data-canvas-width="314.5861333333333">health concern. However, our model could not differentiate the effect</div><div style="left: 408px; top: 535.234px; font-size: 11.3333px; font-family: serif; transform: scaleX(1.00014);" data-canvas-width="314.74480000000005">of indirect fecal-oral transmission through contamination of drinking</div>water by droppings versus contamination through drinking.}, number={1}, journal={Online Journal of Public Health Informatics}, author={Lau, Eric and Zhang, Shengqiu and Leung, Connie and Cowling, Benjamin J. and Wu, Joseph T. and Peiris, Malik}, year={2017}, month={May} }