Epizootic of highly pathogenic H7N3 Avian Influenza in an ecologic reserve in Mexico

This report includes a 2015 epizootic of highly pathogenic H7N3 avian influenza virus among captive and wild birds at “El Zapotal” ecologic reserve, located in the state of Chiapas, Mexico. Epidemiological control measures were implemented to prevent virus dissemination. The infection with the highly pathogenic H7N3 virus was detected predominantly among Plain Chachalaca (Ortalis vetula), with occasional detections in a White-fronted Parrot (Amazona albifrons) and a single Clay-colored Thrush (Turdus grayi). Here, we describe the characteristics of the outbreak environment, the surveillance strategy, the biosecurity measures, and the evaluation of the site, including external farms. These actions, timely implemented by the veterinary authorities, helped to contain the outbreak beyond the ecologic reserve. This contingency showed the importance of developing a more complete analysis of the existing risks and the challenges to implement minimal biosecurity measures in these facilities.


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Type A influenza viruses (AIVs) typically circulate in migratory and non-migratory wild 44 aquatic waterfowl, gulls, and shorebirds [1]. Geographic barriers have limited 45 intercontinental exchange of AIVs resulting in continental lineages of viral diversity by 46 regions [2, 3,4]. They are further divided into subtypes based on the antigenic 47 characterization of the virus' surface glycoproteins, hemagglutinin (HA) and neuraminidase 48 (NA). In wild birds, 16 HA and 9 NA subtypes have been identified in many different 49 combinations which have been isolated from a total of more than 125 bird species that 50 belong to 26 different families [1,2,5,6]. AIVs maintained in wild birds periodically spill-51 over into domestic birds, as wild and domestic mammals, and have been postulated to 52 contribute to pandemic human influenza viruses [7,8,9]. susceptibility [11,12]. In domestic chickens, significant lesions that are consistently 63 associated with HP AIV infections include necrosis and inflammation of organs such as 64 heart, brain, spleen, intestinal tract, lungs, and skeletal muscles [11].
There is limited information about HPAI outbreaks in wild birds, but HPAI infections have 66 shown a range of syndromes that can go from asymptomatic to severe symptomatic 67 conditions. These range from respiratory and/or digestive tract infections to critical lesions 68 in other organs including the heart, brain and pancreas [11]. The reporting of this is type of 69 infection in wild birds has increased during the last 15 years [13,14,15]. 70 In Mexico, during an epizootic in poultry, a continued transmission of HPAI H7N3 virus 71 75 reports, the lesions described included severe damage of the brain, heart and pancreas and 76 the isolation of the H5N1 and H7N3 viruses from trachea, intestine and heart.

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Most of the HP AIV identified in wild birds have been detected in typical reservoir species 78 [7, 16, 17], although a diversity of additional species has also been reported to be affected; 79 such is the case of passerine [18,19] and psittacine birds [20]. The role of passerines as 80 virus reservoirs in nature has been gaining terrain, facilitating viral spread between wild 81 and domestic hosts [20,21].

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This study describes the initial evidences of mortality in a wild population of Plain 83 chachalacas (Ortalis vetula), following an outbreak in a natural reserve in Mexico. We also 84 identified the presence of the HPAIV H7N3 in White-fronted Parrot (Amazona albifrons), 85 and Clay-colored Thrush (Turdus grayi), which were reported for the first time in an 86 ecologic reserve where a regional fauna zoo is present. We also highlighted the procedures 87 implemented by the veterinary authorities to achieve its control [23,25].   10 km perimeter around El Zapotal (Fig. 2). This group carried out a minimal biosecurity 124 evaluation of the farms, in order to avoid cross-contamination of poultry. During this 125 contingency, the access of official veterinarians to commercial farms was forbidden.  swabs, however none of the samples collected had the A H7N3 virus (Table 1).

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Group C. This group carried out biosecurity evaluation of the farms. Around the ecologic 210 reserve, we identified 11 commercial farms (Fig. 2)  compliance with minimal biosecurity practices, 29 farms were audited, 10 in the perifocal 12 215 area (Fig 2) and 19 in the area where they wanted to improve the biosecurity conditions.

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Among these farms, 21 were considered to have in place appropriate biosecurity measures, 217 whereas 8 were required to improve their preventive infrastructure.

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64% of the cases were found by controlled depopulation and 36% were detected through Mexico.

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The state of Jalisco, located in west-central Mexico, provides the largest production of  [20].

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In addition, wild birds interact with poultry in a close vicinity. If these birds were AIV