Influenza A viruses are amongst the most challenging viruses that threaten both human and animal health. Constantly evolving and crossing species barrier, the emergence of novel zoonotic pathogens is one of the greatest challenges to global health security. During the last decade, considerable attention has been paid to influenza virus infections in dogs, as two canine H3N8 and H3N2 subtypes caused several outbreaks through the United States and Southern Asia, becoming endemic. Cats, even though less documented in the literature, still appear to be susceptible to many avian influenza infections. While influenza epidemics pose a threat to canine and feline health, the risks to humans are largely unknown. Here, we review most recent knowledge of the epidemiology of influenza A viruses in dogs and cats, existing evidences for the abilities of these species to host, sustain intraspecific transmission, and generate novel flu A lineages through genomic reassortment. Such enhanced understanding suggests a need to reinforce surveillance of the role played by companion animals-human interface, in light of the "One Health" concept and the potential emergence of novel zoonotic viruses.

Background: Identifying the causes of Acute Undifferentiated Febrile Illness(AUFI) is key to improve the management of returning travellers with fever. We evaluated a BioFire®FilmArray® prototype panel of multiplex nucleic acid amplification tests(NAAT) targeting different relevant pathogens in travellers returning with fever. Methods: Prospective, multicenter study to evaluate a prototype panel in whole blood samples of adult international travellers presenting with AUFI in three European travel Clinics/Hospitals (November2017-November2019). We evaluated 15 target analytes: Plasmodium spp., P.falciparum, P.knowlesi, P.malariae, P.ovale, P.vivax, chikungunya virus, dengue virus, Zika virus, Anaplasma phagocytophilum, Borrelia spp., Leptospira spp., Orientia tsutsugamushi, Rickettsia spp., Salmonella spp. Results were compared with composite reference standards(CRS) for each target infection, including direct methods (smear microscopy, rapid diagnostic test(RDT), reference NAAT, blood cultures) and indirect methods(paired serology). Findings: Among 455 travellers with AUFI, 229 target infections were diagnosed; the prototype panel detected 143 (overall sensitivity and specificity of 62.5% and 99·8%, respectively). The panel identified all Plasmodium infections(n = 82). Sensitivity for dengue(n = 71) was 92·9%; 80·8% and 68·5% compared to RDT, NAAT and CRS. Compared to direct methods and CRS, respectively, the prototype panel detected 4/4 and 4/6 chikungunya, 2/2 and 4/29 Leptospira spp., 1/1 and 1/6 O.tsutsugamushi, 2/2 and 2/55 Rickettsia spp., but 0/2 and 0/10 Zika, 0/1 and 0/11 A.phagocytophylum, 0/3 Borrelia spp. diagnosed by serology and 1/7 Salmonella spp. diagnosed by blood cultures. 77/86 (89·5%) infections not detected by the panel were diagnosed by serology. Interpretation: The prototype panel allowed rapid and reliable diagnosis for malaria, dengue and chikungunya. Further improvements are needed to improve its sensitivity for Zika and important travel-related bacterial infections.