Moutinho Isa, Cardoso Sara, Henriques Mafalda, Gonçalves João, Tavares Luís, Gil Solange, Nunes Telmo, Aires-da-Silva Frederico
Center for Interdisciplinary Research in Animal Health (CIISA), Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal.
Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), Lisbon, Portugal.
Front Vet Sci. 2025 Jun 23;12:1542397. doi: 10.3389/fvets.2025.1542397. eCollection 2025.
Since the onset of the COVID-19 pandemic, the transmission of SARS-CoV-2 between humans and cats has been well-documented. However, the dynamics of this cross-species transmission remain insufficiently understood. Seroprevalence studies in cat populations across different contexts and regions are crucial for estimating viral infection rates and tracking viral evolution. Furthermore, identifying risk factors associated with human-to-cat transmission is essential.
This study, conducted during the COVID-19 pandemic, assessed SARS-CoV-2 transmission and seroprevalence in 76 cats from COVID-19-positive households in the Lisbon area. Antibodies against SARS-CoV-2 variants (alpha, delta and omicron) were detected using enzyme-linked immunosorbent assay (ELISA). Positive samples were further tested for neutralizing antibodies using surrogate virus neutralization test (sVNT) and pseudotyped virus assays. To identify risk factors for human-to-cat SARS-CoV-2 transmission, we analyzed the association between animal characteristics, cat-owner interactions, owner clinical signs and sVNT results.
Of the 76 cats tested, 23 (30.3%) were ELISA-positive for SARS-CoV-2 antibodies. Among these, 16 (69.6%) exhibited potent neutralizing antibodies confirmed via sVNT and pseudotyped virus assays. Compared to our previous study of cats with unknown exposure to SARS-CoV-2 in the Lisbon area, this study found significantly higher rates of seroprevalence (30.3% vs. 14.7%) and neutralizing antibody prevalence (69.6% vs. 20.4%) in cats from COVID-19-positive households. None of the risk factors studied showed a statistically significant association with seropositivity in cats.
These findings suggest a greater exposure and infection risk in cats from COVID-19-positive households. The absence of significant associations with the analyzed risk factors highlights the complexity of human-to-cat SARS-CoV-2 transmission. Future studies should further investigate the impact of demographic characteristics, health conditions, lifestyle, owner-cat interactions, and owners' symptoms during infection to better understand their role in SARS-CoV-2 transmission from humans to cats and to inform strategies for controlling future outbreaks.
自新冠疫情爆发以来，严重急性呼吸综合征冠状病毒2（SARS-CoV-2）在人与猫之间的传播已有充分记录。然而，这种跨物种传播的动态过程仍未得到充分了解。在不同环境和地区对猫群进行血清流行率研究对于估计病毒感染率和追踪病毒进化至关重要。此外，确定与人类向猫传播相关的风险因素也至关重要。
本研究在新冠疫情期间进行，评估了里斯本地区76只来自新冠阳性家庭的猫的SARS-CoV-2传播情况和血清流行率。使用酶联免疫吸附测定（ELISA）检测针对SARS-CoV-2变体（阿尔法、德尔塔和奥密克戎）的抗体。对阳性样本进一步使用替代病毒中和试验（sVNT）和假型病毒试验检测中和抗体。为了确定人类向猫传播SARS-CoV-2的风险因素，我们分析了动物特征、猫主人互动、主人临床症状与sVNT结果之间的关联。
在检测的76只猫中，23只（30.3%）SARS-CoV-2抗体ELISA检测呈阳性。其中，16只（69.6%）通过sVNT和假型病毒试验确认表现出强效中和抗体。与我们之前对里斯本地区接触SARS-CoV-2情况不明的猫的研究相比，本研究发现来自新冠阳性家庭的猫的血清流行率（30.3%对14.7%）和中和抗体流行率（69.6%对20.4%）显著更高。所研究的风险因素均未显示与猫的血清阳性有统计学上的显著关联。
这些发现表明来自新冠阳性家庭的猫有更大的接触和感染风险。与分析的风险因素缺乏显著关联凸显了人类向猫传播SARS-CoV-2的复杂性。未来的研究应进一步调查人口统计学特征、健康状况、生活方式、主人与猫的互动以及主人感染期间的症状的影响，以更好地了解它们在SARS-CoV-2从人类传播到猫的过程中的作用，并为控制未来疫情爆发的策略提供依据。
