The Upper Respiratory Tract of Felids Is Highly Susceptible to SARS-CoV-2 Infection.

Natural or experimental infection of domestic cats and virus transmission from humans to captive predatory cats suggest that felids are highly susceptible to SARS-CoV-2 infection. However, it is unclear which cells and compartments of the respiratory tract are infected. To address this question, primary cell cultures derived from the nose, trachea, and lungs of cat and lion were inoculated with SARS-CoV-2. Strong viral replication was observed for nasal mucosa explants and tracheal air-liquid interface cultures, whereas replication in lung slices was less efficient. Infection was mainly restricted to epithelial cells and did not cause major pathological changes. Detection of high ACE2 levels in the nose and trachea but not lung further suggests that susceptibility of feline tissues to SARS-CoV-2 correlates with ACE2 expression. Collectively, this study demonstrates that SARS-CoV-2 can efficiently replicate in the feline upper respiratory tract ex vivo and thus highlights the risk of SARS-CoV-2 spillover from humans to felids.

First direct human-to-cat transmission of the SARS-CoV-2 B.1.1.7 variant.

A highly transmissible severe acute respiratory coronavirus 2 (SARS-CoV-2) caused the coronavirus diseases 2019 (COVID-19) pandemic, which resulted the highest morbidity and mortality rates among SARS-CoV and MERS-CoV. SARS-CoV-2 B.1.1.7 variant indicated the higher transmission among human-to-human and increasing hospitalisation. SARS-CoV-2 infection was observed in domestic animals showing human-to-pet transmission. In the current study, we report the first direct known human-to-cat transmission of the SARS-CoV-2 B.1.1.7 variant within the same family. Previous findings showed that companion animals can get infected by COVID-19 patients after 3-6 weeks; however, according to our molecular findings, the cat was infected by the viral variant at the same period. Moreover, B.1.1.7 infection caused and developed several clinical symptoms including cardiac and ocular abnormalities. Overall, our findings determined the first direct and high transmission ability of the B.1.1.7 variant from COVID-19 affected family members to cat. This result showed that the SARS-CoV-2 B.1.1.7 variant could have the highest transition capacity from human to domestic cat as shown for human-to-human. The governmental or worldwide policies should consider more detailed against the war with COVID-19 pandemic.

SARS-CoV-2 infection in domestic and feral cats: current evidence and implications.

Current evidence indicates that cats play a limited role in COVID-19 epidemiology, and pets are probably dead-end hosts of SARS-CoV-2 and pose negligible risks of transmission to humans. Still, one health concept is to be adopted widely as a component of mitigation strategies to tackle the ongoing pandemic. Therefore, in terms of the magnitude of infection and potential to transmit SARS-CoV-2 to humans, our surveillance efforts should mainly focus on mustelids (especially minks, ferrets, and others) for early detection and control of infection. This will ensure that SARS-CoV-2 will not get established in the wild animal population of these susceptible species. We agree with Dr. Passarella Teixeira on the possibility of domestic and feral cats acting as an urban reservoir, subsequently transmitting the virus to human beings. However, it is less likely that such a phenomenon will be reported even if it has occurred due to the efficient and extensive human-to-human transmission of SARS-CoV-2.

Do Dogs and Cats Passively Carry SARS-CoV-2 on Hair and Pads?

The epidemiological role of domestic animals in the spread and transmission of SARS-CoV-2 to humans has been investigated in recent reports, but some aspects need to be further clarified. To date, only in rare cases have dogs and cats living with COVID-19 patients been found to harbour SARS-CoV-2, with no evidence of pet-to-human transmission. The aim of the present study was to verify whether dogs and cats act as passive mechanical carriers of SARS-CoV-2 when they live in close contact with COVID-19 patients. Cutaneous and interdigital swabs collected from 48 dogs and 15 cats owned by COVID-19 patients were tested for SARS-CoV-2 by qRT-PCR. The time elapsed between owner swab positivity and sample collection from pets ranged from 1 to 72 days, with a median time of 23 days for dogs and 39 days for cats. All samples tested negative, suggesting that pets do not passively carry SARS-CoV-2 on their hair and pads, and thus they likely do not play an important role in the virus transmission to humans. This data may contribute to confirming that the direct contact with the hair and pads of pets does not represent a route for the transmission of SARS-CoV-2.

The Second Wave of SARS-CoV-2 Circulation-Antibody Detection in the Domestic Cat Population in Germany.

Registered cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in the German human population increased rapidly during the second wave of the SARS-CoV-2 pandemic in winter 2020/21. Since domestic cats are susceptible to SARS-CoV-2, the occurrence of trans-species transmission needs to be monitored. A previous serosurvey during the first wave of the pandemic detected antibodies against SARS-CoV-2 in 0.65% of feline serum samples that were randomly sampled across Germany. In the here-presented follow-up study that was conducted from September 2020 to February 2021, the seroprevalence rose to 1.36% (16/1173). This doubling of the seroprevalence in cats is in line with the rise of reported cases in the human population and indicates a continuous occurrence of trans-species transmission from infected owners to their cats.

SARS-CoV-2 infection, disease and transmission in domestic cats.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the cause of Coronavirus Disease 2019 (COVID-19) and responsible for the current pandemic. Recent SARS-CoV-2 susceptibility studies in cats show that the virus can replicate in these companion animals and transmit to other cats. Here, we present an in-depth study of SARS-CoV-2 infection, disease and transmission in domestic cats. Cats were challenged with SARS-CoV-2 via intranasal and oral routes. One day post challenge (DPC), two sentinel cats were introduced. Animals were monitored for clinical signs, clinicopathological abnormalities and viral shedding. Postmortem examinations were performed at 4, 7 and 21 DPC. Viral RNA was not detected in blood but transiently in nasal, oropharyngeal and rectal swabs and bronchoalveolar lavage fluid as well as various tissues. Tracheobronchoadenitis of submucosal glands with the presence of viral RNA and antigen was observed in airways of the infected cats. Serology showed that both, principals and sentinels, developed antibodies to SARS-CoV-2. All animals were clinically asymptomatic during the course of the study and capable of transmitting SARS-CoV-2 to sentinels. The results of this study are critical for understanding the clinical course of SARS-CoV-2 in a naturally susceptible host species, and for risk assessment.

Transmammary transmission of Troglostrongylus brevior feline lungworm: a lesson from our gardens.

Feline lungworms such as Aerulostrongylus abstrusus and Troglostrongylus brevior are snail-borne pathogens causing respiratory disease in domestic cats. Paratenic hosts such as rodents and reptiles have also been implicated in the epidemiology of these parasites. Although A. abstrusus has been recognized for a long time as the most prevalent lungworm among cats worldwide, T. brevior is of major concern in kittens. Bearing in mind that disease due to T. brevior occurs mainly in pediatric patients younger than 6 months of age, the diagnosis of this parasite in two kittens presenting severe respiratory disease from the garden of one of the authors inspired us to investigate the potential routes of transmission for T. brevior in domestic cats. Of the three queens (A, B and C) that delivered kittens (n = 8), only cat A was positive for T. brevior, presenting her two kittens severe respiratory clinical signs, which lead to the exitus in one of them, 18 days of age. In addition, three kittens, the offspring of queen B, turned to be positive at the coprological examination after suckling from queen A, whereas those from queen C (that suckled only on their own mother) remained negative. A series of coprological, histological and molecular tests were conducted to confirm the presence of T. brevior in the patients as well as in the other cats cohabiting the same garden. Adult nematodes were retrieved from the trachea and bronchi of the dead kitten (kitten 1A), and larvae at the histology of the lung and liver parenchyma associated with bronco pneumonitis and lymphocytic pericholangitis, respectively. Cornu aspersum (n = 60), Eobania vermiculata (n = 30) snails (intermediate hosts) as well as lizards and rats (potential paratenic hosts) were collected from the same garden and processed through tissue digestion and molecular detection. Troglostrongylus brevior larvae were recovered through tissue digestion from two C. aspersum (3.33 %) and it was confirmed by PCR-sequencing approach, which also detected T. brevior DNA in the liver and lungs of one rat and in the coelomatic cavity of one gecko lizard. During the COVID-19 lockdown, when scientists spent more time at home, we grasp the opportunity to decipher T. brevior biology and ecology starting in a small ecological niche, such as the garden of our house. Data herein presented led us to suggest: i) the transmammary transmission of T. brevior in domestic cats; ii) the role of intermediate and paratenic hosts (including reptiles) in the epidemiology of the infection which they transmit; as well as iii) the importance of observational parasitology in studying any event that certainly occurs in small ecological niches, as it could be in our home gardens.