High Seroprevalence against SARS-CoV-2 among Dogs and Cats, Poland, 2021/2022.

The coronavirus SARS-CoV-2 is responsible for a pandemic in the human population that has unfolded since the beginning of 2020 and has led to millions of deaths globally. Apart from humans, SARS-CoV-2 has been confirmed in various animal species, including felines, canines, mustelids, and primates. Of these species, dogs and cats are the most popular companion animals worldwide. Several seroprevalence studies have already been performed in these animal species; however, the results vary depending on the location and especially the time of sampling. Here, serum samples were collected from a total of 388 dogs and 243 cats from three veterinary clinics in two cities (Gdansk and Olsztyn) in Poland between October 2021 and February 2022, when the country was in the midst of the fourth wave of viral spread. All sera were tested for antibodies against SARS-CoV-2 by a multispecies ELISA based on the receptor-binding domain and by an indirect immunofluorescence assay (iIFA). Overall, 18.9% of the feline sera and 16.0% of the canine sera tested positive using ELISA and iIFA. This relatively high seroprevalence among randomly selected animals is most likely related to the high case numbers in the human population and indicates a continuous occurrence of transspecies virus transmissions from infected owners to their pets. Hence, dogs and cats should be included in monitoring studies and/or outbreak investigations for a better understanding of the epidemiology of this virus.

Feline Infectious Peritonitis: Immunohistochemical Features of Ocular Inflammation and the Distribution of Viral Antigens in Structures of the Eye.

Feline infectious peritonitis (FIP) is a serious, widely distributed systemic disease caused by feline coronavirus (FCoV), in which ocular disease is common. However, questions remain about the patterns of ocular inflammation and the distribution of viral antigen in the eyes of cats with FIP. This study characterized the ocular lesions of FIP including the expression of glial fibrillary acidic protein and proliferating cell nuclear antigen by Müller cells in the retina in cases of FIP and to what extent macrophages are involved in ocular inflammation in FIP. Immunohistochemistry for FCoV, CD3, CD79a, glial fibrillary acidic protein, calprotectin, and proliferating cell nuclear antigen was performed on paraffin sections from 15 naturally occurring cases of FIP and from controls. Glial fibrillary acidic protein expression was increased in the retina in cases of FIP. Müller cell proliferation was present within lesions of retinal detachment. Macrophages were present in FIP-associated ocular lesions, but they were the most numerous inflammatory cells only within granulomas (2/15 cats, 13%). In cases of severe inflammation of the ciliary body with damage to blood vessel walls and ciliary epithelium (3/15, 20%), some macrophages expressed FCoV antigens, and immunolabeling for calprotectin on consecutive sections suggested that these FCoV-positive macrophages were likely to be recently derived from blood. In cases of severe and massive inflammation of most ocular structures (4/15, 26%), B cells and plasma cells predominated over T cells and macrophages. These results indicate that gliosis can be present in FIP-affected retinas and suggest that breakdown of the blood-ocular barrier can allow FCoV-bearing macrophages to access the eye.

Toxoplasma gondii antibodies in domestic cats in Olsztyn urban area, Poland.

The aim of the investigation was to determine the prevalence of T. gondii among a domestic cat population in an urban area in Olsztyn. In total, 135 serum samples of cats collected in several veterinary outpatient clinics in Olsztyn were examined by direct agglutination assay. The Toxo-Screen DA BioMerieux commercial test detected anti-Toxoplasma gondii IgG antibodies. The results of studies indicated that cats bred under different conditions in the city of Olsztyn have contact with various forms of invasive T. gondii. The high percentage of seropositive results at a 1:40 dilution (65.9%) suggests a past infection, and the high percentage of seropositive cases at a 1:4000 dilution (68,1%) indicates a current or recent toxoplasmosis process. This could indicate that there is a permanent source of T. gondii infection in the habitable environment of the cats. The high percentage of T. gondii seropositive results among domestic cats in Olsztyn proves the presence of circulation of the parasite in the environment.