Rapid antigen detection of severe acute respiratory syndrome coronavirus-2 in stray cats: A cross-sectional study.

Background and Aim: Although reverse zoonotic transmission events from humans to domestic cats have been described, there is currently little evidence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) circulation in stray cats. Due to the evidence of natural and experimental infections in cats and the capacity to disseminate the virus among them, this study aimed to identify the SARS-CoV-2 antigen in stray cats from the Federal University of Sergipe in Brazil. Materials and Methods: One hundred twenty six stray cats from the university were screened for SARS-CoV-2 antigens by random sampling. Throat swab samples were tested for the virus using rapid antigen detection tests. Results: Of the 126 animals tested, 30 (23.60%) were positive for SARS-CoV-2 antigens. To our knowledge, for the first time, this study detected the SARS-CoV-2 antigen in stray cats and confirmed the presence of SARS-CoV-2 infections in Brazil's stray cat population. Conclusion: The detection of SARS-CoV-2 in stray cats poses a risk for infected and healthy animals and possibly for humans who attend the university daily. As a limitation of the study, the small sample size necessitates caution when interpreting the results. This underscores the need for further research in this area to help control diseases in stray animals during potential pandemics. This highlights the need for monitoring and controlling the spread of the virus in stray animal populations.

The rising incidence of feline and cat-transmitted sporotrichosis in Latin America.

INTRODUCTION: Sporotrichosis is a subcutaneous mycosis caused by different species of thermodimorphic fungi belonging to the genus Sporothrix. These fungi may affect a wide range of warm-blooded animals, including humans, dogs and, mainly, cats. METHODS: In this article, we conducted a narrative literature review about the status of feline and cat-transmitted sporotrichosis in Latin American countries, with emphasis on Brazil. RESULTS: From a global perspective, Latin America is one of the main foci of human and feline sporotrichosis. In humans, the disease has been reported in several countries, with endemic transmission occurring in Brazil, Colombia, Costa Rica, Guatemala, Mexico and Uruguay. Sporothrix brasiliensis is the most common species identified in human cases in Brazil, whereas Sporothrix schenckii predominates in other countries. CONCLUSION: Domestic cats are the main source of infection in the zoonotic transmission cycle of sporotrichosis in Latin America. Cases of feline sporotrichosis have been reported in several countries, including Argentina, Brazil, Chile, Colombia, Mexico, Panama, Paraguay and Peru.

Potentially zoonotic parasites in the soil of public squares in the city of Aracaju (Sergipe, Northeastern Brazil).

This study evaluated the soil contamination of public squares in the city of Aracaju, Sergipe, by potentially zoonotic parasites and correlated their occurrence with climatic variables (temperature, humidity and precipitation). Samples were collected over a 18-month period, from 20 different public squares, and submitted to three different parasitological techniques: Faust's, Hoffman's and Rugai's methods, adapted to soil samples. Results indicated the presence of several potentially zoonotic parasitic species in eighteen of the 20 squares analyzed (90%). The parasites identified included Ancylostoma spp., Strongyloides stercoralis, Toxocara spp., Dipylidium caninum, Trichuris sp., Capillaria sp. and Giardia sp. They were identified during all months of the year and no influence of temperature, humidity or precipitation on the occurrence of those parasites was observed. Such results demonstrate that public squares in the city of Aracaju pose a parasitic contamination risk for people and pets that visit those places as a leisure activity.

An experimental protocol for the establishment of dogs with long-term cellular immune reactions to Leishmania antigens.

Domestic dogs are considered to be the main reservoirs of zoonotic visceral leishmaniasis. In this work, we evaluated a protocol to induce Leishmania infantum/Leishmania chagasi-specific cellular and humoral immune responses in dogs, which consisted of two injections of Leishmania promastigote lysate followed by a subcutaneous inoculation of viable promastigotes. The primary objective was to establish a canine experimental model to provide positive controls for testing immune responses to Leishmania in laboratory conditions. After inoculation of viable promastigotes, specific proliferative responses of peripheral blood mononuclear cells (PBMCs) to either Leishmania lysate or recombinant proteins, the in vitro production of interferon-γ by antigen-stimulated PBMCs and a significant increase in circulating levels of anti-Leishmania antibodies were observed. The immunized dogs also displayed positive delayed-type hypersensitivity reactions to Leishmania crude antigens and to purified recombinant proteins. An important finding that supports the suitability of the dogs as positive controls is that they remained healthy for the entire observation period, i.e., more than seven years after infection. Following the Leishmania antigen lysate injections, the infection of dogs by the subcutaneous route appears to induce a sustained cellular immune response, leading to an asymptomatic infection. This provides a useful model for both the selection of immunogenic Leishmania antigens and for immunobiological studies on their possible immunoprotective activities.

An experimental protocol for the establishment of dogs with long-term cellular immune reactions to Leishmania antigens

Domestic dogs are considered to be the main reservoirs of zoonotic visceral leishmaniasis. In this work, we evaluated a protocol to induce Leishmania infantum/Leishmania chagasi-specific cellular and humoral immune responses in dogs, which consisted of two injections of Leishmania promastigote lysate followed by a subcutaneous inoculation of viable promastigotes. The primary objective was to establish a canine experimental model to provide positive controls for testing immune responses to Leishmania in laboratory conditions. After inoculation of viable promastigotes, specific proliferative responses of peripheral blood mononuclear cells (PBMCs) to either Leishmania lysate or recombinant proteins, the in vitro production of interferon-γ by antigen-stimulated PBMCs and a significant increase in circulating levels of anti-Leishmania antibodies were observed. The immunized dogs also displayed positive delayed-type hypersensitivity reactions to Leishmania crude antigens and to purified recombinant proteins. An important finding that supports the suitability of the dogs as positive controls is that they remained healthy for the entire observation period, i.e., more than seven years after infection. Following the Leishmania antigen lysate injections, the infection of dogs by the subcutaneous route appears to induce a sustained cellular immune response, leading to an asymptomatic infection. This provides a useful model for both the selection of immunogenic Leishmania antigens and for immunobiological studies on their possible immunoprotective activities.

Peripheral blood mononuclear cell supernatants from asymptomatic dogs immunized and experimentally challenged with Leishmania chagasi can stimulate canine macrophages to reduce infection in vitro.

Leishmania chagasi is the causative agent of visceral leishmaniasis in both humans and dogs in the New World. The dog is the main domestic reservoir and its infection displays different clinical presentations, from asymptomatic to severe disease. Macrophages play an important role in the control of Leishmania infection. Although it is not an area of intense study, some data suggest a role for canine macrophages in parasite killing by a NO-dependent mechanism. It has been proposed that control of human disease could be possible with the development of an effective vaccine against canine visceral leishmaniasis. Development of a rapid in vitro test to predict animal responses to Leishmania infection or vaccination should be helpful. In this study, an in vitro model was established to test whether peripheral blood mononuclear cell (PBMC) supernatants from dogs immunized with promastigote lysates and infected with L. chagasi promastigotes could stimulate macrophages from healthy dogs in order to control parasite infection. PBMC from a majority of the immunized and experimentally infected dogs expressed IFN-gamma mRNA and secreted IFN-gamma when stimulated with soluble L. chagasi antigen (SLA) in vitro. Additionally, the supernatants from stimulated PBMC were able to reduce the percentage of infected donor macrophages. The results also indicate that parasite killing in this system is dependent on NO, since aminoguanidine (AMG) reversed this effect. This in vitro test appears to be useful for screening animal responses to parasite inoculation as well as studying the lymphocyte effector mechanisms involved in pathogen killing by canine macrophages.

Frequência de anticorpos anti-Neospora caninum em cães nos municípios de Salvador e Lauro de Freitas, Estado da Bahia - Brasil / Frequency of antibodies anti-Neospora caninum on dogs from Salvador and Lauro de Freitas, Bahia state - Brasil

A freqüência de anticorpos IgG anti-Neospora caninum foi estudada em 415 amostras séricas de cães domiciliados e errantes, procedentes dos municípios baianos de Salvador e Lauro de Freitas, utilizando-se a técnica de imunofluorescência indireta, com ponto de corte igual a 1:50. Anticorpos da classe IgG anti-N. caninum foram detectados em 13,3% (22/165) dos cães domiciliados e em 11,2% (28/250) dos errantes. As freqüências de soropositivos machos e fêmeas foram 8,0% (6/75) e 18,4% (14/76) nos cães domiciliados e 12,6% (17/135) e 9,6% (11/115) nos errantes, respectivamente. Não houve diferenças estatisticamente significativas entre sexo, idade, raça e a freqüência de soropositividade ao N. caninum dos cães domiciliados e errantes.

The frequency of anti-Neospora caninum IgG antibodies was studied in 415 serum samples from owned and stray dogs from Salvador and Lauro de Freitas counties. The Indirect immunofluorescence was performed using a cut-off of 1:50. Anti-N. caninum IgG antibodies were detected in 13.3% (22/165) owned dogs and in 11.2% (28/250) stray dogs. The frequencies of males and females seropositivity were 8.0% (6/75) and 18.4% (14/76) for owned dogs and 12.6 % (17/ 135) and 9.6% (11/115) in the stray dogs population, respectively. There were not a statistical significant difference between sex, age, breed and the dogs anti-N. caninum IgG antibodies incidence.