Molecular detection and characterization of SARS-CoV-2 in cats and dogs of positive owners during the first COVID-19 wave in Brazil.

Despite previous reports of SARS-CoV-2 infection in dogs and cats worldwide, the type of swab sample used for its detection through RT-qPCR needs to be better compared and described. Accordingly, as part of a multicenter study in Brazil, the aim of the present study was to assess which rectal or oropharyngeal swabs would be more appropriate for detecting SARS-CoV-2 in cats and dogs, through viral load comparison. Pets of owners diagnosed with COVID-19 in the last 7 days were eligible. A total of 148 animals from four of the five Brazilian geographical regions were analyzed, among which 10/48 cats (20.83%) and 11/100 dogs (11.00%) were positive. The results suggested that oropharyngeal swabs should be considered for SARS-CoV-2 detection, particularly in cats, due to the higher cDNA viral load. Also, the genomic results showed similarities between SARS-CoV-2 animal variants and human variants that were circulating at the time of sampling, thus corroborating the existence of zooanthroponotic transmission. In conclusion, the present study highlighted the importance of SARS-CoV-2 monitoring among cats and dogs, as virus modification may indicate the possibility of mutations in animals and spillover back to owners. Thus, positive individuals should always self-isolate from their pets during COVID-19, to prevent trans-species transmission and mutation.

The role of pets in SARS-CoV-2 transmission: an exploratory analysis.

PURPOSE: There is evidence that humans can transmit SARS-CoV-2 to cats and dogs. However, there is no evidence that they can transmit it back to humans or play any role in SARS-CoV-2 transmission. Here, we present an exploratory analysis on that matter. METHODS: We conducted a case-control study with participants with flu-like symptoms seeking care at a primary healthcare unit to be tested for COVID-19. They were asked if they owned pet cats and/or dogs in their residences, and this variable was evaluated as exposure. RESULTS: The odds ratio of "having dogs and/or cats in the residence" was 1.29 (95% CI 1.08-1.54) of "having only dogs and no cats" was 1.26 (1.05-1.52), and "no dogs and only cats" was 1.29 (0.95-1.75). CONCLUSION: Having a cat/dog in the house can affect the risk of infection by SARS-CoV-2.

Detecting Leishmania in dogs: A hierarchical-modeling approach to investigate the performance of parasitological and qPCR-based diagnostic procedures.

BACKGROUND: Domestic dogs are primary reservoir hosts of Leishmania infantum, the agent of visceral leishmaniasis. Detecting dog infections is central to epidemiological inference, disease prevention, and veterinary practice. Error-free diagnostic procedures, however, are lacking, and the performance of those available is difficult to measure in the absence of fail-safe "reference standards". Here, we illustrate how a hierarchical-modeling approach can be used to formally account for false-negative and false-positive results when investigating the process of Leishmania detection in dogs. METHODS/FINDINGS: We studied 294 field-sampled dogs of unknown infection status from a Leishmania-endemic region. We ran 350 parasitological tests (bone-marrow microscopy and culture) and 1,016 qPCR assays (blood, bone-marrow, and eye-swab samples with amplifiable DNA). Using replicate test results and site-occupancy models, we estimated (a) clinical sensitivity for each diagnostic procedure and (b) clinical specificity for qPCRs; parasitological tests were assumed 100% specific. Initial modeling revealed qPCR specificity < 94%; we tracked the source of this unexpected result to some qPCR plates having subtle signs of possible contamination. Using multi-model inference, we formally accounted for suspected plate contamination and estimated qPCR sensitivity at 49-53% across sample types and dog clinical conditions; qPCR specificity was high (95-96%), but fell to 81-82% for assays run in plates with suspected contamination. The sensitivity of parasitological procedures was low (~12-13%), but increased to ~33% (with substantial uncertainty) for bone-marrow culture in seriously-diseased dogs. Leishmania-infection frequency estimates (~49-50% across clinical conditions) were lower than observed (~60%). CONCLUSIONS: We provide statistical estimates of key performance parameters for five diagnostic procedures used to detect Leishmania in dogs. Low clinical sensitivies likely reflect the absence of Leishmania parasites/DNA in perhaps ~50-70% of samples drawn from infected dogs. Although qPCR performance was similar across sample types, non-invasive eye-swabs were overall less likely to contain amplifiable DNA. Finally, modeling was instrumental to discovering (and formally accounting for) possible qPCR-plate contamination; even with stringent negative/blank-control scoring, ~4-5% of positive qPCRs were most likely false-positives. This work shows, in sum, how hierarchical site-occupancy models can sharpen our understanding of the problem of diagnosing host infections with hard-to-detect pathogens including Leishmania.

Severe acute respiratory syndrome coronavirus 2 in cats: a systematic review.

The epidemiological role of cats in the coronavirus disease pandemic remains unclear despite of several studies that have been conducted to understand it, in other words it is not yet known whether the cat would be able to transmit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to humans. Taking that into account, the objective of this study was to conduct a systematic review to identify what is known and not known on this topic. Our results revealed that cats can be infected through an airborne (perhaps oral, too) route and that the clinical development of the infection in cats is parallel to that in humans. The majority of infected cats remained asymptomatic, and more severe clinical cases described occurred only in animals with comorbidities. In addition to infection, cats achieved seroconversion with detectable titers. However, the epidemiological role of cats in relation to transmission routes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains unclear and needs to be studied further. We emphasize that, regardless of the conclusion regarding the epidemiological role of cats, this reinforces the concepts of ONE HEALTH to be incorporated into the studies and practices of epidemiological surveillance of infectious diseases, with multidisciplinary teams, to achieve an understanding of the transmission of diseases with zoonotic potential.

O papel epidemiológico dos gatos na pandemia da doença causada pelo novo coronavírus ainda não foi esclarecido. Apesar de vários estudos realizados, ainda não foi determinado se os gatos poderiam transmitir o vírus da síndrome respiratória aguda grave coronavírus 2 (SARS-CoV-2) para os humanos. Diante disso, o objetivo deste estudo foi realizar uma revisão sistemática sobre esse tema. Nossos resultados destacam os achados de que os gatos podem ser infectados por via aérea, talvez oral também, e de que o desenvolvimento clínico da infecção em gatos guarda um paralelo com a infecção em humanos, pois a maioria dos gatos infectados que foram estudados permaneceu assintomática, e os casos clínicos mais graves descritos ocorreram apenas em animais com comorbidades. Além da presença do vírus, os gatos também desenvolvem anticorpos específicos. Ressaltamos que, independentemente da conclusão quanto ao papel epidemiológico dos gatos, os achados desse estudo reforçam os conceitos de ÚNICA SAÚDE a serem incorporados aos estudos e práticas de vigilância epidemiológica de doenças infecciosas, com equipes multidisciplinares, para o entendimento da transmissão de doenças com potencial zoonótico.

A cross-sectional approach including dog owner characteristics as predictors of visceral leishmaniasis infection in dogs.

BACKGROUND: Visceral leishmaniasis (VL) is relevant for human and animal public health. Several factors have been associated with the risk of Leishmania infantum infection in dogs. However, dog owner characteristics have been rarely explored. OBJECTIVES: To estimate the prevalence and to identify the associated factors for VL infection including dog owners characteristics. METHODS: A cross-sectional study was conducted including dogs from an endemic canine visceral leishmaniasis (CVL) region in the Federal District, Brazil. The infection was detected using parasitological, serological, and molecular methods. The associated factors were identified through Poisson regression modelling. FINDINGS: The prevalence of infection was 26.25% [95% confidence interval (CI): 20.05 to 33.57]. The associated factors were: short coat prevalence ratio (PR) = 2.33 (95% CI: 1.02 to 5.22); presence of backyard with predominance of soil and/or vegetation PR = 4.15 (95% CI: 1.35 to 12.77); and highest gross family income score PR = 2.03 (95% CI: 1.16 to 3.54). MAIN CONCLUSION: This is the first study that relates higher socioeconomic status of dog owners as an independent factor associated with higher prevalence of VL infection, along with other strongly associated factors related to receptive environment for phlebotomines. Our findings strengthen the need for exploration of the biological and behavioural bases linking dog owner characteristics to the risk of canine infection in prospective cohort studies.

A cross-sectional approach including dog owner characteristics as predictors of visceral leishmaniasis infection in dogs

BACKGROUND Visceral leishmaniasis (VL) is relevant for human and animal public health. Several factors have been associated with the risk of Leishmania infantum infection in dogs. However, dog owner characteristics have been rarely explored. OBJECTIVES To estimate the prevalence and to identify the associated factors for VL infection including dog owners characteristics. METHODS A cross-sectional study was conducted including dogs from an endemic canine visceral leishmaniasis (CVL) region in the Federal District, Brazil. The infection was detected using parasitological, serological, and molecular methods. The associated factors were identified through Poisson regression modelling. FINDINGS The prevalence of infection was 26.25% [95% confidence interval (CI): 20.05 to 33.57]. The associated factors were: short coat prevalence ratio (PR) = 2.33 (95% CI: 1.02 to 5.22); presence of backyard with predominance of soil and/or vegetation PR = 4.15 (95% CI: 1.35 to 12.77); and highest gross family income score PR = 2.03 (95% CI: 1.16 to 3.54). MAIN CONCLUSION This is the first study that relates higher socioeconomic status of dog owners as an independent factor associated with higher prevalence of VL infection, along with other strongly associated factors related to receptive environment for phlebotomines. Our findings strengthen the need for exploration of the biological and behavioural bases linking dog owner characteristics to the risk of canine infection in prospective cohort studies.

Improving the reference standard for the diagnosis of canine visceral leishmaniasis: a challenge for current and future tests.

BACKGROUND: Studies aimed at validating canine visceral leishmaniasis diagnostic tests present heterogeneous results regarding test accuracy, partly due to divergences in reference standards used and different infection evolution periods in animals. OBJECTIVE: This study aimed to evaluate the accuracy of the rapid test-dual path platform (TR-DPP) (Biomanguinhos®), EIE-Leishmaniose-Visceral-Canina-Biomanguinhos (EIE-LVC) (Biomanguinhos®), enzyme-linked immunosorbent assay (ELISA) rK39 (in-house), and the direct agglutination test (DAT-Canis) against a reference standard comprising parasitological and molecular techniques. METHODS: A phase II/III validation study was carried out in sample sera from 123 predominantly asymptomatic dogs living in an area endemic for visceral leishmaniasis. FINDINGS: Sixty-nine (56.1%) animals were considered infected according to the reference standard. For each test, the sensitivity and specificity, respectively, were as follows: TR-DPP, 21.74% [confidence interval (CI)95% 13.64% to 32.82%] and 92.59% (CI95% 82.45% to 97.08%); EIE-LVC, 11.59% (CI95% 5.9% to 21.25%) and 90.74% (CI95% 80.09% to 95.98%); ELISA rK39, 37.68% (CI95% 27.18% to 49.48%) and 83.33% (CI95% 71.26% to 90.98%); and DAT-Canis, 18.84% (CI95% 11.35% to 29.61%) and 96.30% (CI95% 87.46% to 98.98%). CONCLUSION: We concluded that improving the sensitivity of serum testing for diagnosing asymptomatic dogs must constitute a priority in the process of developing new diagnostic tests to be used in the visceral leishmaniasis control program in Brazil.

Improving the reference standard for the diagnosis of canine visceral leishmaniasis: a challenge for current and future tests

BACKGROUND Studies aimed at validating canine visceral leishmaniasis diagnostic tests present heterogeneous results regarding test accuracy, partly due to divergences in reference standards used and different infection evolution periods in animals. OBJECTIVE This study aimed to evaluate the accuracy of the rapid test-dual path platform (TR-DPP) (Biomanguinhos®), EIE-Leishmaniose-Visceral-Canina-Biomanguinhos (EIE-LVC) (Biomanguinhos®), enzyme-linked immunosorbent assay (ELISA) rK39 (in-house), and the direct agglutination test (DAT-Canis) against a reference standard comprising parasitological and molecular techniques. METHODS A phase II/III validation study was carried out in sample sera from 123 predominantly asymptomatic dogs living in an area endemic for visceral leishmaniasis. FINDINGS Sixty-nine (56.1%) animals were considered infected according to the reference standard. For each test, the sensitivity and specificity, respectively, were as follows: TR-DPP, 21.74% [confidence interval (CI)95% 13.64% to 32.82%] and 92.59% (CI95% 82.45% to 97.08%); EIE-LVC, 11.59% (CI95% 5.9% to 21.25%) and 90.74% (CI95% 80.09% to 95.98%); ELISA rK39, 37.68% (CI95% 27.18% to 49.48%) and 83.33% (CI95% 71.26% to 90.98%); and DAT-Canis, 18.84% (CI95% 11.35% to 29.61%) and 96.30% (CI95% 87.46% to 98.98%). CONCLUSION We concluded that improving the sensitivity of serum testing for diagnosing asymptomatic dogs must constitute a priority in the process of developing new diagnostic tests to be used in the visceral leishmaniasis control program in Brazil.