Cross-sectional analysis of students and school workers reveals a high number of asymptomatic SARS-CoV-2 infections during school reopening in Brazilian cities

Brazil experienced one of the most prolonged periods of school closures, and reopening could have exposed students to high rates of SARS-CoV-2 infection. However, the infection status of students and school workers at the time of the reopening of schools located in Brazilian cities is unknown. Here we evaluated viral carriage by RT-PCR and seroprevalence of anti-SARS-CoV-2 antibodies (IgM and IgG) by immunochromatography in 2259 individuals (1139 students and 1120 school workers) from 28 schools in 28 Brazilian cities. We collected the samples within 30 days after public schools reopened and before the start of vaccination campaigns. Most students (n = 421) and school workers (n = 446) had active (qRT-PCR + IgM− IgG− or qRT-PCR + IgM + IgG−/+) SARS-CoV-2 infection. Regression analysis indicated a strong association between the infection status of students and school workers. Furthermore, while 45% (n = 515) of the students and 37% (n = 415) of the school workers were neither antigen nor antibody positive in laboratory tests, 16% of the participants (169 students and 193 school workers) were oligosymptomatic, including those reinfected. These individuals presented mild symptoms such as headache, sore throat, and cough. Notably, most of the individuals were asymptomatic (83.9%). These results indicate that many SARS-CoV-2 infections in Brazilian cities during school reopening were asymptomatic. Thus, our study highlights the need to promote a coordinated public health effort to guarantee a safe educational environment while avoiding exacerbating pre-existent social inequalities in Brazil, reducing social, mental, and economic losses for students, school workers, and their families

Seroconversion and seroreactivity patterns of dairy goats naturally exposed to caprine arthritis-encephalitis virus in Brazil Soroconversão e sororeatividade de cabras leiteiras naturalmente expostas ao virus da artrite-encefalite caprina no Brasil

A labelled avidin-biotin ELISA (lab-ELISA) using repeated serum samples of goats showed a progressive seroconversion with higher seroconversion rate at the period going from the beginning of the breeding up to the last half of lactation (35.0%), compared to that recorded at the beginning of breeding (17.8%)(p<0.05). Furthermore, the seroreactivity pattern, evaluated by a lab-ELISA standard-curve with serum samples collected at 30-40 days intervals during 12 months, was caracterized by high individual variability. No seroreversion was observed and there were higher titers in the group of animals which delivered kids and established a lactation period (n=6; mean titre=913.4 units) compared to the group of goats that failed to conceived (n=4; mean titre=261.2 units) (p<0.01).<br>Foram realizados exames sorológicos em cabras leiteiras, utilizando-se ELISA marcado com avidina-biotina (LAB-ELISA). Esses exames mostraram soroconversão progressiva, com uma taxa maior entre os animais a partir do início da reprodução até a última metade da lactação (35%) comparada à observada nos animais até o início da reprodução (17,8%)(p<0,05). Além disso, o padrão de sororeatividade das amostras colhidas a cada 30-40 dias, durante 12 meses, avaliado pelo LAB-ELISA, foi caracterizado por alta variabilidade individual. Não foi observada sororeversão, e títulos mais altos foram obtidos mais no grupo constituído por animais que entraram em lactação (n=6, média de títulos=913,4) do que no grupo constituído por animais que cruzaram, mas não conceberam (n=4, média de títulos=261,2)(p<0,01)

Prevalência da infecção pelo vírus da artrite encefalite caprina no estado do Ceará, Brasil Prevalence of caprine arthritis encephalitis virus infection in the State of Ceará, Brazil

A elevação do risco de contaminação pelo vírus da artriteencefalite caprina (CAEV) em rebanhos caprinos nativos e sem raça definida (SRD) tem sido verificada paralelamente à introdução de caprinos de raças exóticas no Brasil, o que motivou a realização deste levantamento epidemiológico no Estado do Ceará. Para o diagnóstico da infecção pelo CAEV, utilizou-se a microtécnica de imunodifusão em gel de ágar. Foram pesquisadas 4019 amostras de soro caprino em 30 municípios do Ceará. A prevalência da infecção pelo CAEV verificada foi de 1% (40/4019 animais), sendo a maior prevalência (11,1%) na região metropolitana de Fortaleza. Analisando a distribuição de animais soropositivos nos municípios pesquisados, constatou-se que um terço dos municípios (10/30) apresentaram pelo menos um animal soropositivo. Verificou-se maior prevalência (p<5%) nos caprinos mais velhos quando comparados com os jovens. A análise por sexo e composição do rebanho mostrou que os machos estavam estatisticamente mais afetados (p<5%). Considerando-se o grau de sangue, 5,02% de raças puras e 0,12% de animais mestiços apresentavam anticorpos contra CAEV. Dentre os soropositivos, a raça Parda Alpina foi estatisticamente mais afetada (p<5%). Com base nos resultados, pode-se verificar que o lentivírus de pequenos ruminantes já se encontra disseminado nas várias regiões do Ceará e que, provavelmente, os reprodutores sejam a principal fonte de transmissão viral entre os rebanhos nativos/SRD.<br>This epidemiological study in the State of Ceará, Brazil was motivated by the risk of infection with caprine arthritis encephalitis virus (CAEV) through introduction of exotic caprines. For diagnosis of CAEV infection the agar gel imunodifusion microtechnic was used. 4019 goat serum samples were collected in 30 counties. The prevalence of CAEV infection was 1% (40/4019 animals). The highest prevalence (11.1%) was found in the metropolitan area of Fortaleza, the area with highest goat milk production. The analysis of the distribution of seropositive animals in the studied counties showed that 33% (10/30) had at least one positive animal. The highest prevalence was found (p <0.05) in older animals. The males were more affected (p<0.05). The pure breeds presented 5.02% of animals with antibodies against the CAEV and the half-breeds 0,12%. The Alpine breed was the more affected (p<0.05) among all breeds studied. It was verified that the small ruminant lentivirus is already disseminated in several areas of the Stete of Ceará and that the males are probably the main source of transmission to the native/SRD flocks