Logistics Workers Are a Key Factor for SARS-CoV-2 Spread in Brazilian Small Towns: Case-Control Study.

BACKGROUND: Data on how SARS-CoV-2 enters and spreads in a population are essential for guiding public policies. OBJECTIVE: This study seeks to understand the transmission dynamics of SARS-CoV-2 in small Brazilian towns during the early phase of the epidemic and to identify core groups that can serve as the initial source of infection as well as factors associated with a higher risk of COVID-19. METHODS: Two population-based seroprevalence studies, one household survey, and a case-control study were conducted in two small towns in southeastern Brazil between May and June 2020. In the population-based studies, 400 people were evaluated in each town; there were 40 homes in the household survey, and 95 cases and 393 controls in the case-control study. SARS-CoV-2 serology testing was performed on participants, and a questionnaire was applied. Prevalence, household secondary infection rate, and factors associated with infection were assessed. Odds ratios (ORs) were calculated by logistic regression. Logistics worker was defined as an individual with an occupation focused on the transportation of people or goods and whose job involves traveling outside the town of residence at least once a week. RESULTS: Higher seroprevalence of SARS-CoV-2 was observed in the town with a greater proportion of logistics workers. The secondary household infection rate was 49.1% (55/112), and it was observed that in most households (28/40, 70%) the index case was a logistics worker. The case-control study revealed that being a logistics worker (OR 18.0, 95% CI 8.4-38.7) or living with one (OR 6.9, 95% CI 3.3-14.5) increases the risk of infection. In addition, having close contact with a confirmed case (OR 13.4, 95% CI 6.6-27.3) and living with more than four people (OR 2.7, 95% CI 1.1-7.1) were also risk factors. CONCLUSIONS: Our study shows a strong association between logistics workers and the risk of SARS-CoV-2 infection and highlights the key role of these workers in the viral spread in small towns. These findings indicate the need to focus on this population to determine COVID-19 prevention and control strategies, including vaccination and sentinel genomic surveillance.

Effects of castration on androgen receptors and gonadotropins in the pituitary of adult male viscachas.

The aims of the present study were to determine whether castration results in quantitative immunohistochemical changes in androgen receptors (AR), LH-immunoreactive (IR) cells and FSH-IR cells, and to analyse the colocalisation of AR and gonadotropins in the pituitary pars distalis (PD) of viscachas. Pituitaries were processed for light and electron microscopy. AR-IR, LH-IR and FSH-IR cells were detected by immunohistochemistry. In morphometric studies, the percentage of AR-IR, LH-IR, FSH-IR, LH-IR/AR-IR and FSH-IR/AR-IR cells was determined. In intact viscachas, AR were distributed throughout the PD; they were numerous at the caudal end, with intense immunostaining. LH-IR cells and FSH-IR cells were found mainly in the ventral region and at the rostral end of the PD. Approximately 45%-66% of LH-IR cells and 49%-57% of FSH-IR cells expressed AR in the different zones of the PD. In castrated viscachas, there was a significant decrease in the percentage of AR-IR, LH-IR, FSH-IR, and FSH-IR/AR-IR cells. Some pituitary cells from castrated viscachas also exhibited ultrastructural changes. These results provide morphological evidence that gonadal androgens are directly related to the immunolabelling of AR, LH and FSH. Moreover, the colocalisation of AR and FSH is most affected by castration, suggesting the existence of a subpopulation of gonadotrophs with different regulatory mechanisms for hormonal synthesis, storage and secretion.