The Role of Molossidae and Vespertilionidae in Shaping the Diversity of Alphacoronaviruses in the Americas.

Bats are reservoirs of diverse coronaviruses (CoVs), including progenitors of severe acute respiratory syndrome CoV (SARS-CoV) and SARS-CoV-2. In the Americas, there is a contrast between alphacoronaviruses (alphaCoVs) and betaCoVs: while cospeciation prevails in the latter, alphaCoV evolution is dominated by deep and recent host switches. AlphaCoV lineages are maintained by two different bat family groups, Phyllostomidae and Vespertilionidae plus Molossidae. In this study, we used a Bayesian framework to analyze the process of diversification of the lineages maintained by Molossidae and Vespertilionidae, adding novel CoV sequences from Argentina. We provide evidence that the observed CoV diversity in these two bat families is shaped by their geographic distribution and that CoVs exhibit clustering at the level of bat genera. We discuss the causes of the cocirculation of two independent clades in Molossus and Tadarida as well as the role of Myotis as the ancestral host and a major evolutionary reservoir of alphaCoVs across the continent. Although more CoV sampling efforts are needed, these findings contribute to a better knowledge of the diversity of alphaCoVs and the links between bat host species. IMPORTANCE Bats harbor the largest diversity of coronaviruses among mammals. In the Americas, seven alphacoronavirus lineages circulate among bats. Three of these lineages are shared by members of two bat families: Vespertilionidae and Molossidae. Uncovering the relationships between these coronaviruses can help us to understand patterns of cross-species transmission and, ultimately, which hosts are more likely to be involved in spillover events. We found that two different lineages cocirculate among the bat genera Molossus and Tadarida, which share roosts and have common viral variants. The bat genus Myotis functions as a reservoir of coronavirus diversity and, as such, is a key host. Although there were some spillovers recorded, there is a strong host association, showing that once a successful host jump takes place, it is transmitted onward to members of the same bat genus.

Infección bacteriana potencialmente grave en los lactantes de 1 a 3 meses de edad con fiebre sin foco / Serious bacterial infections in1 to 3 month ol infants with fever without a source

Fundamento. Es habitual la realización de exploraciones complementarias a los lactantes de corta edad con fiebre sin foco (FSF) para identificar a aquellos con alto riesgo de infección bacteriana potencialmente grave (IBPG). Objetivo. Conocer la prevalencia y la etiología de la IBPG en los lactantes de 1 a 3 meses de edad con FSF. Método. Estudio retrospectivo de los lactantes de 1 a 3 meses de edad atendidos en urgencias de un hospital pediátrico de tercer nivel por FSF durante un año (diciembre 2009 - diciembre 2010). Se excluyeron los pacientes a los que no se había realizado hemocultivo (HC) y/o urocultivo (UC). Resultados. Se incluyeron 275 pacientes (61,1% de sexo masculino), con una mediana de edad de 57 días (P25-75: 42-74 días). La mediana de evolución de la fiebre fue de 8 horas (P25-75: 3-13,25) y 117 (47,6%) acudieron con fiebre de menos de 6 horas de evolución. Presentaban un triángulo de evaluación pediátrica alterado 16 pacientes (5,8%). Cincuenta y un lactantes (18,5%) fueron diagnosticados de una IBPG, siendo la infección urinaria la principal entidad responsable (90,2%) y Escherichia coli el principal microorganismo aislado. Seis pacientes (2,2%) presentaron un HC positivo. A diferencia de los parámetros analíticos, la anamnesis y la exploración física no fueron útiles en la identificación de los pacientes con IBPG. Conclusiones. La prevalencia de IBPG, especialmente la infección urinaria, en los lactantes febriles de corta edad es significativa. La poca utilidad de los signos clínicos obliga a la realización de exploraciones complementarias(AU)

Background. It is common practice to order diagnostic tests to febrile young infants in order to identify those at greater risk for serious bacterial infection (SBI). Objective. To determine the prevalence and etiology of SBI in 1 to 3- month-old infants who present with fever without a source (FWS). Method. Retrospective study of all infants aged 1 to 3 months who presented to the emergency department of a tertiary pediatric hospital with FWS from December 2009 through December 2010. Patients on whom blood or urine cultures were not obtained were excluded. Results. 275 infants (61.1% males), with a median age of 57 days (P25-75; 42-74) were included. The median duration of the fever was 8 hours (P25-75; 3-13.25) and 117 (47.6%) children were seen within the first 6 hours. Sixteen patients (5.8%) were not well appearing. Fifty-one infants (18.5%) were diagnosed with SBI, being urinary tract infection (UTI) the main diagnosis (90.2%) and Escherichia coli the most commonly isolated organism. Six patients (2.2%) had a positive blood culture. In contrast to the laboratory data, clinical features were not useful in the identification of those patients with SBI. Conclusions. The rate of SBI, and more notably UTI, was significant among our young febrile infants. Because of the non-specific clinical signs, it is necessary to perform additional diagnostic studies to better identify those patients at risk for SBI(AU)