On the etiology of an outbreak of winter dysentery in dairy cows in Brazil

Abstract

Winter dysentery (WD) is a seasonal infectious disease described worldwide that causes a marked decrease in milk production in dairy cows. In the Northern hemisphere, where the disease is classically recognized, bovine coronavirus (BCoV) has been assigned as a major etiologic agent of the disease. Nonetheless, in the Southern hemisphere, an in-deep etiological survey on WD cases had not been carried out. This study aimed to survey for BCoV by nested-RT-PCR, rotavirus by polyacrylamide gel electrophoresis (PAGE) and ELISA, bacteria by classical bacteriological methods and PCR for virulence factors and parasites by sugar flotation test on fecal samples of 21 cows from a farm during an outbreak of WD in São Paulo state, Southeastern Brazil. BCoV was detected in all 21 samples, while rotavirus was detected in two symptomatic cows. Escherichia coli, Yersinia intermedia, Providencia rustigianii Proteus penneri, Klebsiella terrigena and Enterobacter aglomerans were detected in samples from both asymptomatic and healthy cows in different associations. The study of E. coli virulence factors revealed that the strains isolated were all apathogenic. Cysts of Eimeria sp. and eggs of Strongyloidea were detected at low numbers in four of the symptomatic cows, with one co-infestation. These results suggest BCoV as the main etiologic agent of the cases of WD in Brazil, a conclusion that, with the clinical and epidemiological patterns of the disease studied herein, match those already described elsewhere. These findings give basis to the development of preventive measures and contribute to the understanding of the etiology of WD.

El tercer gran salto: los coronavirus animales en América Latina

“…Estudios de brotes de WD y NCD, demostraron valores altos de prevalencia de los BCoV en granjas bovinas brasileñas (Brandão et al, 2007;Stipp et al, 2009;Takiuchi et al, 2009), mientras que la prevalencia fue menor en granjas chilenas (Santibáñez Contreras et al, 2012) y uruguayas (Castells et al, 2019), asociando las cepas aisladas en este último país, con las de sus países vecinos (Brasil y Argentina).…”

Phylogenetic Analysis: Basic Concepts and Its Use as a Tool for Virology and Molecular Epidemiology

“…Além disso, o fragmento sequenciado nesse estudo, na região hipervariável do gene da glicoproteína espiculada, foi eleito um bom marcador genético a ser usado em maiores estudos sobre eficiência de imunógenos, pois é a proteína mais exposta à pressão seletiva imunológica, portanto, a mais propensa a polimorfismos [8]. A diversidade molecular de Coronavírus em morcegos e cães no Brasil também foi inferida através do uso de análises filogenéticas [9,10,74].…”

Detecção simultânea de Coronavírus bovino e Rotavírus do grupo A em amostras fecais de bovinos utilizando uma multiplex hemi-nested RT-PCR

“…Por sua vez, a disenteria de inverno é uma doença aguda de ocorrência epizoótica com tendência sazonal e distribuição mundial, que acomete bovinos adultos, com maior prevalência na população de bovinos leiteiros, causada pelo coronavírus bovino (BCoV), com casos de associação com Salmonella sp, rotavírus, BVDV, Crysptosporidium parvum e Eimeria bovis (DURHAM et al, 1989;PARK et al, 2006;BRANDÃO et al, 2007).…”