Clinical, pathological and epidemiological aspects of outbreaks of bluetongue disease in sheep in the central region of Rio Grande do Sul

Abstract

This article describes the clinical, pathological and epidemiological aspects of 17 outbreaks of bluetongue (BT) disease in sheep occurring between December 2014 and July 2015 in the central region of Rio Grande do Sul state (RS), southern Brazil. Affected farms were visited for clinical examination, necropsy, sample collection and epidemiological investigation. The outbreaks were seasonal and occurred during the summer and autumn. A total of 180 sheep (20.4%) out of 884 in 17 small herds were affected. All ages of Texel and mixed breed sheep were affected. However, lambs (younger than one year) had higher morbidity than adult sheep. The most frequent clinical signs were anorexia, lethargy, loss of body condition, facial swelling mainly involving the lips, and greenish seromucous or mucous nasal discharge. Pulmonary lesions characterized by edema were the most prevalent findings; however, erosive and ulcerative lesions in the upper gastrointestinal tract, as well as cardiac, skeletal muscle and esophageal striated muscle necrosis, and hemorrhage in the pulmonary artery were also frequent. The bluetongue virus (BTV) genome was detected by RT-PCR in blood and tissue samples (spleen and lungs) of 21 animals from 17 outbreaks. The virus involved in the outbreak 3 was subsequently isolated and shown to belong to serotype 17, for the first time reported in Brazil. In summary, our data support the BTV genotype 17 as the etiological agent of the outbreaks and indicate that the central region of RS is an area at risk for BT in sheep, a disease previously not recognized in the region.

Potential Acute Renal Injury in Sheep with Bluetongue Serotype 4

“…In previous studies, multifocal tubular necrosis was present in kidney biopsies of BTV serotype 17 infected sheep in Brazil [42], proximal tubular necrosis and haemorrhage was found in the kidneys of 70% experimentally infected white-tailed deer [43]. Similarly, glomerular congestion, erythrocytes and clumped protein in Bowman's space and tubules, tubulonephrosis, interstitial mononuclear nephritis, and interstitial haemorrhages were evident in naturally infected goats with BTV serotype 1 in Spain [44].…”

“…These findings indicate the impact of BTV-4 on renal tubular structure (enzymuria, cylindruria) and function (decreased USG, proteinuria) without evidence of alteration in glomerular filtration rate (absence of severe azotemia and hyperphosphatemia). There are no histopathological studies on ovine kidneys infected by the BTV-4 serotype and further investigation such as experimental infection using the same strain of virus is required to verify urinalysis results with any anatomical derangements in the kidneys [42][43][44]. Based on this evidence, veterinary practitioners should be cautious to avoid the use of potential nephrotoxic medication at the supportive treatment protocol of bluetongue.…”

Detección de anticuerpos contra el virus de lengua azul en ovinos de dos localidades de Junín, Perú

“…El 56.1% (46/82) de las muestras de los ovinos Blackbelly tuvieron anticuerpos contra el VLA. Los anticuerpos detectados evidencian la exposición al virus por la picadura del mosquito transmisor, más no enfermedad clínica, indicando que esta infección es enzoótica en el trópico y subtrópico con condiciones ecológicas que caracterizan al ámbito geográfico comprendido entre 40° N y 35° S y donde parte de los EEUU, América Central y parte de América del Sur están comprendidos (Purse et al, 2005 En América Latina se han reportado la enfermedad clínica de lengua azul en dos cérvidos (Mazama gouazoubira) y en un venado (Blastocerus dichotomus) en dos zoológicos de Rio de Janeiro, y en ocho ovinos y una cabra en el estado de Paran; asimismo, en 2017 hubo severos brotes en ovinos del Estado de Rio Grande do Sul, Brasil, causado por el serotipo 17 (Bianchi et al, 2017). Los países donde se ha logrado aislar al VLA son Brasil y Argentina (Lager, 2004).…”

Detección del virus de la lengua azul en ovinos por RT- PCR en tiempo real en diferentes sistemas de producción en San Martín, Perú

“…ej., fiebre en ovinos y bovinos, salivación en bovinos, edema facial en ovinos) se observaron en rebaños infectados y no infectados, estos signos no son un indicativo de la enfermedad (15) . Así mismo, las lesiones macroscópicas son edema pulmonar, consolidación pulmonar cráneo -ventral, lengua tumefacta y cianótica; y en mucosa ruminal lesiones hemorrágicas (16) . El bovino, caprino, bubalinos y otros rumiantes silvestres, actúan como reservorios del virus, siendo animales que podrían no manifestar signos clínicos (17,18,19) , sin embargo, existen reportes de mortalidad en bovinos con el serotipo 8 del VLA (20) ; otros signos clínicos como la amaurosis que es la imposibilidad de pararse y la ausencia de reflejo de succión en terneros infectados (21) .…”