Epidemiological study of Middle East respiratory syndrome coronavirus infection in dromedary camels in Saudi Arabia, April-May 2015.

A cross-sectional study was conducted in five regions in Saudi Arabia to investigate the epidemiology of Middle East respiratory syndrome coronavirus (MERS-CoV) infection in dromedary camels (Camelus dromedarius) during April and May2015. Serum and nasal swab samples were tested for MERS-CoV antibodies andribonucleic acid (RNA) using a recombinant enzyme-linked immunosorbent assay (rELISA) and real-time reverse-transcription polymerase chain reaction (rRT-PCR), respectively. The overall MERS-CoV antibody seroprevalence was 80.5%, whereas the overall viral RNA prevalence was 2.4%. The associations of risk factors with each prevalence were quantified using univariate and multivariate analyses. The multivariate models identified region, age, grazing system, exposure to wild animals and dung removal as factors significantly associated with seroprevalence (p ??0.05). A higher seroprevalence was more likely to occur in camels from the Riyadh, Eastern, Northern and Makkah regions than those from the Jazan region; camels ??4 and 1-3 years of age (marginally significant) than calves < 1 year; and camels raised in zero grazing and semi-open grazing systems than those raised in an open grazing system. However, the presence of wild animals and daily dung removal were negatively associated with seroprevalence. On the other hand, region and sex were significantly associated with MERS-CoV RNA prevalence(p ??0.05). A higher viral RNA prevalence was more likely to occur in camels from the Riyadh region and Eastern region (marginally significant) than in those from the Makkah region, and in male camels than female camels. In conclusion, the risk factors identified in this study can be considered to be predictors of MERS-CoV infection in camels and should be taken into account when developing an efficient and cost-effective control strategy.

Une étude transversale a été réalisée au cours des mois d'avril et de mai 2015 dans cinq régions d'Arabie saoudite afin d'élucider l'épidémiologie de l'infection par le coronavirus responsable du syndrome respiratoire du Moyen-Orient(MERS­CoV) chez les dromadaires (Camelus dromedarius). Des échantillons de sérum et des écouvillons nasaux prélevés de dromadaires ont été analysés afin de détecter la présence d'anticorps dirigés contre le MERS-CoV ou d'ARN de ce même virus, en utilisant respectivement une épreuve immuno-enzymatique recombinante (ELISAr) et une amplification en chaîne par polymérase couplée à une transcription inverse (PCR­RT) en temps réel. La prévalence sérologique globale des anticorps dirigés contre le MERS-CoV s'élevait à 80,5 %, tandis que la prévalence globale de l'ARN viral était de 2,4 %. Les corrélations entre les facteurs de risque et les prévalences obtenues ont été quantifiées au moyen d'analyses à une seule et à plusieurs variables. Les modèles à plusieurs variables ont fait apparaître une association significative (p ??0,05) entre la prévalence sérologique et les facteurs suivants : la région, l'âge des animaux, le système pastoral pratiqué, l'exposition à la faune sauvage et l'élimination du fumier. La probabilité d'une forte prévalence sérologique était plus élevée chez les dromadaires provenant des régions de Riyad, de l'Est, du Nord et de la Mecque que chez ceux de la région de Jizan ; chez les dromadaires âgés de plus de quatre ans, ou âgés d'un à trois ans (différence marginalement significative) plutôt que chez les jeunes de moins d'un an ; et enfin chez les dromadaires nourris en stabulation (zéro pâturage) ou en pâturage semi-ouvert plutôt que chez ceux nourris dans des systèmes de pâturage ouvert. En revanche, une corrélation négative a été constatée entre la prévalence sérologique d'une part et la présence d'animaux sauvages et/ou l'élimination quotidienne du fumier, d'autre part. En ce qui concerne la détection virale, une corrélation significative (p ??0,05) a été constatée entre la région et le sexe des animaux et la prévalence de l'ARN du MERS-CoV. La probabilité d'une prévalence plus élevée de l'ARN viral était plus prononcée chez les dromadaires des régions de Riyad et de l'Est (différence marginalement significative) que chez ceux de la région de La Mecque, et chez les mâles que chez les chamelles. En conclusion, les facteurs de risque identifiés dans cette étude peuvent servir d'annonciateurs de l'infection par le MERS-CoV chez les dromadaires et devraient être pris en compte pour élaborer une stratégie efficace et rentable de lutte contre cette maladie.

Los autores describen un estudio transversal efectuado en abril y mayo de 2015 en cinco regiones de Arabia Saudí con objeto de investigar la epidemiologia de la infección de dromedarios (Camelus dromedarius) por el coronavirus del síndrome respiratorio de Oriente Medio (MERS­CoV). A tal efecto se analizaron muestras de suero y exudado nasal para detectar en ellas anticuerpos contra el MERS­CoV y ácido ribonucleico (ARN) del virus, empleando para ello, respectivamente, una técnica de ensayo inmunoenzimático recombinante (ELISAr) y una de reacción en cadena de la polimerasa acoplada a transcripción inversa en tiempo real (rRT­PCR, por sus siglas en inglés). Se calculó que la seroprevalencia global de anticuerpos contra el virus era del 80,5% y que la prevalencia global de ARN vírico era del 2,4%. Utilizando análisis multifactoriales y de una sola variable se cuantificó también la correlación de cada una de esas prevalencias con una serie de factores de riesgo. Con los modelos multifactoriales se observó que la región, la edad, el régimen de pastoreo, la exposición a animales salvajes y la retirada de estiércol eran factores que presentaban una asociación significativa con la seroprevalencia (p ??0,05): era más probable encontrar niveles elevados de seroprevalencia en dromedarios de las regiones de Riad y La Meca y las regiones oriental y septentrional del país que en los de la región de Jizán; en los de 4 o más años y entre 1 y 3 años de edad (correlación ligeramente significativa) que en las crías menores de 1 año; y en los animales estabulados o criados en sistemas de pasto semiabierto que en los criados con regímenes de pasto al aire libre. La presencia de animales salvajes y la retirada cotidiana del estiércol, por su parte, presentaban una correlación negativa con la seroprevalencia. Por otro lado, los factores asociados significativamente con la prevalencia de ARN vírico (p ??0,05) eran la región y el sexo: había mayor probabilidad de encontrar niveles elevados de prevalencia de ARN vírico en dromedarios de la región de Riad y la región oriental (correlación ligeramente significativa) que en los de la región de La Meca, y en machos más que en hembras. En conclusión, los factores de riesgo detectados con este estudio pueden ser considerados predictivos de la infección de dromedarios por el MERS­CoV y deben ser tenidos en cuenta para elaborar una estrategia de lucha que ofrezca a la vez eficacia y rentabilidad.

Factors associated with rift valley fever in south-west Saudi Arabia.

The authors undertook a study of environmental and animal risk factors associated with Rift Valley fever (RVF) in south-west Saudi Arabia. An enzyme-linked immunosorbent assay was used to detect the presence of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against the RVF virus in serum samples from sentinel animals. In addition, a further 32 known IgM-positive serum samples were tested using the reverse transcription polymerase chain reaction (RT-PCR) to detect the RVF virus genome. The results were analysed using the univariate odds ratio (OR). To control for confounding, Mantel-Haenszel adjusted odds ratio (M-H OR) was used. Positive associations were found between RVF and the following factors: a dense mosquito population (OR = 4.2), high rainfall (M-H OR = 2) and the presence of lakes and/or ponds (M-H OR = 2.2). The RVF virus genome was detected in four (12.5%) serum samples, indicating an early stage of RVF. The study found that the probability of detecting the virus genome was greater in animals with a high percentage of IgM antibodies against the virus (OR = 3) and in animals who had aborted (OR = 4.3). In addition, more sheep than goats tested positive for the presence of the genome (OR = 4). The authors conclude that the environmental and animal risk factors identified in this study can be considered good predictors for RVF and that the animal factors, in particular, should be considered when developing an efficient and cost-effective control strategy.

The persistence of rift valley fever in the Jazan region of Saudi Arabia.

A survey was conducted in the Jazan region of Saudi Arabia to investigate the presence of Rift Valley fever (RVF) in sheep and goats, by clinical identification of suspected herds and detection of immunoglobulin M (IgM) antibodies to RVF virus. The level of herd immunity was identified by detecting immunoglobulin G (IgG) antibodies. Rift Valley fever was diagnosed in six out of eight districts included in the survey. Twenty-two animals from 17 herds tested positive for the presence of IgM antibodies against RVF in these districts. The infection rate ranged from 0.12% in the Sabya district to 1.04% in the Jizan district. The level of herd immunity ranged from 22.2% in Jizan to 39.3% in the Alarda district. It can be concluded that the presence of IgM antibodies in clinically suspected herds suggests persistent RVF infection in the Jazan region. Thus, RVF control programmes should be continued to prevent the recurrence of outbreaks in the region and the possible further spread of infection to other regions of Saudi Arabia.

Impact of stocking density, breed, and feathering on the prevalence of abdominal skin scratches in broiler chickens.

Associations between abdominal skin scratches and stocking density, strain of birds, and degree of feathering were investigated in a clinical trial. Four hundred eighty 1-day-old male broiler chicks from two different strains (A and B) were assigned to four groups: 1) high density (0.07 m2/bird) and strain A, 2) high density and strain B, 3) normal density (0.14 m2/bird) and strain A, and 4) normal density and strain B. Birds were examined for scratches and feathering at 28, 35, and 42 days of age. Two outcomes were considered for scratches: presence (yes/no) and severity (severe [if a deep cut or at least three superficial cuts were present]/not severe). Only the examination at 35 days of age was blind. The outcome "scratches" was significantly associated with stocking density at all ages (P < or = 0.0001), strain A at 28 days of age (P = 0.0480), and poor feathering at 35 days of age (P < or = 0.0001). The outcome "severe scratches" was significantly associated with stocking density at 35 (P = 0.0003) and 42 days of age (P = 0.0021), strain A at 35 (P = 0.0089) and 42 days of age (P = 0.0306), and poor feathering at 35 days of age (P = 0.0018). Stocking density, strain of birds, and degree of feathering could be considered as potential risk factors for abdominal scratches in broiler chickens.

Description of cellulitis lesions and associations between cellulitis and other categories of condemnation.

A total of 110 broiler flocks processed in a single processing plant in southern Ontario were studied for purposes of describing the cellulitis lesions and investigating possible associations between cellulitis and other categories of condemnation at the processing plant. Two hundred and ninety-five carcasses condemned for cellulitis were examined. They came from 65 of the 110 flocks. The lesions tended to be unilateral with most carcasses (87%) having one lesion. The majority of the lesions (92%) were located on the abdomen. Almost 65% of the lesions were large (> or = 8.1 cm2), and 27% were medium (2.1-8.0 cm2). On the basis of gross appearance, 69% of the lesions were classified as severe, 26% moderate, and 5% mild. Of 149 lesions examined histologically, 74% were classified as chronic, 21% ongoing, and 5% mild-acute. Condemnation data from the 110 broiler flocks were analyzed using Poisson regression. Simple relationships were examined between a count outcome (number of cellulitis-condemned carcasses per flock) and other categories of condemnation and average bird weight. Cellulitis was significantly associated with average bird weight (P = 0.0018), Escherichia coli-related conditions (SEROSITIS; P < or = 0.0001), ascites (P = 0.0004), cyanosis (P < or = 0.0001), valgus varus deformity (P < or = 0.0001), REJECT (combined carcass condemnations for bruising, mutilation, and contamination; P = 0.0003), and the interaction terms "average bird weight and ascites" (AVWT*ASCIT; P < or = 0.0001) and "average bird weight and cyanosis" (AVWT*CYAN; P < or = 0.0001). Average bird weight, SEROSITIS, ascites, cyanosis, valgus varus deformity, and AVWT*ASCIT were the only significant factors after adjusting for clustering. No association was observed between cellulitis and emaciation and dead on arrival. Variables significantly associated with cellulitis in the multivariate analysis could be considered as potential predictors. These predictors may share common risk factors predisposing broiler chickens to cellulitis.

Farm management risk factors associated with cellulitis in broiler chickens in southern Ontario.

A mail survey of 171 farms with broiler chicken flocks processed in a single processing plant in southern Ontario was conducted during the period July-August 1993 as part of a retrospective study. The population farm prevalence of cellulitis was 31/10,000 birds. The survey provided information about the management of broiler chickens in southern Ontario and allowed investigation of the association between cellulitis and management risk factors. Univariate and multivariate analyses were performed to examine the relationship between a binary outcome (high/low prevalence) and management risk factors using logistic regression. Cellulitis was positively associated (P < or = 0.05) with male and mixed (males and females) flocks, use of straw as litter, certain feed companies, use of zinc bacitracin as a growth promoter, and other diseases diagnosed at the processing plant. Total down time was negatively associated with cellulitis.

A prospective study of cellulitis in broiler chickens in southern Ontario.

This study investigated the associations among cellulitis and hatchery, farm, and abattoir factors. Forty-four broiler flocks from 24 farms located in southern Ontario were followed from hatching to processing. Poisson regression was used to analyze the data. Cellulitis as a count outcome (CELLCOUNT) was significantly associated (P < or = 0.05) with the hatchery of origin, strain of birds, farm size, type of litter, lighting system, total down time, prevalence of abdominal scratches, Escherichia coli-related conditions (SEROSITIS), ascites, and valgus varus deformity. However, only farm size, abdominal scratches, SEROSITIS, ascites, and valgus varus deformity were significant (P < or = 0.05) after adjusting for clustering. No significant associations were found between cellulitis and source of eggs, sex, average bird weight, feed company, growth promoter, or stocking density. Factors significantly associated with cellulitis in this study could be considered as potential risk factors for cellulitis in broiler chickens in southern Ontario.