-
Journal of Virological Methods Nov 2023Epizootic hemorrhagic disease virus (EHDV) is a Culicoides-transmitted virus circulating in multiple serotypes. It has become a concern in the European Union as a novel...
Epizootic hemorrhagic disease virus (EHDV) is a Culicoides-transmitted virus circulating in multiple serotypes. It has become a concern in the European Union as a novel strain of the serotype 8 (EHDV-8) of clear Northern African origin, has been recently discovered in symptomatic cattle in Italy (islands of Sardinia and Sicily), Spain, and Portugal. Current molecular typing methods targeting the S2 nucleotide sequences -coding for the outermost protein of the virion VP2- are not able to detect the novel emerging EHDV-8 strain as they enrolled the S2 sequence of the unique EHDV-8 reference strain isolated in Australia in 1982. Thus, in this study, we developed and validated a novel typing assay for the detection and quantitation of the novel EHDV-8 RNA from field samples, including blood of ruminants and insects. This molecular tool will certainly support EHDV-8 surveillance and control.
Topics: Animals; Cattle; Hemorrhagic Disease Virus, Epizootic; Serogroup; Australia; Biological Assay; RNA
PubMed: 37690747
DOI: 10.1016/j.jviromet.2023.114808 -
Veterinary Research Communications Feb 2024Bluetongue is an arthropod-borne viral infection that is notifiable in several countries and causes significant economic losses and major concerns for ruminant trade. In...
Bluetongue is an arthropod-borne viral infection that is notifiable in several countries and causes significant economic losses and major concerns for ruminant trade. In this study, we investigated bluetongue 1seroprevalence in the Campania region, southern Italy, in cattle and buffalo populations, and assessed which factors were correlated with a high risk of exposure. The infection was widespread, as evidenced by the high individual (43.6%) and herd prevalence (85.4%). The highest prevalence was found in adult animals. Among the climatic factors analyzed, average temperature played a prominent role, being capable of affecting the probability of being positive for this infection. Surprisingly, exposure to Schmallenberg virus did not predispose animals to be positive for bluetongue virus, even though these infections share the same vector (Culicoides). Our data, consistent with those in the literature, suggest the transversal spread of bluetongue virus in the Mediterranean area, and indicate a limited co-exposure rate between Bluetongue and Schmallenberg viruses.
Topics: Sheep; Animals; Cattle; Buffaloes; Bluetongue; Bluetongue virus; Seroepidemiologic Studies; Italy; Sheep Diseases
PubMed: 37682447
DOI: 10.1007/s11259-023-10215-w -
PLoS Computational Biology Sep 2023African horse sickness is an equine orbivirus transmitted by Culicoides Latreille biting midges. In the last 80 years, it has caused several devastating outbreaks in the...
African horse sickness is an equine orbivirus transmitted by Culicoides Latreille biting midges. In the last 80 years, it has caused several devastating outbreaks in the equine population in Europe, the Far and Middle East, North Africa, South-East Asia, and sub-Saharan Africa. The disease is endemic in South Africa; however, a unique control area has been set up in the Western Cape where increased surveillance and control measures have been put in place. A deterministic metapopulation model was developed to explore if an outbreak might occur, and how it might develop, if a latently infected horse was to be imported into the control area, by varying the geographical location and months of import. To do this, a previously published ordinary differential equation model was developed with a metapopulation approach and included a vaccinated horse population. Outbreak length, time to peak infection, number of infected horses at the peak, number of horses overall affected (recovered or dead), re-emergence, and Rv (the basic reproduction number in the presence of vaccination) were recorded and displayed using GIS mapping. The model predictions were compared to previous outbreak data to ensure validity. The warmer months (November to March) had longer outbreaks than the colder months (May to September), took more time to reach the peak, and had a greater total outbreak size with more horses infected at the peak. Rv appeared to be a poor predictor of outbreak dynamics for this simulation. A sensitivity analysis indicated that control measures such as vaccination and vector control are potentially effective to manage the spread of an outbreak, and shortening the vaccination window to July to September may reduce the risk of vaccine-associated outbreaks.
Topics: Animals; Horses; South Africa; African Horse Sickness; Disease Outbreaks; Basic Reproduction Number; Computer Simulation
PubMed: 37672554
DOI: 10.1371/journal.pcbi.1011448 -
Parasites & Vectors Aug 2023After several years without bluetongue disease, a ruminant illness caused by Culicoides-borne bluetongue virus (BTV), two new autochthonous cases were reported in...
BACKGROUND
After several years without bluetongue disease, a ruminant illness caused by Culicoides-borne bluetongue virus (BTV), two new autochthonous cases were reported in 2018 in Germany. By contrast, Schmallenberg virus (SBV), another Culicoides-borne virus pathogenic to ruminants, has continuously circulated in Germany since its first emergence in 2011. The disease outbreaks have triggered numerous studies on the biology of the Culicoides vectors, but many ecological details are still obscure.
METHODS
Culicoides biting midge species were collected with UV-light traps on 10 farms in Germany, with one trap inside and one trap outside barns on each of the farms. Traps were run once a week for 24 h from January to December 2019. Collected biting midges were morphologically identified, counted and statistically evaluated, with a focus on the Obsoletus Group and the Pulicaris Complex of the ceratopogonid genus Culicoides, which are believed to contain the major virus vectors. Temperature and relative humidity recorded at each trap were linked to the quantity of caught Culicoides. Correlations between relative Culicoides abundance and presence of livestock or type of husbandry were also investigated.
RESULTS
A total of 38,886 Culicoides biting midges were trapped, with most of them belonging to the Obsoletus Group (51.0%) and the Pulicaris Complex (38.8%). The majority of captured specimens were collected in traps inside the barns. Obsoletus Group individuals were caught from late January to the last week of December while Pulicaris Complex individuals were captured from the end of March to early December. The lowest average temperatures at which members of the two groups were collected were 10.7 °C and 12.8 °C, respectively. While temperature had a statistically significant effect on the activity of both the Obsoletus Group and the Pulicaris Complex, relative humidity only significantly affected the activity of the latter. The presence of livestock significantly influenced the number of captured Obsoletus Group, but not of Pulicaris Complex specimens. Inside the barns, no statistical difference was found between numbers of caught Obsoletus Group and Pulicaris Complex specimens in livestock holdings with deep litter and manure scraper or slatted floor husbandry systems.
CONCLUSIONS
The almost year-round presence of Obsoletus Group biting midges and the demonstrated high relative abundance of other potential Culicoides vector species inside barns suggest a high risk of indoor virus transmission to ruminants should BTV or SBV circulate locally. Appropriate structural, organisational and vector control measures to reduce biting midge exposure should be implemented.
Topics: Humans; Sheep; Animals; Ceratopogonidae; Germany; Bluetongue; Bluetongue virus; Cold Temperature; Livestock
PubMed: 37653421
DOI: 10.1186/s13071-023-05920-z -
Infection, Genetics and Evolution :... Oct 2023Biting midges are vectors of arboviruses such as bluetongue virus, bovine ephemeral fever virus, Akabane virus, African horse sickness virus, epizootic haemorrhagic...
Biting midges are vectors of arboviruses such as bluetongue virus, bovine ephemeral fever virus, Akabane virus, African horse sickness virus, epizootic haemorrhagic disease virus and Schmallenberg virus. Fast and accurate identification of biting midges is crucial in the study of Culicoides-borne diseases. Morphological identification of biting midges has revealed the presence of cryptic species. A total of 20 species are reported in Madagascar. In this study, we assessed wing morphometric analysis for identification of seven species namely C. dubitatus Kremer, Rebholtz-Hirtzel and Delécolle, C. enderleini Cornet and Brunhes, C. kibatiensis Goetghebuer, C. miombo Meiswinkel, C. moreli Clastrier, C. nevilli Cornet and Brunhes, and C. zuluensis de Meillon. Culicoides enderleini, C. miombo, C. moreli, C. nevilli and C. zuluensis are vectors diseases. A molecular approach, based on the cytochrome oxidase I gene (Cox1), was used for species delimitation. The molecular analysis presented seven different clades grouped two-by-two according to morphological characters. A total of 179 wing images were digitised. We found morphometric variation among seven species based on 11 landmarks and two outlines. Wing shape variation plots showed that species overlapped with species belonging to the same group. The cross-validation revealed a relatively high percentage of correct classification in most species, ranging from 91.3% to 100% for landmarks; 60% to 82.6% for outlines-1 and 77.1% to 91.3% for outlines-2. Our study suggests that wing geometric morphometric analysis is a robust tool for reliable "Moka Fohy" identification in Madagascar. This inexpensive and simple method is a precise supplement to morphological identification, with reaches the accuracy of Cox1 barcoding.
Topics: Animals; Cattle; Ceratopogonidae; Madagascar; Arboviruses; African Horse Sickness Virus; Orthobunyavirus
PubMed: 37640128
DOI: 10.1016/j.meegid.2023.105494 -
The Veterinary Quarterly Dec 2023Recent research focused on farmed deer has exposed many knowledge gaps regarding health assessment protocols for white-tailed deer (WTD). The objectives of this study...
Recent research focused on farmed deer has exposed many knowledge gaps regarding health assessment protocols for white-tailed deer (WTD). The objectives of this study were to establish de novo blood analyte reference intervals for farmed WTD fawns at birth (1-2 days of age; = 84) and again at weaning (76-125 days of age; = 28), to compare data at birth and at weaning to understand how these analytes are affected by the intrinsic factors age and sex in clinically normal WTD fawns, and to compare between clinically normal and sick WTD weanlings (respiratory disease = 12; orbivirus-infected = 6). Reference intervals were established for WTD fawns at birth and weaning. Female WTD neonates had significantly higher red blood cell counts, hematocrit, and hemoglobin compared to males. Most blood analytes were significantly different in clinically normal WTD neonates compared to weanlings, suggesting an effect of age. The observed sex- and age-related variations in WTD highlight the need to establish reference intervals that account for intrinsic factors. The comparison of clinically normal and sick WTD weanlings in this study identified higher MCHC and absolute monocytes in sick weanlings but these findings were presumably not biologically relevant given the small sample size for sick fawns. While the reference interval data presented herein will be useful for the veterinary care of WTD fawns at critical time periods in a high-density farm setting, this study also demonstrates the need to identify more sensitive and specific biomarkers for the assessment of health status in farmed WTD with specific underlying diseases.
Topics: Female; Male; Animals; Deer; Weaning; Farms; Age Factors
PubMed: 37589252
DOI: 10.1080/01652176.2023.2249072 -
Parasites & Vectors Aug 2023Culicoides biting midges (Diptera: Ceratopogonidae) are economically important blood-feeding pests closely associated with livestock production. They are the principal...
BACKGROUND
Culicoides biting midges (Diptera: Ceratopogonidae) are economically important blood-feeding pests closely associated with livestock production. They are the principal vectors of two hemorrhagic disease viruses affecting both wild and domestic ruminants within the US: bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). BTV impacts the US agriculture sector through direct commodity loss and strict international livestock trade restrictions. Yet, despite posing a considerable threat to US livestock, Culicoides are understudied, and management strategies are lacking. Current control tools for Culicoides are limited to synthetic chemicals, predominantly pyrethroids. With limited products available for livestock producers, proper pesticide rotation is difficult. The present study investigates the efficacy of fluralaner, an isoxazoline insecticide, beyond its current labeled use as an ectoparasiticide in anticipation of adding a new class of pesticides into rotation for use against biting midges.
METHODS
The efficacy of fluralaner was evaluated by conducting contact, topical, and oral toxicity bioassays on adult female Culicoides sonorensis. Contact toxicity was assessed by using a modified WHO cone assay, which simulates exposure through landing on an insecticide-treated surface. A modified WHO topical toxicity assay, in which fluralaner dilutions were administered to the lateral thorax, was used to assess topical toxicity. For evaluation of oral toxicity, females were offered a blood meal spiked with fluralaner in an artificial membrane feeding system to simulate a systemic insecticide.
RESULTS
Contact exposure of fluralaner did not cause extensive or consistent mortality. Even the highest concentration tested (100 mg/ml) resulted in an average of only 24.3% mortality at 24 h, and mortality did not significantly differ between exposed and control midges at any concentration. One hundred percent mortality was consistently achieved at concentrations of 1 mg/ml when fluralaner was applied topically. The LC for topical exposure to fluralaner at 24 h was estimated to be 0.011 mg/ml. Oral exposure to fluralaner through ingestion of a spiked blood meal proved to be the most effective exposure method, significantly increasing mortality in a dose-dependent manner at 1 h post-exposure. The LC at 24 h following ingestion was 14.42 ng/ml.
CONCLUSION
Our results suggest that fluralaner is a viable candidate for use as an insecticide against adult biting midges if exposed orally, such as in a systemic given to livestock. As withdrawal period requirements for meat animals present unique yet definitive challenges, pharmacokinetic studies of isoxazoline drugs need to be pursued and finalized for livestock before fluralaner may be used as a management strategy in this manner. Alternatively, livestock not raised for consumption, such as hair sheep, would directly benefit from administering oral fluralaner as a component of a BTV disease management program.
Topics: Sheep; Female; Animals; Ceratopogonidae; Insecticides; Insect Vectors; Ruminants; Bluetongue virus; Bluetongue
PubMed: 37580834
DOI: 10.1186/s13071-023-05899-7 -
Archives of Virology Aug 2023Here, we report the complete genome sequences of epizootic hemorrhagic disease (EHD) virus serotypes 5 (EHDV-5) and 6 (EHDV-6) isolated in the Yaeyama Islands of Okinawa...
Here, we report the complete genome sequences of epizootic hemorrhagic disease (EHD) virus serotypes 5 (EHDV-5) and 6 (EHDV-6) isolated in the Yaeyama Islands of Okinawa Prefecture, Japan. The EHDV-5 strain, ON-11/E/16, which was isolated in 2016, is, to our knowledge, the second EHDV-5 strain to be isolated after the first was isolated in Australia in 1977. In each of the genome segments, ON-11/E/16 was most closely related to EHDV strains of different serotypes isolated in Australia and Japan. Our results support the idea that various serotypes of EHDV have been circulating while causing reassortment in the Asia-Pacific region. In all genome segments, the EHDV-6 strain, ON-3/E/14, which was isolated in 2014, was highly similar to EHDV-6 strain HG-1/E/15, which was detected in affected cattle during the EHD epidemic in Hyogo prefecture in 2015. Therefore, these two EHDV-6 strains, ON-3/E/14 and HG-1/E/15, may have the same origin. However, it is unclear whether EHDV-6 was transmitted directly between the locations where those strains were isolated/detected (approx. 1,500 km apart) or whether EHDV-6 strains of the same origin entered each location at different times. In addition, we cannot rule out the possibility that EHDV-6 infection has spread unnoticed through asymptomatic cattle in other areas of Japan. Therefore, further investigation into EHDV infection in cattle is necessary for a more detailed understanding of the ecology of EHDV in Japan.
Topics: Animals; Cattle; Serogroup; Reoviridae Infections; Hemorrhagic Disease Virus, Epizootic; Phylogeny; Japan; Cattle Diseases
PubMed: 37578645
DOI: 10.1007/s00705-023-05853-z -
Tropical Animal Health and Production Aug 2023Bluetongue virus (BTV) is a vector-borne virus that primarily affects sheep. However, the disease is usually asymptomatic in cattle without obvious clinical signs...
Bluetongue virus (BTV) is a vector-borne virus that primarily affects sheep. However, the disease is usually asymptomatic in cattle without obvious clinical signs related to BTV infection. Although there is evidence of BTV antibodies through serology in Egypt, it is still unknown whether Egyptian cattle have ever been exposed to the virus in the north or south of the country. The study's aims were to determine the seroprevalence of BTV and evaluate the potential risk factors for BTV infection in cattle in Egypt. We used a competitive ELISA to screen 690 healthy cattle for BTV-specific immunoglobulin G (IgG) antibodies in four governorates in Egypt. A total seroprevalence of BTV antibodies in examined cattle was 51.47%, 95%CI: 48.01-55.45. The odds of BTV seropositivity were higher in Aswan (OR=1.30, 95%CI: 0.71-2.36), females (OR=3.29, 95%CI: 1.87-5.79), and elder cattle >8 years (OR=12.91, 95%CI: 6.63-25.13). Moreover, cattle contacted with other animals (OR=1.40, 95%CI: 0.94-2.10), with history of abortion (OR=4.88, 95%CI: 3.14-7.59), and those living with presence of insects (OR=12.34, 95%CI: 8-19.30) were more likely to be infected with bluetongue (BT). To effectively predict and respond to a potential BTV outbreak in Egypt, surveillance for BTV infection should be expanded to cover other susceptible ruminants and the range of the insect vectors.
Topics: Female; Cattle; Animals; Sheep; Bluetongue virus; Seroepidemiologic Studies; Cattle Diseases; Ruminants; Bluetongue; Antibodies, Viral; Risk Factors; Sheep Diseases
PubMed: 37540299
DOI: 10.1007/s11250-023-03701-5 -
Viruses Jul 2023Bluetongue (BT), a viral disease of ruminants, is endemic throughout South Africa, where outbreaks of different serotypes occur. The predominant serotypes can differ...
Bluetongue (BT), a viral disease of ruminants, is endemic throughout South Africa, where outbreaks of different serotypes occur. The predominant serotypes can differ annually due to herd immunity provided by annual vaccinations using a live attenuated vaccine (LAV). This has led to both wild-type and vaccine strains co-circulating in the field, potentially leading to novel viral strains due to reassortment and recombination. Little is known about the molecular evolution of the virus in the field in South Africa. The purpose of this study was to investigate the genetic diversity of field strains of BTV in South Africa and to provide an initial assessment of the evolutionary processes shaping BTV genetic diversity in the field. Complete genomes of 35 field viruses belonging to 11 serotypes, collected from different regions of the country between 2011 and 2017, were sequenced. The sequences were phylogenetically analysed in relation to all the BTV sequences available from GenBank, including the LAVs and reference strains, resulting in the analyses and reassortment detection of 305 BTVs. Phylogenomic analysis indicated a geographical selection of the genome segments, irrespective of the serotype. Based on the initial assessment of the current genomic clades that circulate in South Africa, the selection for specific clades is prevalent in directing genome segment reassortment, which seems to exclude the vaccine strains and in multiple cases involves Segment-2 resulting in antigenic shift.
Topics: Animals; Bluetongue virus; Reassortant Viruses; Antigenic Drift and Shift; South Africa; Biological Evolution
PubMed: 37515297
DOI: 10.3390/v15071611