Culicoides
            species as potential vectors of African horse sickness virus in the southern regions of South Africa

In South Africa, outbreaks of African horse sickness (AHS) occur in summer; no cases are reported in winter, from July to September. The AHS virus (AHSV) is transmitted almost exclusively by Culicoides midges (Diptera: Ceratopogonidae), of which Culicoides imicola is considered to be the most important vector. The over-wintering mechanism of AHSV is unknown. In this study, more than 500 000 Culicoides midges belonging to at least 26 species were collected in 88 light traps at weekly intervals between July 2010 and September 2011 near horses in the Onderstepoort area of South Africa. The dominant species was C. imicola. Despite relatively low temperatures and frost, at least 17 species, including C. imicola, were collected throughout winter (June–August). Although the mean number of midges per night fell from > 50 000 (March) to < 100 (July and August), no midge-free periods were found. This study, using virus isolation on cell cultures and a reverse transcriptase polymerase chain reaction (RT-PCR) assay, confirmed low infection prevalence in field midges and that the detection of virus correlated to high numbers. Although no virus was detected during this winter period, continuous adult activity indicated that transmission can potentially occur. The absence of AHSV in the midges during winter can be ascribed to the relatively low numbers collected coupled to low infection prevalence, low virus replication rates and low virus titres in the potentially infected midges. Cases of AHS in susceptible animals are likely to start as soon as Culicoides populations reach a critical level.

Download Full-text

Virus recovery rates for wild-type and live-attenuated vaccine strains of African horse sickness virus serotype 7 in orally infected South African Culicoides species

Medical and Veterinary Entomology ◽

10.1111/j.1365-2915.2007.00706.x ◽

2007 ◽

Vol 21 (4) ◽

pp. 377-383 ◽

Cited By ~ 23

Author(s):

G. J. VENTER ◽

J. T. PAWESKA

Keyword(s):

South African ◽

African Horse Sickness ◽

Culicoides Species ◽

Wild Type ◽

African Horse Sickness Virus ◽

Recovery Rates ◽

Live Attenuated Vaccine ◽

Attenuated Vaccine ◽

Virus Serotype ◽

Virus Recovery

Download Full-text

Barcoding of the Genus Culicoides (Diptera: Ceratopogonidae) in Austria—An Update of the Species Inventory Including the First Records of Three Species in Austria

Pathogens ◽

10.3390/pathogens9050406 ◽

2020 ◽

Vol 9 (5) ◽

pp. 406

Author(s):

Carina Zittra ◽

Günther Wöss ◽

Lara Van der Vloet ◽

Karin Bakran-Lebl ◽

Bita Shahi Barogh ◽

...

Keyword(s):

African Horse Sickness ◽

Culicoides Species ◽

African Horse Sickness Virus ◽

Molecular Analyses ◽

Equine Encephalitis Virus ◽

Obsoletus Group ◽

Worldwide Distribution ◽

Veterinary Importance ◽

Morphologic Analysis ◽

I Gene

Ceratopogonidae are small nematoceran Diptera with a worldwide distribution, consisting of more than 5400 described species, divided into 125 genera. The genus Culicoides is known to comprise hematophagous vectors of medical and veterinary importance. Diseases transmitted by Culicoides spp. Such as African horse sickness virus, Bluetongue virus, equine encephalitis virus (Reoviridae) and Schmallenberg virus (Bunyaviridae) affect large parts of Europe and are strongly linked to the spread and abundance of its vectors. However, Culicoides surveillance measures are not implemented regularly nor in the whole of Austria. In this study, 142 morphologically identified individuals were chosen for molecular analyses (barcoding) of the mitochondrial cytochrome c oxidase subunit I gene (mt COI). Molecular analyses mostly supported previous morphologic identification. Mismatches between results of molecular and morphologic analysis revealed three new Culicoides species in Austria, Culicoides gornostaevae Mirzaeva, 1984, which is a member of the Obsoletus group, C. griseidorsum Kieffer, 1918 and C. pallidicornis Kieffer, 1919 as well as possible cryptic species. We present here the first Austrian barcodes of the mt COI region of 26 Culicoides species and conclude that barcoding is a reliable tool with which to support morphologic analysis, especially with regard to the difficult to identify females of the medically and economically important genus Culicoides.

Download Full-text

The Absence of Abdominal Pigmentation in Livestock Associated Culicoides following Artificial Blood Feeding and the Epidemiological Implication for Arbovirus Surveillance

Pathogens ◽

10.3390/pathogens10121571 ◽

2021 ◽

Vol 10 (12) ◽

pp. 1571

Author(s):

Maria Goffredo ◽

Michela Quaglia ◽

Matteo De Ascentis ◽

Silvio Gerardo d’Alessio ◽

Valentina Federici ◽

...

Keyword(s):

South African ◽

Blood Feeding ◽

African Horse Sickness ◽

Culicoides Species ◽

African Horse Sickness Virus ◽

Artificial Blood ◽

Parity Rate ◽

Feeding Methods ◽

Feeding Trials ◽

Blood Meal Size

Culicoides midges (Diptera: Ceratopogonidae), the vectors of economically important arboviruses such as bluetongue virus and African horse sickness virus, are of global importance. In the absence of transovarial transmission, the parity rate of a Culicoides population provides imperative information regarding the risk of virus dispersal. Abdominal pigmentation, which develops after blood feeding and ovipositioning, is used as an indicator of parity in Culicoides. During oral susceptibility trials over the last three decades, a persistent proportion of blood engorged females did not develop pigment after incubation. The present study, combining a number of feeding trials and different artificial feeding methods, reports on this phenomenon, as observed in various South African and Italian Culicoides species and populations. The absence of pigmentation in artificial blood-fed females was found in at least 23 Culicoides species, including important vectors such as C. imicola, C. bolitinos, C. obsoletus, and C. scoticus. Viruses were repeatedly detected in these unpigmented females after incubation. Blood meal size seems to play a role and this phenomenon could be present in the field and requires consideration, especially regarding the detection of virus in apparent “nulliparous” females and the identification of overwintering mechanisms and seasonally free vector zones.

Download Full-text