Abstract:
Culicoides Latreille (Diptera: Ceratopogonoidae) biting midges are found throughout most of the world. As proven vectors of viruses, nematodes and protozoa of medical and veterinary importance they have a negative economic impact wherever they are prevalent. This is especially true in the equine and livestock industries. For this reason, Culicoides midges have been studied fairly extensively. Despite this, there are still areas in which more information is required to allow us to better understand the role of these tiny insects in the epidemiology of high impact arbovirus infections.
This dissertation describes a prospective study in which weekly collections of Culicoides midges at Onderstepoort were performed over the period of a year. The objectives were to determine to what extent inter-seasonal activity of midges is present in the Onderstepoort area in South Africa. By making use of carbon dioxide (CO2) traps it was possible to determine potential daytime activity of Culicoides midges. A special effort was made to determine the role of domestic dogs in the epidemiology of African horse sickness (AHS) in South Africa. Blood meal analysis of freshly blood fed females was performed to shed light on the host preferences of livestock associated Culicoides species in South Africa.
The study showed both inter-seasonal and daytime activity of Culicoides midges in the Onderstepoort area of South Africa. This may have an impact on the potential overwintering of Culicoides transmitted diseases in the area and the control measures implemented to curb the spread of diseases such as AHS. The study showed that Culicoides midges will feed on dogs and are thereby likely able to transmit African horse sickness virus (AHSV) to canines. However, the small numbers of positive canine blood meals compared to those taken from livestock suggests that dogs are only incidental hosts and therefore only play a minor role in the epidemiology of AHSV.
