Blowflies as vectors of Bacillus anthracis in the Kruger National Park

Abstract

Anthrax, caused by Bacillus anthracis, is endemic in the Kruger National Park (KNP). The epidemiology of B. anthracis is dependent on various factors including vectors. The aims of this study were to examine non-biting blowflies for the presence of B. anthracis externally and internally after feeding on an anthrax-infected carcass and to determine the role of flies in disseminating B. anthracis onto the surrounding vegetation. During an anthrax outbreak in 2014 in the endemic Pafuri region, blowflies associated with two 2–3-day-old anthrax-positive carcasses (kudu and impala) as well as surrounding vegetation were collected and investigated for the presence of B. anthracis spores. The non-biting blowflies (n = 57) caught included Chrysomya albiceps, Ch. marginalis and Lucilia spp. Bacillus anthracis spores were isolated from 65.5% and 25.0% of blowflies collected from the kudu and impala carcasses, respectively. Chrysomya albiceps and Ch. marginalis have the potential to disseminate B. anthracis to vegetation from infected carcasses and may play a role in the epidemiology of anthrax in the KNP. No B. anthracis spores were initially isolated from leaves of the surrounding vegetation using selective media. However, 170 and 500 spores were subsequently isolated from Abutilon angulatum and Acacia sp. leaves, respectively, when using sheep blood agar. Conservation implications: The results obtained in this study have no direct conservation implications and only assist in the understanding of the spread of the disease.

Keywords

• Bacillus anthracis
• anthrax
• blowflies
• Chrysomya marginalis
• Chrysomya albiceps
• Lucilia