Abstract
ObjectivesAnthrax is a disease with an age old history in Africa caused by the Gram-positive endospore forming soil bacterium Bacillus anthracis. Epizootics of wild ungulates occur annually in the enzootic region of Pafuri, Kruger National Park (KNP) in the Limpopo Province of South Africa. Rigorous routine surveillance and diagnostics in KNP, has not revealed these rare isolates since the 1990s, despite unabated annual outbreaks. In 2011 a cheetah was diagnosed as anthrax positive from a private game reserve in Limpopo Province and reported to State Veterinary Services for further investigation. Isolation, molecular diagnostics, whole genome sequencing and comparative genomics were carried out for B. anthracis KC2011.ResultsBacteriological and molecular diagnostics confirmed the isolate as B. anthracis. Subsequent typing and whole genome single nucleotide polymorphisms analysis indicated it clustered alongside B. anthracis SA A0091 in the B.Br.010 SNP branch. Unlike B. anthracis KrugerB strain, KC2011 strain has unique SNPs and represents a new branch in the B-clade. The isolation and genotypic characterisation of KC2011 demonstrates a gap in the reporting of anthrax outbreaks in the greater Limpopo province area. The identification of vulnerable and susceptible cheetah mortalities due to this strain has implications for conservation measures and disease control.
Highlights
Anthrax is a zoonotic disease with an age old history in Africa [1], causing acute mortalities
Bacteriological and molecular diagnostics confirmed the isolate as B. anthracis
Subsequent typing and whole genome single nucleotide polymorphisms analysis indicated it clustered alongside B. anthracis SA A0091 in the B.Br
Summary
Anthrax is a zoonotic disease with an age old history in Africa [1], causing acute mortalities. It primarily affects ungulates with episodic spill over into humans and carnivores [2, 3]. The virulence factors of this bacterium are on the two plasmids, pXO1 (181 kilobases) and pXO2 (94 kilobases), encoding the toxin and capsule genes respectively [8, 9]. The toxin complex is composed of three components namely, lethal toxin (LF) made up of the protective (PA) and lethal factor (EF) [10, 11].
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