Abstract
Anthrax outbreaks in livestock have social, economic and health implications, altering farmer’s livelihoods, impacting trade and posing a zoonotic risk. Our study investigated the survival of Bacillus thuringiensis and B. anthracis spores sporulated at 15, 20, or 37°C, over 33 days of composting. Spores (∼7.5 log10 CFU g-1) were mixed with manure and composted in laboratory scale composters. After 15 days, the compost was mixed and returned to the composter for a second cycle. Temperatures peaked at 71°C on day 2 and remained ≥55°C for an average of 7 days in the first cycle, but did not exceed 55°C in the second. For B. thuringiensis, spores generated at 15 and 21°C exhibited reduced (P < 0.05) viability of 2.7 and 2.6 log10 CFU g-1 respectively, as compared to a 0.6 log10 CFU g-1 reduction for those generated at 37°C. For B. anthracis, sporulation temperature did not impact spore survival as there was a 2.5, 2.2, and 2.8 log10 CFU g-1 reduction after composting for spores generated at 15, 21, and 37°C, respectively. For both species, spore viability declined more rapidly (P < 0.05) in the first as compared to the second composting cycle. Our findings suggest that the duration of thermophilic exposure (≥55°C) is the main factor influencing survival of B. anthracis spores in compost. As sporulation temperature did not influence survival of B. anthracis, composting may lower the viability of spores associated with carcasses infected with B. anthracis over a range of sporulation temperatures.
Highlights
Anthrax is a lethal mammalian disease, capable of infecting animals and humans and remains an ongoing global problem (Spencer, 2003; Sternbach, 2003)
All the composters heated rapidly, with temperatures peaking after 2 days at 72◦C for composters containing B. anthracis and 70◦C for those containing B. thuringiensis (Figure 2A)
During the first composting cycle, temperature remained above 55◦C for 8 and 5 days for B. anthracis and B. thuringiensis, respectively (Figure 2A)
Summary
Anthrax is a lethal mammalian disease, capable of infecting animals and humans and remains an ongoing global problem (Spencer, 2003; Sternbach, 2003). Before the development of a vaccine for the treatment of livestock in the 1870’s, anthrax was one of the leading causes of worldwide mortality in cattle, goats, horses, and sheep (Hugh-Jones and Blackburn, 2009). Spores are the primary infectious form of B. anthracis with infection occurring through ingestion, inhalation or cutaneous exposure (Thappa and Karthikeyan, 2001). As few as ten inhaled B. anthracis spores are sufficient to cause infection in cattle and sheep (Smith, 1973), while 500–55,000 inhaled spores is the estimated range for a lethal dose for humans (Wallin et al, 2007)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
