Investigation into Bacillus anthracis Spore in Soil and Analysis of Environmental Parameters Related to Repeated Anthrax Outbreak in Sirajganj, Bangladesh

Abstract

The study was conducted for the isolation and detection of Bacillus anthracis spores from soil collected from Sirajganj district (a north-western district of Bangladesh), and to assess the parameters that may relate to the repeated anthrax outbreak. A total of 48 soil samples were collected from the study area during January to November 2012. Endospores were extracted from soil and the Bacillus anthracis was identified using conventional bacteriological, biochemical and sensitivity test against Penicillin-G. The viable B. anthracis spores could be detected from 14 (29.17%) soil samples. Moisture content, pH, calcium and organic carbon contents of the soils were measured and the values of the endospore positive samples ranged from 6.31-28.37%, 5.17-7.22, 484.35-1372.35 ppm and 0.15-2.35%, respectively. All the endospore positive soil samples were of loamy type, while none of the clay type soil was found to be positive for B. anthracis, suggesting the influence of soil type on the occurrence of anthrax endospore in studied area. The mean pH of anthrax positive soil was weakly acidic (6.38±0.15), indicating that a suitable pH range for anthrax spore was present in the soil of Sirajganj. During the disease outbreak period (May and June) the average temperature of
this area was 320C and the average rainfall was 158 mm and 90 mm, respectively. Although the temperature variation had no significant influence on the occurrence of anthrax spore, rainfall was found to be significant.