Pakistan's experience of a bioterrorism-related anthrax scare.

From November 2001 to March 2002, the National Institute of Health, Islamabad, Pakistan, received 230 samples from 194 different sources for analysis for anthrax spores. These samples were taken from letters/packages suspected of containing anthrax and from individuals exposed to them. When cultured on sheep blood agar, 141 samples yielded growth suggestive of Bacillus species. On the basis of growth characteristics, absence of beta-haemolysis, absent or doubtful motility and morphological characters of the isolates on Gram stain, 62 isolates were considered suspicious and were inoculated into guinea-pigs. Inoculated animals remained healthy well beyond the required observation period of 5 days. All the samples were therefore reported as negative for B. anthracis. Systems for handling and analysing suspected anthrax-contaminated materials are discussed.