Epidemiological Investigation and Source Tracing of an Inhalation Anthrax Case with Traceability to Yunnan Province -...

Anthrax is a zoonotic disease caused by the bacterium Bacillus anthracis (B. anthracis). Inhalation anthrax, caused by inhalation of B. anthracis spores, is the rarest and most fatal form of anthrax. Historically, naturally acquired inhalation anthrax cases have mainly been associated with occupational exposure to infected animals or animal products, such as in wool mills or tanneries.

This report documents the first case of inhalation anthrax in China that was linked to environmental exposure in a historically endemic area, without direct contact with sick animals or animal products. The case was reported in Guangdong Province, however, the source was traced to the patient's newly built residence in Zhenxiong County, Yunnan Province, where environmental samples tested positive for B. anthracis nucleic acid. Three anthrax outbreaks have occurred in this region since 1990.

In anthrax-endemic areas, environmental exposure to contaminated soil or dust can pose a significant risk of anthrax infection, even without direct animal contact. Although rare, inhalation anthrax can occur naturally as B. anthracis spores can survive extreme environmental conditions in the soil or hay for long periods. As it is difficult to distinguish acute pulmonary infection from inhalational anthrax, severe cases were frequently initially suggested by metagenomic sequencing of the alveolar fluid, with similar findings reported for meningeal anthrax in the cerebrospinal fluid.