Background: Anthrax is a life-threatening infectious disease that normally affects animals, especially ruminants. It is caused by the bacteria Bacillus anthracis. The most common mode of infection is through the skin, which causes a painless sore that usually heals without treatment. If left untreated, cutaneous anthrax may progress in up to 20% of cases to septicaemia with potentially lethal outcome.
Methodology: We visited a small tribal village of the state of West Bengal, where an outbreak of cutaneous anthrax was suspected following slaughtering a dead bullock. The population at risk were subjected to detailed interrogation, thorough clinical examination and relevant investigations.
Results: The mean age of our study population was 32.1 years, and 100% were male. The mean incubation period was three days. Most cases (81.8%) were exposed to the bacteria during butchering. The predominantly affected sites were fingers (54.5%), followed by forearms (18.2%), around elbows (18.2%) and arm (9.1%). All cases initially had painless papules, ulcers with vesicles; dissemination of the lesion was seen in 27.3% of patients. 9 patients (who were alive) underwent complete blood count, baseline biochemistry and chest X-ray. Smears were made from the cutaneous lesions for gram's stain in 5 patients. Wound swabs were also inoculated in nutrient broth and subcultured in blood agar media. FNAC from the enlarged axillary lymph node was done in 1 patient and blood was sent for aerobic culture in 2 individuals. Both the blood cultures were sterile. Smears made from the culture obtained from cutaneous lesion of one of the affected person revealed gram positive aerobic spore bearing non-motile bacilli in long chain with capsular halo suggesting Bacillus anthracis. In this outbreak, the attack rate was 7% and case fatality rate was 18%.
Conclusion: Cutaneous anthrax should be considered as a differential diagnosis in cases presenting with painless ulcers, vesicles or eschars with a recent history of exposure to animals or animal products. It is important to recognise the clinical aspects of this disease in routine practice since any delay in treatment may have fatal consequences, as observed in this study.