Cutaneous anthrax outbreak associated with handling dead animals, Rhino Camp sub-county: Arua District, Uganda, January-May 2018.

Background: On 18 January 2018 a 40 year old man presented with skin lesions at Rhino Camp Health Centre. A skin lesion swab was collected on 20 January 2018 and was confirmed by PCR at Uganda Virus Research Institute on 21 January 2018. Subsequently, about 9 persons were reported to have fallen ill after reporting contact with livestock that died suddenly. On 9 February 2018, Arua District notified Uganda Ministry of Health of a confirmed anthrax outbreak among humans in Rhino Camp sub-county. We investigated to determine the scope and mode of transmission and exposures associated with identified anthrax to guide control and prevention measures.

Methods: We defined a suspected cutaneous anthrax case as onset of skin lesions (e.g., papule, vesicle, or eschar) in a person residing in Rhino Camp sub-county, Arua District from 25 December 2017 to 31 May 2018. A confirmed case was a suspected case with PCR-positivity for Bacillus anthracis from a clinical sample. We identified cases by reviewing medical records at Rhino Camp Health Centre. We also conducted additional case searches in the affected community with support from Community Health Workers. In a retrospective cohort study, we interviewed all members of households in which at least one person had contact with the carcasses of or meat from animals suspected to have died of anthrax. We collected and tested hides of implicated animals using an anthrax rapid diagnostic test.

Results: We identified 14 case-patients (1 confirmed, 13 suspected); none died. Only males were affected (affected proportion: 12/10,000). Mean age of case-persons was 33 years (SD: 22). The outbreak lasted for 5 months, from January 2018-May 2018, peaking in February. Skinning (risk ratio = 2.7, 95% CI = 1.1-6.7), dissecting (RR = 3.0, 95% CI = 1.2-7.6), and carrying dead animals (RR = 2.7, 95% CI = 1.1-6.7) were associated with increased risk of illness, as were carrying dissected parts of animals (RR = 2.9, 95% CI 1.3-6.5) and preparing and cooking the meat (RR = 2.3, 95% CI 0.9-5.9). We found evidence of animal remains on pastureland.

Conclusion: Multiple exposures to the hides and meat of animals that died suddenly were associated with this cutaneous anthrax outbreak in Arua District. We recommended public education about safe disposal of carcasses of livestock that die suddenly.