Cutaneous anthrax associated with handling carcasses of animals that died suddenly of unknown cause: Arua District, Uganda, January 2015–August 2017

Abstract

Background Anthrax is a zoonotic disease that can be transmitted to humans from infected animals. During May–June 2017, three persons with probable cutaneous anthrax were reported in Arua District, Uganda; one died. All had recently handled carcasses of livestock that died suddenly and a skin lesion from a deceased person tested positive by PCR for Bacillus anthracis. During July, a bull in the same community died suddenly and the blood sample tested positive by PCR for Bacillus anthracis. The aim of this investigation was to establish the scope of the problem, identify exposures associated with illness, and recommend evidence-based control measures. Methods A probable case was defined as acute onset of a papulo-vesicular skin lesion subsequently forming an eschar in a resident of Arua District during January 2015–August 2017. A confirmed case was a probable case with a skin sample testing positive by polymerase chain reaction (PCR) for B. anthracis. Cases were identified by medical record review and active community search. In a case-control study, exposures between case-patients and frequency- and village-matched asymptomatic controls were compared. Key animal health staff were interviewed to learn about livestock deaths. Results There were 68 case-patients (67 probable, 1 confirmed), and 2 deaths identified. Cases occurred throughout the three-year period, peaking during dry seasons. All cases occurred following sudden livestock deaths in the villages. Case-patients came from two neighboring sub-counties: Rigbo (attack rate (AR) = 21.9/10,000 population) and Rhino Camp (AR = 1.9/10,000). Males (AR = 24.9/10,000) were more affected than females (AR = 0.7/10,000). Persons aged 30–39 years (AR = 40.1/10,000 population) were most affected. Among all cases and 136 controls, skinning (ORM-H = 5.0, 95%CI: 2.3–11), butchering (ORM-H = 22, 95%CI: 5.5–89), and carrying the carcass of livestock that died suddenly (ORM-H = 6.9, 95%CI: 3.0–16) were associated with illness. Conclusions Exposure to carcasses of animals that died suddenly was a likely risk factor for cutaneous anthrax in Arua District during 2015–2017. The recommendations are investigation of anthrax burden in livestock, prevention of animal infections through vaccinations, safe disposal of the carcasses, public education on risk factors for infection and prompt treatment of illness following exposure to animals that died suddenly.

Outbreak of cutaneous anthrax associated with handling meat of dead cows in Southwestern Uganda, May 2018

“…Members of the affected community reported that they had experienced a long dry season, lasting over 6 months (November 2017–April 2018) without rainfall [ 17 ]. In preparation for the rainfall, a central valley dam was constructed on 28 February–2 March 2018 in Rupyani village for water harvesting; both cows and goats reportedly drank water from the reservoir provided by the dam.…”

“…These factors were present most likely influencing the anthrax outbreak in both animals and humans. Previous investigations of outbreaks in Uganda that have been done recently also found the association of anthrax to handling of meat from animals that died suddenly [ 4 , 6 , 17 ].…”

Investigation on an outbreak of cutaneous anthrax in a county of Shandong Province, China, 2021

“…The majority of cases were adult males, consistent with the majority of adult males working in livestock slaughtering and livestock product processing. Vegetative forms of Bacillus anthracis are easily killed during normal cooking, but spores are much more resistant to adverse conditions and require heating to at least 100 °C for 15 min for inactivation [ 15 ]. Most of the livestock products have been recovered and destroyed, and those sold are cooked food, so there were no gastrointestinal anthrax cases identified.…”

“…We also made several recommendations to the local government, livestock anthrax which could be prevented by animal vaccination. Effective herd immunity against anthrax in cattle requires at least 80% of the animals in an area to be vaccinated [ 15 ]. During an outbreak, all livestock in areas around the affected area should be vaccinated, routinely vaccinate livestock from now on.…”

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“…Humans at higher risk are predominantly in anthrax-enzootic areas and working in close proximity to livestock, or handling animal tissues [2,54,62]. Economically disadvantaged groups that eat fallen or sick livestock are at particular risk for ingestional anthrax [27,39].…”