Rates and risk factors for human cutaneous anthrax in the country of Georgia: National surveillance data, 2008-2015

Abstract

Introduction: Anthrax is endemic in the country of Georgia. The most common cutaneous anthrax form accounts for 95% of anthrax cases and often is self-resolving. Humans are infected from processing contaminated animal products, contacting sick animals, or by insect bites.

Objective: We aimed to describe the burden of human cutaneous anthrax and associated risk factors using the national surveillance data.

Methods: We extracted all human cutaneous anthrax cases from Electronic Integrated Disease Surveillance System (EIDSS) from 1 January 2008 to 31 December 2015. We conducted descriptive analyses to characterize the number of confirmed, probable and suspected cases by age groups, gender, ethnicity, year and geographic area.

Results: Out of 911 reported cutaneous anthrax cases, 299 (33%) were rejected. Out of remaining 612 cases, 437 (71%), 172 (28%), and 3 (<0.004%) were classified as confirmed, probable and suspected cases of cutaneous Anthrax, respectively; 467 (76.3%) were male. Georgians accounted for 56% (343/612) of cutaneous anthrax cases. Handling animal products (aOR 4.36, 95% CI 2.61-7.26) and living near pastoralist routes (aOR 2.74, 95%CI 1.57-4.76) were associated with cutaneous anthrax.

Conclusions: This study provides eight-year trends for cutaneous anthrax in humans in the country of Georgia. A comprehensive explanation for the observed rise and fall of the incidence rates of human cutaneous anthrax in 2008-2015 remains to be clarified but is likely associated with discontinuation of mandatory national livestock vaccination in 2008 coupled with weakened human and animal national health systems which were disrupted after the Soviet Union collapsed. Our analysis identifies living near pastoralist routes, handling animal products and travel to endemic areas within two weeks before the disease onset as risk factors for cutaneous anthrax. The evidence underscores the importance of One Health recommendations to activate anthrax awareness campaigns, supervise the destruction of known anthrax carcasses, record global position system coordinates of sites and disinfect infected soils and introduce a participatory health education tool on anthrax.

Fig 1. Incidence of human cutaneous anthrax in the most affected regions of Georgia, 2008–2015.

National cumulative incidence rates from 2008 to 2015 was calculated per 100 000 population by geographic location. Three regions with the highest incidence rate and incidence rate in the capital city (Tbilisi) are presented on the line chart. The graph describes the increase in incidence in 2012–2013 years.

Fig 2. Annual cases of cutaneous anthrax by week in the year in Georgia (EIDSS 2008–2015).

Variation in weekly counts of disease occurrence and shifts in seasonal cycles are presented on the figure.