Risk factors associated with the occurrence of anthrax outbreaks in livestock in the country of Georgia: A case-control investigation 2013-2015

Abstract

Introduction Anthrax is considered endemic in livestock in Georgia. In 2007, the annual vaccination became the responsibility of livestock owners, while contracting of private veterinarians was not officially required. Six years later, due to increase in human outbreaks associated with livestock handling, there is a need to find out the risk factors of livestock anthrax in Georgia. Objective To identify exposures and risk factors associated with livestock anthrax. Methods A matched case-control study design was used to recruit the owners of individual livestock anthrax cases that occurred between June 2013 and May 2015, and owners of unaffected livestock from within (“village control”) and outside the village (“area control”). We collected data about the case and control livestock animals’ exposure and risk factors within the one-month prior to the disease onset of the case livestock (or matched case for the controls). We used logistic regression analysis (univariate and multivariable) to calculate the odds ratios of exposures and risk factors. Results During the study period, 36 anthrax cases met the case definition and were enrolled in the study; 67 matched village control livestock and 71 matched area control livestock were also enrolled. The findings from multivariable logistic regression analysis demonstrate that vaccination within the last two years significantly reduced the odds of anthrax in cattle (OR = 0.014; 95% Confidence interval = <0.001, 0.99). The other factors that were significantly protective against anthrax were ‘animals being in covered fence area/barn’ (OR = 0.065; p-value = 0.036), and ‘female animal being pregnant or milking compared to heifer’ (OR = 0.006; p-value = 0.037). Conclusions The information obtained from this study has involved and been presented to decision makers, used to build technical capacity of veterinary staff, and to foster a One Health approach to the control of zoonotic diseases which will optimize prevention and control strategies. Georgia has embedded the knowledge and specific evidence that vaccination is a highly protective measure to prevent anthrax deaths among livestock, to which primary emphasis of the anthrax control program will be given. Education of livestock keepers in Georgia is an overriding priority.

Spatial clustering of livestock Anthrax events associated with agro-ecological zones in Kenya, 1957–2017

“…An interesting finding in our study was the 10-fold higher anthrax events in cattle when compared to other livestock, findings similar to those reported in Australia, Lesotho, Zambia, and Zimbabwe [ 36 – 40 ]. Whereas it is possible that this finding represents reporting bias in favor of cattle, it may not fully explain the high levels of cattle events reported since livestock anthrax reports are closely linked with human infections that drive the reporting.…”

A qualitative exploratory study using One Health approach for developing an intervention package for elimination of human anthrax in an endemic district of Odisha, India

“…Most of the laboratory facilities are situated far away from the endemic area, making it difficult to transport the samples for analysis due to limited transport facilities in those areas 1 16 . Studies in Georgia has highlighted the importance of supervision during carcasses disposal, monitoring by service providers, training sessions for surveillance system strengthening and inter-sectoral coordination as key strategies to prevent anthrax 17 18 .…”

Knowledge, attitudes, and practices related to anthrax and animal care: A case-control study in Georgia

“…A greater proportion of controls reported knowing of animal anthrax deaths compared to human infections. Perhaps this experience motivated the controls to vaccinate their animals against anthrax, as a key finding from the primary case-control study found a statistically significant protective effect of anthrax vaccination within the previous two years [10].…”

“…Separate area controls were included to examine risk factors and exposures that could affect herd-level management practices to understand what some herds are doing differently that puts them at risk for the disease. These controls were outside the “intervention zone” that received anthrax control measures following the animal anthrax death [10], but were proximal to expect similar anthrax risk.…”

“…Cases and controls were ≥18 years of age, agreed to participate, and gave verbal consent. The full case definition and design is described elsewhere [10]; only cattle handlers are included in this analysis due to small numbers of other animal species in the study. The CDC National Center for Emerging and Zoonotic Infectious Diseases Human Subjects Advisor determined the study was a non-research activity, and ethical review by the NFA Department of Law was not required.…”