The effect of seasonal variation on anthrax epidemiology in the upper Zambezi floodplain of western Zambia

Abstract

Anthrax has become endemic throughout the upper Zambezi floodplain located in the Western Province of Zambia over the recent years. To date, no comprehensive study has been carried out to determine whether recurrence of anthrax outbreaks may be linked to differences in precipitation and human activities. Retrospective data for the period 1999 to 2007 showed that a total of 1,216 bovine cases of anthrax were reported. During the same period, 1,790 human anthrax cases and a corresponding case fatality rate of 4.63% (83/1,790) was documented in the upper Zambezi floodplain. Occurrence of human cases was highly correlated with cattle outbreaks (r = 0.94, p < 0.001). Differences in precipitation were significantly associated with the occurrence of anthrax outbreaks (χ2 = 4.75, p < 0.03), indicating that the likelihood of outbreaks occurring was higher during the dry months when human occupancy of the floodplain was greater compared to the flooding months when people and livestock moved out of this region. Human dependency on the floodplain was shown to significantly influence the epidemiology of anthrax in the upper Zambezi floodplain of western Zambia. Methods for mitigating anthrax outbreaks by disrupting the cycle of transmission are herein highlighted.

Risk mapping and eco‐anthropogenic assessment of anthrax in the upper Zambezi basin

“…This finding was also observed by Munang'andu and co‐workers who attributed this observation partly to the alluvial soils of the plains (Munang'andu et al . ). From the final multivariate multiple logistic regression model, anthropological factors that were strongly associated with anthrax outbreaks included herd size, cattle management systems (especially transhumance animals that were grazed in the flood plains most times of the year).…”

“…Similarly, Munang'andu and co‐workers attributed this observation to consumption of dead carcasses as a sequel of an anthrax outbreak (Munang'andu et al . ). From the multiple logistic regression analysis, transhumance grazing system was one of the significant risk factors of anthrax occurrence in the upper Zambezi basin.…”

“…For the period 1999 ‐ 2007 (Munang'andu et al . ) reported a total of 1216 bovine cases, 1790 human cases and a human case fatality rate of 4.63% (83/1790) in the Zambezi flood plain. In this study, human cases were highly correlated with cattle cases ( r = 0.94).…”

“…Anthrax resulting from contaminated meat consumption has been reported in pigs, dogs, cats, mink, wild carnivores and humans. Although the exact mode of transmission from cattle to each human is not usually identified, Munang'andu et al, in 2012 observed in Zambia that during outbreaks people involved in skinning infected carcasses, handling meat and processing skins and hides for making drums or stools were more susceptible to the disease than those who consumed cooked meat. Meat from animals that died on the floodplains was carried to upland areas to the owners for consumption or to be shared or sold.…”

An Aggregate of Four Anthrax Cases during the Dry Summer of 2011 in Epirus, Greece

“…In addition, isolated human diseases have been reported after laboratory accidents or as a result of intended assaults (terrorist or criminal) [1,5]. In general, the incidence of naturally acquired human cases indicates total disease activity across all susceptible animal species in a certain region [6]. …”