The pattern of anthrax at the wildlife-livestock-human interface in Zimbabwe

Abstract

Anthrax is an important but neglected zoonosis in southern Africa and elsewhere which occurs naturally in herbivorous wildlife and livestock. Fatal outbreaks in animals are spaced by potentially extended periods of non-activity during which the bacterium is maintained in soil. The ecology of the pathogen in the multi-host system and the environment is still not fully understood. This study investigated the patterns of anthrax in Zimbabwe in order to better understand the occurrence of disease in susceptible wildlife and livestock and hence its control. The study used available data in governmental reports between 1995 and 2018 and structured interviewer-administered questionnaires of local communities in three porous wildlife-livestock-human interface sites where livestock/wildlife interactions were documented from previous researches. Two non-interface sites were also included for comparison based on known previous anthrax outbreaks. Respondents from non-interface sites had significantly higher odds (χ 2 = 23.2, OR = 3.5, 2.1<OR<5.8, p<0.001) of reporting anthrax outbreaks than their counterparts at the interface. Overall 20.0% (74/372) of the respondents reported that some anthrax carcasses were left to dissipate into the environment indicating a risk of environmental contamination. In livestock a total of 214 outbreaks with 2911 losses (mainly cattle) were recorded between 2000 and 2018, while 10 outbreaks with 3171 deaths were noted in wildlife. In humans 99 outbreaks were recorded involving 903 individual cases with 16 fatalities due to enteric infections following the consumption of infected meat between 2010 and 2018. Since its first incidence in wildlife in 2004–2005 in the south-eastern Lowveld of Zimbabwe, anthrax appears to be establishing endemic status along the Zambezi River basin. The disease has expanded spatially affecting 45 (72.6%) of the country’s 62 rural districts in a single decade. Thus, robust multi-disciplinary efforts are encouraged for surveillance and disease containment measures to minimize its impact on livestock, wildlife and humans.

Modelling climate change impacts on the spatial distribution of anthrax in Zimbabwe

“…Under the Animal Health and Public Health Acts of Zimbabwe, anthrax is a notifiable disease and reporting all observed and confirmed outbreaks in animals and humans is therefore mandatory [ 9 , 24 ]. Hence, the surveillance system for anthrax in both the animal and human sectors is based on notification [ 9 ].…”

“…The disease also affects human beings with 1.83 billion people living within high anthrax-risk areas and Africa recording the highest human incidences of the disease [ 4 ]. In fact, human anthrax cases often associated with animal anthrax epidemics in resource poor communities occur at least every year in African countries such as Zambia, Zimbabwe, and Ethiopia [ 8 , 9 ]. Thus, there is need to develop or adopt methods that allow for better understanding of current and future spatial distribution of anthrax as a preamble to identifying potential anthrax hotspots [ 10 ].…”

Some Peculiarities of Anthrax Epidemiology in Herbivorous and Carnivorous Animals

“…Only humans avoid this scheme because (1) their chances of being eaten by predators during illness, and even after death, became vanishingly small in the early stages of the development of society; (2) there are religious, cultural, and, later, sanitary and regulatory prohibitions on eating animals that have died from the disease (not always strictly enforced in areas lacking food security or significant food inspection, especially during times of famine, see for example [ 7 ]); (3) for humans, contact and inhalation routes of anthrax infection are more significant than the trophic route typical of natural conditions. During the processing of livestock raw materials contaminated with B. anthracis spores for the production of clothing, tools, jewelry, housing construction, etc., there is the possibility of spores getting into skin lesions, as well as the formation and subsequent inhalation of spore-containing aerosols.…”

A Retrospective Study on the Epidemiology of Anthrax Among Livestock from 2011 to 2020 in Awi Administrative Zone, Amhara Region, Northwest Ethiopia

“…8,9 Anthrax is an important but neglected zoonosis in many parts of the world. 10 It is a World Organization for Animal Health (WOAH)-listed and reportable disease. 8 The disease is mainly endemic in developing countries.…”