A study of the epidemiology and socio-economic impact of anthrax in Luangwa Valley in Zambia

Abstract

Anthrax is endemic in Luangwa National Park and the adjoining Game Management areas. The first official case of the disease was reported in 1922 in Luambe National Park. In 1987 a large-scale anthrax epidemic ravaged almost the entire Luangwa Valley. Since then at least three epidemics of the disease have been reported. Localised sporadic cases of the disease occur almost annually. Despite the frequent epidemics little is known of anthrax in terms of its epidemiology and impact on conservation. Mortalities were not investigated as wildlife officials attributed the mortalities to natural factors, animal population densities were not estimated and a no systematic disease surveillance programme exists. The number of animals that have died of the disease is not known. Anthrax mortalities are estimated in thousands. For example it is estimated that 4200 hippos and 1000 other animals, including five wild dogs, succumbed to the disease in 1987. No wild dog has been reported in the area since the 1987 epidemic. The objectives of this study were: # to describe the epidemiology and the socio-economic impact of anthrax in the Luangwa Valley ; # to examine the control measures adopted when epidemics occur; # to suggest alternative methods of dealing with disease outbreaks in the light of a quantitative risk and cost benefit analyses. Data was collected from reports was undertaken at the veterinary department, the wildlife offices and the national archives. Informal discussions were held with the local community on anthrax epidemics using the rapid rural appraisal technique. Data on animal demographics and rainfall were collected from National Parks and Wildlife Service and the National Meteorological Department. Soil, faeces, and bone samples were collected where large numbers of carcasses had been found during epidemics in the Luangwa National Park. These samples were examined for viable anthrax spores by the Department of Scientific Services in the Kruger National Park, South Africa. Information gleaned from official and verbal reports were collated and are presented in tabular from. The information found is inadequate to enable comprehensive quantitative risk and cost/benefit analyses. The economic cost of the disease arises mainly from the trade embargo resulting from veterinary quarantine regulations and the value of animal carcasses. Different scenarios were developed and are examined to present a risk analysis for proposed alternative control measures that could be adopted by the veterinary department when anthrax occurs in the Luangwa Valley. The probability of spreading anthrax by allowing trade in game trophies after treatment with formalin is estimated to be 0.0003-0.5. Although the impact of the disease on the economic utilisation of wild herbivores and community based natural resource management in the area has never been investigated the potential cost of anthrax epidemics is significant. The estimated cost of anthrax epidemics, depending on the size, as a result of the current disease control strategy are 124,3 – 2079,5 million Zambian Kwacha. The proposed alternative disease control measures could decrease the cost to 43,5 – 852, 6 million Zambian Kwacha. It is suggested that various measures be adopted to enable a better understanding of the dynamics of anthrax in the Luangwa Valley. These include : # the establishment of a veterinary unit with in the park # improved surveillance and reporting of diseases # regular censuses and estimates of population densities within the Park # improved communication between the veterinary Department and the Wildlife Authority.