Detection and identification by PCR of Clostridium chauvoei in clinical isolates, bovine faeces and substrates from biogas plant

<p>Abstract</p> <p>Background</p> <p><it>Clostridium chauvoei </it>causes blackleg, an acute disease associated with high mortality in ruminants. The apparent primary port of entry is oral, during grazing on pasture contaminated by spores. Cases of blackleg can occur year after year on contaminated pastures. A method to determine the prevalence of <it>C. chauvoei </it>spores on pasture would be useful.</p> <p>The standard method for <it>C. chauvoei </it>detection is culture and biochemical identification, which requires a pure culture. In most muscle samples from cattle dead from blackleg the amount of <it>C. chauvoei </it>in samples is high and the bacterium can easily be cultured, although some samples may be contaminated. Detection by PCR would be faster and independent of contaminating flora.</p> <p>Digested residues from biogas plants provide an excellent fertiliser, but it is known that spore-forming baeria such as <it>Clostridium </it>spp. are not reduced by pasteurisation. The use of digested residues as fertiliser may contribute to the spread of <it>C. chauvoei</it>. Soil, manure and substrate from biogas plants are contaminated with other anaerobic bacteria which outgrow <it>C. chauvoei</it>. Therefore, detection by PCR is would be useful. This study applied a PCR-based method to detect of <it>C. chauvoei </it>in 25 muscle and blood samples, 114 manure samples, 84 soil samples and 33 samples from the biogas process.</p> <p>Methods</p> <p>Muscle tissues from suspected cases of blackleg were analysed both by the standard culture method followed by biochemical identification and by PCR, with and without preculture. To investigate whether muscle tissue samples are necessary, samples taken by swabs were also investigated. Samples from a biogas plant and manure and soil from farms were analysed by culture followed by PCR. The farms had proven cases of blackleg. For detection of <it>C. chauvoei </it>in the samples, a specific PCR primer pair complementary to the spacer region of the 16S-23S rRNA gene was used.</p> <p>Results</p> <p><it>Clostridium chauvoei </it>was detected in 32% of muscle samples analysed by culture with identification by biochemical methods and in 56% of cases by culture in combination with PCR. <it>Clostridium chauvoei </it>was detected in 3 (out of 11) samples from the biogas plants collected before pasteurisation, but samples taken after pasteurisation and after digestion all tested negative. <it>Clostridium chauvoei </it>was not detected in any soil or silage samples and only one manure samples tested positive.</p> <p>Conclusion</p> <p>The diagnostic method used for <it>C. chauvoei </it>was not applicable in estimating the risk of blackleg on particular pastures from manure or soil samples, but found to be highly useful for clinical samples.</p

Carnivory in the common hippopotamus H ippopotamus amphibius: implications for the ecology and epidemiology of anthrax in African landscapes

The common hippopotamus Hippopotamus amphibius ('hippo') is a keystone species whose foraging activities and behaviour have profound effects on the structure and dynamics of terrestrial and aquatic ecosystems within its habitat. Although hippos are typically regarded as obligate herbivores and short-grass grazing specialists, field studies have demonstrated that hippos are facultative carnivores that consume flesh and intestinal tissues from the carcasses of other animals. Carnivory by hippos is not an aberrant behaviour restricted to particular individuals in certain localities, but a behaviour pattern that occurs within populations distributed in most of the hippo's current range in eastern and southern Africa. Carnivory is frequently associated with communal feeding involving multiple individuals or entire social groups of hippos. The observed tendency of hippos to feed on carcasses, including those of other hippos, has important implications for the ecology and epidemiology of anthrax and other ungulate-associated zoonotic diseases in African landscapes. Scavenging and carnivory by hippos may explain why the spatiotemporal patterns and dynamics of anthrax mortality among hippos often differ markedly from those of other anthrax-susceptible herbivores within the same habitats, and why levels of hippo mortality from anthrax may be orders of magnitude higher than those of other anthrax-susceptible ungulate populations within the same localities. Recognition of the role of carnivory as a key factor in modulating the dynamics of mass anthrax outbreaks in hippos can provide a basis for improved understanding and management of the effects of anthrax outbreaks in hippo and human populations