
Abstract
Bovine tuberculosis (bTB) caused by Mycobacterium bovis is an important re-emerging disease affecting livestock, wildlife and humans. Epidemiological studies are crucial to identifying the source of bTB infection, and its transmission dynamics and host preference, and thus to the implementation of effective strategies to contain it. In this study, we typed M. bovis isolates from livestock, and investigated their genetic diversity and distribution. A total of 204 M. bovisisolates were collected from cattle (n = 164) and Sicilian black pigs (n = 40) reared in a limited area of the province of Messina, northeastern Sicily, an area that had previously been identified as having the highest incidence of bTB in livestock on the island. All M. bovis isolates were typed by both spoligotyping and 12-loci MIRU-VNTR analysis. Results from both methods were then combined in order to improve the discriminatory power of M. bovis typing. We identified 73 combined genetic profiles. Thirty-five point six percent of the profiles were common to at least two animals, whereas 64.4% of profiles occurred in only one animal. A number of genetic profiles were predominant in either cattle or black pigs. We identified common genetic patterns in M. bovis isolates originating not only from neighboring districts, but also from non-neighboring districts. Our findings suggest that bTB is widespread in our setting, and is caused by a large number of genetically diverse M. bovis strains. The ecology and farming practices characteristic of the area may explain the substantial M. bovis heterogeneity observed, and could represent obstacles to bTB eradication.
Author summary
Bovine tuberculosis is a widespread infectious disease affecting both domestic and wild animals, as well as humans. In addition to being of public health concern, the disease, caused mainly by Mycobacterium bovis, has a significant economic impact on the farming industry due to the costs of eradication efforts. In Sicily, the largest of the Italian islands, bovine tuberculosis in livestock is of great concern, and targeted control strategies are needed. Molecular epidemiology is an essential tool for determining the distribution of a disease, so as to control it and minimize its threat to the population. We typed M. bovis isolates isolated from cattle and pigs reared in a limited area of Sicily. An in-depth comparison of the genetic makeup of these isolates allowed us a better understanding of the genetic diversity and distribution of the pathogen in our population of animals. We found that the disease is widespread in the area and caused by a large variety of M. bovis strains, which are in several cases common to different species of livestock. The paper concludes with a discussion of the findings in light of the environmental and ecological setting, and of farming practices in the area. The results are expected to contribute to the improvement of surveillance and control programs of bovine tuberculosis in the region.
Credit: Janice Haney Carr CDC
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Citation: Marianelli C, Amato B, Boniotti MB, Vitale M, Pruiti Ciarello F, Pacciarini ML, et al. (2019) Genotype diversity and distribution of Mycobacterium bovis from livestock in a small, high-risk area in northeastern Sicily, Italy. PLoS Negl Trop Dis 13(7): e0007546. https://doi.org/10.1371/journal.pntd.0007546
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