5 FINAL CONSIDERATIONS
By combining epidemiological history and WGS of M. bovis strains,
we show that the increase in fatal cases observed in the safari park
coincided with changes in populational density and nutritional status,
and that many pathogen introductions occurred over time. These
observations demonstrate that wildlife populations found to be
chronically infected and frequently asymptomatic may suddenly suffer
from acute, fatal disease following populational disturbances, such as
the ones observed herein. The negligence of successive pathogen
introductions likely potentiated the outbreak, contributing to disease
spread in different animal species. The M. bovis strains
circulating in the park were classified as Lb3 (CC Eu2), a common
lineage found in Brazil, and share phylogenetic relationships with
extant M. bovis strains circulating in farmed cattle. Thus, at
some point in time, transmission occurred between cattle and the
wildlife maintained in the safari park. The use of WGS to delineate the
history of this outbreak highlights the importance of genomic
surveillance to follow disease introduction into animal populations and
transmission between individuals.
With this study we make a pledge for action. It is imperative that
reporting of TB cases in wildlife, captive or free-ranging, becomes
mandatory in Brazil as to understand the true size of the problem. This
should follow increased investments in pathogen identification, as
wildlife are affected by both M. bovis and M. tuberculosis(Murakami et al., 2012). Finally, a national plan for control of TB in
wildlife should be designed to incorporate specific guidelines to
contain and solve outbreaks and prevent possible zoonotic transmission
to veterinarians and caretakers, considering species-specific conditions
and difficulties in diagnosing the disease in wild animals, particularly
when dealing with endangered species.