Assessing the impact of feline immunodeficiency virus and bovine tuberculosis co-infection in African lions

Abstract

Bovine tuberculosis (BTB), caused by Mycobacterium bovis, is a disease that was introduced relatively recently into the Kruger National Park (KNP) lion population. Feline immunodeficiency virus (FIV ple ) is thought to have been endemic in lions for a much longer time. In humans, co-infection between Mycobacterium tuberculosis and human immunodeficiency virus increases disease burden. If BTB were to reach high levels of prevalence in lions, and if similar worsening effects would exist between FIV ple and BTB as for their human equivalents, this could pose a lion conservation problem. We collected data on lions in KNP from 1993 to 2008 for spatio-temporal analysis of both FIV ple and BTB, and to assess whether a similar relationship between the two diseases exists in lions. We found that BTB prevalence in the south was higher than in the north (72 versus 19% over the total study period) and increased over time in the northern part of the KNP (0-41%). No significant spatio-temporal differences were seen for FIV ple in the study period, in agreement with the presumed endemic state of the infection. Both infections affected haematology and blood chemistry values, FIV ple in a more pronounced way than BTB. The effect of co-infection on these values, however, was always less than additive. Though a large proportion (31%) of the lions was co-infected with FIV ple and M. bovis, there was no evidence for a synergistic relation as in their human counterparts. Whether this results from different immunopathogeneses remains to be determined.

Host and parasite diversity jointly control disease risk in complex communities

“…Antagonistic effects among parasites could result from competition for a shared resource (e.g., space or host cells) or interactions mediated through host immunity (7). Based on the differences in infection sites among the parasites included here and their low metabolic demands within second intermediate hosts, cross-reactive immunity is perhaps the most probable mechanism, consistent with a growing emphasis on the role of host immunity in determining coinfection outcomes (31,(33)(34)(35)(36). That host diversity generally had stronger inhibitory effects on parasite loads than did parasite diversity may stem from the greater potential for low-competence hosts to function as population sinks for invading parasites, whereas immune-mediated competition associated with coinfection acts primarily to weaken persistence of parasites that have already colonized (2,37).…”

Hematologic and serum chemistry reference intervals for free-ranging lions (Panthera leo)

“…feline immunodeficiency virus and bovine tuberculosis (BTB)) may account for significant differences in blood value parameters (Maas et al, 2012 We conclude that these reference intervals can be used by veterinarians and wildlife researchers to assess the health status of free-ranging lions, and we propose they can also be used for captive lions as they are arguably more informative than the currently available mean, SD, minimal and maximal values.…”

“…The complete lion data set is described elsewhere (Maas et al, 2012). The selection of the lions used for the current study was based on the body condition, only including clinically healthy lions with a good body condition score (scored 4/5 and 5/5, where 5 represents an excellent body condition).…”

Infectious disease agents mediate interaction in food webs and ecosystems

“…More fieldwork is needed to elucidate such interactions between infectious agents, but effects may be difficult to disentangle. For example, Maas et al [71] looked at more than 600 lions in Kruger Park, searching for possible synergistic effects between bovine tuberculosis and feline immunodeficiency virus, potentially mimicking the influence of tuberculosis and HIV established in humans, but found no evidence for a similar relation in lions.…”