during 20082013 , a total of 68 satellite or global positioning system radio collars were deployed on african buffalo captured in southern gonarezhou np ; in northern kruger np , south of the limpopo river ; and in zimbabwe , north of limpopo river ( on sengwe communal land ) .
of the 68 buffalo , 47 were adult females , selected because their behavior is representative of core herd movements .
two adult males were also equipped with global positioning system devices because males are believed to move between herds ( 7 ) ; however , these devices failed after a few weeks because the collars fell off .
nineteen subadult female buffalo 2.54.5 years of age ( age determined by teeth eruption ) were also selected because individuals from this group are believed to disperse from their native herds ( 8 ; r. bengis , pers .
blood samples were taken and stored appropriately for disease screening , and individually numbered ear - tags were applied . during the study ,
extraordinarily long - distance movements for 3 subadult females were plotted by satellite telemetry readings ( figure 1 ) . in january 2014 , a 2.5-year - old female buffalo collared in south africa walked a maximum direct distance of 95 km . in 6 days , she crossed into zimbabwe , then into mozambique , and into zimbabwe again to enter gonarezhou np , with localizations within the home range of the buffalo herd in which btb was first diagnosed in a female buffalo in 2008 ( 6 ) .
this subadult buffalo later left the park and visited a commercial farm area before reentering gonarezhou np . in february 2014
, another 4-year - old female buffalo walked a direct distance of 64 km in 8 days .
finally , in march 2013 , a 4.5-year - old female captured in july 2011 was sighted in a location deep into communal land at a distance of 96 km from her capture site .
in contrast to these young female buffalo , no adult females collared in this study moved such long distances outside their home range during 20082014 .
the long - distance travel of these 3 subadult females occurred over a few days during the rainy season ( figure 2 ) and included movements outside the gltfca boundary .  
cumulative home - range area of 15 buffalo collared with global positioning system devices in kruger national park , south africa , in november 2013 . only buffalo with collars that functioned for an entire year are displayed .
data for 2 subadult female buffalo ( paths displayed in figure 1 ) are shown ( id65 and id68 ) separately from data for the 13 other buffalo ( subadult and adult females ) .
our findings strengthen the hypothesis that btb was spread from kruger np to gonarezhou np through buffalo - to - buffalo transmission by subadult females that dispersed from their native herds .
buffalo populations in kruger and gonarezhou nps are connected through long - distance movements of individuals , specifically prebreeding heifers .
although this movement is important for buffalo conservation in tfcas , it could also facilitate the spread of animal diseases , including zoonoses , across borders . in 2010 and 2011 ,
btb , rift valley fever , and brucellosis were detected in kruger np buffaloes , although a previous study failed to detect brucellosis in the gonarezhou np population ( 9 ) ( table ) .
buffalo id65 , which was initially captured in kruger np , was seen among a breeding herd in gonarezhou np , indicating the possibility of direct , buffalo - to - buffalo transmission of btb by dispersing infected individuals , without the need for bridge hosts ( e.g. , other wild or domestic ungulate species ) ( 10 ) .
* individuals and herds belong to the same population ( see figure 1 , adult female home range ) .
calf , < 2.5 y of age ; subadult , 2.54.5 y ; adult , > 4.5 y.  laboratory tests used : for bovine tuberculosis , gamma - interferon test and isolation ; for brucellosis , rose bengal and complement fixation tests ; for rift valley fever , indirect elisa test . 
published results ( 9 ) for the same diseases tested in the gonarezhou national park buffalo population in zimbabwe are shown in parentheses . 
 difference between kruger and gonarezhou population results for brucellosis was significant by fisher exact test for equality of proportion for small samples ( p<0.02 ) .
additional ecological information on buffalo dispersion is needed : frequency of dispersion events ; size , age , and sex composition of the dispersing groups ; and information about whether dispersed individuals later return to their home ranges .
subadult females appear to be particularly prone to dispersing behavior , unlike adult females , and we speculate that they may do so in small groups of individuals that are approximately the same age ( 8) .
no record exists of subadult female buffalo mixing with male bachelor groups , which are also known to connect to adjacent herds ( 7 ) .
. one possible explanation may be an out - breeding mechanism ( 11 ) that occurs before the start of reproduction ; subadult females may leave their native herd to begin their reproduction in a distant herd to minimize in - breeding . furthermore , abundant resources ( i.e. , water and grazing areas ) available during the rainy season maximize the probability of success of such behavior .
we found that subadult females were infected with btb , brucellosis , and rift valley fever ( table ) , diseases with different mechanisms of transmission .
age and social position in the herd may influence individuals rate of exposure to pathogenic infections and consequently may affect the dynamics of infection within and between herds .
our results indicate that subadult female buffalo could play a role in the spread of diseases among distant populations , across protected areas and international borders , and during the rainy season .
this seasonal pattern contrasts with the timing of most wildlife and livestock contact between adult females , which has been observed to occur predominantly during the dry season in the study area ( 4 ) .
buffalo have been observed far outside the boundaries of protected areas , even outside the gltfca , in communal land where livestock farming is the main livelihood ; these observations considerably widen the wildlife  livestock interface area where disease spread can occur ( 12 ) .
livestock interfaces can encompass large areas , rather than being a fence or strip of land at the edge of protected areas .
these data should assist in refining disease modeling by showing the importance of temporal and spatial considerations and by redefining variables ( e.g. , age and sex ) involved in risk for pathogen spillover or emergence ( i.e. , identifying super - spreaders ) ( 13 ) .
our results suggest that the spillover of btb and other zoonoses at the wildlife  livestock  human interface constitutes a risk to animal and human health in the gltfca ( 9,14 ) .
the health issue in tfcas can not be overlooked and must be part of any management decision . combining ecological and epidemiologic knowledge is necessary to understand disease dynamics in these complex agro - ecosystems .
 we report on the long - distance movements of subadult female buffalo within a transfrontier conservation area in africa . 
 our observations confirm that bovine tuberculosis and other diseases can spread between buffalo populations across national parks , community land , and countries , thus posing a risk to animal and human health in surrounding wildlife areas . 
The Study
Conclusions