Bone density and calcium and phosphorus content of the giraffe (Giraffa camelopardalis) and African buffalo (Syncerus caffer) skeletons

Apart from its slender appearance, four main factors lead to questions regarding the bone density, mineral content and morphology of the giraffe skeleton: X A rapid vertical growth rate ¡V especially in the neck and metapodials X Biomechanical considerations pertaining to the tall and slender shape of the skeleton X A proportionally larger skeleton in relation to body mass X A seemingly abnormal mineral balance in their diet with possible signs of mineral deficiency (i.e. osteophagia) In this study the skeleton of the giraffe was compared with that of the African buffalo with regards to bone density, skeletal calcium (Ca) and phosphorus (P) content and certain femoral and metacarpal morphological characteristics. The aim was to establish if, compared to buffalo, the features of the giraffe skeleton differed in any unique way. Fourteen similar bones or parts of bones were collected from carcasses of six adult giraffe bulls and nine adult buffalo bulls. These bones were cleaned, weighed and their volume determined through water displacement, from which their density could be calculated. Hereafter, Ca and P content were analysed in 10 bones from each carcass. Morphological characteristics of cross-sections from femoral and metacarpal shafts were also measured. No significant differences between the density or mineral content of bones in the two species could be found. In both species 19,5% Ca and 9,5% P were measured in defatted bone. Although similar in mineral concentration, the giraffe skeleton contains three times more absolute Ca and P, which translates into a 1,5-2-fold higher dietary requirement for these minerals compared to buffaloes. A gradation in the volume and weight of cervical vertebrae was also seen in giraffes. This could hold biomechanical advantage for the carriage and manoeuvrability of the long neck. Bone wall thickness of the giraffe femur and metacarpus is increased compared to buffaloes. This could hold biomechanical advantage for the slender legs that are subjected to increased vertical forces. Adequate Ca seems to be acquired through very specific browse selection, which seems to be of evolutionary origin, while the acquisition of adequate P seems to be critical and a possible cause for osteophagia. This study is the first of its kind in these species and therefore also provide valuable baseline data for future work in this field.Dissertation (MSc (Veterinary Science))--University of Pretoria, 2004.Production Animal Studiesunrestricte

Ecological suitability modeling for anthrax in the Kruger National Park, South Africa

The spores of the soil-borne bacterium, Bacillus anthracis, which causes anthrax are highly resistant to adverse environmental conditions. Under ideal conditions, anthrax spores can survive for many years in the soil. Anthrax is known to be endemic in the northern part of Kruger National Park (KNP) in South Africa (SA), with occasional epidemics spreading southward. The aim of this study was to identify and map areas that are ecologically suitable for the harboring of B. anthracis spores within the KNP. Anthrax surveillance data and selected environmental variables were used as inputs to the maximum entropy (Maxent) species distribution modeling method. Anthrax positive carcasses from 1988±2011 in KNP (n = 597) and a total of 40 environmental variables were used to predict and evaluate their relative contribution to suitability for anthrax occurrence in KNP. The environmental variables that contributed the most to the occurrence of anthrax were soil type, normalized difference vegetation index (NDVI) and precipitation. Apart from the endemic Pafuri region, several other areas within KNP were classified as ecologically suitable. The outputs of this study could guide future surveillance efforts to focus on predicted suitable areas for anthrax, since the KNP currently uses passive surveillance to detect anthrax outbreaks.S1 Table. Worldclim variables used in Maxent model.S2 Table. Overview of environmental data used in Maxent indicating the variables, type of data and source.S1 Fig. Spatially unique cases of Bacillus anthracis and the predicted suitability for B. anthracis occurrence.S2 Fig. Twelve environmental variables used in the final Maxent model.http://www.plosone.orgam2018Production Animal StudiesVeterinary Tropical Disease

Patterns of rabies cases in South Africa between 1993 and 2019, including the role of wildlife

DATA AVAILABILITY STATEMENT : The data that support the findings of this study are openly available in DALRRD. (2019). Rabies Data South Africa from http://www.daff.gov.za/daffweb3/Branches/Agricultural-Production-Health-Food-Safety/Animal-Health/Epidemiology/diseasedatabase], reference number [17].Rabies is a global viral zoonosis endemic to South Africa, resulting in fatal encephalitis in warm-blooded animals, including humans. The loss of human lives and economic losses in rural areas through loss of livestock are substantial. A review was conducted of all confirmed animal rabies cases in South Africa from 1993 to 2019, with a total of 11 701 cases identified to species level to assess the role that wildlife plays in the epidemiology of rabies. A spatio-temporal cluster analysis using a discrete Poisson space-time probability model, accounting for underlying estimated dog and livestock densities, identified 13 significant clusters (p < .05). These included four long-term clusters lasting more than 8 years in duration and seven short-term clusters lasting less than 2 years, with the remaining two clusters being of intermediate length. Outside of these endemic clusters, wildlife outbreaks in the remainder of South Africa were often less than one and a half years in duration most likely due to the rapid decline of wildlife vectors, especially jackals associated with rabies infection. Domestic dogs accounted for 59.8% of cases, with domestic cats (3.2%), livestock (21.1%) and wildlife (15.8%) making up the remainder of the cases. Yellow mongoose (Cynictis penicillata) was the most frequently affected wildlife species, followed by bat-eared fox (Otocyon megalotis), black-backed jackal (Canis mesomelas), meerkat (Suricata suricatta) and aardwolf (Proteles cristatus). Rabies in wildlife species followed different spatial distributions: black-backed jackal cases were more common in the north-western parts of South Africa, yellow mongoose cases more frequent in central South Africa, and bat-eared fox and aardwolf cases were more frequent in southern and western South Africa. Clusters often spanned several provinces, showing the importance of coordinated rabies control campaigns across administrative boundaries, and high-risk areas were highlighted for rabies in South Africa.The South African Veterinary Association Wildlife Group.http://wileyonlinelibrary.com/journal/tbedhj2023Centre for Veterinary Wildlife StudiesProduction Animal StudiesVeterinary Tropical Disease

Spatial partitioning by a subordinate carnivore is mediated by conspecific overlap

There are several hypotheses that could explain territory size in mammals, including the resource dispersion hypothesis (RDH), the intruder pressure hypothesis (IPH), and the intraguild predation hypothesis (IGPH). In this study, we tested predictions of these three hypotheses regarding territories of 19 packs of endangered African wild dogs (Lycaon pictus) over 2 years in the Kruger National Park, South Africa. If territory size was supported by the RDH, then we would observe (1) wild dog territories would be larger when resource patches were more dispersed, (2) pack sizes would be larger when resource patches were rich, and (3) pack size would not affect territory size. If supported by the IPH, then we would observe (4) larger territories would experience less intrusions, and (5) there would be an increase in territory overlap in areas of low resource dispersion. Finally, if supported by the IGPH, we would observe (6) territories would be larger in areas of higher lion (Panthera leo) density, as evidence of a spatial avoidance strategy. We found that the IGPH was fully supported (6), the IPH half supported (5), and the RDH partially supported (1 and 3), where we found spatial partitioning of wild dogs with lions, potentially mediated by resources and territory overlap with conspecifics. Ultimately, our results show that subordinate carnivores must balance a trade-off between dominant interspecific competitors and conspecifics to successfully coexist in areas with dominant carnivores.South African National Parks (SANParks) honorary rangers and the Endangered Wildlife Trust (EWT).http://link.springer.com/journal/4422020-09-18hj2020Mammal Research InstituteZoology and Entomolog

Immunological evidence of variation in exposure and immune response to Bacillus anthracis in herbivores of Kruger and Etosha national parks

Exposure and immunity to generalist pathogens differ among host species and vary across spatial scales. Anthrax, caused by a multi-host bacterial pathogen, Bacillus anthracis, is enzootic in Kruger National Park (KNP), South Africa and Etosha National Park (ENP), Namibia. These parks share many of the same potential host species, yet the main anthrax host in one (greater kudu (Tragelaphus strepsiceros) in KNP and plains zebra (Equus quagga) in ENP) is only a minor host in the other. We investigated species and spatial patterns in anthrax mortalities, B. anthracis exposure, and the ability to neutralize the anthrax lethal toxin to determine if observed host mortality differences between locations could be attributed to population-level variation in pathogen exposure and/or immune response. Using serum collected from zebra and kudu in high and low incidence areas of each park (18- 20 samples/species/area), we estimated pathogen exposure from anti-protective antigen (PA) antibody response using enzyme-linked immunosorbent assay (ELISA) and lethal toxin neutralization with a toxin neutralization assay (TNA). Serological evidence of pathogen exposure followed mortality patterns within each system (kudus: 95% positive in KNP versus 40% in ENP; zebras: 83% positive in ENP versus 63% in KNP). Animals in the high-incidence area of KNP had higher anti-PA responses than those in the low-incidence area, but there were no significant differences in exposure by area within ENP. Toxin neutralizing ability was higher for host populations with lower exposure prevalence, i.e., higher in ENP kudus and KNP zebras than their conspecifics in the other park. These results indicate that host species differ in their exposure to and adaptive immunity against B. anthracis in the two parks. These patterns may be due to environmental differences such as vegetation, rainfall patterns, landscape or forage availability between these systems and their interplay with host behavior (foraging or other risky behaviors), resulting in differences in exposure frequency and dose, and hence immune response.NSF Division of Environmental Biology.https://www.frontiersin.org/journals/immunologydm2022Veterinary Tropical Disease

Serological evidence of vaccination and perceptions concerning foot-and-mouth disease control in cattle at the wildlife-livestock interface of the Kruger National Park, South Africa

Communal livestock farming areas adjoining the Greater Kruger National Park Area within South Africa are part of the Foot-and-mouth disease (FMD) Protection Zone with Vaccination due to the proximity to wildlife reservoirs. FMD and its control affect the productivity of resource-poor farmers who often depend on livestock for their livelihoods. A cross-sectional study was performed with the objectives to evaluate the perceptions of farmers concerning FMD control, estimate the proportion of cattle with presumed protective antibody titres against FMD, as well as the proportion of herds with adequate herd immunity at the wildlife-livestock interface within Mpumalanga Province. One hundred and four farmers were interviewed with 73% (76/104) being cattle owners and the remainder hired cattle herders. The majority of respondents (79%, 82/104) reported a high level of satisfaction with the current animal health programmes in general. The educational level of the respondents varied by satisfaction level: the median (interquartile range; IQR) education level was standard 9 (2–12) for non-satisfied respondents, standard 3 (0–6) for little satisfied and standard 7 (2–11) for very satisfied respondents (P = 0.036). Animals are not always treated at FMD inspections points, but satisfied respondents were more likely to seek veterinary assistance (P = 0.001). The majority of respondents (92%, 96/104) identified the African buffalo (Syncerus caffer) as a risk factor for FMD outbreaks. Liquid-phase blocking ELISA antibody titres ≥1.6log10 were used to indicate positive serology secondary to FMD vaccination. At the time of sampling and relative to this threshold, 23% (95% confidence interval (CI): 12%–34%) of the sampled cattle had positive serology to SAT-1, 41% (95%CI: 33%–48%) to SAT-2 and 29% (95%CI: 19%–39%) to SAT-3. The median (IQR) time between the previous vaccination and sampling was 189 (168–241) days. The sampled cattle had a longer inter-vaccination interval as scheduled by state veterinary services and antibody levels were low at the time of the study. The majority of respondents expressed high satisfaction with the currently applied FMD vaccination programme, which provides an opportunity for progressive adaption of animal health programmes within the study area.This work was funded by contract agreement with the Peace Parks Foundation (Project No. A0U199), with additional support from the Research Development Programme (Project No. A0T384) at the University of Pretoria and Incentive Funding for Rated Researchers from the National Research Foundation (Project No. 76734).http://www.elsevier.com/locate/prevetmedhj2019Production Animal Studie

Environmental drivers of biseasonal anthrax outbreak dynamics in two multihost savanna systems

Environmental factors are common forces driving infectious disease dynamics. We compared interannual and seasonal patterns of anthrax infections in two multihost systems in southern Africa: Etosha National Park, Namibia, and Kruger National Park, South Africa. Using several decades of mortality data from each system, we assessed possible transmission mechanisms behind anthrax dynamics, examining (1) within- and between-species temporal case correlations and (2) associations between anthrax mortalities and environmental factors, specifically rainfall and the Normalized Difference Vegetation Index (NDVI), with empirical dynamic modeling. Anthrax cases in Kruger had wide interannual variation in case numbers, and large outbreaks seemed to follow a roughly decadal cycle. In contrast, outbreaks in Etosha were smaller in magnitude and occurred annually. In Etosha, the host species commonly affected remained consistent over several decades, although plains zebra (Equus quagga) became relatively more dominant. In Kruger, turnover of the main host species occurred after the 1990s, where the previously dominant host species, greater kudu (Tragelaphus strepsiceros), was replaced by impala (Aepyceros melampus). In both parks, anthrax infections showed two seasonal peaks, with each species having only one peak in a year. Zebra, springbok (Antidorcas marsupialis), wildebeest (Connochaetes taurinus), and impala cases peaked in wet seasons, while elephant (Loxodonta africana), kudu, and buffalo (Syncerus caffer) cases peaked in dry seasons. For common host species shared between the two parks, anthrax mortalities peaked in the same season in both systems. Among host species with cases peaking in the same season, anthrax mortalities were mostly synchronized, which implies similar transmission mechanisms or shared sources of exposure. Between seasons, outbreaks in one species may contribute to more cases in another species in the following season. Higher vegetation greenness was associated with more zebra and springbok anthrax mortalities in Etosha but fewer elephant cases in Kruger. These results suggest that host behavioral responses to changing environmental conditions may affect anthrax transmission risk, with differences in transmission mechanisms leading to multihost biseasonal outbreaks. This study reveals the dynamics and potential environmental drivers of anthrax in two savanna systems, providing a better understanding of factors driving biseasonal dynamics and outbreak variation among locations.The National Science Foundation of South Africa.https://onlinelibrary.wiley.com/r/ecmam2023Veterinary Tropical Disease

Endemic persistence of a highly contagious pathogen : foot-and-mouth disease in its wildlife host

Extremely contagious pathogens are a global biosecurity threat because of their high burden of morbidity and mortality, as well as their capacity for fast-moving epidemics that are difficult to quell. Understanding the mechanisms enabling persistence of highly transmissible pathogens in host populations is thus a central problem in disease ecology. Through a combination of experimental and theoretical approaches, we investigated how highly contagious foot-and-mouth disease viruses persist in the African buffalo, which serves as their wildlife reservoir. We found that viral persistence through transmission among acutely infected hosts alone is unlikely. However, the inclusion of occasional transmission from persistently infected carriers reliably rescues the most infectious viral strain from fade-out. Additional mechanisms such as antigenic shift, loss of immunity, or spillover among host populations may be required for persistence of less transmissible strains.DATA AND MATERIALS AVAILABLITY : Code for our parameter analyses and model simulations are available on Github (https://github.com/SimonGubbins/FMDVInBuffalo/tree/1.0.0 and https://github.com/janmedlock/FMDV/tree/Science_publication) and archived at ZenodoSUPPLEMENTARY MATERIAL 1 : Materials and Methods; Supplementary Text S1 to S6; Figs. S1 to S13; Tables S1 to S7; References (54–83).SUPPLEMENTARY MATERIAL 2 : MDAR Reproducibility Checklist.USDA-NIFA AFRI and by the UK Biotechnology and Biological Sciences Research Council.http://www.sciencemag.orghj2022Microbiology and Plant PathologyVeterinary Tropical Disease

A spatio-temporal probability model of cattle and African buffalo (Syncerus caffer) contact as a proxy for foot-and-mouth disease risk : a case study at the wildlife-livestock interface of the Kruger National Park, South Africa

The work presented here investigates a number of important components in the epidemiology of foot-and-mouth disease (FMD) at the wildlife-livestock interface along the Kruger National Park (KNP) and its adjoining private and provincial nature reserves (APNR). This epidemiological setting is unique and complex, mainly due to the presence of African buffaloes (Syncerus caffer) persistently infected with the Southern African Territories (SAT) strains of the FMD virus. Despite a great deal of experimentation and field research, FMD transmission from both persistently- and acutely-infected buffaloes to cattle is still poorly understood, although it is accepted that the two species have to be in close contact for it to occur. And even then, ‘close contact’ is ill-defined. Comparisons of three intensive study sites in the FMD protection zone, comprising both communally-farmed as well as smallholder cattle rangelands, were conducted to better understand this livestock system and determine livestock distribution patterns. This vast heterogeneous landscape of the FMD protection zone follows a latitudinal gradient of both human density and rainfall (increasing from north to south), which is reflected in similar gradients in cattle densities, the number of households owning cattle, consumption patterns as well as herding practice, whilst inversely associated with cattle sales and calf mortality rates. Distribution studies of the cattle in these study sites revealed a dry season dependence on water, and contraction of home ranges around preferred habitat during the warm wet season. Herding, or the lack thereof, was evident in daily activity budgets of these cattle. Interestingly, seasonal differences in stray buffalo dispersal patterns were the inverse of their domestic counterparts, being condensed along the fence line during the dry season. Stray buffalo events mainly consisted of single animals or very small groups, predominated by adult bulls. Most of these animals were destroyed soon after straying from the FMD infected zone, although some managed to move into areas with unvaccinated cattle, especially along major river courses. Swift removal of stray buffaloes from livestock areas is paramount, since recent outbreaks all share the characteristic of stray buffaloes being reported roaming the outbreak-area over extended periods (months) prior to an outbreak. Combining cattle and stray buffalo habitat suitability estimates revealed areas likely to facilitate contact between these species, which was mostly driven by cattle dispersal into those condensed areas along the fence and rivers more suitable for stray buffaloes during the cool dry season. This is also the season when acute infection with FMD is most likely in buffaloes. Yet, when adjusting cattle habitat suitability to incorporate their density, the concentration of preferred habitat during the warm wet season forms small pockets of high cattle density, amplifying contact risk with stray buffaloes in these areas. Simulation of stray buffalo movements along a least cost path, which incorporates fence permeability, is shown to be a useful visual aid to finding high-risk stray buffalo movement corridors. Contact-risk models performed well in retrospectively identifying high risk areas during recent outbreaks. These risk outputs have value in informing risk-based surveillance and strategic vaccination programs as well as in the delineation of disease control zones.Thesis (PhD)--University of Pretoria, 2015.Veterinary Tropical DiseasesPhDUnrestricte

Ecological suitability modeling for anthrax in the Kruger National Park, South Africa.

The spores of the soil-borne bacterium, Bacillus anthracis, which causes anthrax are highly resistant to adverse environmental conditions. Under ideal conditions, anthrax spores can survive for many years in the soil. Anthrax is known to be endemic in the northern part of Kruger National Park (KNP) in South Africa (SA), with occasional epidemics spreading southward. The aim of this study was to identify and map areas that are ecologically suitable for the harboring of B. anthracis spores within the KNP. Anthrax surveillance data and selected environmental variables were used as inputs to the maximum entropy (Maxent) species distribution modeling method. Anthrax positive carcasses from 1988-2011 in KNP (n = 597) and a total of 40 environmental variables were used to predict and evaluate their relative contribution to suitability for anthrax occurrence in KNP. The environmental variables that contributed the most to the occurrence of anthrax were soil type, normalized difference vegetation index (NDVI) and precipitation. Apart from the endemic Pafuri region, several other areas within KNP were classified as ecologically suitable. The outputs of this study could guide future surveillance efforts to focus on predicted suitable areas for anthrax, since the KNP currently uses passive surveillance to detect anthrax outbreaks