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1.
Am Nat ; 204(2): 133-146, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39008835

RESUMEN

AbstractInfectious disease dynamics operate across biological scales: pathogens replicate within hosts but transmit among populations. Functional changes in the pathogen-host interaction thus generate cascading effects across organizational scales. We investigated within-host dynamics and among-host transmission of three strains (SAT-1, -2, -3) of foot-and-mouth disease viruses (FMDVs) in their wildlife host, African buffalo. We combined data on viral dynamics and host immune responses with mathematical models to ask the following questions: How do viral and immune dynamics vary among strains? Which viral and immune parameters determine viral fitness within hosts? And how do within-host dynamics relate to virus transmission? Our data reveal contrasting within-host dynamics among viral strains, with SAT-2 eliciting more rapid and effective immune responses than SAT-1 and SAT-3. Within-host viral fitness was overwhelmingly determined by variation among hosts in immune response activation rates but not by variation among individual hosts in viral growth rate. Our analyses investigating across-scale linkages indicate that viral replication rate in the host correlates with transmission rates among buffalo and that adaptive immune activation rate determines the infectious period. These parameters define the virus's relative basic reproductive number (ℛ0), suggesting that viral invasion potential may be predictable from within-host dynamics.


Asunto(s)
Búfalos , Virus de la Fiebre Aftosa , Fiebre Aftosa , Animales , Búfalos/virología , Virus de la Fiebre Aftosa/inmunología , Virus de la Fiebre Aftosa/crecimiento & desarrollo , Fiebre Aftosa/transmisión , Fiebre Aftosa/virología , Fiebre Aftosa/inmunología , Interacciones Huésped-Patógeno/inmunología , Replicación Viral , Modelos Biológicos
2.
Proc Natl Acad Sci U S A ; 118(3)2021 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-33431676

RESUMEN

Pathogen interactions arising during coinfection can exacerbate disease severity, for example when the immune response mounted against one pathogen negatively affects defense of another. It is also possible that host immune responses to a pathogen, shaped by historical evolutionary interactions between host and pathogen, may modify host immune defenses in ways that have repercussions for other pathogens. In this case, negative interactions between two pathogens could emerge even in the absence of concurrent infection. Parasitic worms and tuberculosis (TB) are involved in one of the most geographically extensive of pathogen interactions, and during coinfection worms can exacerbate TB disease outcomes. Here, we show that in a wild mammal natural resistance to worms affects bovine tuberculosis (BTB) severity independently of active worm infection. We found that worm-resistant individuals were more likely to die of BTB than were nonresistant individuals, and their disease progressed more quickly. Anthelmintic treatment moderated, but did not eliminate, the resistance effect, and the effects of resistance and treatment were opposite and additive, with untreated, resistant individuals experiencing the highest mortality. Furthermore, resistance and anthelmintic treatment had nonoverlapping effects on BTB pathology. The effects of resistance manifested in the lungs (the primary site of BTB infection), while the effects of treatment manifested almost entirely in the lymph nodes (the site of disseminated disease), suggesting that resistance and active worm infection affect BTB progression via distinct mechanisms. Our findings reveal that interactions between pathogens can occur as a consequence of processes arising on very different timescales.


Asunto(s)
Búfalos/inmunología , Resistencia a la Enfermedad , Hemoncosis/microbiología , Pulmón/inmunología , Ganglios Linfáticos/inmunología , Tricostrongiliasis/microbiología , Tuberculosis Bovina/microbiología , Animales , Antinematodos/farmacología , Búfalos/microbiología , Búfalos/parasitología , Bovinos , Coinfección , Progresión de la Enfermedad , Eosinófilos/efectos de los fármacos , Eosinófilos/inmunología , Eosinófilos/microbiología , Eosinófilos/parasitología , Heces/parasitología , Femenino , Fenbendazol/farmacología , Hemoncosis/tratamiento farmacológico , Hemoncosis/mortalidad , Hemoncosis/parasitología , Haemonchus/efectos de los fármacos , Haemonchus/genética , Haemonchus/patogenicidad , Inmunoglobulina A/sangre , Pulmón/efectos de los fármacos , Pulmón/microbiología , Pulmón/parasitología , Ganglios Linfáticos/efectos de los fármacos , Ganglios Linfáticos/microbiología , Ganglios Linfáticos/parasitología , Mastocitos/efectos de los fármacos , Mastocitos/inmunología , Mastocitos/microbiología , Mastocitos/parasitología , Mycobacterium bovis/crecimiento & desarrollo , Mycobacterium bovis/patogenicidad , Índice de Severidad de la Enfermedad , Análisis de Supervivencia , Tricostrongiliasis/tratamiento farmacológico , Tricostrongiliasis/mortalidad , Tricostrongiliasis/parasitología , Trichostrongylus/efectos de los fármacos , Trichostrongylus/genética , Trichostrongylus/patogenicidad , Tuberculosis Bovina/tratamiento farmacológico , Tuberculosis Bovina/mortalidad , Tuberculosis Bovina/parasitología
3.
Immunogenetics ; 75(2): 115-132, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36512055

RESUMEN

African buffalo (Syncerus caffer) have been distinct from the Auroch lineage leading to domestic cattle for 5 million years, and are reservoirs of multiple pathogens, that affect introduced domestic cattle. To date, there has been no analysis of the class I MHC locus in African buffalo. We present the first data on African buffalo class I MHC, which demonstrates that gene and predicted protein coding sequences are approximately 86-87% similar to that of African domestic cattle in the peptide binding region. The study also shows concordance in the distribution of codons with elevated posterior probabilities of positive selection in the buffalo class I MHC and known antigen binding sites in cattle. Overall, the diversity in buffalo class I sequences appears greater than that in cattle, perhaps related to a more complex pathogen challenge environment in Africa. However, application of NetMHCpan suggested broad clustering of peptide binding specificities between buffalo and cattle. Furthermore, in the case of at least 20 alleles, critical peptide-binding residues appear to be conserved with those of cattle, including at secondary anchor residues. Alleles with six different length transmembrane regions were detected. This preliminary analysis suggests that like cattle, but unlike most other mammals, African buffalo appears to exhibit configuration (haplotype) variation in which the loci are expressed in distinct combinations.


Asunto(s)
Theileria parva , Theileriosis , Animales , Bovinos/genética , Theileria parva/genética , Haplotipos , Búfalos/genética , Variación Genética , Péptidos/genética
4.
Proc Natl Acad Sci U S A ; 115(29): 7545-7550, 2018 07 17.
Artículo en Inglés | MEDLINE | ID: mdl-29967175

RESUMEN

Coinfecting parasites and pathogens remain a leading challenge for global public health due to their consequences for individual-level infection risk and disease progression. However, a clear understanding of the population-level consequences of coinfection is lacking. Here, we constructed a model that includes three individual-level effects of coinfection: mortality, fecundity, and transmission. We used the model to investigate how these individual-level consequences of coinfection scale up to produce population-level infection patterns. To parameterize this model, we conducted a 4-y cohort study in African buffalo to estimate the individual-level effects of coinfection with two bacterial pathogens, bovine tuberculosis (bTB) and brucellosis, across a range of demographic and environmental contexts. At the individual level, our empirical results identified bTB as a risk factor for acquiring brucellosis, but we found no association between brucellosis and the risk of acquiring bTB. Both infections were associated with reductions in survival and neither infection was associated with reductions in fecundity. The model reproduced coinfection patterns in the data and predicted opposite impacts of coinfection at individual and population scales: Whereas bTB facilitated brucellosis infection at the individual level, our model predicted the presence of brucellosis to have a strong negative impact on bTB at the population level. In modeled populations where brucellosis was present, the endemic prevalence and basic reproduction number ([Formula: see text]) of bTB were lower than in populations without brucellosis. Therefore, these results provide a data-driven example of competition between coinfecting pathogens that occurs when one pathogen facilitates secondary infections at the individual level.


Asunto(s)
Brucelosis , Búfalos/microbiología , Coinfección , Modelos Biológicos , Tuberculosis Bovina , Animales , Brucelosis/epidemiología , Brucelosis/microbiología , Brucelosis/transmisión , Brucelosis/veterinaria , Bovinos , Coinfección/epidemiología , Coinfección/microbiología , Coinfección/transmisión , Coinfección/veterinaria , Femenino , Tuberculosis Bovina/epidemiología , Tuberculosis Bovina/microbiología , Tuberculosis Bovina/transmisión
5.
J Virol ; 93(15)2019 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-31092573

RESUMEN

African buffaloes (Syncerus caffer) are the principal "carrier" hosts of foot-and-mouth disease virus (FMDV). Currently, the epithelia and lymphoid germinal centers of the oropharynx have been identified as sites for FMDV persistence. We carried out studies in FMDV SAT1 persistently infected buffaloes to characterize the diversity of viruses in oropharyngeal epithelia, germinal centers, probang samples (oropharyngeal scrapings), and tonsil swabs to determine if sufficient virus variation is generated during persistence for immune escape. Most sequencing reads of the VP1 coding region of the SAT1 virus inoculum clustered around 2 subpopulations differing by 22 single-nucleotide variants of intermediate frequency. Similarly, most sequences from oropharynx tissue clustered into two subpopulations, albeit with different proportions, depending on the day postinfection (dpi). There was a significant difference between the populations of viruses in the inoculum and in lymphoid tissue taken at 35 dpi. Thereafter, until 400 dpi, no significant variation was detected in the viral populations in samples from individual animals, germinal centers, and epithelial tissues. Deep sequencing of virus from probang or tonsil swab samples harvested prior to postmortem showed less within-sample variability of VP1 than that of tissue sample sequences analyzed at the same time. Importantly, there was no significant difference in the ability of sera collected between 14 and 400 dpi to neutralize the inoculum or viruses isolated at later time points in the study from the same animal. Therefore, based on this study, there is no evidence of escape from antibody neutralization contributing to FMDV persistent infection in African buffalo.IMPORTANCE Foot-and-mouth disease virus (FMDV) is a highly contagious virus of cloven-hoofed animals and is recognized as the most important constraint to international trade in animals and animal products. African buffaloes (Syncerus caffer) are efficient carriers of FMDV, and it has been proposed that new virus variants are produced in buffalo during the prolonged carriage after acute infection, which may spread to cause disease in livestock populations. Here, we show that despite an accumulation of low-frequency sequence variants over time, there is no evidence of significant antigenic variation leading to immune escape. Therefore, carrier buffalo are unlikely to be a major source of new virus variants.


Asunto(s)
Búfalos , Portador Sano/veterinaria , Evolución Molecular , Virus de la Fiebre Aftosa/crecimiento & desarrollo , Fiebre Aftosa/inmunología , Fiebre Aftosa/virología , Evasión Inmune , Animales , Proteínas de la Cápside/genética , Portador Sano/inmunología , Portador Sano/virología , Epitelio/virología , Virus de la Fiebre Aftosa/genética , Virus de la Fiebre Aftosa/inmunología , Inestabilidad Genómica , Centro Germinal/virología , Mutación , Orofaringe/virología , Análisis de Secuencia de ADN
6.
BMC Microbiol ; 20(1): 49, 2020 03 04.
Artículo en Inglés | MEDLINE | ID: mdl-32131736

RESUMEN

BACKGROUND: Bovine tuberculosis (bTB) affects cattle and wildlife in South Africa with the African buffalo (Syncerus caffer) as the principal maintenance host. The presence of a wildlife maintenance host at the wildlife/livestock interface acting as spill-over host makes it much more challenging to control and eradicate bTB in cattle. Spoligotyping and mycobacterial interspersed repetitive unit-variable number of tandem repeat (MIRU-VNTR) genotyping methods were performed to investigate the genetic diversity of Mycobacterium bovis (M. bovis) isolates from cattle and wildlife, their distribution and transmission at the wildlife/livestock interface in northern Kwa-Zulu Natal (KZN), South Africa. RESULTS: SB0130 was identified as the dominant spoligotype pattern at this wildlife/livestock interface, while VNTR typing revealed a total of 29 VNTR profiles (strains) in the KZN province signifying high genetic variability. The detection of 5 VNTR profiles shared between cattle and buffalo suggests M. bovis transmission between species. MIRU-VNTR confirmed co-infection in one cow with three strains of M. bovis that differed at a single locus, with 2 being shared with buffalo, implying pathogen introduction from most probably unrelated wildlife sources. CONCLUSION: Our findings highlight inter and intra species transmission of bTB at the wildlife/livestock interface and the need for the implementation of adequate bTB control measures to mitigate the spread of the pathogen responsible for economic losses and a public health threat.


Asunto(s)
Animales Salvajes/microbiología , Técnicas de Genotipaje/métodos , Ganado/microbiología , Mycobacterium bovis/clasificación , Tuberculosis Bovina/transmisión , Animales , Búfalos/microbiología , Bovinos , Evolución Molecular , Variación Genética , Repeticiones de Minisatélite , Mycobacterium bovis/genética , Filogenia , Sudáfrica
7.
Ecol Appl ; 30(8): e02203, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32598524

RESUMEN

In many savannah regions of Africa, pronounced seasonal variability in rainfall results in wildlife being restricted to floodplains and other habitats adjacent to permanent surface water in the dry season. During the wet season, rainfall fills small-scale, ephemeral water sources that allow wildlife to exploit forage and other resources far from permanent surface water. These water sources remain difficult to quantify, however, due to their small and ephemeral nature, and as a result are rarely included in quantitative studies of wildlife distribution, abundance, and movement. Our goal was to map ephemeral water in Bwabwata National Park in Namibia using two different approaches and to relate measures of ephemeral water to the abundance, distribution, and movement of two large wildlife species. We used high-resolution Google Earth and Esri World imagery to visually identify waterholes. Additionally, we used Sentinel-2 satellite imagery to map ephemeral water across the study area using the Normalized Difference Water Index. With these mapped waterhole layers and data from GPS-collared individuals of African elephant (Loxodonta africana) and African buffalo (Syncerus caffer), we evaluated the importance of ephemeral water in conditioning abundance and movement of these two species. The two approaches to mapping ephemeral water resulted in the visual identification of nearly 10,000 waterholes, and a predicted ephemeral water layer of ~76% accuracy. The inclusion of ephemeral water into models of abundance and movement resulted in improved goodness of fit relative to those without water, and water impacts on abundance and movement were among the strongest of all variables considered. The potential importance of ephemeral water in conditioning the movements and distributions of large herbivores in African savannahs has been difficult to quantify relative to vegetation drivers. Our results suggest research into ephemeral water impacts deserves more attention.


Asunto(s)
Elefantes , Agua , África , Animales , Ecosistema , Estaciones del Año
8.
BMC Ecol ; 20(1): 6, 2020 02 03.
Artículo en Inglés | MEDLINE | ID: mdl-32013942

RESUMEN

BACKGROUND: Assessing wildlife movements and habitat use is important for species conservation and management and can be informative for understanding population dynamics. The African buffalo (Syncerus caffer) population of Ruaha National Park, Tanzania has been declining, and little was known about the movement, habitat selection, and space use of the population, which is important for understanding possible reasons behind the decline. A total of 12 African buffalo cows from four different herds were collared with satellite transmitters. Movements were assessed over 2 years from 11 animals. RESULTS: The space use of the individual collared buffaloes as an approximation of the 95% home range size estimated using Brownian bridge models, ranged from 73 to 601 km2. The estimated home ranges were larger in the wet season than in the dry season. With the exception of one buffalo all collared animals completed a wet season migration of varying distances. A consistent pattern of seasonal movement was observed with one herd, whereas the other herds did not behave the same way in the two wet seasons that they were tracked. Herd splitting and herd switching occurred on multiple occasions. Buffaloes strongly associated with habitats near the Great Ruaha River in the dry season and had little association to permanent water sources in the wet season. Daily movements averaged 4.6 km (standard deviation, SD = 2.6 km), with the longest distances traveled during November (mean 6.9 km, SD = 3.6 km) at the end of the dry season and beginning of the wet season. The shortest daily distances traveled occurred in the wet season in April-June (mean 3.6 km, SD = 1.6-1.8 km). CONCLUSION: The Great Ruaha River has experienced significant drying in the last decades due to water diversions upstream, which likely has reduced the suitable range for buffaloes. The loss of dry season habitat due to water scarcity has likely contributed to the population decline of the Ruaha buffaloes.


Asunto(s)
Búfalos , Parques Recreativos , Animales , Bovinos , Ecosistema , Femenino , Estaciones del Año , Tanzanía
9.
Parasitology ; 145(11): 1430-1439, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-29729680

RESUMEN

The extent of sequence diversity among the genes encoding 10 antigens (Tp1-10) known to be recognized by CD8+ T lymphocytes from cattle immune to Theileria parva was analysed. The sequences were derived from parasites in 23 buffalo-derived cell lines, three cattle-derived isolates and one cloned cell line obtained from a buffalo-derived stabilate. The results revealed substantial variation among the antigens through sequence diversity. The greatest nucleotide and amino acid diversity were observed in Tp1, Tp2 and Tp9. Tp5 and Tp7 showed the least amount of allelic diversity, and Tp5, Tp6 and Tp7 had the lowest levels of protein diversity. Tp6 was the most conserved protein; only a single non-synonymous substitution was found in all obtained sequences. The ratio of non-synonymous: synonymous substitutions varied from 0.84 (Tp1) to 0.04 (Tp6). Apart from Tp2 and Tp9, we observed no variation in the other defined CD8+ T cell epitopes (Tp4, 5, 7 and 8), indicating that epitope variation is not a universal feature of T. parva antigens. In addition to providing markers that can be used to examine the diversity in T. parva populations, the results highlight the potential for using conserved antigens to develop vaccines that provide broad protection against T. parva.


Asunto(s)
Antígenos de Protozoos/inmunología , Linfocitos T CD8-positivos/inmunología , Variación Genética , Theileria parva/genética , Theileria parva/inmunología , Alelos , Animales , Antígenos de Protozoos/genética , Secuencia de Bases , Búfalos , Línea Celular , Epítopos/inmunología
10.
Emerg Infect Dis ; 22(2): 277-80, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26812531

RESUMEN

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.


Asunto(s)
Migración Animal , Búfalos , Zoonosis/epidemiología , Zoonosis/etiología , África Austral , Animales , Bovinos , Femenino , Geografía , Humanos , Masculino , Riesgo
11.
J Anim Ecol ; 85(5): 1222-33, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27174037

RESUMEN

Community assembly is a fundamental process that has long been a central focus in ecology. Extending community assembly theory to communities of co-infecting parasites, we used a gastrointestinal nematode removal experiment in free-ranging African buffalo to examine the community assembly patterns and processes. We first asked whether reassembled communities differ from undisturbed communities by comparing anthelmintic-treated and control hosts. Next, we examined the temporal dynamics of assembly using a cross-section of communities that reassembled for different periods of time since last experimental removal. Next, we tested for evidence of assembly processes that might drive such reassembly patterns: environmental filtering based on host traits (i.e. habitat patches), interspecific interactions, priority effects and chance dispersal from the environmental pool of infective stages (i.e. the regional species pool). On average, reassembled parasite communities had lower abundance, but were more diverse and even, and these patterns varied tightly with reassembly time. Over time, the communities within treated hosts progressively resembled controls as diversity and evenness decreased, while total abundance increased. Notably, experimental removal allowed us to attribute observed differences in abundance, diversity and evenness to the process of community assembly. During early reassembly, parasite accumulation was biased towards a subordinate species and, by excluding stochastic assembly processes (i.e. chance dispersal and priority effects), we were able to determine that early assembly is deterministic. Later in the reassembly process, we established that host traits, as well as stochastic dispersal from the environmental pool of infective stages, can affect the community composition. Overall, our results suggest that there is a high degree of resiliency and environmental dependence to the worm communities of buffalo. More generally, our data show that both deterministic and stochastic processes may play a role in the assembly of parasite communities of wild hosts, but their relative importance may vary temporally. Consequently, the best strategy for managing reassembling parasite communities may also need to shift over time.


Asunto(s)
Biota , Búfalos/parasitología , Interacciones Huésped-Parásitos , Nematodos/fisiología , Animales , Antinematodos/administración & dosificación , Fenbendazol/administración & dosificación , Enfermedades Gastrointestinales/tratamiento farmacológico , Enfermedades Gastrointestinales/parasitología , Enfermedades Gastrointestinales/veterinaria , Infecciones por Nematodos/tratamiento farmacológico , Infecciones por Nematodos/parasitología , Infecciones por Nematodos/veterinaria , Dinámica Poblacional , Distribución Aleatoria , Sudáfrica , Procesos Estocásticos
12.
J Anim Ecol ; 84(4): 999-1009, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25714466

RESUMEN

Chronic infections may have negative impacts on wildlife populations, yet their effects are difficult to detect in the absence of long-term population monitoring. Brucella abortus, the bacteria responsible for bovine brucellosis, causes chronic infections and abortions in wild and domestic ungulates, but its impact on population dynamics is not well understood. We report infection patterns and fitness correlates of bovine brucellosis in African buffalo based on (1) 7 years of cross-sectional disease surveys and (2) a 4-year longitudinal study in Kruger National Park (KNP), South Africa. We then used a matrix population model to translate these observed patterns into predicted population-level effects. Annual brucellosis seroprevalence ranged from 8·7% (95% CI = 1·8-15·6) to 47·6% (95% CI = 35·1-60·1) increased with age until adulthood (>6) and varied by location within KNP. Animals were on average in worse condition after testing positive for brucellosis (F = -5·074, P < 0·0001), and infection was associated with a 2·0 (95% CI = 1·1-3·7) fold increase in mortality (χ(2)  = 2·039, P = 0·036). Buffalo in low body condition were associated with lower reproductive success (F = 2·683, P = 0·034), but there was no association between brucellosis and pregnancy or being observed with a calf. For the range of body condition scores observed in the population, the model-predicted growth rate was λ = 1·11 (95% CI = 1·02-1·21) in herds without brucellosis and λ = 1·00 (95% CI = 0·85-1·16) when brucellosis seroprevalence was 30%. Our results suggest that brucellosis infection can potentially result in reduced population growth rates, but because these effects varied with demographic and environmental conditions, they may remain unseen without intensive, longitudinal monitoring.


Asunto(s)
Brucella abortus/patogenicidad , Brucelosis/veterinaria , Búfalos/microbiología , Fertilidad , Animales , Brucelosis/epidemiología , Brucelosis/microbiología , Estudios Transversales , Femenino , Estudios Longitudinales , Masculino , Dinámica Poblacional , Embarazo , Estudios Seroepidemiológicos , Sudáfrica , Análisis de Supervivencia
13.
Acta Vet Hung ; 63(1): 11-5, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25655411

RESUMEN

Although thiafentanil oxalate has been widely used for wildlife immobilisation on different species, no report has been published about its usefulness on African buffalo (Syncerus caffer). Thirty-four African buffaloes were successfully immobilised at Loskop Dam Nature Reserve, South Africa in July 2013. The animals were kept in bomas of the nature reserve. The purpose of the immobilisation was to provide opportunity for microchip implantation, ear tag placement, intradermal tuberculin test and blood sampling. All animals were immobilised with thiafentanil oxalate 6 mg/animal (0.007-0.01 mg/kg) and azaperone 40 mg/animal (0.07-0.04 mg/kg) using Dan-inject darts and gun. The opioid reversal agent naltrexone hydrochloride 60 mg/animal (0.07-0.1 mg/kg) was given intravenously to the ear vein. The mean induction time was 3.9 ± 0.2 min, the recovery time was 1.65 ± 0.87 min. The results of the present study indicate that thiafentanil oxalate, this low-volume, high-potency, reversible drug combined with azaperone provides fast induction and smooth recovery. The authors recommend this drug combination as a reliable immobilising regimen for African buffalo.

14.
Proc Biol Sci ; 280(1765): 20130624, 2013 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-23804614

RESUMEN

Changes in host diversity have been postulated to influence the risk of infectious diseases, including both dilution and amplification effects. The dilution effect refers to a negative relationship between biodiversity and disease risk, whereas the amplification effect occurs when biodiversity increases disease risk. We tested these effects with an influential disease, bovine tuberculosis (BTB), which is widespread in many countries, causing severe economic losses. Based on the BTB outbreak data in cattle from 2005 to 2010, we also tested, using generalized linear mixed models, which other factors were associated with the regional BTB presence in cattle in Africa. The interdependencies of predictors and their correlations with BTB presence were examined using path analysis. Our results suggested a dilution effect, where increased mammal species richness was associated with reduced probability of BTB presence after adjustment for cattle density. In addition, our results also suggested that areas with BTB infection in the preceding year, higher cattle density and larger percentage of area occupied by African buffalo were more likely to report BTB outbreaks. Climatic variables only indirectly influenced the risk of BTB presence through their effects on cattle density and wildlife distribution. Since most studies investigating the role of wildlife species on BTB transmission only involve single-species analysis, more efforts are needed to better understand the effect of the structure of wildlife communities on BTB dynamics.


Asunto(s)
Animales Salvajes/fisiología , Densidad de Población , Tuberculosis Bovina/epidemiología , Tuberculosis Bovina/transmisión , África/epidemiología , Animales , Animales Salvajes/clasificación , Búfalos/fisiología , Bovinos/fisiología , Brotes de Enfermedades , Humanos , Mycobacterium bovis , Análisis de Regresión , Factores de Riesgo , Especificidad de la Especie , Tuberculosis Bovina/microbiología
15.
Ir Vet J ; 76(Suppl 1): 14, 2023 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-37491403

RESUMEN

Bovine tuberculosis (bTB) was first diagnosed in cattle in South Africa in 1880 and proclaimed a controlled disease in 1911. Testing of cattle for bTB is voluntary and only outbreaks of disease are reported to the National Department of Agriculture so the prevalence of the disease in cattle is largely unknown. There is a Bovine Tuberculosis Scheme which is aimed at the control of bTB in cattle but the same measures of test and slaughter, and the quarantining of the property apply to wildlife as well. bTB was first diagnosed in wildlife in a greater kudu in the Eastern Cape in 1928 and has to date been found in 24 mammalian wildlife species. The African buffalo has become a maintenance host of the disease, which is considered endemic in the Kruger National Park, the Hluhluwe-iMfolozi Park and the Madikwe Game Park. Control of bTB at the wildlife-livestock interface is difficult because of spill-over and spill-back between species. Only buffalo are required by law to be tested before translocation, but bTB has been introduced to the Madikwe Game Park probably by the translocation of other infected wildlife species. There is no national control strategy for the control of bTB in wildlife. Indirect tests have been developed to test for bTB in eight species, 6 of which can be considered endangered. More research needs to be done to develop an effective and efficient vaccine to combat the transmission of bTB within and between species. New policies need to be developed that are effective, affordable and encompassing to control the spread of bTB in South Africa.

16.
Ticks Tick Borne Dis ; 14(6): 102247, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37651847

RESUMEN

The Amblyomma genus is represented on the African continent by 24 species, out of which 17 are known to occur in different ecological niches of southern Africa. Amblyomma, known for their aggressive hunting behaviour and aptitude as pathogen vectors, are of main concern to travellers, mainly in rural and conservation areas of Africa. In this study, we highlight the overlapping distribution of Amblyomma eburneum and Amblyomma variegatum found on African buffaloes (Syncerus caffer) at Coutada 11, Central Mozambique. In total, 1,039 Amblyomma ticks were collected and morphologically identified using taxonomic keys, and genomic DNA was extracted. They were subjected to reverse line blotting for pathogen identification followed by molecular analysis (COI sequencing) of both tick species. Pathogens such as Ehrlichia ruminantium, Anaplasma centrale, Theileria sp., Babesia sp. and Rickettsia africae were detected, of which R. africae is zoonotic. Ehrlichia ruminantium, R. africae, Theileria mutans and Theileria velifera are well-established pathogens transmitted by Amblyomma ticks; however, Anaplasma spp. and Babesia spp. are not, suggesting residual parasite DNA in the bloodmeal. Little is mentioned in the literature about A. eburneum, including its role as a vector and reservoir for pathogens. In Mozambique A. eburneum is currently restricted to wildlife but the spread of the tick may be observed given the climate change that is occurring. The infection rates for the pathogens in both Amblyomma tick species were lower than expected, but this may be due to the low host density in the forest niche and the innate immunity of these hosts. With the propensity of ticks of the Amblyomma genus to form parapatric distributions, the mechanisms that allows for the overlapping distribution of these two Amblyomma species while maintaining tick species identity is of great interest.


Asunto(s)
Babesia , Ehrlichia ruminantium , Rickettsia , Theileria , Enfermedades por Picaduras de Garrapatas , Garrapatas , Animales , Garrapatas/microbiología , Amblyomma , Búfalos , Prevalencia , Simpatría , Enfermedades por Picaduras de Garrapatas/epidemiología , Enfermedades por Picaduras de Garrapatas/veterinaria , Enfermedades por Picaduras de Garrapatas/microbiología , Rickettsia/genética , Babesia/genética , Ehrlichia ruminantium/genética , Theileria/genética
17.
PeerJ Comput Sci ; 9: e1728, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38192486

RESUMEN

The one-dimensional cutting-stock problem (1D-CSP) consists of obtaining a set of items of different lengths from stocks of one or different lengths, where the minimization of waste is one of the main objectives to be achieved. This problem arises in several industries like wood, glass, and paper, among others similar. Different approaches have been designed to deal with this problem ranging from exact algorithms to hybrid methods of heuristics or metaheuristics. The African Buffalo Optimization (ABO) algorithm is used in this work to address the 1D-CSP. This algorithm has been recently introduced to solve combinatorial problems such as travel salesman and bin packing problems. A procedure was designed to improve the search by taking advantage of the location of the buffaloes just before it is needed to restart the herd, with the aim of not to losing the advance reached in the search. Different instances from the literature were used to test the algorithm. The results show that the developed method is competitive in waste minimization against other heuristics, metaheuristics, and hybrid approaches.

18.
Pathogens ; 12(12)2023 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-38133306

RESUMEN

Peste des petits ruminants (PPR) is a highly contagious viral disease of small ruminants that threatens livelihoods and food security in developing countries and, in some cases, wild ungulate species conservation. The Greater Serengeti-Mara Ecosystem (GSME) encompasses one of the major wildlife populations of PPR virus (PPRV)-susceptible species left on earth, although no clinical disease has been reported so far. This study aimed to gain further knowledge about PPRV circulation in the GSME by identifying which factors predict PPRV seropositivity in African buffalo (Syncerus caffer). Following an ecological niche modeling framework to map host-pathogen distribution, two models of PPRV exposure and buffalo habitat suitability were performed using serological data and buffalo censuses. Western Maasai Mara National Reserve and Western Serengeti National Park were identified as high-risk areas for PPRV exposure in buffalo. Variables related to wildlife-livestock interaction contributed to the higher risk of PPRV seropositivity in buffalo, providing supportive evidence that buffalo acquire the virus through contact with infected livestock. These findings can guide the design of cost-effective PPRV surveillance using buffalo as a sentinel species at the identified high-risk locations. As more intensive studies have been carried out in Eastern GSME, this study highlights the need for investigating PPRV dynamics in Western GSME.

19.
J Wildl Dis ; 58(2): 298-308, 2022 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-35276000

RESUMEN

Measuring inflammatory markers is critical to evaluating both recent infection status and overall human and animal health; however, there are relatively few techniques that do not require specialized equipment or personnel for detecting inflammation among wildlife. Such techniques are useful in that they help determine individual and population-level inflammatory status without the infrastructure and reagents that many more-specific assays require. One such technique, known as the erythrocyte sedimentation rate (ESR), is a measure of how quickly erythrocytes (red blood cells) settle in serum, with a faster rate indicating a general, underlying inflammatory process is occurring. The technique is simple, inexpensive, and can be performed in the field without specialized equipment. We took advantage of a population of African buffalo (Syncerus caffer), well studied from June 2014 to May 2017, to understand the utility of ESR in an important wildlife species. When ESR was compared with other markers of immunity in African buffalo, it correlated to known measures of inflammation. We found that a faster ESR was significantly positively correlated with increased total globulin levels and significantly negatively correlated with increased red blood cell count and albumin levels. We then evaluated if ESR correlated to the incidence of five respiratory pathogens and infection with two tick-borne pathogens in African buffalo. Our results suggest that elevated ESR is associated with the incidence of bovine viral diarrhea virus infection, parainfluenza virus, and Mannheimia haemolytica infections as well as concurrent Anaplasma marginale and Anaplasma centrale coinfection. These findings suggest that ESR is a useful field test as an inflammatory marker in individuals and herds, helping us better monitor overall health status in wild populations.


Asunto(s)
Búfalos , Garrapatas , Animales , Animales Salvajes , Sedimentación Sanguínea/veterinaria , Inflamación/veterinaria
20.
Multimed Tools Appl ; 81(10): 13935-13960, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35233181

RESUMEN

Breast cancer is one of the primary causes of death that is occurred in females around the world. So, the recognition and categorization of initial phase breast cancer are necessary to help the patients to have suitable action. However, mammography images provide very low sensitivity and efficiency while detecting breast cancer. Moreover, Magnetic Resonance Imaging (MRI) provides high sensitivity than mammography for predicting breast cancer. In this research, a novel Back Propagation Boosting Recurrent Wienmed model (BPBRW) with Hybrid Krill Herd African Buffalo Optimization (HKH-ABO) mechanism is developed for detecting breast cancer in an earlier stage using breast MRI images. Initially, the MRI breast images are trained to the system, and an innovative Wienmed filter is established for preprocessing the MRI noisy image content. Moreover, the projected BPBRW with HKH-ABO mechanism categorizes the breast cancer tumor as benign and malignant. Additionally, this model is simulated using Python, and the performance of the current research work is evaluated with prevailing works. Hence, the comparative graph shows that the current research model produces improved accuracy of 99.6% with a 0.12% lower error rate.

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