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1.
Rev Sci Tech ; 37(2): 341-357, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30747143

RESUMO

The impact of infectious disease may become progressively more harmful to a species' survival as a wild population approaches an 'extinction vortex'. This risk is especially relevant for pathogens that spread rapidly and result in high mortality rates. Rabies, a virus that infects many mammalian species, can be efficiently transmitted through infected saliva, and is fatal without prior vaccination or rapid post-exposure prophylaxis (in humans). The authors conducted an extensive literature review to identify all wild mammal species reported to have been infected with rabies virus. They found reports of infection in 190 mammalian species, including 16 with elevated risk of extinction and two for which rabies is a direct conservation threat: the Ethiopian wolf (Canis simensis) and the African wild dog (Lycaon pictus). This paper discusses selected examples in which rabies has contributed to the population decline of a species of conservation concern. In addition, the authors note the importance of the transmission of rabies virus (RABV) from domestic dogs to wildlife, and the many challenges associated with the vaccination of wild animals. With this in mind, they present potential solutions to reduce the burden of rabies on wildlife. Once stable control of RABV is achieved in domestic dogs, remaining rabies threats to wildlife conservation can be addressed more effectively.


Assuntos
Animais Selvagens , Espécies em Perigo de Extinção , Raiva/veterinária , Animais , Conservação dos Recursos Naturais , Extinção Biológica , Raiva/mortalidade
2.
Rev Sci Tech ; 33(2): 593-604, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25707186

RESUMO

Anthrax is a peracute, acute or subacute multispecies bacterial infection that occurs on many continents. It is one of the oldest infectious diseases known; the biblical fifth and sixth plagues (Exodus chapters 7 to 9) that affected first livestock and then humans were probably anthrax. From the earliest historical records until development of an effective vaccine midway through the 20th Century, anthrax was one of the foremost causes of uncontrolled mortality in cattle, sheep, goats, horses and pigs, with 'spill over' into humans, worldwide. With the development of the Sterne spore vaccine, a sharp decline in anthrax outbreaks in livestock occurred during the 1930-1980 era. There were successful national vaccination programmes in many countries during this period, complemented by the liberal use of antibiotics and the implementation of quarantine regulations and carcass disposal. However, a resurgence of this disease in livestock has been reported recently in some regions, where complacency and a false sense of security have hindered vaccination programmes. The epidemiology of anthrax involves an environmental component, as well as livestock, wildlife and human components. This makes anthrax an ideal example for discussion in the One Health context. Many outbreaks of anthrax in wildlife are undetected or unreported, owing to surveillance inadequacies and difficulties. Human disease is generally acquired accidentally during outbreaks of anthrax in domestic livestock and wildlife. The exception is deliberate targeting of humans with anthrax in the course of biowarfare or bioterrorism.


Assuntos
Antraz/veterinária , Saúde Global , Internacionalidade , Zoonoses/prevenção & controle , África , Animais , Animais Selvagens , Antraz/tratamento farmacológico , Antraz/patologia , Antraz/prevenção & controle , Antraz/transmissão , Antibacterianos/uso terapêutico , Vacinas Bacterianas/imunologia , Humanos
3.
Vet Immunol Immunopathol ; 148(1-2): 145-8, 2012 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-21616546

RESUMO

Foot-and-mouth disease virus, a highly contagious pathogen that can cause lameness, low weight and decreased milk production, is a scourge of agricultural livestock around the world. Although the acute phase of infection is rarely fatal, infection may persist in animals that have apparently recovered, creating a viral reservoir that some fear could contribute to the spread of disease. We have used an array of molecular techniques to search for traces of virus in tissues from the mouths and throats of infected cattle. In a carefully controlled study, we have found evidence of intact, non-replicating virus particles trapped by follicular dendritic cells within the germinal centres of lymph nodes. Strikingly, virus was present for up to 38 days post infection, even though it was undetectable in surrounding tissues. The retention of intact virus within germinal centres is likely to have a role in stimulating the long lasting immune response that is characteristic of viral infections. Our data suggests that this capture may also be responsible for preserving intact viruses capable of infecting susceptible cells as they come into contact with germinal centres. African buffalo (Syncerus caffer) are typically infected with all three South African Territories types of FMDV by 2 years of age and these viruses can be transmitted to farmed livestock. Buffalo harbour persistent virus in greater amounts and for longer periods than cattle and thus provided us with further opportunities to define the sites of viral localisation.


Assuntos
Búfalos/virologia , Doenças dos Bovinos/virologia , Vírus da Febre Aftosa/imunologia , Febre Aftosa/virologia , Tecido Linfoide/virologia , Animais , Bovinos , Doenças dos Bovinos/imunologia , Reservatórios de Doenças , Febre Aftosa/imunologia , Tecido Linfoide/imunologia
4.
J S Afr Vet Assoc ; 82(2): 80-5, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22135920

RESUMO

Papillomavirus was detected electron microscopically in cutaneous fibropapillomas of a giraffe (Giraffa camelopardalis) and a sable antelope (Hippotragus niger). The virus particles measured 45 nm in diameter. Histopathologically, the lesions showed histopathological features similar to those of equine sarcoid as well as positive immunoperoxidase-staining of tissue sections for papillomavirus antigen. Polymerase chain reaction (PCR) detected bovine papillomavirus (BPV) DNA. Bovine papillomavirus-1 was characterised by real-time PCR in the sable and giraffe, and cloning and sequencing of the PCR product revealed a similarity to BPV-1. As in the 1st giraffe, the lesions from a 2nd giraffe revealed locally malignant pleomorphism, possibly indicating the lesional end-point of papilloma infection. Neither virus particles nor positively staining papillomavirus antigen could be demonstrated in the 2nd giraffe but papillomavirus DNA was detected by real-time PCR which corresponded with BPV-1 and BPV-2.


Assuntos
Antílopes/virologia , Artiodáctilos/virologia , Papillomavirus Bovino 1/isolamento & purificação , Infecções por Papillomavirus/veterinária , Animais , DNA Viral/análise , Feminino , Fibroma/diagnóstico , Fibroma/patologia , Fibroma/veterinária , Masculino , Infecções por Papillomavirus/diagnóstico , Infecções por Papillomavirus/patologia , Reação em Cadeia da Polimerase/veterinária , Neoplasias Cutâneas/diagnóstico , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/veterinária , África do Sul
5.
J S Afr Vet Assoc ; 82(2): 97-106, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22135923

RESUMO

Skin lesions associated with papillomaviruses have been reported in many animal species and man. Bovine papillomavirus (BVP) affects mainly the epidermis, but also the dermis in several species including bovine, the best-known example being equine sarcoid, which is associated with BVP types 1 and 2. This publication describes and illustrates the macroscopic and histological appearance of BPV-associated papillomatous, fibropapillomatous or sarcoid-like lesions in Cape mountain zebra (Equus zebra zebra) from the Gariep Dam Nature Reserve, 2 giraffes (Giraffa camelopardalis) from the Kruger National Park, and a sable antelope (Hippotragus niger) from the Kimberley area of South Africa. An African buffalo (Syncerus caffer) cow from Kruger National Park also had papillomatous lesions but molecular characterisation of lesional virus was not done. Immunohistochemical staining using polyclonal rabbit antiserum to chemically disrupted BPV-1, which cross-reacts with the L1 capsid of most known papillomaviruses, was positive in cells of the stratum granulosum of lesions in Giraffe 1, the sable and the buffalo and negative in those of the zebra and Giraffe 2. Fibropapillomatous and sarcoid-like lesions from an adult bovine were used as positive control for the immunohistochemistry and are described and the immunohistochemistry illustrated for comparison. Macroscopically, both adult female giraffe had severely thickened multifocal to coalescing nodular and occasionally ulcerated lesions of the head, neck and trunk with local poorly-circumscribed invasion into the subcutis. Necropsy performed on the 2nd giraffe revealed neither internal metastases nor serious underlying disease. Giraffe 1 had scattered, and Giraffe 2 numerous, large, anaplastic, at times indistinctly multinucleated dermal fibroblasts with bizarre nuclei within the sarcoid-like lesions, which were BPV-1 positive in Giraffe 1 and BPV-1 and -2 positive in Giraffe 2 by RT-PCR. The sable antelope presented with a solitary large lesion just proximal to the right hind hoof, which recurred after excision, and was BPV-1 positive by RT-PCR. Other wart-like growths were present elsewhere on the body. The Cape mountain zebra either succumbed from their massive lesions or were euthanased or removed from the herd because of them. The lesions were BPV-1 and/or -2 positive by RT-PCR. The buffalo lesions were wart-like papillomatous projections in the inguinal and udder region. Stratum granulosum cells that stained immunohistochemically positive in the various species appeared koilocyte-like, as described in human papillomaviral lesions.


Assuntos
Papillomavirus Bovino 1/isolamento & purificação , Fibroma/veterinária , Imuno-Histoquímica/veterinária , Infecções por Papillomavirus/veterinária , Neoplasias Cutâneas/veterinária , Animais , Antílopes/virologia , Artiodáctilos/virologia , Búfalos/virologia , DNA Viral/isolamento & purificação , Surtos de Doenças/veterinária , Equidae/virologia , Feminino , Fibroma/epidemiologia , Fibroma/patologia , Fibroma/virologia , Masculino , Infecções por Papillomavirus/epidemiologia , Infecções por Papillomavirus/patologia , Infecções por Papillomavirus/virologia , Pele/patologia , Pele/virologia , Dermatopatias Virais/epidemiologia , Dermatopatias Virais/patologia , Dermatopatias Virais/veterinária , Dermatopatias Virais/virologia , Neoplasias Cutâneas/epidemiologia , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/virologia , África do Sul/epidemiologia , Especificidade da Espécie
6.
Vet Microbiol ; 144(3-4): 384-91, 2010 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-20188497

RESUMO

African lions in the southern half of Kruger National Park (KNP) are infected with Mycobacterium bovis. Historically, reliable detection of mycobacteriosis in lions was limited to necropsy and microbiological analysis of lesion material collected from emaciated and ailing or repeat-offender lions. We report on a method of cervical intradermal tuberculin testing of lions and its interpretation capable of identifying natural exposure to M. bovis. Infected lions (n=52/95) were identified by detailed necropsy and mycobacterial culture. A large proportion of these confirmed infected lions (45/52) showed distinct responses to bovine tuberculin purified protein derivative (PPD) while responses to avian tuberculin PPD were variable and smaller. Confirmed uninfected lions from non-infected areas (n=11) responded variably to avian tuberculin PPD only. Various non-tuberculous mycobacteria (NTM) were cultured from 45/95 lions examined, of which 21/45 were co-infected with M. bovis. Co-infection with M. bovis and NTM did not influence skin reactions to bovine tuberculin PPD. Avian tuberculin PPD skin reactions were larger in M. bovis-infected lions compared to uninfected ones. Since NTM co-infections are likely to influence the outcome of skin testing, stricter test interpretation criteria were applied. When test data of bovine tuberculin PPD tests were considered on their own, as for a single skin test, sensitivity increased (80.8-86.5%) but false positive rate for true negatives (18.75%) remained unchanged. Finally, the adapted skin test procedure was shown not to be impeded by persistent Feline Immunodeficiency Virus(Ple) co-infection.


Assuntos
Leões , Mycobacterium bovis , Teste Tuberculínico/veterinária , Tuberculose/veterinária , Animais , Sensibilidade e Especificidade , África do Sul/epidemiologia , Teste Tuberculínico/métodos
7.
Transbound Emerg Dis ; 56(1-2): 18-30, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19200295

RESUMO

A longitudinal study was performed in the Kruger National Park, South Africa to investigate the role of impala (Aepyceros melampus) in maintaining SAT serotypes of foot-and-mouth disease (FMD) virus. Three sampling sites with different histories of FMD outbreaks in impala and also of varying ecology were chosen. At three monthly intervals approximately 40 impala were bled and examined for clinical FMD at each of these sites for a period of 6 years, followed by 4 years of less frequent sampling. During the 10 years of the study, clinical disease was only observed once at a single sampling site, while at two of the three locations, serological evidence of infection was detected; in one locality this was a frequent occurrence. The discrepancy between clinically evident disease and serological evidence of infection indicated that sub-clinical infection with these viruses may be more regular than previously suspected. Furthermore, there was evidence that either SAT-serotype infection is maintained within local impala populations for prolonged periods or that re-infection of impala by buffalo occurs repetitively, sometimes at frequent intervals. A mixed-effects logistic regression model showed that females and older animals had a higher risk of seropositivity, while summer and autumn also represent periods when there is a heightened risk of seropositivity (as opposed to winter and spring which previous studies had shown to be associated with clinical disease). Comparison of impala and buffalo ratios in the three sampling regions indicated that the higher the impala density, the more likely disease transmission is from buffalo to impala, and that this is independent of buffalo numbers (presumably above an undetermined threshold). This study confirmed the potential role of impala for propagating FMD in southern Africa and this factor should therefore be considered when designing control strategies where wildlife and domestic animals interact.


Assuntos
Antílopes/virologia , Anticorpos Antivirais/sangue , Reservatórios de Doenças/veterinária , Vírus da Febre Aftosa/imunologia , Febre Aftosa/epidemiologia , Febre Aftosa/transmissão , Animais , Animais Selvagens , Búfalos/virologia , Surtos de Doenças/veterinária , Estudos Longitudinais , Estações do Ano , Estudos Soroepidemiológicos , África do Sul/epidemiologia
8.
Vet Microbiol ; 133(4): 335-43, 2009 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-18786785

RESUMO

Bovine tuberculosis is endemic in African buffalo and a number of other wildlife species in the Kruger National Park (KNP) and Hluhluwe-iMfolozi Park (HiP) in South Africa. It was thought that the infection had been introduced into the KNP ecosystem through direct contact between cattle and buffalo, a hypothesis which was confirmed in this study by IS6110 and PGRS restriction fragment length polymorphism (RFLP) typing. The molecular characterisation of 189 Mycobacterium bovis isolates from nine wildlife species in the HiP, including three smaller associated parks, and the Kruger National Park with adjacent areas showed that the respective epidemics were each caused by an infiltration of a single M. bovis genotype. The two M. bovis strains had different genetic profiles, as demonstrated by hybridisation with the IS6110 and PGRS RFLP probes, as well as with regard to evidence of evolutionary changes to the IS profile. While the M. bovis type in HiP was transmitted between buffaloes and to at least baboon, bushpig and lion without obvious genetic changes in the RFLP patterns, in the KNP a dominant strain was represented in 73% of the M. bovis isolates, whilst the remaining 27% were variants of this strain. No species-specific variants were observed, except for one IS6110 type which was found only in a group of five epidemiologically related greater kudu. This finding was attributed to species-specific behaviour patterns rather than an advanced host-pathogen interaction.


Assuntos
Epidemiologia Molecular , Mycobacterium bovis/genética , Tuberculose/epidemiologia , Tuberculose/veterinária , Animais , Animais Selvagens , Antílopes , Búfalos , Felidae , Hyaenidae , Filogenia , África do Sul/epidemiologia , Suínos
9.
Epidemiol Infect ; 135(4): 529-40, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-16959052

RESUMO

This review examines the current situation of bovine tuberculosis (bTB) in southern African savannah systems, and uses theory on multi-species host-pathogen systems to suggest possible options for future research and management. In southern Africa, the buffalo (Syncerus caffer) and the Kafue lechwe [Marsh antelope] (Kobus leche) have been found to be maintenance hosts for this disease, but the importance of other host species is becoming apparent. The role of other host species in the maintenance and spread of the disease varies, depending on the spatial distribution and resource utilization patterns of the species, disease susceptibility, transmission modes and the ecology of both host(s) and vector(s). Future research needs to identify the pathogenicity of bTB in each of the host species, and the mechanisms and rates of inter- and intra-specific transmission among different species, in order to develop multi-host models to understand the development and spread of the disease.


Assuntos
Mycobacterium bovis/patogenicidade , Tuberculose Bovina/epidemiologia , África Austral/epidemiologia , Animais , Bovinos , Interações Hospedeiro-Parasita , Humanos
10.
Vet Microbiol ; 112(2-4): 91-100, 2006 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-16343819

RESUMO

Tuberculosis, caused by Mycobacterium bovis, was first diagnosed in African buffalo in South Africa's Kruger National Park in 1990. Over the past 15 years the disease has spread northwards leaving only the most northern buffalo herds unaffected. Evidence suggests that 10 other small and large mammalian species, including large predators, are spillover hosts. Wildlife tuberculosis has also been diagnosed in several adjacent private game reserves and in the Hluhluwe-iMfolozi Park, the third largest game reserve in South Africa. The tuberculosis epidemic has a number of implications, for which the full effect of some might only be seen in the long-term. Potential negative long-term effects on the population dynamics of certain social animal species and the direct threat for the survival of endangered species pose particular problems for wildlife conservationists. On the other hand, the risk of spillover infection to neighboring communal cattle raises concerns about human health at the wildlife-livestock-human interface, not only along the western boundary of Kruger National Park, but also with regards to the joint development of the Greater Limpopo Transfrontier Conservation Area with Zimbabwe and Mozambique. From an economic point of view, wildlife tuberculosis has resulted in national and international trade restrictions for affected species. The lack of diagnostic tools for most species and the absence of an effective vaccine make it currently impossible to contain and control this disease within an infected free-ranging ecosystem. Veterinary researchers and policy-makers have recognized the need to intensify research on this disease and the need to develop tools for control, initially targeting buffalo and lion.


Assuntos
Animais Selvagens/microbiologia , Mycobacterium bovis , Tuberculose/veterinária , Animais , Animais Domésticos , Animais Selvagens/classificação , Búfalos , Bovinos , Conservação dos Recursos Naturais , Humanos , Leões , Vigilância da População , África do Sul/epidemiologia , Tuberculose/diagnóstico , Tuberculose/epidemiologia , Tuberculose/prevenção & controle
11.
Onderstepoort J Vet Res ; 73(4): 293-303, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17283730

RESUMO

An infection model for Mycobacterium bovis in African buffaloes, Syncerus caffer, was developed, using the intratonsilar route of inoculation. Two groups of 11 buffaloes each, aged approximately 18 months, were infected with either 3.2 x 10(2) cfu (low dose) or 3 x 10(4) cfu (high dose) of M. bovis strain isolated from a buffalo. A control group of six buffaloes received saline via the same route. The infection status was monitored in vivo using the comparative intradermal tuberculin test, and in vitro by the modified interferon-gamma assay. All buffaloes were euthanazed 22 weeks post infection and lesion development was assessed by macroscopic examination, culture and histopathology. It was found that the high dose caused macroscopic lesions in nine out of 11 buffaloes. Mycobacterium bovis was isolated from all buffaloes in the high-dose group and from six out of 11 in the low-dose group.


Assuntos
Búfalos/microbiologia , Modelos Animais de Doenças , Mycobacterium bovis/patogenicidade , Tuberculose Bovina/microbiologia , Animais , Bovinos , Contagem de Colônia Microbiana/veterinária , Interferon gama/sangue , Mycobacterium bovis/imunologia , Tonsila Palatina/microbiologia , Distribuição Aleatória , Especificidade da Espécie , Teste Tuberculínico/veterinária
12.
Onderstepoort J Vet Res ; 72(2): 145-51, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16137132

RESUMO

A survey to determine the prevalence of bovine tuberculosis caused by Mycobacterium bovis and certain other infectious diseases was conducted on 42 free-ranging African buffaloes, (Syncerus caffer) from May to June 1997 in the Queen Elizabeth National Park, Uganda. Using the gamma interferon test, exposure to M. bovis was detected in 21.6% of the buffaloes. One dead buffalo and an emaciated warthog (Phacochoerus aethiopicus) that was euthanased, were necropsied; both had miliary granulomas from which M. bovis was isolated. None of the buffaloes sampled in Sector A of the park, which has no cattle interface, tested positive for bovine tuberculosis (BTB) exposure. The prevalence and distribution of BTB does not appear to have changed significantly since the 1960s, but this may be due to fluxes in the buffalo population. Serological testing for foot-and-mouth disease (FMD) demonstrated positive exposure of 57.1% of the buffaloes sampled, with types A, O and SAT 1-3, which is the first known report of FMD antibodies to A and O types in free ranging African buffaloes. Foot-and-mouth disease virus types SAT 1 and SAT 3 were isolated from buffalo probang samples. Two percent of the buffaloes had been exposed to brucellosis. None of the buffaloes tested had antibodies to rinderpest, leptospirosis or Q fever.


Assuntos
Anticorpos Antibacterianos/sangue , Anticorpos Antivirais/sangue , Búfalos , Febre Aftosa/epidemiologia , Mycobacterium bovis/isolamento & purificação , Tuberculose/veterinária , Animais , Feminino , Masculino , Estudos Soroepidemiológicos , Testes Sorológicos/veterinária , Tuberculose/epidemiologia , Uganda/epidemiologia
13.
Vet Microbiol ; 100(1-2): 31-41, 2004 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-15135511

RESUMO

Bartonella species are emerging pathogens that have been isolated worldwide from humans and other mammals. Our objective was to estimate the prevalence of Bartonella infection in free-ranging African lions (Panthera leo) and cheetahs (Acinonyx jubatus). Blood and/or serum samples were collected from a convenience sample of 113 lions and 74 cheetahs captured in Africa between 1982 and 2002. Whole blood samples available from 58 of the lions and 17 of the cheetahs were cultured for evidence of Bartonella spp., and whole blood from 54 of the 58 lions and 73 of the 74 cheetahs tested for the presence of Bartonella DNA by TaqMan PCR. Serum samples from the 113 lions and 74 cheetahs were tested for the presence of antibodies against Bartonella henselae using an immunofluorescence assay. Three (5.2%) of the 58 lions and one (5.9%) of the 17 cheetahs were bacteremic. Two lions were infected with B. henselae, based on PCR/RFLP of the citrate synthase gene. The third lion and the cheetah were infected with previously unidentified Bartonella strains. Twenty-three percent of the 73 cheetahs and 3.7% of the 54 lions tested by TaqMan PCR were positive for Bartonella spp. B. henselae antibody prevalence was 17% (19/113) for the lions and 31% (23/74) for the cheetahs. The prevalence of seropositivity, bacteremia, and positive TaqMan PCR was not significantly different between sexes and age categories (juvenile versus adult) for both lions and cheetahs. Domestic cats are thus no longer the only known carriers of Bartonella spp. in Africa. Translocation of B. henselae seronegative and TaqMan PCR negative wild felids might be effective in limiting the spread of Bartonella infection.


Assuntos
Acinonyx/microbiologia , Infecções por Bartonella/veterinária , Bartonella henselae/isolamento & purificação , Leões/microbiologia , África Oriental/epidemiologia , Animais , Anticorpos Antibacterianos/sangue , Infecções por Bartonella/microbiologia , Bartonella henselae/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Feminino , Imunofluorescência , Masculino , Reação em Cadeia da Polimerase/veterinária , Polimorfismo de Fragmento de Restrição , Estudos Soroepidemiológicos , África do Sul/epidemiologia
14.
Rev Sci Tech ; 23(2): 497-511, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15702716

RESUMO

There are huge numbers of wild animals distributed throughout the world and the diversity of wildlife species is immense. Each landscape and habitat has a kaleidoscope of niches supporting an enormous variety of vertebrate and invertebrate species, and each species or taxon supports an even more impressive array of macro- and micro-parasites. Infectious pathogens that originate in wild animals have become increasingly important throughout the world in recent decades, as they have had substantial impacts on human health, agricultural production, wildlife-based economies and wildlife conservation. The emergence of these pathogens as significant health issues is associated with a range of causal factors, most of them linked to the sharp and exponential rise of global human activity. Among these causal factors are the burgeoning human population, the increased frequency and speed of local and international travel, the increase in human-assisted movement of animals and animal products, changing agricultural practices that favour the transfer of pathogens between wild and domestic animals, and a range of environmental changes that alter the distribution of wild hosts and vectors and thus facilitate the transmission of infectious agents. Two different patterns of transmission of pathogens from wild animals to humans are evident among these emerging zoonotic diseases. In one pattern, actual transmission of the pathogen to humans is a rare event but, once it has occurred, human-to-human transmission maintains the infection for some period of time or permanently. Some examples of pathogens with this pattern of transmission are human immunodeficiency virus/acquired immune deficiency syndrome, influenza A, Ebola virus and severe acute respiratory syndrome. In the second pattern, direct or vector-mediated animal-to-human transmission is the usual source of human infection. Wild animal populations are the principal reservoirs of the pathogen and human-to-human disease transmission is rare. Examples of pathogens with this pattern of transmission include rabies and other lyssaviruses, Nipah virus, West Nile virus, Hantavirus, and the agents of Lyme borreliosis, plague, tularemia, leptospirosis and ehrlichiosis. These zoonotic diseases from wild animal sources all have trends that are rising sharply upwards. In this paper, the authors discuss the causal factors associated with the emergence or re-emergence of these zoonoses, and highlight a selection to provide a composite view of their range, variety and origins. However, most of these diseases are covered in more detail in dedicated papers elsewhere in this Review.


Assuntos
Animais Domésticos/microbiologia , Animais Selvagens/microbiologia , Doenças Transmissíveis Emergentes/transmissão , Reservatórios de Doenças/veterinária , Zoonoses , Animais , Animais Domésticos/parasitologia , Animais Domésticos/virologia , Animais Selvagens/parasitologia , Animais Selvagens/virologia , Doenças Transmissíveis Emergentes/epidemiologia , Meio Ambiente , Saúde Global , Humanos , Densidade Demográfica , Dinâmica Populacional , Especificidade da Espécie
15.
Onderstepoort J Vet Res ; 69(3): 221-7, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12356169

RESUMO

A survey to determine the bovine tuberculosis status of buffalo herds north of the Olifants River in the Kruger National Park was conducted, using a new diagnostic approach. Diagnosis of Mycobacterium bovis infection was accomplished using the gamma-interferon assay technique in 608 adult buffaloes out of a total of 29 discreet herds. The animals were immobilized in groups of 10-15, bled, individually marked and then revived and released on site. As soon as test results were available (after 26-36 h), the same buffalo herd was relocated by tracking the frequency of a radio-collar previously fitted to one adult cow per group during the initial operation. Bovine reactors were identified, darted and euthanased from the helicopter. Necropsy and culture findings of all culled buffaloes showed excellent correlation with the results of the ante-mortem gamma-interferon test. The survey revealed that over and above the two positive herds that had been identified during a previous survey carried out in 1996, there were three additional, but previously unidentified, infected herds in the region north of the Olifants River.


Assuntos
Búfalos , Interferon gama/sangue , Mycobacterium bovis/imunologia , Tuberculose/veterinária , Animais , Feminino , Masculino , Estudos Soroepidemiológicos , África do Sul/epidemiologia , Tuberculose/diagnóstico , Tuberculose/epidemiologia , Tuberculose/microbiologia
16.
Rev Sci Tech ; 21(2): 317-34, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11974618

RESUMO

Mycobacterium bovis is emerging as an important pathogen of free-ranging wildlife in which it is a potential source of infection for domestic animals and a threat to valuable wildlife species. This review examines the procedures for the detection, diagnosis and management of M. bovis in wildlife populations. The ante-mortem detection of M. bovis infection in wildlife is difficult, due to the common occurrence of subclinical infections and the deficiencies of the currently available diagnostic tests. Serological tests are insensitive, while tests measuring cell-mediated immune responses show promise, but have not been sufficiently developed for routine use in most species. The diagnosis of M. bovis in free-ranging wildlife relies on post-mortem examination supported by histopathology and microbiology. A feature of M. bovis infections is the variation in the appearance and distribution of lesions in the different host species. Bacterial culture remains the gold standard for diagnosis of tuberculosis, while histopathology is limited by the frequent inability to distinguish lesions caused by M. bovis from those produced by other mycobacterial species. Deoxyribonucleic acid (DNA) fingerprinting and advanced typing techniques are increasingly being used to unravel the epidemiology of mycobacterial infections, including tuberculosis in free-ranging wildlife. An understanding of the epidemiology is essential if procedures are to be developed for the management of tuberculosis in wildlife. Few management options are currently available, especially for protected wildlife. Vaccination is the subject of much research, but further developments are required before it can be used to control tuberculosis in any animals, let alone in free-ranging wildlife.


Assuntos
Animais Selvagens , Mycobacterium bovis , Tuberculose/veterinária , Animais , Tuberculose/diagnóstico , Tuberculose/prevenção & controle
17.
Rev Sci Tech ; 21(1): 53-65, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11974630

RESUMO

The long-standing conflict between livestock owners and animal health authorities on the one hand, and wildlife conservationists on the other, is largely based on differing attitudes to controlling diseases of livestock which are associated with wildlife. The authors have attempted to highlight the fact that these disease problems are frequently bi-directional at the wildlife/livestock interface. The different categories of diseases involved are presented. A new dimension being faced by veterinary regulatory authorities is the spectre of emerging sylvatic foci of diseases, such as bovine tuberculosis, bovine brucellosis and possibly rinderpest; these diseases threaten to undermine national and international eradication schemes, which have been implemented and executed with significant success, and at great cost. Conversely, wildlife-based ecotourism world-wide has expanded rapidly over the past decade and is the source of lacking foreign revenue for many developing countries. Traditional subsistence farming is still the largest source of much-needed protein on some continents and this, together with the growth and hunger of historically disadvantaged communities for land, is forcing enterprises and communities with markedly different objectives and land-use practices to operate effectively in close proximity. Some land-users rely exclusively on wildlife, others on livestock and/or agronomy, while yet others need to combine these activities. The net result may be an expansion or intensification of the interface between wildlife and domestic livestock, which will require innovative control strategies that permit differing types of wildlife/livestock interaction, and that do not threaten the land-use options of neighbours, or the ability of a country to market animals and animal products profitably.


Assuntos
Animais Domésticos , Animais Selvagens , Doenças Transmissíveis/veterinária , Animais , Controle de Doenças Transmissíveis/métodos , Controle de Doenças Transmissíveis/normas , Doenças Transmissíveis/diagnóstico , Doenças Transmissíveis/epidemiologia , Doenças Transmissíveis/transmissão , Doenças Transmissíveis Emergentes/prevenção & controle , Doenças Transmissíveis Emergentes/transmissão , Doenças Transmissíveis Emergentes/veterinária , Surtos de Doenças/prevenção & controle , Surtos de Doenças/veterinária , Humanos
18.
Arch Virol ; 146(8): 1537-51, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11676416

RESUMO

Genetic relationships of 50 SAT-1 type foot-and-mouth disease viruses were determined by phylogenetic analysis of an homologous 417 nucleotide region encoding the C-terminal half of the VP1 gene and part of the 2A segment. Viruses obtained from persistently-infected African buffalo populations were selected in order to assess the regional genetic variation within the host species and compared with ten viruses recovered from recent and historical cases of clinical infection. Phylogenetic reconstructions identified three independently evolving buffalo virus lineages within southern Africa, that correspond with the following discrete geographic localities: (1) South Africa and southern Zimbabwe, (2) Namibia, Botswana and western Zimbabwe, and (3) Zambia, Malawi and northern Zimbabwe. This strict geographic grouping of viruses derived from buffalo was shown to be useful for determining the origin of recent SAT-1 epizootics in livestock. The percentage of conserved amino acid sites across the 50 SAT-1 viruses compared in this study was 50%. Most mutations were clustered within three discrete hypervariable regions, which coincide with the immunogenic G-H loop, H-1 loop and C-terminus region of the protein. Despite the high levels of variation within the primary sequence, secondary structural features appear to be conserved.


Assuntos
Capsídeo/genética , Surtos de Doenças , Vírus da Febre Aftosa/genética , Febre Aftosa/epidemiologia , Variação Genética , África ao Sul do Saara/epidemiologia , Sequência de Aminoácidos , Animais , Búfalos , Capsídeo/química , Proteínas do Capsídeo , Bovinos , Células Cultivadas , Febre Aftosa/virologia , Vírus da Febre Aftosa/classificação , Dados de Sequência Molecular , Filogenia , Suínos
19.
Onderstepoort J Vet Res ; 68(2): 119-30, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11585089

RESUMO

The presence of bovine tuberculosis (Mycobacterium bovis) in the Kruger National Park (KNP) was determined for the first time in 1990. It was diagnosed in an African buffalo (Syncerus caffer) bull, which was found recumbent and in an emaciated and moribund state near the south-western boundary fence. This prompted an investigation into the bovine tuberculosis (BTB) status of the KNP, with emphasis on its epidemiological determinants and risk factors. This report documents the findings of surveys that were conducted from 1990 to 1996. It was found that BTB had entered the KNP ecosystem relatively recently (+/- 1960), and has found favourable circumstances for survival and propagation in a fully susceptible and immunologically naive buffalo population. Indications are that it entered the KNP from across the southern river boundary, where the presence of infected domestic cattle herds had been documented. From there the infection spread through the southern buffalo population and is currently spreading in a northward direction. It was estimated that this northward spread took place at a rate of about 6 km per year; the prospect being that, if this rate of spread is maintained, the entire KNP may be affected in less than 30 years from now. Spillover from buffalo had already occurred in species such as chacma baboon (Papio ursinus), lion (Panthera leo), cheetah (Acinonyx jubatus), kudu (Tragelaphus strepsiceros) and leopard (Panthera pardus). Although there is no indication yet that these species act as maintenance hosts, the possibility is raised that these, or an as yet overlooked species, might assume such a role in future. In the KNP, BTB manifests itself as a chronic and predominantly subclinical disease in buffalo. It may take years for clinical signs to develop, and then only at a terminal stage, when emaciation is a constant feature. It is suspected that the time from infection to death is variable and dependent on the animal's immune response, which can be weakened by such factors as stress, old age or droughts. It was found that, in the interim, buffalo have a normal reproductive life. On necropsy, buffalo show almost exclusively lung and upper respiratory tract involvement, pointing to an aerogenous mode of transmission. Histologically, little sign of encapsulation of lesions was detected, which suggests that they are exceptionally susceptible to BTB and that most lesions are open and infectious and progressive, leading ultimately to death of the individual. Evidence also indicates that BTB is progressive within the herd context (92% being the highest prevalence rate thus far determined in a buffalo herd) as well as progressive within the KNP buffalo population (the implication being that virtually all buffalo herds in the KNP will eventually be infected). Preliminary data suggest a positive correlation between disease prevalence and mortality, with potential mortality reaching up to 10% in buffalo herds having BTB prevalence rates of 50 % and higher. Only the future will tell what the effect of the disease on the population dynamics of buffalo will be.


Assuntos
Búfalos , Mycobacterium bovis , Tuberculose/veterinária , Animais , Bovinos , Mycobacterium bovis/isolamento & purificação , Prevalência , Fatores de Risco , África do Sul/epidemiologia , Tuberculose/epidemiologia , Tuberculose/fisiopatologia , Tuberculose Bovina/epidemiologia
20.
Rev Sci Tech ; 20(1): 86-111, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11288522

RESUMO

Mycobacterium bovis has been isolated from a wide range of wildlife species, in addition to domestic animals. This review examines the role played by various species in the maintenance of M. bovis in wildlife communities and the spread to domestic animals. Badgers (Meles meles), brushtail possums (Trichosurus vulpecula), deer (Odocoileus virginianus), bison (Bison bison) and African buffalo (Syncerus caffer) are examples of wildlife that are maintenance hosts of M. bovis. The importance of these hosts has been highlighted by the growing realisation that these animals can represent the principal source of infection for both domestic animals and protected wildlife species. The range of methods for controlling M. bovis in wildlife is limited. While population control has been used in some countries, this approach is not applicable in many situations where protected wildlife species are concerned. Vaccination is a potential alternative control method, although as yet, no practical, effective system has been developed for vaccinating wildlife against bovine tuberculosis. Tuberculosis caused by M. bovis has also been a problem in captive wildlife and in recently domesticated animals such as farmed deer. Control of M. bovis in this group of animals is dependent on the judicious use of diagnostic tests and the application of sound disease control principles. The advances in the development of bovine tuberculosis vaccines for cattle and farmed deer may offer valuable insights into the use of vaccination for the control of tuberculosis in a range of captive wildlife species.


Assuntos
Animais Domésticos , Animais Selvagens , Cervos , Mycobacterium bovis/isolamento & purificação , Tuberculose Bovina/epidemiologia , Tuberculose/veterinária , África/epidemiologia , Animais , Austrália/epidemiologia , Bison , Búfalos , Carnívoros , Bovinos , Humanos , Irlanda/epidemiologia , Mycobacterium bovis/imunologia , Nova Zelândia/epidemiologia , América do Norte , Primatas , Suínos , Tuberculose/epidemiologia , Tuberculose/prevenção & controle , Tuberculose/transmissão , Tuberculose Bovina/prevenção & controle , Tuberculose Bovina/transmissão , Reino Unido/epidemiologia , Vacinação/veterinária
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