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1.
Microorganisms ; 12(4)2024 Apr 22.
Article in English | MEDLINE | ID: mdl-38674782

ABSTRACT

This research examined the positivity ratio of Crimean-Congo haemorrhagic fever (CCHF) antibodies in cattle and sheep within Namibia's Omaheke region after a human disease outbreak in the same geographical area. A total of 200 samples (100 cattle and 100 sheep) were randomly collected from animals brought to two regional auction sites, and then tested using the ID Screen® CCHF Double Antigen Multi-Species Enzyme-Linked Immunosorbent Assay kit. Of the cattle samples, 36% tested positive, while 22% of the sheep samples were seropositive. The cattle had a significantly higher positivity ratio than sheep at the individual animal level (p = 0.0291). At the herd level, 62.5% of cattle herds and 45.5% of sheep flocks had at least one positive animal, but this difference was statistically insignificant (p = 0.2475). The fourteen cattle farms with at least one seropositive animal were dispersed across the Omaheke region. In contrast, the ten sheep farms with seropositive cases were predominantly situated in the southern half of the region. The study concluded that the CCHF is endemic in the Omaheke region and likely in most of Namibia, underscoring the importance of continued surveillance and preventive measures to mitigate the impact of CCHFV on animal health and potential spillover into human populations.

2.
Acta Trop ; 249: 107085, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38016512

ABSTRACT

Since its first identification in 2015, porcine circovirus 3 (PCV-3) has been reported worldwide with a high frequency and in the presence of several clinical conditions, although its impact on pig health and productivity is still debated. Data on the presence of PCV-3 in Africa are, however, limited. A previous study performed on commercial pigs in Namibia failed to identify the pathogen. In the present study, the viral circulation in backyard farms, characterised by lower biosecurity measures and frequent animal exchange between farms, was assessed. The susceptibility of warthogs to PCV-3 infection and their potential epidemiological role were also evaluated. Tonsils from 77 pigs from backyard piggeries and 55 warthogs were collected in different regions of Namibia and tested by PCR. Positive samples were sequenced and compared to PCV-3 strains circulating globally. Forty-two out of 77 pigs (54.54 %) and 12 out of 55 warthogs (21.82 %) tested positive, demonstrating the presence of PCV-3 in the country and suggesting that the high biosecurity measures implemented in the commercial farms that previously tested negative for PCV-3 probably prevented viral introduction. The partial ORF2 gene was successfully sequenced in samples from 27 pigs and 6 warthogs. Genetically, the identified strains were part of 3 distinct groups which included both backyard pigs and warthogs from different regions of Namibia. There is also evidence for the occurrence of multiple introduction events most likely from Asian countries, either directly into Namibia or through other African countries. Considering the strict Namibian regulations on live animal importation, understanding the source of viral introduction is challenging, although semen importation or the habit of feeding backyard pigs with human food waste might have played a role. Pig exchanges between farms for breeding purposes or wildlife movements could also have been involved in PCV-3 dispersal within Namibia. Despite the significant advances in the field, further studies should be undertaken to properly understand PCV-3 epidemiology in Namibia and its impact on pig productivity and wildlife health.


Subject(s)
Circoviridae Infections , Circovirus , Refuse Disposal , Swine Diseases , Animals , Humans , Animals, Wild , Circoviridae Infections/epidemiology , Circoviridae Infections/veterinary , Circovirus/genetics , Farms , Food , Genetic Variation , Swine , Swine Diseases/epidemiology , Swine Diseases/diagnosis , Namibia
3.
Infect Ecol Epidemiol ; 13(1): 2229589, 2023.
Article in English | MEDLINE | ID: mdl-37398877

ABSTRACT

Brucellosis is a worldwide zoonosis that is endemic in Namibia. This study estimated seroprevalence of brucellosis, and determined the presence of Brucella infection in slaughtered cattle using the genus-specific 16-23S rRNA interspacer PCR (ITS-PCR), and the species-specific AMOS-PCR. Between December 2018 and May 2019, sera (n = 304), pooled lymph nodes (n = 304), and individual spleen (n = 304) were collected from slaughtered cattle from 52 farms. Sera were tested for anti-Brucella antibodies using the Rose Bengal test (RBT), and the complement fixation test (CFT). Seroprevalence was 2.3% (7/304) (RBT) and 1.6% (5/304) (CFT). Prevalence of positive herds was 9.6% (5/52). Lymph node (n = 200) and spleen (n = 200) samples from seronegative cattle tested negative for Brucella spp. DNA on ITS-PCR, but Brucella spp. DNA was detected in lymph nodes (85.7%, 6/7) and spleen (85.7%, 6/7) from RBT positive cattle. ITS-PCR confirmed isolates from lymph node (51.4%, 4/7) and spleen (85.7%, 6/7) as Brucella spp.; while AMOS-PCR and Brucella abortus species specific (BaSS) PCR confirmed the isolates as Brucella abortus, and field strains, respectively. Provision of adequate protective gear, and the promotion of brucellosis awareness among abattoir workers is recommended to prevent zoonotic infection.

4.
One Health ; 16: 100562, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37363208

ABSTRACT

Dog-mediated rabies is responsible for tens of thousands of human deaths annually, and in resource-constrained settings, vaccinating dogs to control the disease at source remains challenging for various reasons. Currently, rabies elimination efforts rely on mass dog vaccination by the parenteral route. While oral rabies vaccination (ORV) of dogs is primarily considered a tool to increase herd immunity, particularly by targeting free-roaming and stray dogs, here, we are showcasing an ORV-only approach as an emergency response model. Using a third-generation vaccine and a standardized egg-flavored bait, we assessed the effectiveness and vaccination under field conditions in the Zambezi region of Namibia. During this trial, with four teams and within four working days, 3097 dogs were offered a bait, of which 88,0% were considered vaccinated. Teams managed to vaccinate, on average, over 20 dogs/h, despite using a door-to-door vaccination approach. The favorable results both in terms of bait acceptance and successful vaccination as well as field applicability and effectiveness further support the great potential of ORV in dog rabies control programmes.

5.
Animals (Basel) ; 13(9)2023 Apr 24.
Article in English | MEDLINE | ID: mdl-37174486

ABSTRACT

The known host range of circoviruses is continuously expanding because of more intensive diagnostic activities and advanced sequencing tools. Recently, a new circovirus (penguin circovirus (PenCV)) was identified in the guano and cloacal samples collected from Adélie penguins (Pygoscelis adeliae) and chinstrap penguins (Pygoscelis antarcticus) in Antarctica. Although the virus was detected in several asymptomatic subjects, a potential association with feather disease was speculated. To investigate the occurrence and implications of PenCV in other penguin species located outside of Antarctica, a broad survey was undertaken in African penguins (Spheniscus demersus) on two islands off the southern Namibian coast. For this purpose, specific molecular biology assays were developed and validated. None of the 151 blood samples tested positive for PenCV. Several reasons could explain the lack of PenCV positive samples. African penguins and Pygoscelis species are separated by approximately 6000 km, so there is almost no opportunity for transmission. Similarly, host susceptibility to PenCV might be penguin genus-specific. Overall, the present study found no evidence of PenCV in African penguin colonies in Namibia. Further dedicated studies are required to assess the relevance of PenCV among different penguin species.

6.
Infect Genet Evol ; 112: 105458, 2023 08.
Article in English | MEDLINE | ID: mdl-37257803

ABSTRACT

Canine circovirus (CanineCV) is a DNA virus affecting domestic dogs and other wild carnivore species. Despite the potential implications for dogs' health and wildlife conservation, data on CanineCV presence, epidemiology and genetic features from Africa is still poor. In the present study, biological specimens collected between 2020 and 2022 from a total of 32 jackals and 575 domestic dogs were tested for the presence of CanineCV DNA to evaluate its frequency. Furthermore, sequencing was conducted on positive samples to characterize the strains and compare them with publicly available sequences through phylogenetic analysis. A high CanineCV prevalence was observed both in jackals (43.75%; 95 CI: 28.17% - 60.67%) and domestic dogs (27.13%; 95 CI: 23.66% - 30.91%). All aside from one Namibian strain formed an independent clade, suggestive of extremely rare introduction events, followed by local persistence, circulation, and evolution. Remarkably, different recombination events were observed involving strains from both jackals and domestic dogs, which testify to the likely strain exchange between these populations. Distinctive amino acid residues were also observed in jackals. The limitations of the considered host populations however prevent a definitive conclusion on host adaptation, biological, and clinical features. Further studies should be performed to expand our current knowledge of the CanineCV disease scenario in Namibia, other African regions, and associated host species in Africa.


Subject(s)
Circovirus , Dog Diseases , Animals , Dogs , Animals, Wild , Jackals/genetics , Circovirus/genetics , Namibia/epidemiology , Molecular Epidemiology , Phylogeny , Dog Diseases/epidemiology
7.
Trop Med Infect Dis ; 8(4)2023 Mar 29.
Article in English | MEDLINE | ID: mdl-37104329

ABSTRACT

West Nile virus (WNV) is an important zoonotic Flavivirus responsible for mild fever to severe neurological disease in humans and horses. Despite the occurrence of major previous outbreaks in Namibia and the likelihood of the current endemicity of the virus, only limited investigations and monitoring activities of WNV have been performed in the country. The use of animal sentinels is a valuable approach toward investigating the infection presence in an area and to predict the potential occurrence of human outbreaks. Serological investigations in dogs hold several advantages, considering their infection susceptibility, the ease of sample handling, and the evaluation of risk factors of pet owners that share the same habit with their pets. To evaluate the usefulness of such a sero-epidemiological investigation in Namibia, a broad serosurvey was performed in 2022 that included 426 archived domestic dog samples from eight Namibian regions. Although the ELISA prevalence, indicative of Flavivirus infection, was relatively high (16.43%; 95 CI: 13.10-20.39%), the virus neutralization test confirmed only a minority of cases, highlighting a prevalence of 2.82% (95 CI: 1.47-4.90%), significantly lower than in Namibian donkeys and reports from other countries. Variables that could explain the recorded differences remain to be explored, including animal exposure, variable vector presence, distribution, and feeding preferences. The study results suggest the limited usefulness of dogs as sentinels for WNV monitoring in Namibia.

8.
Microbiol Resour Announc ; 12(4): e0103422, 2023 Apr 18.
Article in English | MEDLINE | ID: mdl-36920210

ABSTRACT

In this report, we describe eight complete genome sequences of African horse sickness virus (AHSV) strains belonging to four different serotypes, namely, AHSV-5, AHSV-6, AHSV-8, and AHSV-9. Samples were collected in Namibia and South Africa from infected horses between 2000 and 2011. As expected, phylogenetic analyses of the variable outer capsid protein VP2 genomic sequences of AHSV-6 and AHSV-8 show higher nucleotide identity between the isolated viruses than that of the relevant reference strains. The full-genome sequence of AHSV will provide useful information on its geographical origin, and it will also be instrumental for comparing the distribution of the Namibian isolate with that of global isolates.

9.
Viruses ; 15(2)2023 01 28.
Article in English | MEDLINE | ID: mdl-36851585

ABSTRACT

Rabies is endemic in Namibia and is present both in wildlife carnivores and domestic free-roaming dogs. The disease thus represents a challenge for public human and veterinary disease control. Namibia has implemented a national strategic plan to control rabies and the country's activities are supported by international organizations. To this end, rabies diagnosis at the Central Veterinary Laboratory (CVL) was improved in the frame of a World Organization for Animal Health (WOAH) laboratory twinning program: from practical sampling techniques and the use of lateral flow devices to a novel universal and discriminatory quantitative real-time Reverse transcription polymerase chain reaction (RT-qPCR), which easily identify dog-associated rabies viruses. The procedures applied and the results can be used as a template to improve rabies laboratory diagnosis.


Subject(s)
Rabies virus , Rabies , Humans , Animals , Dogs , Rabies/diagnosis , Rabies/epidemiology , Rabies/prevention & control , Namibia/epidemiology , Rabies virus/genetics , Animals, Wild , Diagnostic Tests, Routine
10.
Emerg Microbes Infect ; 12(1): 2167610, 2023 Dec.
Article in English | MEDLINE | ID: mdl-36632773

ABSTRACT

In January 2022, significant mortality was observed among Cape cormorants (Phalacrocorax capensis) on the west coast of Namibia. Samples collected were shown to be positive for H5N1 avian influenza by multiplex RT-qPCR. Full genome analysis and phylogenetic analysis identified the viruses as belonging to clade 2.3.4.4b and that it clustered with similar viruses identified in Lesotho and Botswana in 2021. This is the first genomic characterization of H5N1 viruses in Namibia and has important implications for poultry disease management and wildlife conservation in the region.


Subject(s)
Influenza A Virus, H5N1 Subtype , Influenza A virus , Influenza in Birds , Animals , Influenza A Virus, H5N1 Subtype/genetics , Phylogeny , Namibia , Birds , Disease Outbreaks , Poultry
11.
Vet Res Commun ; 47(2): 981-985, 2023 Jun.
Article in English | MEDLINE | ID: mdl-36494511

ABSTRACT

Thirty swine samples collected from different regions of Namibia between 2019 and 2020 were screened for the presence of porcine parvovirus 1 (PPV1) by PCR. Eleven samples (37%) were positive. Phylogenetic analysis of a partial sequence of the structural protein gene (VP2) identified two distinct clusters, one which contained sequences that were highly similar to PPV1 previously identified in warthogs in Namibia. These results indicate possible PPV1 transmission between warthogs and domestic pigs and highlight the importance of wildlife as sources of pathogens.


Subject(s)
Parvovirus, Porcine , Swine Diseases , Swine , Animals , Sus scrofa , Parvovirus, Porcine/genetics , Phylogeny , Namibia/epidemiology , Swine Diseases/epidemiology
12.
Acta Trop ; 238: 106739, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36375521

ABSTRACT

The commercial farming and trading of parrots and ornamental birds as companion animals are important economic activities in many countries. Some of the bird species farmed/traded are captured from the wild or are closely related to wild birds and therefore represent a risk of pathogen exchange/introduction. Beak and feather disease virus (BFDV) and avian poliomavirus (APV) are among the viruses with the biggest impact on companion bird populations and have been detected in different hosts worldwide. Despite their relevance for both domesticated and wild birds, our knowledge of BFDV and APV epidemiology remains limited in several African countries. In the present study, 143 cloacal swabs were collected from companion birds in Windhoek, Namibia, and tested by polymerase chain reaction for BFDV and APV. Of the samples tested, 35/143 (24.48%) tested positive for BFDV; 11/143 (7.69%) were positive for APV; and 6/143 (4.2%) tested positive for both pathogens. Positive amplicons, consisting of segments of the ORF1 and VP1 genes, were sequenced and compared with sequences from viruses identified in other countries. Four Namibian-only clades of BFDV were identified, loosely related to foreign strains, which suggest the occurrence of multiple introduction events in the past, potentially from South Africa, followed by local, independent evolution. In contrast, the Namibian APV sequences were identical to each other and form a single clade. In both instances, no correlation was observed between the sampling host and the viral phylogeny, suggesting the absence of host-specific adaptation and a remarkable, unconstrained viral circulation within Namibian borders. Therefore, while regulations and control measures developed against foreign strain introduction have proven to be effective over time, the spread of BFDV and APV within Namibia's borders appears undeterred. Additional resources should be dedicated to limit strain circulation in commercial farming facilities, markets and small-scale traders.


Subject(s)
Bird Diseases , Circoviridae Infections , Circovirus , Parrots , Polyomavirus , Animals , Circovirus/genetics , Circoviridae Infections/epidemiology , Circoviridae Infections/veterinary , Namibia/epidemiology , Polyomavirus/genetics , Sequence Analysis , Bird Diseases/epidemiology , Phylogeny
13.
Front Vet Sci ; 10: 1323974, 2023.
Article in English | MEDLINE | ID: mdl-38288380

ABSTRACT

Introduction: The swine sector in Africa plays an important role in local economies, contributing to poverty alleviation and community subsistence. In addition, intensive farming is progressively becoming more important in the region. Therefore, any disease affecting swine populations can have detrimental effects on local communities. Porcine Reproductive and Respiratory Syndrome (PRRS) is among the most important infectious diseases affecting swine worldwide, but information on its epidemiology in Africa is extremely limited. Material and methods: In the present study, 147 healthy butchered pigs, originating from 15 Namibian intensive and rural farms were tested by RT-PCR and the ORF7 genes of positive samples were sequenced for further genetic characterization and phylogenetic analysis. Additionally, 55 warthogs were also evaluated using the same approach. Results: Overall, 7 out of 147 pigs (4.76%) tested positive, all originating from 3 rural farms (with a within-herd detection frequency higher than 14%) characterized by strong epidemiological links. All industrial pig and warthog samples were negative. Sequence analysis revealed that all strains belonged to the Betaarterivirus suid1 species, previously known as PRRSV type I, and were likely imported from Europe at least 6 years ago, evolving independently thereafter. When and how the first introduction occurred could not be determined due to the absence of other African sequences for comparison. Discussion: The present work provides the first detection and characterization of PRRSV molecular epidemiology in Namibia. Based on the present findings, the presence of the PPRSV appears marginal and limited to backyard farms. While biosecurity measures applied in industrial farms appear to be effective in preventing viral introduction, PRRSV circulation in rural settings still represents a potential threat, and considering the socio-economical implication of livestock diseases decreasing animal performances in rural areas, active monitoring should be encouraged to promptly act against emerging menaces and guarantee the welfare of local pig populations.

14.
Vaccines (Basel) ; 10(12)2022 Dec 13.
Article in English | MEDLINE | ID: mdl-36560544

ABSTRACT

The pandemic of coronavirus disease 19 (COVID-19) has focused the attention of researchers, and especially public opinion, on the role of the human-animal-environment interface in disease emergence. At the beginning of the COVID-19 pandemic, media reports regarding the role of pets in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused significant concern and social anxiety. Although nowadays proven negligible in developed countries, essentially no studies have been performed in low-income African areas where companion animals are often raised differently from high income countries, and the contact patterns occurring in these scenarios could affect the epidemiological scenario. An extensive molecular biology survey was performed from March 2022 to September 2022 on Namibian dogs residing in urban and rural areas, showing a low but not negligible SARS-CoV-2 prevalence (1%; 95CI: 0.33-2.32%) of 5 out of 500. In only one instance (i.e., a 4-year-old female Labrador) was there a clear association that could be established between the infections of the owner and animal. In all other cases, no evidence of human infection could be obtained and no episodes of COVID-19 were reported by the owners. Although no consistent evidence of pet-to-pet transmission was proven in the present study, a cautionary principle suggests intensive and dedicated investigation into companion animal populations, especially when animal contact is frequent and a particularly susceptible population is present.

15.
Trop Anim Health Prod ; 54(6): 346, 2022 Oct 15.
Article in English | MEDLINE | ID: mdl-36242679

ABSTRACT

This study investigated outbreaks of seemingly related abortions and orchitis which occurred in the Khomas, Omaheke and Otjozondjupa regions of Namibia from 2016 to 2018, affecting cattle, sheep and goats. Fifty-nine questionnaires were administered, and 48 were completed giving an 81.4% return. The outbreaks were limited to Namibia's east and central regions, mainly on farms rearing cattle, sheep and goats and on farms with a mixture of these species. There was no significant difference between Khomas and other regions on abortion reporting at the farm level [X2 (1, N = 48) = 0.0002, p = 0.987851]. However, there was a significant difference in the abortions at the animal level among the three regions [X2 (2, N = 6246) = 239.8339, p = .00001]. In addition, the proportions of abortions calculated at the animal level at each farm were significantly different when the Khomas region was compared to the other regions. Seventeen cattle sera, 35 sheep sera, 52 caprine sera, 18 bovine liver samples, one caprine liver, five aborted cattle foetuses, two cattle placentas, 18 testes (one bull, eight bucks and nine rams) and ten bull sheath scrapings were collected and tested. Histopathology, microbiology, serology, immunohistochemistry, real-time PCR and mineral analytical techniques were used to establish the aetiology of the abortion and orchitis outbreaks. The gross and histopathological findings on the 18 testicles were characteristic of chronic orchitis. In aborted foetuses, significant histopathological findings included meconium aspiration, funisitis and cardiomyopathy. Placentitis and endometritis were the primary pathologies observed in cows. The bacteria isolated from microbiological samples included Enterococcus spp. (65.5% [19/29]), Enterobacter spp. (6.9% [2/29]) and Streptococcus spp. (10.3% [3/29]), Trueperella pyogenes (3.4% [1/29]), Stenotrophomonas maltophilia (3.4% [1/29]), Staphylococcus epidermidis (3.4% [1/29]), Providencia rettgeri (3.4% [1/29]) and Acinetobacter lwoffii (3.4% [1/29]), mostly opportunistic bacteria. On mineral analysis, 28%, 33%, 83%, 33% and 17% (n = 18) of cattle livers were low in copper, zinc, manganese, selenium and iron, respectively. Twenty-three percent (12/52) of the caprine sera were positive for Brucella melitensis on the Rose Bengal and complement fixation tests. Thirty-five ovine sera were tested for B. melitensis, B. ovis and Coxiella burnetii, and the prevalence for each was 2.9% (1/35). PCR tests on foetuses were all negative for Brucella spp., Coxiella burnetii, Chlamydia spp., Listeria monocytogenes, Salmonella spp., Campylobacter fetus spp., Leptospira pathogenic strains, bovine viral diarrhoea virus, Rift Valley fever virus, Anaplasma phagocytophilum and bovine herpes virus 4 Campylobacter fetus spp. and Trichomonas foetus spp. The authors concluded that Brucella spp., Enterococcus spp., Escherichia coli, Streptococcus spp., Trueperella pyogenes and Coxiella burnetii could have contributed to this outbreak. Micronutrient imbalances and pathogenic abiotic nanoparticles were also identified as possible contributors to the abortion outbreaks.


Subject(s)
Brucella , Cattle Diseases , Coxiella burnetii , Goat Diseases , Meconium Aspiration Syndrome , Orchitis , Q Fever , Selenium , Abortion, Veterinary/epidemiology , Abortion, Veterinary/microbiology , Animals , Cattle , Cattle Diseases/epidemiology , Cattle Diseases/microbiology , Copper , Disease Outbreaks/veterinary , Female , Goat Diseases/epidemiology , Goat Diseases/microbiology , Goats , Infant, Newborn , Iron , Livestock , Male , Manganese , Meconium Aspiration Syndrome/epidemiology , Meconium Aspiration Syndrome/veterinary , Micronutrients , Namibia/epidemiology , Orchitis/veterinary , Pregnancy , Q Fever/epidemiology , Q Fever/veterinary , Real-Time Polymerase Chain Reaction/veterinary , Rose Bengal , Sheep , Zinc
16.
Prev Vet Med ; 209: 105780, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36274539

ABSTRACT

Canine parvovirus is a member of the Carnivore protoparvovirus 1 species that, after a relatively recent origin, has reached a worldwide distribution. Like other ssDNA viruses, it is featured by a remarkable evolutionary rate and thus genetic variability. CPV-2 is responsible for a severe systemic infection affecting especially domestic dogs. However, other carnivores, including wild species, are susceptible and thus represents a menace to wildlife conservation too. Despite the relevance of the topic, molecular epidemiology data are scarce and outdated in certain areas of the world, like Africa and, in particular, Namibia. The present study investigates the occurrence and genetic features of CPV in Namibian domestic dogs and jackals. The VP2 of detected strains was characterized and analyzed to assess the viral circulation and link among host species, Namibian districts and foreign countries. With the only exception of one New-CPV-2a, all the detected strains belonged to the CPV-2c antigenic variant and were closely related to strains of Asian origin. Nevertheless, a dedicated phylogeographic analysis revealed that the introduction was more likely mediated by other African countries, highlighting the challenge of controlling illegal animal imports across land borders. Similarly, the absence of any geographical clustering within Namibia testify a substantially unconstrained viral circulation among districts. The absence/incomplete vaccination status reported by the animal owners could have significantly contributed to the infection's success after its introduction. Finally, infection of a wild jackal was also proven. Although the limited wild animals' sample size prevents any definitive conclusion, the identity of the sequences from the jackal and the ones originating from the domestic dogs suggests a potential inter-species transmission. The epidemiological and clinical implications in wild specie remain obscure.


Subject(s)
Carnivora , Dog Diseases , Parvoviridae Infections , Parvovirus, Canine , Dogs , Animals , Parvovirus, Canine/genetics , Molecular Epidemiology , Jackals/genetics , Parvoviridae Infections/epidemiology , Parvoviridae Infections/veterinary , Namibia/epidemiology , Phylogeny , Carnivora/genetics , Animals, Wild , Dog Diseases/epidemiology
17.
PLoS Negl Trop Dis ; 16(8): e0010422, 2022 08.
Article in English | MEDLINE | ID: mdl-35994498

ABSTRACT

Dog-mediated rabies is responsible for tens of thousands of human deaths annually, and in resource-constrained settings, vaccinating dogs to control the disease at source remains challenging. Currently, rabies elimination efforts rely on mass dog vaccination by the parenteral route. To increase the herd immunity, free-roaming and stray dogs need to be specifically addressed in the vaccination campaigns, with oral rabies vaccination (ORV) of dogs being a possible solution. Using a third-generation vaccine and a standardized egg-flavoured bait, bait uptake and vaccination was assessed under field conditions in Namibia. During this trial, both veterinary staff as well as dog owners expressed their appreciation to this approach of vaccination. Of 1,115 dogs offered a bait, 90% (n = 1,006, 95%CI:91-94) consumed the bait and 72.9% (n = 813, 95%CI:70.2-75.4) of dogs were assessed as being vaccinated by direct observation, while for 11.7% (n = 130, 95%CI:9.9-17.7) the status was recorded as "unkown" and 15.4% (n = 172, 95%CI: 13.4-17.7) were considered as being not vaccinated. Smaller dogs and dogs offered a bait with multiple other dogs had significantly higher vaccination rates, while other factors, e.g. sex, confinement status and time had no influence. The favorable results of this first large-scale field trial further support the strategic integration of ORV into dog rabies control programmes. Given the acceptance of the egg-flavored bait under various settings worldwide, ORV of dogs could become a game-changer in countries, where control strategies using parenteral vaccination alone failed to reach sufficient vaccination coverage in the dog population.


Subject(s)
Dog Diseases , Rabies Vaccines , Rabies , Administration, Oral , Animals , Dog Diseases/epidemiology , Dog Diseases/prevention & control , Dogs , Humans , Namibia , Rabies/epidemiology , Rabies/prevention & control , Rabies/veterinary , Vaccination/methods , Vaccination/veterinary
18.
Animals (Basel) ; 12(13)2022 Jun 30.
Article in English | MEDLINE | ID: mdl-35804594

ABSTRACT

Understanding virus circulation in wild animals, particularly those that have contact with domestic animals, is crucial for disease management and control. In Africa, warthogs are known to be asymptomatic carriers of porcine pathogens; a recent study in Namibia has shown them to be positive for Porcine circovirus-2 (PCV-2). In this study, the same samples used for the PCV-2 investigation in Namibia were further screened for the presence of African swine fever virus (ASFV) and porcine parvovirus 1 (PPV1) by PCR. Of the 42 animals tested, 2 (4.8%) and 13 (31%) were positive for AFSV and PPV1, respectively. The two AFSV were also co-infected with PPV1. Combing the results of this study with the results of the previous PCV-2 investigation, four warthogs were shown to be co-infected with both PPV1 and PCV-2. Sequence and phylogenetic analysis revealed that the AFSV belonged to genotype (Ib) but were from different serogroups. Unexpectedly, the ASFVs from the warthogs were genetically distinct to those observed in an outbreak in the same region of Namibia that occurred less than fifteen months prior to the sampling of the warthogs. In fact, a stronger genetic relationship was observed between the warthog viruses and historical Namibian and South African ASFVs identified in 1980, 2004 and 2008. For the PPV1s, the closest relative to the Namibian PPV1 were viruses identified in wild boar in Romania in 2011. This study confirms that warthogs are carriers of porcine pathogens and the data should encourage further studies on larger populations of wild and domestic swine to more fully understand the epidemiology and transmission of viral pathogens from these species.

19.
Adv Virus Res ; 112: 115-173, 2022.
Article in English | MEDLINE | ID: mdl-35840180

ABSTRACT

Rabies infects all mammals; however, transmission cycles are only maintained in certain bat and carnivore species. The high incidence of rabies in Greater Kudu (Tragelaphus strepsiceros) observed in Namibia for over 40 years has led to postulation that independent virus transmission is occurring within this antelope population. We have analysed extensive experimental, epidemiological, phylogeographic and deep sequence data, which collectively refute maintenance of an independent rabies cycle in kudu. As rabies in kudu continues to have a negative impact on the Namibian agricultural sector, measures to protect kudu have been investigated, including the use of a third-generation oral rabies vaccine. Initial results show protection of kudu from rabies infection via the oral route, with an appropriate bait design, different application schedules and vaccination doses further enhancing the immune response. Rabies in kudu is a complex interplay at the wildlife-livestock interface and requires a concerted approach to successfully control.


Subject(s)
Antelopes , Rabies Vaccines , Rabies virus , Rabies , Animals , Animals, Wild , Antelopes/physiology , Rabies/epidemiology , Rabies/prevention & control , Rabies/veterinary , Rabies virus/genetics
20.
Transbound Emerg Dis ; 69(5): e2677-e2687, 2022 Sep.
Article in English | MEDLINE | ID: mdl-35695014

ABSTRACT

Beak and feather disease virus (BFDV) infects domestic and wild psittacine species and is able to cause progressive beak, claw and feather malformation and necrosis. In addition to having an impact on the health and welfare of domesticated birds, BFDV represents a significant threat to wild endangered species. Understanding the epidemiology, dynamics, viral migration rate, interaction between wild and domestic animals and the effect of implemented control strategies is fundamental in controlling the spread of the disease. With this in mind, a phylodynamic and phylogeographic analysis has been performed on a database of more than 400 replication-associated protein (Rep) gene (ORF1) sequences downloaded from Genbank including some recently generated sequences from fifteen samples collected in Namibia. The results allowed us to reconstruct the variation of viral population size and demonstrated the effect of enforced international bans on these dynamics. A good correlation was found between viral migration rate and the intensity of animal trade between regions over time. A dominant flux of viral strains was observed from wild to domestic populations, highlighting the directionality of viral transmission and the risk associated with the capturing and trade of wild birds. Nevertheless, the flow of viruses from domestic to wild species was not negligible and should be considered as a threat to biodiversity. Therefore, considering the strong relationship demonstrated in this study between animal trade and BFDV viral fluxes more effort should be made to prevent contact opportunities between wild and domestic populations from different countries in order to control disease spread.


Subject(s)
Bird Diseases , Circoviridae Infections , Circovirus , Parrots , Viruses , Animals , Bird Diseases/epidemiology , Circoviridae Infections/epidemiology , Circoviridae Infections/veterinary , Circovirus/genetics , Phylogeny , Phylogeography
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