Onderstepoort Journal of Veterinary Research最新文献

Avian influenza (AI) is a significant disease affecting chickens and other avian species. Wild birds are thought to contribute to the virus transmission. The present study intends to explore the existence of AI type A virus in wild birds at the Six April Zoo, Khartoum State, Sudan. A total of 42 cloacal and tracheal swabs were collected from clinically healthy individuals belonging to five different wild bird species. The selected wild bird species were Common crane Grus grus, Sudan crowned crane Balearica pavonina, Helmeted guinea fowl Numida meleagris, Duck sp. Anatidae and Chestnut-billed sand grouse Pterocles exustus. Swabs were examined for AI virus antigen using the agar gel immunodiffusion (AGID) test, and all tested swabs produced positive results. The swab samples were inoculated into embryonated chicken eggs. The isolated virus was identified by AGID test and polymerase chain reaction. The virus was isolated from swabs collected from Grus grus, Balearica pavonina, Numida meleagris, Duck sp. Anatidae and Pterocles exustus. Subtyping of the isolated viruses was performed using reverse transcriptase-polymerase chain reaction, which identified the H5 subtype.Contribution: The present study confirmed the existence and isolation of type A AI virus from different species of wild birds as well as subtyping of its virus for the first time in Khartoum State, Sudan.

Peste des petits ruminants (PPR) is an endemic, transboundary animal disease (TAD) that affects small ruminants and threatens Nigeria's food and economic security. This study evaluated the PPR cases in Nigeria using data from the World Animal Health Information System (WAHIS). Secondary data of PPR (2015-2024) were analysed as descriptive statistics, and we forecasted PPR cases from 2025 to 2030. Our findings showed temporal variations in PPR reports and case trends, with more cases (reports) between 2020 and 2024. There were significant variations in PPR cases across the six agro-ecological zones of Nigeria (p = 0.025) and across the states (p  0.001). Bauchi (27.6%, n = 19 557/70 827) had over one-quarter of all national disease load, and Katsina had 9.6% (n = 6767/70 827) of the national PPR cases over the study period. Seven states had less than 50 cases, with Lagos and Ogun states having the lowest reports of PPR with 19 and 9 cases, respectively. Trend analysis forecasted an annual increase in the number of PPR cases, with at least 20 048 PPR cases in 2025, 22 838 cases in 2026, 25 737 cases in 2027, 28 745 cases in 2028, 31 860 cases in 2029, with the estimated number of cases rising to approximately 35 085 cases by 2030. The average case fatality rate for the 10 years was 14.1%. Hence, we estimated that at least 23 168 animals will be lost to PPR over the forecasted period.Contribution: The study emphasises the need for region-specific surveillance, targeted vaccination strategies, and predictive modelling tools for effective control and eradication efforts.

Neosporosis is a leading cause of bovine abortions worldwide, with a substantial economic impact because of reproductive losses, costing the cattle industry billions of dollars annually. Despite the global significance of Neospora caninum, molecular studies on this protozoan parasite have yet to be conducted in cattle in Southern Africa, leaving a critical knowledge gap in countries like Namibia, where beef production is vital to the economy. This study aimed to detect latent N. caninum infections in beef cattle brain and heart muscle samples collected from abattoirs and blood samples from Neospora-seropositive animals within Namibia's Khomas region. One hundred and ninety-nine samples were collected, comprising 110 brain samples, 75 heart muscle samples and 14 whole blood samples. Conventional polymerase chain reaction (PCR) analysis was performed using Np6 and Np21 primers targeting a ≈340 base pair (bp) segment of the Nc5 gene. All samples tested negative. These results were likely because of the low prevalence of this parasite in Namibian beef cattle, as reported in a previous serosurvey. Future studies focusing on aborted foetuses over a longer timeframe may increase the likelihood of detecting positive cases.Contribution: This study represents the first published molecular investigation of N. caninum in beef cattle in Southern Africa. The negative results underscore the challenges of detecting N. caninum in tissues from clinically healthy cattle, particularly in a semi-arid country like Namibia, where the prevalence of the pathogen is inherently low.

African swine fever (ASF) is a severe viral haemorrhagic disease affecting domestic pigs, maintained by ASF virus within an ancient sylvatic cycle involving Ornithodoros ticks that inhabit warthog burrows. This study aimed to develop and optimise a multiplex polymerase chain reaction (PCR) assay to differentiate three Ornithodoros species in South Africa - O. moubata, O. phacochoerus and O. waterbergensis, to enhance ASF vector identification and management. The final multiplex PCR effectively distinguished between species with specific amplicon sizes: 180 base pairs (bp) for O. moubata, 640 bp for O. phacochoerus and 1000 bp for O. waterbergensis.Contribution: This refined multiplex PCR method demonstrates proof of concept as a reliable and rapid tool for distinguishing Ornithodoros species and correlating them with their geographical origins. This assay, based on amplification size, provides crucial information about the distribution of these species, which could enhance ASF control efforts.

Brucellosis, a contagious zoonotic bacterial infection affecting livestock and wildlife, is primarily caused by Brucella abortus, globally. However, in South Africa, the true prevalence of bovine brucellosis remains unknown because of a lack of epidemiological data. Therefore, this study used diagnostic data to evaluate and determine the seropositivity of bovine brucellosis based on Rose Bengal test (RBT) screening and confirmation with complement fixation test (CFT) in Limpopo and Free State provinces between 2013 and 2022. The use and limitations of this data were also evaluated based on the bovine brucellosis scheme in South Africa. The study revealed the overall seropositivity of 4.2% (n = 8980/212 440) for bovine brucellosis based on RBT and CFT in series. In Limpopo province, the brucellosis seropositivity was slightly higher at 4.3% (n = 7488/173 011) compared to 3.8% (n = 1492/39 429) in Free State province. Analysis of brucellosis distribution over the study period indicated significant variation (p  0.001) both between and within the provinces. Notably, the highest prevalence in Limpopo occurred during 2013-2017, whereas in Free State, peak prevalence was observed in 2013 and 2016. Challenges preventing an accurate reflection of the brucellosis seropositivity in these provinces for the period include a lack of data on vaccination history and herd status of the samples submitted, as well as the inability to match the CFT results from different laboratories, because some laboratories are only accredited to perform the RBT.Contribution: Insights gained from retrospective studies such as this study can play crucial roles in shaping effective control and preventative measures against bovine brucellosis. Given the challenges in obtaining confirmatory test results, we suggest that brucellosis tests be conducted at a single central laboratory or that the government provides a central database where all laboratories can enter their data. Furthermore, information submitted to the laboratories must make herd and vaccine history compulsory for sample submission to ensure more accurate data.

Salmonella Typhimurium is a major cause of human and animal salmonellosis, impacting global socioeconomic factors. This study examined antibiotic resistance patterns, virulence genes and plasmids in S. Typhimurium isolates from nine South African provinces (1999-2021). Among 180 randomly selected isolates, 129 were confirmed as S. Typhimurium from animal (n = 94), food (n = 16), environment (n = 7) and feed (n = 12) sources using polymerase chain reaction (PCR). Phenotypic resistance was assessed against 13 antibiotics, revealing high resistance levels: 86.8% to ciprofloxacin, 69.0% to ceftriaxone and 65.1% to piperacillin. Multidrug resistance (up to 11 antibiotics) was observed. Genetic analysis identified resistance genes, including blaPSE (32.6%), blaCMY-2 (21.7%), tetA (24.0%), tetB (22.5%), qnrB (21.7%) and qnrA (20.2%). Class 1 integrons were found in 47.4% of isolates. Virulence genes were prevalent, including sopB (95.3%), sspH1 (82.9%), sifA (82.9%), pefA (79.8%), spvC (79.1%), sspH2 (77.5%), srgA (71.3%) and invA (100%). Plasmid analysis detected 2 kb, 8 kb and 90 kb plasmids, with the 90 kb plasmid being most common (71.3%). Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR identified 44 clusters (A-RR), including 6 major clusters.Contribution: These findings highlight the urgent need for enhanced surveillance and intervention strategies to curb antibiotic resistance and virulence in S. Typhimurium populations in South Africa, stressing the importance of monitoring and control measures to address this public health threat.

In a controlled experiment, we compared renal-hepatal, haematological and organ histopathology responses in chickens treated with Crude extracts of Capsicum annuum L. and Carica papaya L. to those treated with synthetic anthelmintics. Twenty-one indigenous seven-week-old chickens were fed on Nuvita® feeds Uganda limited and adlib tap municipal water. They were divided into seven groups of three chickens per group. The treatments were; CPLe (Carica papaya L. ethanol extract), CPLa (Carica papaya L. acetone extract), CAFe (Capsicum annuum L. ethanol extract), CAFa (Capsicum annuum L. acetone extract), levamisole, piperazine and phosphate buffered saline (PBS). CPLe, CPLa, CAFe, CAFa were given at a dose of 0.48 g per bird (1.37 g/kg body weight) as determined from a previous in-vitro experiment. Levamisole hydrochloride was given at 25 mg/kg body weight and piperazine citrate at 100 mg/kg body weight. The control group received 0.2% dimethyl sulfoxide (DMSO) in PBS. The treatments were individually administered orally and repeated on the second day. The birds were bled and sacrificed one week after treatment. Blood was submitted for haematology and harvesting of serum for renal-hepatal function tests. The heart, kidneys and liver were also harvested for histological examinations. CPLe caused significantly raised albumin compared to CAFe (p = 0.02), levamisole caused significantly raised AST compared to CAFe (p = 0.04). All extracts and synthetic anthelmentics increased the number of eosinophils, indicating an increased inflammatory response. CPLa, CAFe, CAFa and levamisole were toxic to the kidneys. All extracts were toxic to the liver except CPLe. Piperazine and levamisole were as well toxic to the liver.Contribution: Plant extracts are not necessarily safer than synthetic anthelmintics and should be used with caution.

Ectoparasites can severely impact wildlife species, both through their feeding behaviour and by facilitating secondary infestations or bacterial infections. Here, we report on two cases of periorbital damage caused by ixodid tick infestations in cheetahs (Acinonyx jubatus), including a rare record of traumatic myiasis in wildlife. Both cheetahs were recently reintroduced to the Marromeu-Coutada Complex in Central Mozambique and had sustained relatively severe injuries. This ostensibly yielded them immunocompromised and thus more vulnerable to tick infestations, particularly when exposed to novel species. These incidents occurred during the peak hot-wet season in which adult tick abundance is likely highest. These cases provide novel insights into the risks of tick infestations for reintroduced cheetahs and the importance of intensive post-release monitoring to allow for timeous veterinary intervention.Contribution: This study falls within the scope of the journal. Ixodid ticks are of veterinary importance for wildlife and domestic animals across Africa because of the associated direct damage and potential spread of tick-borne pathogens. This study investigates two cases of tick infestations in cheetahs recently reintroduced into a tropical environment. The identified risk factors appear to be exposure to novel ectoparasites, injuries, and the hot-wet season. This highlights the need to consider ectoparasite risk when planning wildlife translocations.

The widespread use of parabens has led to their accumulation in aquatic environments. This study examined the effects of methylparaben on rainbow trout, dividing 96 fish into control and treatment groups (1 mg/L, 5 mg/L, and 8 mg/L). Results showed dose-dependent weight loss, altered hepatosomatic indices, increased serum urea, uric acid, and Malondialdehyde (MDA) levels, and decreased Glutathione Peroxidase (GSH-Px) activity. Histopathological analysis revealed liver and kidney abnormalities in treated groups, including hepatocyte degeneration, proliferation in the bile duct, glomerular atrophy, reduced haematopoietic tissue, increased melanomacrophage centres, necrosis and fibrosis.Contribution: These findings highlight methylparaben's toxic effects, emphasising the need for stricter regulations and further research to safeguard aquatic ecosystems and understand its impact on aquatic organisms.

African swine fever (ASF) is a highly fatal viral haemorrhagic disease affecting pigs. This study uses official surveillance data to investigate the persistence and spread of ASF in wild boar populations in Serbia from 2020 to 2024. A total of 480 ASF cases were analysed, with spatiotemporal clustering conducted via SaTScan™ and proximity analyses performed in the Quantum Geographic Information System. The yearly prevalence of ASF in wild boar rose steadily from 0.66% in 2020 to 1.47% in 2023. Seasonal trends showed a significant increase in cases during winter (68%) and spring (24%). Five distinct clusters were identified, predominantly near the borders with North Macedonia and Bulgaria, suggesting potential cross-border transmission. Proximity to major roads was significantly associated with ASF case distribution (p  0.01), while proximity to water bodies and elevation showed no consistent pattern. The findings highlight critical gaps in current passive surveillance systems, which likely underestimate ASF prevalence. The study underscores the need for enhanced surveillance in remote and wooded areas and proposes strategies to improve ASF monitoring and control in wild boar populations.Contribution: This study highlights the feasibility of cost-effective, non-invasive surveillance methods for ASF detection, offering critical insights for low-income countries where resources for intensive disease monitoring are limited. By demonstrating how environmental and anthropogenic factors drive ASF dynamics, this research provides actionable strategies for improving regional and global ASF control efforts.