Onderstepoort Veterinary Academic Hospital

RaTexT®, an innovative rapid tick exposure test, was recently developed to provide farmers with quick, on-site results to improve their acaricide resistance management. This was achieved by exposing partially engorged adult ticks to a specially designed acaricide-impregnated matrix fitted inside a transparent polypropylene box. Each RaTexT® box contains six strips of four small, interconnected compartments, in which ticks are exposed immediately after removal from cattle in the field. In this study, we assessed whether a single strip of four interconnected compartments, instead of six strips, was sufficient to accurately detect resistance to deltamethrin and to a combination of cypermethrin, chlorpyrifos and piperonyl butoxide (PBO). We also statistically analysed the optimal number of ticks per compartment (ranging between 5 and 8). Moreover, the test reproducibility was checked by two independent observers who counted dead and live ticks in each compartment. Finally, a comparative analysis was undertaken between adult ticks exposed in RaTexT® and in the adult immersion test (AIT), and also with larvae in the resistance intensity test (RIT) and in the larval packet test (LPT). The novelty of this study lies in comparing adult ticks exposed in RaTexT and in the AIT Test, thereby overcoming limitations of previous studies, in which adults in RaTexT were compared with larvae in the LPT. The internal coefficient of variation (CV) was calculated for each dose, box and acaricidal product to assess within-box consistency. The effect of the number of ticks per compartment (n = 5-8) was examined using Monte Carlo simulations. Inter-observer reliability of reading RaTexT® was statistically measured using Cohen's kappa coefficient (κ). The comparative performance analysis of the bioassays was conducted using generalised linear models (GLMs) with laboratory and field strains of Rhipicephalus microplus ticks in Brazil. Overall agreement between individual strips and their corresponding box classification was 91.3%, indicating high consistency between replicates. The predefined threshold of ≥ 90% accuracy was met by a single strip, supporting the test's robustness even with minimal replication. The internal coefficient of variation within each RaTexT® box was high for deltamethrin (1.285 at 1× dose, 1.109 at 5× dose and 1.268 at 10× dose), but lower for cypermethrin/chlorpyriphos/PBO (0.648 at 1, 0.305 at 5× dose and 0.194 at 10× dose). Variability in the controls was relatively high (CV 1.776). Monte Carlo simulations showed that diagnostic accuracy gradually increased from 81.2% with five ticks to 86.1% with eight ticks per compartment. Furthermore, there was substantial agreement between the mortality of ticks assessed by two independent observers (κ = 0.664). Finally, the comparative test analysis revealed that the deltamethrin resistance level in RaTexT® matched that observed in the AIT. Resistance to deltamethrin was also confirmed by the LPT, with resistance ratios (RR) of 33.8 and 39.5 for two different field strains (Biotech and UFRRJ, respectively). For cypermethrin/chlorpyriphos/PBO, RaTexT® exhibited significantly lower mortality than the AIT. Resistance was also confirmed by LPT, with RR of 5.2 for Biotech strain and 7.2 for the UFRRJ strain. Overall, these findings demonstrate that RaTexT® is accurate and reproducible with a single test strip, making it a practical and cost-effective test that complements traditional laboratory bioassays.

Equine encephalosis (EE) is caused by an Orbivirus from the family Sedoreoviridae and is thus similar to African horse sickness (AHS) and Bluetongue viruses (BTV). These viruses are transmitted by Culicoides midges. Equine encephalosis can infect horses, donkeys and zebras sub-clinically while only horses develop clinical disease. The vector's distribution is climate-dependent with evidence for circulation in Southern Africa, the Middle East and India. Global warming could facilitate the expansion of this distribution and consequently the potential spread into Europe should not be overlooked. To describe clinical signs, clinicopathological abnormalities, and outcomes in horses naturally infected with EE. A retrospective, descriptive, observational study. Data were obtained from the Onderstepoort Veterinary Academic Hospital's clinical database to identify cases with EE from 2013 to 2023. Data including the history, clinical signs and clinicopathology were analysed. Equine encephalosis cases predominantly occurred from February to April. Twenty-five horses were included. Throughout the disease, 25 (100.0%) horses had pyrexia (mean maximum temperature 39.3°C; SD 0.86°C), 16 (64.0%) horses had tachycardia (median maximum heart rate 52/min; range 36-100/min), 19 (76.0%) horses had tachypnoea (median maximum respiratory rate 24/min; range 12-60/min). Within 24 h of presentation, horses predominantly displayed lymphopenia (median 1.17 × 109 cells/L; range 0.15-9.21 × 109 cells/L), thrombocytopenia (median 67.5 × 109 cells/L; range 3-303 × 109 cells/L), and leukopenia (median 5.44 × 109 cells/L; range 2.08-18.07 × 109 cells/L). Retrospective study design with a small number of cases and many of these evaluated at differing times after infection. Pyrexia, tachycardia and tachypnoea are the most common clinical signs associated with EE. Haematological evaluation appears valuable in EE cases, with leukopenia, lymphopenia, and thrombocytopenia commonly observed. Equine encephalosis is a relevant differential diagnosis for other infectious diseases in horses in geographical regions where EEV and Culicoides vectors are potentially present.

To gain insight into the common pathogenic, bacterial zoonosis represented by Salmonella infections in poultry and humans, we acted to determine salmonellosis prevalence in poultry and humans in Nigeria mapping hotspots. Using multi-sourced data, we conducted a meta-analysis to determine national and sub-national prevalence of salmonellosis in poultry from 2000 until 2020. Bayesian spatial joint modelling was used to map Non-Typhoidal Salmonella (NTS) infections in humans and poultry using climatic and demographic predictor variables. With the overall prevalence in poultry at 31.6%, the highest state-level prevalence rates were seen in Ogun (70.2%), Lagos (61.8%), Zamfara (58.2%) and Bauchi (57.1%). The North-West, South-West and South-South regions of Nigeria have the highest regional-level prevalence in poultry amounting to 38.5%, 36.9% and 33.6%, respectively. Thirteen states have higher than the average national prevalence (31.6%). While we found a negative association between NTS in humans and in poultry, the prevalence of diarrhoea in humans positively predicted salmonellosis in poultry. Not surprisingly, poultry populations positively predicted salmonellosis in other poultry populations. Higher numbers of human cases were predicted in the North, with more poultry cases in the South and in some North-Eastern states. The observed human NTS-poultry salmonellosis correlation is counterfactual to logic and plausibility as high poultry density and contamination in poultry are expected to predict human infection. The outcome pointed to under-reporting linked to self-treatment, under-testing in the public health and veterinary laboratory and lack of uniform primary healthcare services, particularly in under-served areas of Nigeria. Salmonellosis continues to be a serious burden, and provision of better health data is needed.

Countrywide routine entomological surveillance studies in Kenya from 2006 first identified Aedes vittatus, in small numbers (4 specimens), in Mombasa city in 2014 during a dengue outbreak investigation. Significant numbers (1,648 specimens) were collected in January 2018 during a chikungunya outbreak investigation. The presence of Ae. vittatus, and a competent vector of chikungunya virus, complicates disease epidemiology and control efforts in Mombasa underscoring the need to determine its bionomic factors. In June 2021 and December 2021, we conducted mosquito sampling at multiple sites in Mombasa, an island city county, using CO₂-baited Biogent sentinel (BGS) traps and human landing collection (HLC) methods. The collected mosquitoes were identified morphologically, and Ae. vittatus species were confirmed further by molecular characterization based on the cytochrome c oxidase I gene (cox1). Virus isolation from mosquitoes pools was performed in Vero ccl-81 cell cultures. Cultures showing cytopathic effects were harvested and genome-sequenced using the Illumina MiSeq platform to identify the infecting virus. A total of 11,435 mosquitoes were collected; 7,250 by BGS traps and 4,185 by HLC. Overall, Ae. aegypti was the dominant species, accounting for 32.6% (n = 3,725), followed by Culex quinquefasciatus which accounted for 31.8% (n = 3,638) and Ae. vittatus at 24.4% (n = 2,789). Aedes aegypti (n = 2,216; 43%) predominated in HLC collections, followed by Ae. vittatus (n = 1,598; 31%). Although mosquito biting rates per person per hour (b/p/h) were higher for Ae. aegypti (3.2 b/p/h) than Ae. vittatus (2.4 b/p/h), the difference was not statistically significant (t = 6.0081, df = 1, p-value = 0.105). Chikungunya virus isolate belonging to the East Central South African genotype was isolated from a pool of female Ae. vittatus. Aedes vittatus was found widely distributed across the island city in significant numbers, suggesting that the species, which is predominant to most rural areas in Kenya, has invaded the city and successfully established. The presence of this species in the city, a confirmed vector of CHIKV, and along with Ae. aegypti which is the principle vector of CHIKV, potentially magnifies the risk of chikungunya outbreaks. This highlights the significance and need for integrated vector control strategies.

There have been few reports of neoplasia in hyenas to date. In this report, we describe a captive adult female spotted hyena (Crocuta crocuta) that developed inappetence, lethargy and marked abdominal distension over a 3-day period. The hyena was chemically immobilised to allow clinical investigation of the severe symptoms; however, she died before any internal examination occurred. At necropsy, severe serosanguinous hydropericardium was evident, as well as pulmonary congestion and oedema, ascites and chronic passive congestion of the liver with mild fibrosis. Histopathological examination of the pericardial surface revealed fibrous proliferations lined by mostly a single layer of large proliferating neoplastic mesothelial cells forming papillary projections into the lumen of the pericardial sac as well as infiltration into the pericardial connective tissue, with innumerable haemosiderin-laden macrophages in places, suggestive of chronic haemorrhage. The liver revealed severe congestion and interstitial fibrosis, and the lung revealed congestion and oedema, with moderate numbers of alveolar macrophages and marked anthracosis. The diagnosis was pericardial well-differentiated papillary mesothelioma, with death under anaesthesia caused by cardiogenic shock due to pericardial mesothelioma-associated cardiac tamponade. As primary pericardial mesothelioma (PPM) is a rare tumour type for both animals and humans, and this is the first report of a PPM in a hyena, we compare the clinical findings with those seen in other species.

There have been few reports of neoplasia in kangaroos to date. In this report, we describe a 13-year-old male captive Red kangaroo (Osphranter rufus) that developed a mass on the right side of the cloacal aperture. Histopathological analysis of a biopsy of the mass revealed proliferating, neoplastic epithelial islands with necrotic centres infiltrating a moderately desmoplastic dermis. The islands were generally large with extensive central caseation necrosis consisting of cellular debris and innumerable neutrophils. The neoplastic epithelial cells resembled the basal cells observed in the basal layer of the epidermis and were characterised by scant to moderate eosinophilic cytoplasm with indistinct cytoplasmic margins. The diagnosis was basal cell carcinoma (BCC). This is the first report of a BCC in a kangaroo, and we compare the findings with that seen in dogs, cats and humans.

Fasciolosis, caused by Fasciola hepatica and Fasciola gigantica, is a globally significant parasitic disease affecting livestock and humans. Both species exist in South Africa, however, information on their geographical distribution and genetic diversity is limited. This study investigated the genetic diversity and phylogenetic relationships of Fasciola species in South Africa using Pepck, COI and ITS markers. Two hundred and seven Fasciola spp. specimens analysed in this study showed that 74.4% of isolates identified as F. hepatica and 25.6% as F. gigantica based on the Pepck gene. The geographical distribution revealed that F. hepatica occurred in all surveyed provinces but was dominant in the temperate zones of South Africa. Fasciola gigantica was confined to subtropical zones, with co-occurrence observed in Limpopo, Mpumalanga, and KwaZulu-Natal provinces. The COI and ITS genes in both Fasciola species generated fourteen and eight haplotypes respectively, with low to moderate haplotype diversity (Hd = 0.287 – 0.509 for COI and 0.056 – 0.239 for ITS) and low nucleotide diversity (Pi = 0.00085 – 0.00284 for COI and 0.00024 – 0.00034 for ITS), suggesting recent population diversification between the two species. The study samples yielded six haplotypes based on COI, with three haplotypes comprising most samples i.e. Hap-1 (F. gigantica) and Hap-5 and Hap-6 (F. hepatica). With ITS, two haplotypes represented most samples, i.e. Hap-1 (F. gigantica) and Hap-3 (F. hepatica). There was no observed unique distribution of haplotypes based on provinces or agro-ecological climatic zones for both markers. Phylogenetic analysis of both COI and ITS genes confirmed the grouping of the haplotypes and reiterated their relatedness. However, one isolate identified as F. gigantica in COI and with F. hepatica in ITS based on BLAST and further formed haplotypes with F. gigantica and F. hepatica haplogroups for COI and ITS, respectively. This suspected hybrid Fasciola form was from an animal with a mixed infection. These findings highlight the complex genetic structure of Fasciola spp. populations in South Africa and provide new insights into their epidemiology, with implications for targeted control strategies and further investigation of cryptic/hybrid lineages.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-25952-y.

Positioning of the breast during mammography examination is critical to producing optimum quality images. However, the variation in female thorax and body habitus may affect mammography positioning for best image quality. This study aims to establish populational female thoracic (rib cage) sizes and quantify female body habitus categories. A retrospective analysis of 347 female computed tomography (CT) chest axial scans was retrieved from an open access database to establish female rib cage sizes. Dimensions of the rib cage were measured digitally across six cross sections with six anterior rib landmark points and recorded in millimetres (mm). A Bayesian Network (BN) model was developed to establish the relationships of information extracted from the rib cage image data to quantify and categorise female body habitus. Female body habitus (thoracic size) were classified into three cohort categories: lean (20.5 %), norm (55.6 %) and curvaceous (23.9 %). The mean values (115-126 mm) and the corresponding 80 % prediction interval ranges for the healthy female rib cage size were obtained through the BN scenario analysis. The significance of this study is that it categorised 55.6 % of female thoracic sizes as being normal on a larger group of female population. This study contributed to a good understanding of the range of female body habitus (thoracic size) to improve positioning practice and maximise image quality. This study used a BN model to establish a range of female thorax sizes using CT chest images to support improved positioning practices. These ranges of thorax sizes should be integrated as a body habitus criterion in the current image evaluation system to maximise image quality and subsequent breast cancer diagnosis.

BackgroundDue to limited documentation on vector-borne pathogens of companion animals in Namibia, a country-wide, multi-site field study was conducted to estimate the prevalence of these pathogens in domestic dogs.MethodsSamples of whole blood and serum from 375 dogs in 15 towns across eight regions were analysed. Vector-borne pathogens were screened by light microscopic examination of blood smears, point-of-care serology, and quantitative real-time polymerase chain reaction (qPCR). Haematology and serum biochemistry analyses were also performed.ResultsCollectively, the SNAP® 4Dx® Plus Test provided 64% seropositive results, comprising Ehrlichia species (59%), Anaplasma species (45%), Dirofilaria immitis (2%), and Borrelia burgdorferi (< 1%). Altogether, prevalence as determined by probe-based qPCR assays was 54%, comprising Ehrlichia canis (27%), Hepatozoon canis (25%), Anaplasma species (13%), and Babesia vogeli (8%). Light microscopy yielded the least number of positives, indicating a collective positive result of only 11% in screening for Ehrlichia, Anaplasma, Hepatozoon, Babesia, and microfilaria species. On the whole, Kunene and Otjozondjupa regions showed the highest pathogen prevalence (75%), and the lowest was from Erongo region (38%), on qPCR testing. Significant associations between tick presence and infection by E. canis (P = 0.001), Anaplasma species (P = 0.006), and B. vogeli (P = 0.008) were demonstrated. Likewise, relevant associations between haemoparasite infection and variables of patient signalment, history, and various disease manifestations were shown. Finally, significant associations were found between pathogen infection and numerous clinical pathology abnormalities of the erythron, leukon, and thrombon, including thrombocytopenia (P = 0.022).ConclusionsDiagnostic modalities should be used contextually to test for canine pathogens, with due consideration of the limitations. Appropriate diagnostic testing such as qPCR, guided by relevant known associations with disease manifestation, should guide responsible treatment strategies and identify potential zoonotic risks in pets.Graphical